Use SystemClock* instead of std::shared_ptr<SystemClock> in lower level routines (#8033)

Summary:
For performance purposes, the lower level routines were changed to use a SystemClock* instead of a std::shared_ptr<SystemClock>.  The shared ptr has some performance degradation on certain hardware classes.

For most of the system, there is no risk of the pointer being deleted/invalid because the shared_ptr will be stored elsewhere.  For example, the ImmutableDBOptions stores the Env which has a std::shared_ptr<SystemClock> in it.  The SystemClock* within the ImmutableDBOptions is essentially a "short cut" to gain access to this constant resource.

There were a few classes (PeriodicWorkScheduler?) where the "short cut" property did not hold.  In those cases, the shared pointer was preserved.

Using db_bench readrandom perf_level=3 on my EC2 box, this change performed as well or better than 6.17:

6.17: readrandom   :      28.046 micros/op 854902 ops/sec;   61.3 MB/s (355999 of 355999 found)
6.18: readrandom   :      32.615 micros/op 735306 ops/sec;   52.7 MB/s (290999 of 290999 found)
PR: readrandom   :      27.500 micros/op 871909 ops/sec;   62.5 MB/s (367999 of 367999 found)

(Note that the times for 6.18 are prior to revert of the SystemClock).

Pull Request resolved: https://github.com/facebook/rocksdb/pull/8033

Reviewed By: pdillinger

Differential Revision: D27014563

Pulled By: mrambacher

fbshipit-source-id: ad0459eba03182e454391b5926bf5cdd45657b67

db/blob/blob_file_builder.cc

@@ -27,7 +27,7 @@
 namespace ROCKSDB_NAMESPACE {
 
 BlobFileBuilder::BlobFileBuilder(
-    VersionSet* versions, Env* env, FileSystem* fs,
+    VersionSet* versions, FileSystem* fs,
     const ImmutableCFOptions* immutable_cf_options,
     const MutableCFOptions* mutable_cf_options, const FileOptions* file_options,
     int job_id, uint32_t column_family_id,
@@ -36,14 +36,14 @@ BlobFileBuilder::BlobFileBuilder(
     const std::shared_ptr<IOTracer>& io_tracer,
     std::vector<std::string>* blob_file_paths,
     std::vector<BlobFileAddition>* blob_file_additions)
-    : BlobFileBuilder([versions]() { return versions->NewFileNumber(); }, env,
-                      fs, immutable_cf_options, mutable_cf_options,
-                      file_options, job_id, column_family_id,
-                      column_family_name, io_priority, write_hint, io_tracer,
-                      blob_file_paths, blob_file_additions) {}
+    : BlobFileBuilder([versions]() { return versions->NewFileNumber(); }, fs,
+                      immutable_cf_options, mutable_cf_options, file_options,
+                      job_id, column_family_id, column_family_name, io_priority,
+                      write_hint, io_tracer, blob_file_paths,
+                      blob_file_additions) {}
 
 BlobFileBuilder::BlobFileBuilder(
-    std::function<uint64_t()> file_number_generator, Env* env, FileSystem* fs,
+    std::function<uint64_t()> file_number_generator, FileSystem* fs,
     const ImmutableCFOptions* immutable_cf_options,
     const MutableCFOptions* mutable_cf_options, const FileOptions* file_options,
     int job_id, uint32_t column_family_id,
@@ -70,7 +70,6 @@ BlobFileBuilder::BlobFileBuilder(
       blob_count_(0),
       blob_bytes_(0) {
   assert(file_number_generator_);
-  assert(env);
   assert(fs_);
   assert(immutable_cf_options_);
   assert(file_options_);
@@ -78,7 +77,6 @@ BlobFileBuilder::BlobFileBuilder(
   assert(blob_file_paths_->empty());
   assert(blob_file_additions_);
   assert(blob_file_additions_->empty());
-  clock_ = env->GetSystemClock();
 }
 
 BlobFileBuilder::~BlobFileBuilder() = default;
@@ -185,16 +183,17 @@ Status BlobFileBuilder::OpenBlobFileIfNeeded() {
   FileTypeSet tmp_set = immutable_cf_options_->checksum_handoff_file_types;
   Statistics* const statistics = immutable_cf_options_->statistics;
   std::unique_ptr<WritableFileWriter> file_writer(new WritableFileWriter(
-      std::move(file), blob_file_paths_->back(), *file_options_, clock_,
-      io_tracer_, statistics, immutable_cf_options_->listeners,
+      std::move(file), blob_file_paths_->back(), *file_options_,
+      immutable_cf_options_->clock, io_tracer_, statistics,
+      immutable_cf_options_->listeners,
       immutable_cf_options_->file_checksum_gen_factory,
       tmp_set.Contains(FileType::kBlobFile)));
 
   constexpr bool do_flush = false;
 
   std::unique_ptr<BlobLogWriter> blob_log_writer(new BlobLogWriter(
-      std::move(file_writer), clock_, statistics, blob_file_number,
-      immutable_cf_options_->use_fsync, do_flush));
+      std::move(file_writer), immutable_cf_options_->clock, statistics,
+      blob_file_number, immutable_cf_options_->use_fsync, do_flush));
 
   constexpr bool has_ttl = false;
   constexpr ExpirationRange expiration_range;

db/blob/blob_file_builder.h

@@ -30,7 +30,7 @@ class IOTracer;
 
 class BlobFileBuilder {
  public:
-  BlobFileBuilder(VersionSet* versions, Env* env, FileSystem* fs,
+  BlobFileBuilder(VersionSet* versions, FileSystem* fs,
                   const ImmutableCFOptions* immutable_cf_options,
                   const MutableCFOptions* mutable_cf_options,
                   const FileOptions* file_options, int job_id,
@@ -42,7 +42,7 @@ class BlobFileBuilder {
                   std::vector<std::string>* blob_file_paths,
                   std::vector<BlobFileAddition>* blob_file_additions);
 
-  BlobFileBuilder(std::function<uint64_t()> file_number_generator, Env* env,
+  BlobFileBuilder(std::function<uint64_t()> file_number_generator,
                   FileSystem* fs,
                   const ImmutableCFOptions* immutable_cf_options,
                   const MutableCFOptions* mutable_cf_options,
@@ -74,7 +74,6 @@ class BlobFileBuilder {
 
   std::function<uint64_t()> file_number_generator_;
   FileSystem* fs_;
-  std::shared_ptr<SystemClock> clock_;
   const ImmutableCFOptions* immutable_cf_options_;
   uint64_t min_blob_size_;
   uint64_t blob_file_size_;

db/blob/blob_file_builder_test.cc

@@ -41,7 +41,7 @@ class BlobFileBuilderTest : public testing::Test {
  protected:
   BlobFileBuilderTest() : mock_env_(Env::Default()) {
     fs_ = mock_env_.GetFileSystem().get();
-    clock_ = mock_env_.GetSystemClock();
+    clock_ = mock_env_.GetSystemClock().get();
   }
 
   void VerifyBlobFile(uint64_t blob_file_number,
@@ -110,7 +110,7 @@ class BlobFileBuilderTest : public testing::Test {
 
   MockEnv mock_env_;
   FileSystem* fs_;
-  std::shared_ptr<SystemClock> clock_;
+  SystemClock* clock_;
   FileOptions file_options_;
 };
 
@@ -127,6 +127,7 @@ TEST_F(BlobFileBuilderTest, BuildAndCheckOneFile) {
                             "BlobFileBuilderTest_BuildAndCheckOneFile"),
       0);
   options.enable_blob_files = true;
+  options.env = &mock_env_;
 
   ImmutableCFOptions immutable_cf_options(options);
   MutableCFOptions mutable_cf_options(options);
@@ -140,11 +141,11 @@ TEST_F(BlobFileBuilderTest, BuildAndCheckOneFile) {
   std::vector<std::string> blob_file_paths;
   std::vector<BlobFileAddition> blob_file_additions;
 
-  BlobFileBuilder builder(
-      TestFileNumberGenerator(), &mock_env_, fs_, &immutable_cf_options,
-      &mutable_cf_options, &file_options_, job_id, column_family_id,
-      column_family_name, io_priority, write_hint, nullptr /*IOTracer*/,
-      &blob_file_paths, &blob_file_additions);
+  BlobFileBuilder builder(TestFileNumberGenerator(), fs_, &immutable_cf_options,
+                          &mutable_cf_options, &file_options_, job_id,
+                          column_family_id, column_family_name, io_priority,
+                          write_hint, nullptr /*IOTracer*/, &blob_file_paths,
+                          &blob_file_additions);
 
   std::vector<std::pair<std::string, std::string>> expected_key_value_pairs(
       number_of_blobs);
@@ -210,6 +211,7 @@ TEST_F(BlobFileBuilderTest, BuildAndCheckMultipleFiles) {
       0);
   options.enable_blob_files = true;
   options.blob_file_size = value_size;
+  options.env = &mock_env_;
 
   ImmutableCFOptions immutable_cf_options(options);
   MutableCFOptions mutable_cf_options(options);
@@ -223,11 +225,11 @@ TEST_F(BlobFileBuilderTest, BuildAndCheckMultipleFiles) {
   std::vector<std::string> blob_file_paths;
   std::vector<BlobFileAddition> blob_file_additions;
 
-  BlobFileBuilder builder(
-      TestFileNumberGenerator(), &mock_env_, fs_, &immutable_cf_options,
-      &mutable_cf_options, &file_options_, job_id, column_family_id,
-      column_family_name, io_priority, write_hint, nullptr /*IOTracer*/,
-      &blob_file_paths, &blob_file_additions);
+  BlobFileBuilder builder(TestFileNumberGenerator(), fs_, &immutable_cf_options,
+                          &mutable_cf_options, &file_options_, job_id,
+                          column_family_id, column_family_name, io_priority,
+                          write_hint, nullptr /*IOTracer*/, &blob_file_paths,
+                          &blob_file_additions);
 
   std::vector<std::pair<std::string, std::string>> expected_key_value_pairs(
       number_of_blobs);
@@ -295,6 +297,7 @@ TEST_F(BlobFileBuilderTest, InlinedValues) {
       0);
   options.enable_blob_files = true;
   options.min_blob_size = 1024;
+  options.env = &mock_env_;
 
   ImmutableCFOptions immutable_cf_options(options);
   MutableCFOptions mutable_cf_options(options);
@@ -308,11 +311,11 @@ TEST_F(BlobFileBuilderTest, InlinedValues) {
   std::vector<std::string> blob_file_paths;
   std::vector<BlobFileAddition> blob_file_additions;
 
-  BlobFileBuilder builder(
-      TestFileNumberGenerator(), &mock_env_, fs_, &immutable_cf_options,
-      &mutable_cf_options, &file_options_, job_id, column_family_id,
-      column_family_name, io_priority, write_hint, nullptr /*IOTracer*/,
-      &blob_file_paths, &blob_file_additions);
+  BlobFileBuilder builder(TestFileNumberGenerator(), fs_, &immutable_cf_options,
+                          &mutable_cf_options, &file_options_, job_id,
+                          column_family_id, column_family_name, io_priority,
+                          write_hint, nullptr /*IOTracer*/, &blob_file_paths,
+                          &blob_file_additions);
 
   for (size_t i = 0; i < number_of_blobs; ++i) {
     const std::string key = std::to_string(i);
@@ -347,6 +350,7 @@ TEST_F(BlobFileBuilderTest, Compression) {
       test::PerThreadDBPath(&mock_env_, "BlobFileBuilderTest_Compression"), 0);
   options.enable_blob_files = true;
   options.blob_compression_type = kSnappyCompression;
+  options.env = &mock_env_;
 
   ImmutableCFOptions immutable_cf_options(options);
   MutableCFOptions mutable_cf_options(options);
@@ -360,11 +364,11 @@ TEST_F(BlobFileBuilderTest, Compression) {
   std::vector<std::string> blob_file_paths;
   std::vector<BlobFileAddition> blob_file_additions;
 
-  BlobFileBuilder builder(
-      TestFileNumberGenerator(), &mock_env_, fs_, &immutable_cf_options,
-      &mutable_cf_options, &file_options_, job_id, column_family_id,
-      column_family_name, io_priority, write_hint, nullptr /*IOTracer*/,
-      &blob_file_paths, &blob_file_additions);
+  BlobFileBuilder builder(TestFileNumberGenerator(), fs_, &immutable_cf_options,
+                          &mutable_cf_options, &file_options_, job_id,
+                          column_family_id, column_family_name, io_priority,
+                          write_hint, nullptr /*IOTracer*/, &blob_file_paths,
+                          &blob_file_additions);
 
   const std::string key("1");
   const std::string uncompressed_value(value_size, 'x');
@@ -429,7 +433,7 @@ TEST_F(BlobFileBuilderTest, CompressionError) {
       0);
   options.enable_blob_files = true;
   options.blob_compression_type = kSnappyCompression;
-
+  options.env = &mock_env_;
   ImmutableCFOptions immutable_cf_options(options);
   MutableCFOptions mutable_cf_options(options);
 
@@ -442,11 +446,11 @@ TEST_F(BlobFileBuilderTest, CompressionError) {
   std::vector<std::string> blob_file_paths;
   std::vector<BlobFileAddition> blob_file_additions;
 
-  BlobFileBuilder builder(
-      TestFileNumberGenerator(), &mock_env_, fs_, &immutable_cf_options,
-      &mutable_cf_options, &file_options_, job_id, column_family_id,
-      column_family_name, io_priority, write_hint, nullptr /*IOTracer*/,
-      &blob_file_paths, &blob_file_additions);
+  BlobFileBuilder builder(TestFileNumberGenerator(), fs_, &immutable_cf_options,
+                          &mutable_cf_options, &file_options_, job_id,
+                          column_family_id, column_family_name, io_priority,
+                          write_hint, nullptr /*IOTracer*/, &blob_file_paths,
+                          &blob_file_additions);
 
   SyncPoint::GetInstance()->SetCallBack("CompressData:TamperWithReturnValue",
                                         [](void* arg) {
@@ -506,6 +510,7 @@ TEST_F(BlobFileBuilderTest, Checksum) {
   options.enable_blob_files = true;
   options.file_checksum_gen_factory =
       std::make_shared<DummyFileChecksumGenFactory>();
+  options.env = &mock_env_;
 
   ImmutableCFOptions immutable_cf_options(options);
   MutableCFOptions mutable_cf_options(options);
@@ -519,11 +524,11 @@ TEST_F(BlobFileBuilderTest, Checksum) {
   std::vector<std::string> blob_file_paths;
   std::vector<BlobFileAddition> blob_file_additions;
 
-  BlobFileBuilder builder(
-      TestFileNumberGenerator(), &mock_env_, fs_, &immutable_cf_options,
-      &mutable_cf_options, &file_options_, job_id, column_family_id,
-      column_family_name, io_priority, write_hint, nullptr /*IOTracer*/,
-      &blob_file_paths, &blob_file_additions);
+  BlobFileBuilder builder(TestFileNumberGenerator(), fs_, &immutable_cf_options,
+                          &mutable_cf_options, &file_options_, job_id,
+                          column_family_id, column_family_name, io_priority,
+                          write_hint, nullptr /*IOTracer*/, &blob_file_paths,
+                          &blob_file_additions);
 
   const std::string key("1");
   const std::string value("deadbeef");
@@ -615,11 +620,11 @@ TEST_P(BlobFileBuilderIOErrorTest, IOError) {
   std::vector<std::string> blob_file_paths;
   std::vector<BlobFileAddition> blob_file_additions;
 
-  BlobFileBuilder builder(
-      TestFileNumberGenerator(), &mock_env_, fs_, &immutable_cf_options,
-      &mutable_cf_options, &file_options_, job_id, column_family_id,
-      column_family_name, io_priority, write_hint, nullptr /*IOTracer*/,
-      &blob_file_paths, &blob_file_additions);
+  BlobFileBuilder builder(TestFileNumberGenerator(), fs_, &immutable_cf_options,
+                          &mutable_cf_options, &file_options_, job_id,
+                          column_family_id, column_family_name, io_priority,
+                          write_hint, nullptr /*IOTracer*/, &blob_file_paths,
+                          &blob_file_additions);
 
   SyncPoint::GetInstance()->SetCallBack(sync_point_, [this](void* arg) {
     Status* const s = static_cast<Status*>(arg);

db/blob/blob_file_cache_test.cc

@@ -42,15 +42,15 @@ void WriteBlobFile(uint32_t column_family_id,
 
   std::unique_ptr<WritableFileWriter> file_writer(
       new WritableFileWriter(std::move(file), blob_file_path, FileOptions(),
-                             immutable_cf_options.env->GetSystemClock()));
+                             immutable_cf_options.clock));
 
   constexpr Statistics* statistics = nullptr;
   constexpr bool use_fsync = false;
   constexpr bool do_flush = false;
 
-  BlobLogWriter blob_log_writer(
-      std::move(file_writer), immutable_cf_options.env->GetSystemClock(),
-      statistics, blob_file_number, use_fsync, do_flush);
+  BlobLogWriter blob_log_writer(std::move(file_writer),
+                                immutable_cf_options.clock, statistics,
+                                blob_file_number, use_fsync, do_flush);
 
   constexpr bool has_ttl = false;
   constexpr ExpirationRange expiration_range;

db/blob/blob_file_reader.cc

@@ -118,8 +118,7 @@ Status BlobFileReader::OpenFile(
   }
 
   file_reader->reset(new RandomAccessFileReader(
-      std::move(file), blob_file_path,
-      immutable_cf_options.env->GetSystemClock(), io_tracer,
+      std::move(file), blob_file_path, immutable_cf_options.clock, io_tracer,
       immutable_cf_options.statistics, BLOB_DB_BLOB_FILE_READ_MICROS,
       blob_file_read_hist, immutable_cf_options.rate_limiter,
       immutable_cf_options.listeners));

db/blob/blob_file_reader_test.cc

@@ -50,15 +50,15 @@ void WriteBlobFile(const ImmutableCFOptions& immutable_cf_options,
 
   std::unique_ptr<WritableFileWriter> file_writer(
       new WritableFileWriter(std::move(file), blob_file_path, FileOptions(),
-                             immutable_cf_options.env->GetSystemClock()));
+                             immutable_cf_options.clock));
 
   constexpr Statistics* statistics = nullptr;
   constexpr bool use_fsync = false;
   constexpr bool do_flush = false;
 
-  BlobLogWriter blob_log_writer(
-      std::move(file_writer), immutable_cf_options.env->GetSystemClock(),
-      statistics, blob_file_number, use_fsync, do_flush);
+  BlobLogWriter blob_log_writer(std::move(file_writer),
+                                immutable_cf_options.clock, statistics,
+                                blob_file_number, use_fsync, do_flush);
 
   BlobLogHeader header(column_family_id, compression_type, has_ttl,
                        expiration_range_header);
@@ -280,15 +280,15 @@ TEST_F(BlobFileReaderTest, Malformed) {
 
     std::unique_ptr<WritableFileWriter> file_writer(
         new WritableFileWriter(std::move(file), blob_file_path, FileOptions(),
-                               immutable_cf_options.env->GetSystemClock()));
+                               immutable_cf_options.clock));
 
     constexpr Statistics* statistics = nullptr;
     constexpr bool use_fsync = false;
     constexpr bool do_flush = false;
 
-    BlobLogWriter blob_log_writer(
-        std::move(file_writer), immutable_cf_options.env->GetSystemClock(),
-        statistics, blob_file_number, use_fsync, do_flush);
+    BlobLogWriter blob_log_writer(std::move(file_writer),
+                                  immutable_cf_options.clock, statistics,
+                                  blob_file_number, use_fsync, do_flush);
 
     BlobLogHeader header(column_family_id, kNoCompression, has_ttl,
                          expiration_range);

db/blob/blob_log_sequential_reader.cc

@@ -13,8 +13,8 @@
 namespace ROCKSDB_NAMESPACE {
 
 BlobLogSequentialReader::BlobLogSequentialReader(
-    std::unique_ptr<RandomAccessFileReader>&& file_reader,
-    const std::shared_ptr<SystemClock>& clock, Statistics* statistics)
+    std::unique_ptr<RandomAccessFileReader>&& file_reader, SystemClock* clock,
+    Statistics* statistics)
     : file_(std::move(file_reader)),
       clock_(clock),
       statistics_(statistics),

db/blob/blob_log_sequential_reader.h

@@ -36,8 +36,7 @@ class BlobLogSequentialReader {
 
   // Create a reader that will return log records from "*file_reader".
   BlobLogSequentialReader(std::unique_ptr<RandomAccessFileReader>&& file_reader,
-                          const std::shared_ptr<SystemClock>& clock,
-                          Statistics* statistics);
+                          SystemClock* clock, Statistics* statistics);
 
   // No copying allowed
   BlobLogSequentialReader(const BlobLogSequentialReader&) = delete;
@@ -65,7 +64,7 @@ class BlobLogSequentialReader {
   Status ReadSlice(uint64_t size, Slice* slice, char* buf);
 
   const std::unique_ptr<RandomAccessFileReader> file_;
-  std::shared_ptr<SystemClock> clock_;
+  SystemClock* clock_;
 
   Statistics* statistics_;
 

db/blob/blob_log_writer.cc

@@ -19,9 +19,9 @@
 namespace ROCKSDB_NAMESPACE {
 
 BlobLogWriter::BlobLogWriter(std::unique_ptr<WritableFileWriter>&& dest,
-                             const std::shared_ptr<SystemClock>& clock,
-                             Statistics* statistics, uint64_t log_number,
-                             bool use_fs, bool do_flush, uint64_t boffset)
+                             SystemClock* clock, Statistics* statistics,
+                             uint64_t log_number, bool use_fs, bool do_flush,
+                             uint64_t boffset)
     : dest_(std::move(dest)),
       clock_(clock),
       statistics_(statistics),

db/blob/blob_log_writer.h

@@ -31,8 +31,7 @@ class BlobLogWriter {
   // Create a writer that will append data to "*dest".
   // "*dest" must be initially empty.
   // "*dest" must remain live while this BlobLogWriter is in use.
-  BlobLogWriter(std::unique_ptr<WritableFileWriter>&& dest,
-                const std::shared_ptr<SystemClock>& clock,
+  BlobLogWriter(std::unique_ptr<WritableFileWriter>&& dest, SystemClock* clock,
                 Statistics* statistics, uint64_t log_number, bool use_fsync,
                 bool do_flush, uint64_t boffset = 0);
   // No copying allowed
@@ -69,7 +68,7 @@ class BlobLogWriter {
 
  private:
   std::unique_ptr<WritableFileWriter> dest_;
-  std::shared_ptr<SystemClock> clock_;
+  SystemClock* clock_;
   Statistics* statistics_;
   uint64_t log_number_;
   uint64_t block_offset_;  // Current offset in block

db/builder.cc

@@ -125,7 +125,6 @@ Status BuildTable(
   assert(env);
   FileSystem* fs = db_options.fs.get();
   assert(fs);
-  const auto& clock = env->GetSystemClock();
 
   TableProperties tp;
   if (iter->Valid() || !range_del_agg->IsEmpty()) {
@@ -154,7 +153,7 @@ Status BuildTable(
       file->SetIOPriority(io_priority);
       file->SetWriteLifeTimeHint(write_hint);
       file_writer.reset(new WritableFileWriter(
-          std::move(file), fname, file_options, clock, io_tracer,
+          std::move(file), fname, file_options, ioptions.clock, io_tracer,
           ioptions.statistics, ioptions.listeners,
           ioptions.file_checksum_gen_factory,
           tmp_set.Contains(FileType::kTableFile)));
@@ -176,11 +175,10 @@ Status BuildTable(
 
     std::unique_ptr<BlobFileBuilder> blob_file_builder(
         (mutable_cf_options.enable_blob_files && blob_file_additions)
-            ? new BlobFileBuilder(versions, env, fs, &ioptions,
-                                  &mutable_cf_options, &file_options, job_id,
-                                  column_family_id, column_family_name,
-                                  io_priority, write_hint, io_tracer,
-                                  &blob_file_paths, blob_file_additions)
+            ? new BlobFileBuilder(
+                  versions, fs, &ioptions, &mutable_cf_options, &file_options,
+                  job_id, column_family_id, column_family_name, io_priority,
+                  write_hint, io_tracer, &blob_file_paths, blob_file_additions)
             : nullptr);
 
     CompactionIterator c_iter(
@@ -258,7 +256,7 @@ Status BuildTable(
     // Finish and check for file errors
     TEST_SYNC_POINT("BuildTable:BeforeSyncTable");
     if (s.ok() && !empty) {
-      StopWatch sw(clock, ioptions.statistics, TABLE_SYNC_MICROS);
+      StopWatch sw(ioptions.clock, ioptions.statistics, TABLE_SYNC_MICROS);
       *io_status = file_writer->Sync(ioptions.use_fsync);
     }
     TEST_SYNC_POINT("BuildTable:BeforeCloseTableFile");

db/column_family.cc

@@ -557,8 +557,8 @@ ColumnFamilyData::ColumnFamilyData(
 
   // if _dummy_versions is nullptr, then this is a dummy column family.
   if (_dummy_versions != nullptr) {
-    internal_stats_.reset(new InternalStats(
-        ioptions_.num_levels, db_options.env->GetSystemClock(), this));
+    internal_stats_.reset(
+        new InternalStats(ioptions_.num_levels, ioptions_.clock, this));
     table_cache_.reset(new TableCache(ioptions_, file_options, _table_cache,
                                       block_cache_tracer, io_tracer));
     blob_file_cache_.reset(

db/compaction/compaction_iterator.cc

@@ -80,7 +80,7 @@ CompactionIterator::CompactionIterator(
       earliest_write_conflict_snapshot_(earliest_write_conflict_snapshot),
       snapshot_checker_(snapshot_checker),
       env_(env),
-      clock_(env_->GetSystemClock()),
+      clock_(env_->GetSystemClock().get()),
       report_detailed_time_(report_detailed_time),
       expect_valid_internal_key_(expect_valid_internal_key),
       range_del_agg_(range_del_agg),

db/compaction/compaction_iterator.h

@@ -248,7 +248,7 @@ class CompactionIterator {
   const SequenceNumber earliest_write_conflict_snapshot_;
   const SnapshotChecker* const snapshot_checker_;
   Env* env_;
-  std::shared_ptr<SystemClock> clock_;
+  SystemClock* clock_;
   bool report_detailed_time_;
   bool expect_valid_internal_key_;
   CompactionRangeDelAggregator* range_del_agg_;

db/compaction/compaction_job.cc

@@ -321,7 +321,6 @@ CompactionJob::CompactionJob(
       db_options_(db_options),
       file_options_(file_options),
       env_(db_options.env),
-      clock_(env_->GetSystemClock()),
       io_tracer_(io_tracer),
       fs_(db_options.fs, io_tracer),
       file_options_for_read_(
@@ -421,7 +420,7 @@ void CompactionJob::Prepare() {
 
   if (c->ShouldFormSubcompactions()) {
     {
-      StopWatch sw(clock_, stats_, SUBCOMPACTION_SETUP_TIME);
+      StopWatch sw(db_options_.clock, stats_, SUBCOMPACTION_SETUP_TIME);
       GenSubcompactionBoundaries();
     }
     assert(sizes_.size() == boundaries_.size() + 1);
@@ -587,7 +586,7 @@ Status CompactionJob::Run() {
 
   const size_t num_threads = compact_->sub_compact_states.size();
   assert(num_threads > 0);
-  const uint64_t start_micros = clock_->NowMicros();
+  const uint64_t start_micros = db_options_.clock->NowMicros();
 
   // Launch a thread for each of subcompactions 1...num_threads-1
   std::vector<port::Thread> thread_pool;
@@ -606,7 +605,7 @@ Status CompactionJob::Run() {
     thread.join();
   }
 
-  compaction_stats_.micros = clock_->NowMicros() - start_micros;
+  compaction_stats_.micros = db_options_.clock->NowMicros() - start_micros;
   compaction_stats_.cpu_micros = 0;
   for (size_t i = 0; i < compact_->sub_compact_states.size(); i++) {
     compaction_stats_.cpu_micros +=
@@ -902,7 +901,7 @@ void CompactionJob::ProcessKeyValueCompaction(SubcompactionState* sub_compact) {
   assert(sub_compact);
   assert(sub_compact->compaction);
 
-  uint64_t prev_cpu_micros = clock_->CPUNanos() / 1000;
+  uint64_t prev_cpu_micros = db_options_.clock->CPUNanos() / 1000;
 
   ColumnFamilyData* cfd = sub_compact->compaction->column_family_data();
 
@@ -980,7 +979,7 @@ void CompactionJob::ProcessKeyValueCompaction(SubcompactionState* sub_compact) {
   std::unique_ptr<BlobFileBuilder> blob_file_builder(
       mutable_cf_options->enable_blob_files
           ? new BlobFileBuilder(
-                versions_, env_, fs_.get(),
+                versions_, fs_.get(),
                 sub_compact->compaction->immutable_cf_options(),
                 mutable_cf_options, &file_options_, job_id_, cfd->GetID(),
                 cfd->GetName(), Env::IOPriority::IO_LOW, write_hint_,
@@ -1196,7 +1195,7 @@ void CompactionJob::ProcessKeyValueCompaction(SubcompactionState* sub_compact) {
   }
 
   sub_compact->compaction_job_stats.cpu_micros =
-      clock_->CPUNanos() / 1000 - prev_cpu_micros;
+      db_options_.clock->CPUNanos() / 1000 - prev_cpu_micros;
 
   if (measure_io_stats_) {
     sub_compact->compaction_job_stats.file_write_nanos +=
@@ -1475,7 +1474,7 @@ Status CompactionJob::FinishCompactionOutputFile(
 
   // Finish and check for file errors
   if (s.ok()) {
-    StopWatch sw(clock_, stats_, COMPACTION_OUTFILE_SYNC_MICROS);
+    StopWatch sw(db_options_.clock, stats_, COMPACTION_OUTFILE_SYNC_MICROS);
     io_s = sub_compact->outfile->Sync(db_options_.use_fsync);
   }
   if (s.ok() && io_s.ok()) {
@@ -1714,7 +1713,7 @@ Status CompactionJob::OpenCompactionOutputFile(
 
   // Try to figure out the output file's oldest ancester time.
   int64_t temp_current_time = 0;
-  auto get_time_status = env_->GetCurrentTime(&temp_current_time);
+  auto get_time_status = db_options_.clock->GetCurrentTime(&temp_current_time);
   // Safe to proceed even if GetCurrentTime fails. So, log and proceed.
   if (!get_time_status.ok()) {
     ROCKS_LOG_WARN(db_options_.info_log,
@@ -1751,8 +1750,8 @@ Status CompactionJob::OpenCompactionOutputFile(
   const auto& listeners =
       sub_compact->compaction->immutable_cf_options()->listeners;
   sub_compact->outfile.reset(new WritableFileWriter(
-      std::move(writable_file), fname, file_options_, clock_, io_tracer_,
-      db_options_.statistics.get(), listeners,
+      std::move(writable_file), fname, file_options_, db_options_.clock,
+      io_tracer_, db_options_.statistics.get(), listeners,
       db_options_.file_checksum_gen_factory.get(),
       tmp_set.Contains(FileType::kTableFile)));
 

db/compaction/compaction_job.h

@@ -160,7 +160,6 @@ class CompactionJob {
   const FileOptions file_options_;
 
   Env* env_;
-  std::shared_ptr<SystemClock> clock_;
   std::shared_ptr<IOTracer> io_tracer_;
   FileSystemPtr fs_;
   // env_option optimized for compaction table reads

db/compaction/compaction_picker_fifo.cc

@@ -45,7 +45,7 @@ Compaction* FIFOCompactionPicker::PickTTLCompaction(
   uint64_t total_size = GetTotalFilesSize(level_files);
 
   int64_t _current_time;
-  auto status = ioptions_.env->GetCurrentTime(&_current_time);
+  auto status = ioptions_.clock->GetCurrentTime(&_current_time);
   if (!status.ok()) {
     ROCKS_LOG_BUFFER(log_buffer,
                      "[%s] FIFO compaction: Couldn't get current time: %s. "

db/db_impl/db_impl.cc

@@ -151,13 +151,12 @@ DBImpl::DBImpl(const DBOptions& options, const std::string& dbname,
       own_info_log_(options.info_log == nullptr),
       initial_db_options_(SanitizeOptions(dbname, options)),
       env_(initial_db_options_.env),
-      clock_(initial_db_options_.env->GetSystemClock()),
       io_tracer_(std::make_shared<IOTracer>()),
       immutable_db_options_(initial_db_options_),
       fs_(immutable_db_options_.fs, io_tracer_),
       mutable_db_options_(initial_db_options_),
       stats_(immutable_db_options_.statistics.get()),
-      mutex_(stats_, clock_, DB_MUTEX_WAIT_MICROS,
+      mutex_(stats_, immutable_db_options_.clock, DB_MUTEX_WAIT_MICROS,
              immutable_db_options_.use_adaptive_mutex),
       default_cf_handle_(nullptr),
       max_total_in_memory_state_(0),
@@ -192,7 +191,7 @@ DBImpl::DBImpl(const DBOptions& options, const std::string& dbname,
       bg_purge_scheduled_(0),
       disable_delete_obsolete_files_(0),
       pending_purge_obsolete_files_(0),
-      delete_obsolete_files_last_run_(clock_->NowMicros()),
+      delete_obsolete_files_last_run_(immutable_db_options_.clock->NowMicros()),
       last_stats_dump_time_microsec_(0),
       next_job_id_(1),
       has_unpersisted_data_(false),
@@ -753,7 +752,8 @@ void DBImpl::PersistStats() {
     return;
   }
   TEST_SYNC_POINT("DBImpl::PersistStats:StartRunning");
-  uint64_t now_seconds = clock_->NowMicros() / kMicrosInSecond;
+  uint64_t now_seconds =
+      immutable_db_options_.clock->NowMicros() / kMicrosInSecond;
 
   Statistics* statistics = immutable_db_options_.statistics.get();
   if (!statistics) {
@@ -1654,8 +1654,8 @@ Status DBImpl::GetImpl(const ReadOptions& read_options, const Slice& key,
   }
 #endif  // NDEBUG
 
-  PERF_CPU_TIMER_GUARD(get_cpu_nanos, clock_);
-  StopWatch sw(clock_, stats_, DB_GET);
+  PERF_CPU_TIMER_GUARD(get_cpu_nanos, immutable_db_options_.clock);
+  StopWatch sw(immutable_db_options_.clock, stats_, DB_GET);
   PERF_TIMER_GUARD(get_snapshot_time);
 
   auto cfh = static_cast_with_check<ColumnFamilyHandleImpl>(
@@ -1845,8 +1845,8 @@ std::vector<Status> DBImpl::MultiGet(
     const std::vector<ColumnFamilyHandle*>& column_family,
     const std::vector<Slice>& keys, std::vector<std::string>* values,
     std::vector<std::string>* timestamps) {
-  PERF_CPU_TIMER_GUARD(get_cpu_nanos, clock_);
-  StopWatch sw(clock_, stats_, DB_MULTIGET);
+  PERF_CPU_TIMER_GUARD(get_cpu_nanos, immutable_db_options_.clock);
+  StopWatch sw(immutable_db_options_.clock, stats_, DB_MULTIGET);
   PERF_TIMER_GUARD(get_snapshot_time);
 
 #ifndef NDEBUG
@@ -1975,9 +1975,8 @@ std::vector<Status> DBImpl::MultiGet(
         break;
       }
     }
-
     if (read_options.deadline.count() &&
-        clock_->NowMicros() >
+        immutable_db_options_.clock->NowMicros() >
             static_cast<uint64_t>(read_options.deadline.count())) {
       break;
     }
@@ -1986,7 +1985,7 @@ std::vector<Status> DBImpl::MultiGet(
   if (keys_read < num_keys) {
     // The only reason to break out of the loop is when the deadline is
     // exceeded
-    assert(clock_->NowMicros() >
+    assert(immutable_db_options_.clock->NowMicros() >
            static_cast<uint64_t>(read_options.deadline.count()));
     for (++keys_read; keys_read < num_keys; ++keys_read) {
       stat_list[keys_read] = Status::TimedOut();
@@ -2426,8 +2425,8 @@ Status DBImpl::MultiGetImpl(
     autovector<KeyContext*, MultiGetContext::MAX_BATCH_SIZE>* sorted_keys,
     SuperVersion* super_version, SequenceNumber snapshot,
     ReadCallback* callback) {
-  PERF_CPU_TIMER_GUARD(get_cpu_nanos, clock_);
-  StopWatch sw(clock_, stats_, DB_MULTIGET);
+  PERF_CPU_TIMER_GUARD(get_cpu_nanos, immutable_db_options_.clock);
+  StopWatch sw(immutable_db_options_.clock, stats_, DB_MULTIGET);
 
   // For each of the given keys, apply the entire "get" process as follows:
   // First look in the memtable, then in the immutable memtable (if any).
@@ -2438,7 +2437,7 @@ Status DBImpl::MultiGetImpl(
   uint64_t curr_value_size = 0;
   while (keys_left) {
     if (read_options.deadline.count() &&
-        clock_->NowMicros() >
+        immutable_db_options_.clock->NowMicros() >
             static_cast<uint64_t>(read_options.deadline.count())) {
       s = Status::TimedOut();
       break;
@@ -2991,7 +2990,8 @@ const Snapshot* DBImpl::GetSnapshotForWriteConflictBoundary() {
 SnapshotImpl* DBImpl::GetSnapshotImpl(bool is_write_conflict_boundary,
                                       bool lock) {
   int64_t unix_time = 0;
-  env_->GetCurrentTime(&unix_time).PermitUncheckedError();  // Ignore error
+  immutable_db_options_.clock->GetCurrentTime(&unix_time)
+      .PermitUncheckedError();  // Ignore error
   SnapshotImpl* s = new SnapshotImpl;
 
   if (lock) {
@@ -3136,12 +3136,16 @@ FileSystem* DBImpl::GetFileSystem() const {
   return immutable_db_options_.fs.get();
 }
 
+SystemClock* DBImpl::GetSystemClock() const {
+  return immutable_db_options_.clock;
+}
+
 #ifndef ROCKSDB_LITE
 
-Status DBImpl::StartIOTrace(Env* env, const TraceOptions& trace_options,
+Status DBImpl::StartIOTrace(Env* /*env*/, const TraceOptions& trace_options,
                             std::unique_ptr<TraceWriter>&& trace_writer) {
   assert(trace_writer != nullptr);
-  return io_tracer_->StartIOTrace(env->GetSystemClock(), trace_options,
+  return io_tracer_->StartIOTrace(GetSystemClock(), trace_options,
                                   std::move(trace_writer));
 }
 
@@ -4422,9 +4426,9 @@ Status DBImpl::IngestExternalFiles(
   std::vector<ExternalSstFileIngestionJob> ingestion_jobs;
   for (const auto& arg : args) {
     auto* cfd = static_cast<ColumnFamilyHandleImpl*>(arg.column_family)->cfd();
-    ingestion_jobs.emplace_back(
-        clock_, versions_.get(), cfd, immutable_db_options_, file_options_,
-        &snapshots_, arg.options, &directories_, &event_logger_, io_tracer_);
+    ingestion_jobs.emplace_back(versions_.get(), cfd, immutable_db_options_,
+                                file_options_, &snapshots_, arg.options,
+                                &directories_, &event_logger_, io_tracer_);
   }
 
   // TODO(yanqin) maybe make jobs run in parallel
@@ -4691,9 +4695,9 @@ Status DBImpl::CreateColumnFamilyWithImport(
   // Import sst files from metadata.
   auto cfh = static_cast_with_check<ColumnFamilyHandleImpl>(*handle);
   auto cfd = cfh->cfd();
-  ImportColumnFamilyJob import_job(clock_, versions_.get(), cfd,
-                                   immutable_db_options_, file_options_,
-                                   import_options, metadata.files, io_tracer_);
+  ImportColumnFamilyJob import_job(versions_.get(), cfd, immutable_db_options_,
+                                   file_options_, import_options,
+                                   metadata.files, io_tracer_);
 
   SuperVersionContext dummy_sv_ctx(/* create_superversion */ true);
   VersionEdit dummy_edit;
@@ -4969,7 +4973,8 @@ void DBImpl::WaitForIngestFile() {
 Status DBImpl::StartTrace(const TraceOptions& trace_options,
                           std::unique_ptr<TraceWriter>&& trace_writer) {
   InstrumentedMutexLock lock(&trace_mutex_);
-  tracer_.reset(new Tracer(clock_, trace_options, std::move(trace_writer)));
+  tracer_.reset(new Tracer(immutable_db_options_.clock, trace_options,
+                           std::move(trace_writer)));
   return Status::OK();
 }
 
@@ -4988,8 +4993,8 @@ Status DBImpl::EndTrace() {
 Status DBImpl::StartBlockCacheTrace(
     const TraceOptions& trace_options,
     std::unique_ptr<TraceWriter>&& trace_writer) {
-  return block_cache_tracer_.StartTrace(env_, trace_options,
-                                        std::move(trace_writer));
+  return block_cache_tracer_.StartTrace(immutable_db_options_.clock,
+                                        trace_options, std::move(trace_writer));
 }
 
 Status DBImpl::EndBlockCacheTrace() {

db/db_impl/db_impl.h

@@ -486,6 +486,7 @@ class DBImpl : public DB {
 #endif  // ROCKSDB_LITE
 
   // ---- End of implementations of the DB interface ----
+  SystemClock* GetSystemClock() const;
 
   struct GetImplOptions {
     ColumnFamilyHandle* column_family = nullptr;
@@ -1057,7 +1058,6 @@ class DBImpl : public DB {
   bool own_info_log_;
   const DBOptions initial_db_options_;
   Env* const env_;
-  std::shared_ptr<SystemClock> clock_;
   std::shared_ptr<IOTracer> io_tracer_;
   const ImmutableDBOptions immutable_db_options_;
   FileSystemPtr fs_;

db/db_impl/db_impl_compaction_flush.cc

@@ -2564,7 +2564,7 @@ void DBImpl::BackgroundCallFlush(Env::Priority thread_pri) {
                       s.ToString().c_str(), error_cnt);
       log_buffer.FlushBufferToLog();
       LogFlush(immutable_db_options_.info_log);
-      clock_->SleepForMicroseconds(1000000);
+      immutable_db_options_.clock->SleepForMicroseconds(1000000);
       mutex_.Lock();
     }
 
@@ -2637,7 +2637,8 @@ void DBImpl::BackgroundCallCompaction(PrepickedCompaction* prepicked_compaction,
     if (s.IsBusy()) {
       bg_cv_.SignalAll();  // In case a waiter can proceed despite the error
       mutex_.Unlock();
-      clock_->SleepForMicroseconds(10000);  // prevent hot loop
+      immutable_db_options_.clock->SleepForMicroseconds(
+          10000);  // prevent hot loop
       mutex_.Lock();
     } else if (!s.ok() && !s.IsShutdownInProgress() &&
                !s.IsManualCompactionPaused() && !s.IsColumnFamilyDropped()) {
@@ -2655,7 +2656,7 @@ void DBImpl::BackgroundCallCompaction(PrepickedCompaction* prepicked_compaction,
                       "Accumulated background error counts: %" PRIu64,
                       s.ToString().c_str(), error_cnt);
       LogFlush(immutable_db_options_.info_log);
-      clock_->SleepForMicroseconds(1000000);
+      immutable_db_options_.clock->SleepForMicroseconds(1000000);
       mutex_.Lock();
     } else if (s.IsManualCompactionPaused()) {
       ManualCompactionState* m = prepicked_compaction->manual_compaction_state;

db/db_impl/db_impl_files.cc

@@ -120,7 +120,7 @@ void DBImpl::FindObsoleteFiles(JobContext* job_context, bool force,
              mutable_db_options_.delete_obsolete_files_period_micros == 0) {
     doing_the_full_scan = true;
   } else {
-    const uint64_t now_micros = clock_->NowMicros();
+    const uint64_t now_micros = immutable_db_options_.clock->NowMicros();
     if ((delete_obsolete_files_last_run_ +
          mutable_db_options_.delete_obsolete_files_period_micros) <
         now_micros) {

db/db_impl/db_impl_open.cc

@@ -293,15 +293,15 @@ Status DBImpl::NewDB(std::vector<std::string>* new_filenames) {
     file->SetPreallocationBlockSize(
         immutable_db_options_.manifest_preallocation_size);
     std::unique_ptr<WritableFileWriter> file_writer(new WritableFileWriter(
-        std::move(file), manifest, file_options, clock_, io_tracer_,
-        nullptr /* stats */, immutable_db_options_.listeners, nullptr,
-        tmp_set.Contains(FileType::kDescriptorFile)));
+        std::move(file), manifest, file_options, immutable_db_options_.clock,
+        io_tracer_, nullptr /* stats */, immutable_db_options_.listeners,
+        nullptr, tmp_set.Contains(FileType::kDescriptorFile)));
     log::Writer log(std::move(file_writer), 0, false);
     std::string record;
     new_db.EncodeTo(&record);
     s = log.AddRecord(record);
     if (s.ok()) {
-      s = SyncManifest(clock_, &immutable_db_options_, log.file());
+      s = SyncManifest(&immutable_db_options_, log.file());
     }
   }
   if (s.ok()) {
@@ -1297,7 +1297,7 @@ Status DBImpl::RestoreAliveLogFiles(const std::vector<uint64_t>& wal_numbers) {
 Status DBImpl::WriteLevel0TableForRecovery(int job_id, ColumnFamilyData* cfd,
                                            MemTable* mem, VersionEdit* edit) {
   mutex_.AssertHeld();
-  const uint64_t start_micros = clock_->NowMicros();
+  const uint64_t start_micros = immutable_db_options_.clock->NowMicros();
 
   FileMetaData meta;
   std::vector<BlobFileAddition> blob_file_additions;
@@ -1325,7 +1325,7 @@ Status DBImpl::WriteLevel0TableForRecovery(int job_id, ColumnFamilyData* cfd,
         cfd->GetLatestMutableCFOptions()->paranoid_file_checks;
 
     int64_t _current_time = 0;
-    env_->GetCurrentTime(&_current_time)
+    immutable_db_options_.clock->GetCurrentTime(&_current_time)
         .PermitUncheckedError();  // ignore error
     const uint64_t current_time = static_cast<uint64_t>(_current_time);
     meta.oldest_ancester_time = current_time;
@@ -1399,7 +1399,7 @@ Status DBImpl::WriteLevel0TableForRecovery(int job_id, ColumnFamilyData* cfd,
   }
 
   InternalStats::CompactionStats stats(CompactionReason::kFlush, 1);
-  stats.micros = clock_->NowMicros() - start_micros;
+  stats.micros = immutable_db_options_.clock->NowMicros() - start_micros;
 
   if (has_output) {
     stats.bytes_written = meta.fd.GetFileSize();
@@ -1492,9 +1492,9 @@ IOStatus DBImpl::CreateWAL(uint64_t log_file_num, uint64_t recycle_log_number,
     const auto& listeners = immutable_db_options_.listeners;
     FileTypeSet tmp_set = immutable_db_options_.checksum_handoff_file_types;
     std::unique_ptr<WritableFileWriter> file_writer(new WritableFileWriter(
-        std::move(lfile), log_fname, opt_file_options, clock_, io_tracer_,
-        nullptr /* stats */, listeners, nullptr,
-        tmp_set.Contains(FileType::kWalFile)));
+        std::move(lfile), log_fname, opt_file_options,
+        immutable_db_options_.clock, io_tracer_, nullptr /* stats */, listeners,
+        nullptr, tmp_set.Contains(FileType::kWalFile)));
     *new_log = new log::Writer(std::move(file_writer), log_file_num,
                                immutable_db_options_.recycle_log_file_num > 0,
                                immutable_db_options_.manual_wal_flush);

db/db_impl/db_impl_secondary.cc

@@ -327,8 +327,8 @@ Status DBImplSecondary::GetImpl(const ReadOptions& read_options,
                                 ColumnFamilyHandle* column_family,
                                 const Slice& key, PinnableSlice* pinnable_val) {
   assert(pinnable_val != nullptr);
-  PERF_CPU_TIMER_GUARD(get_cpu_nanos, clock_);
-  StopWatch sw(clock_, stats_, DB_GET);
+  PERF_CPU_TIMER_GUARD(get_cpu_nanos, immutable_db_options_.clock);
+  StopWatch sw(immutable_db_options_.clock, stats_, DB_GET);
   PERF_TIMER_GUARD(get_snapshot_time);
 
   auto cfh = static_cast<ColumnFamilyHandleImpl*>(column_family);

db/db_impl/db_impl_write.cc

@@ -160,7 +160,8 @@ Status DBImpl::WriteImpl(const WriteOptions& write_options,
     RecordTick(stats_, WRITE_WITH_WAL);
   }
 
-  StopWatch write_sw(clock_, immutable_db_options_.statistics.get(), DB_WRITE);
+  StopWatch write_sw(immutable_db_options_.clock,
+                     immutable_db_options_.statistics.get(), DB_WRITE);
 
   write_thread_.JoinBatchGroup(&w);
   if (w.state == WriteThread::STATE_PARALLEL_MEMTABLE_WRITER) {
@@ -465,7 +466,8 @@ Status DBImpl::PipelinedWriteImpl(const WriteOptions& write_options,
                                   uint64_t* log_used, uint64_t log_ref,
                                   bool disable_memtable, uint64_t* seq_used) {
   PERF_TIMER_GUARD(write_pre_and_post_process_time);
-  StopWatch write_sw(clock_, immutable_db_options_.statistics.get(), DB_WRITE);
+  StopWatch write_sw(immutable_db_options_.clock,
+                     immutable_db_options_.statistics.get(), DB_WRITE);
 
   WriteContext write_context;
 
@@ -621,7 +623,8 @@ Status DBImpl::UnorderedWriteMemtable(const WriteOptions& write_options,
                                       SequenceNumber seq,
                                       const size_t sub_batch_cnt) {
   PERF_TIMER_GUARD(write_pre_and_post_process_time);
-  StopWatch write_sw(clock_, immutable_db_options_.statistics.get(), DB_WRITE);
+  StopWatch write_sw(immutable_db_options_.clock,
+                     immutable_db_options_.statistics.get(), DB_WRITE);
 
   WriteThread::Writer w(write_options, my_batch, callback, log_ref,
                         false /*disable_memtable*/);
@@ -676,7 +679,8 @@ Status DBImpl::WriteImplWALOnly(
   WriteThread::Writer w(write_options, my_batch, callback, log_ref,
                         disable_memtable, sub_batch_cnt, pre_release_callback);
   RecordTick(stats_, WRITE_WITH_WAL);
-  StopWatch write_sw(clock_, immutable_db_options_.statistics.get(), DB_WRITE);
+  StopWatch write_sw(immutable_db_options_.clock,
+                     immutable_db_options_.statistics.get(), DB_WRITE);
 
   write_thread->JoinBatchGroup(&w);
   assert(w.state != WriteThread::STATE_PARALLEL_MEMTABLE_WRITER);
@@ -1093,7 +1097,7 @@ IOStatus DBImpl::WriteToWAL(const WriteThread::WriteGroup& write_group,
   }
 
   if (io_s.ok() && need_log_sync) {
-    StopWatch sw(clock_, stats_, WAL_FILE_SYNC_MICROS);
+    StopWatch sw(immutable_db_options_.clock, stats_, WAL_FILE_SYNC_MICROS);
     // It's safe to access logs_ with unlocked mutex_ here because:
     //  - we've set getting_synced=true for all logs,
     //    so other threads won't pop from logs_ while we're here,
@@ -1457,8 +1461,10 @@ Status DBImpl::DelayWrite(uint64_t num_bytes,
   uint64_t time_delayed = 0;
   bool delayed = false;
   {
-    StopWatch sw(clock_, stats_, WRITE_STALL, &time_delayed);
-    uint64_t delay = write_controller_.GetDelay(clock_, num_bytes);
+    StopWatch sw(immutable_db_options_.clock, stats_, WRITE_STALL,
+                 &time_delayed);
+    uint64_t delay =
+        write_controller_.GetDelay(immutable_db_options_.clock, num_bytes);
     if (delay > 0) {
       if (write_options.no_slowdown) {
         return Status::Incomplete("Write stall");
@@ -1475,14 +1481,14 @@ Status DBImpl::DelayWrite(uint64_t num_bytes,
       const uint64_t kDelayInterval = 1000;
       uint64_t stall_end = sw.start_time() + delay;
       while (write_controller_.NeedsDelay()) {
-        if (clock_->NowMicros() >= stall_end) {
+        if (immutable_db_options_.clock->NowMicros() >= stall_end) {
           // We already delayed this write `delay` microseconds
           break;
         }
 
         delayed = true;
         // Sleep for 0.001 seconds
-        clock_->SleepForMicroseconds(kDelayInterval);
+        immutable_db_options_.clock->SleepForMicroseconds(kDelayInterval);
       }
       mutex_.Lock();
       write_thread_.EndWriteStall();

db/db_iter.cc

@@ -45,7 +45,7 @@ DBIter::DBIter(Env* _env, const ReadOptions& read_options,
                ColumnFamilyData* cfd, bool expose_blob_index)
     : prefix_extractor_(mutable_cf_options.prefix_extractor.get()),
       env_(_env),
-      clock_(_env->GetSystemClock()),
+      clock_(_env->GetSystemClock().get()),
       logger_(cf_options.info_log),
       user_comparator_(cmp),
       merge_operator_(cf_options.merge_operator),

db/db_iter.h

@@ -300,7 +300,7 @@ class DBIter final : public Iterator {
 
   const SliceTransform* prefix_extractor_;
   Env* const env_;
-  std::shared_ptr<SystemClock> clock_;
+  SystemClock* clock_;
   Logger* logger_;
   UserComparatorWrapper user_comparator_;
   const MergeOperator* const merge_operator_;

db/error_handler.cc

@@ -670,7 +670,7 @@ void ErrorHandler::RecoverFromRetryableBGIOError() {
       // a period of time and redo auto resume if it is allowed.
       TEST_SYNC_POINT("RecoverFromRetryableBGIOError:BeforeWait0");
       TEST_SYNC_POINT("RecoverFromRetryableBGIOError:BeforeWait1");
-      int64_t wait_until = db_->clock_->NowMicros() + wait_interval;
+      int64_t wait_until = db_options_.clock->NowMicros() + wait_interval;
       cv_.TimedWait(wait_until);
       TEST_SYNC_POINT("RecoverFromRetryableBGIOError:AfterWait0");
     } else {

db/external_sst_file_ingestion_job.h

@@ -74,13 +74,13 @@ struct IngestedFileInfo {
 class ExternalSstFileIngestionJob {
  public:
   ExternalSstFileIngestionJob(
-      const std::shared_ptr<SystemClock>& clock, VersionSet* versions,
-      ColumnFamilyData* cfd, const ImmutableDBOptions& db_options,
-      const EnvOptions& env_options, SnapshotList* db_snapshots,
+      VersionSet* versions, ColumnFamilyData* cfd,
+      const ImmutableDBOptions& db_options, const EnvOptions& env_options,
+      SnapshotList* db_snapshots,
       const IngestExternalFileOptions& ingestion_options,
       Directories* directories, EventLogger* event_logger,
       const std::shared_ptr<IOTracer>& io_tracer)
-      : clock_(clock),
+      : clock_(db_options.clock),
         fs_(db_options.fs, io_tracer),
         versions_(versions),
         cfd_(cfd),
@@ -170,7 +170,7 @@ class ExternalSstFileIngestionJob {
   template <typename TWritableFile>
   Status SyncIngestedFile(TWritableFile* file);
 
-  std::shared_ptr<SystemClock> clock_;
+  SystemClock* clock_;
   FileSystemPtr fs_;
   VersionSet* versions_;
   ColumnFamilyData* cfd_;

db/flush_job.cc

@@ -127,7 +127,7 @@ FlushJob::FlushJob(const std::string& dbname, ColumnFamilyData* cfd,
       pick_memtable_called(false),
       thread_pri_(thread_pri),
       io_tracer_(io_tracer),
-      clock_(db_options_.env->GetSystemClock()),
+      clock_(db_options_.clock),
       full_history_ts_low_(std::move(full_history_ts_low)) {
   // Update the thread status to indicate flush.
   ReportStartedFlush();

db/flush_job.h

@@ -162,7 +162,7 @@ class FlushJob {
   IOStatus io_status_;
 
   const std::shared_ptr<IOTracer> io_tracer_;
-  const std::shared_ptr<SystemClock> clock_;
+  SystemClock* clock_;
 
   const std::string full_history_ts_low_;
 };

db/import_column_family_job.h

@@ -21,14 +21,13 @@ class SystemClock;
 // to ExternalSstFileIngestionJob.
 class ImportColumnFamilyJob {
  public:
-  ImportColumnFamilyJob(const std::shared_ptr<SystemClock>& clock,
-                        VersionSet* versions, ColumnFamilyData* cfd,
+  ImportColumnFamilyJob(VersionSet* versions, ColumnFamilyData* cfd,
                         const ImmutableDBOptions& db_options,
                         const EnvOptions& env_options,
                         const ImportColumnFamilyOptions& import_options,
                         const std::vector<LiveFileMetaData>& metadata,
                         const std::shared_ptr<IOTracer>& io_tracer)
-      : clock_(clock),
+      : clock_(db_options.clock),
         versions_(versions),
         cfd_(cfd),
         db_options_(db_options),
@@ -61,7 +60,7 @@ class ImportColumnFamilyJob {
                              IngestedFileInfo* file_to_import,
                              SuperVersion* sv);
 
-  std::shared_ptr<SystemClock> clock_;
+  SystemClock* clock_;
   VersionSet* versions_;
   ColumnFamilyData* cfd_;
   const ImmutableDBOptions& db_options_;

db/internal_stats.h

@@ -125,8 +125,7 @@ class InternalStats {
     kIntStatsNumMax,
   };
 
-  InternalStats(int num_levels, const std::shared_ptr<SystemClock>& clock,
-                ColumnFamilyData* cfd)
+  InternalStats(int num_levels, SystemClock* clock, ColumnFamilyData* cfd)
       : db_stats_{},
         cf_stats_value_{},
         cf_stats_count_{},
@@ -638,7 +637,7 @@ class InternalStats {
   uint64_t bg_error_count_;
 
   const int number_levels_;
-  const std::shared_ptr<SystemClock> clock_;
+  SystemClock* clock_;
   ColumnFamilyData* cfd_;
   uint64_t started_at_;
 };
@@ -677,8 +676,7 @@ class InternalStats {
     kIntStatsNumMax,
   };
 
-  InternalStats(int /*num_levels*/,
-                const std::shared_ptr<SystemClock>& /*clock*/,
+  InternalStats(int /*num_levels*/, SystemClock* /*clock*/,
                 ColumnFamilyData* /*cfd*/) {}
 
   struct CompactionStats {

db/memtable.cc

@@ -104,7 +104,7 @@ MemTable::MemTable(const InternalKeyComparator& cmp,
                  : 0),
       prefix_extractor_(mutable_cf_options.prefix_extractor.get()),
       flush_state_(FLUSH_NOT_REQUESTED),
-      clock_(ioptions.env->GetSystemClock()),
+      clock_(ioptions.clock),
       insert_with_hint_prefix_extractor_(
           ioptions.memtable_insert_with_hint_prefix_extractor),
       oldest_key_time_(std::numeric_limits<uint64_t>::max()),
@@ -684,7 +684,7 @@ struct Saver {
   Statistics* statistics;
   bool inplace_update_support;
   bool do_merge;
-  std::shared_ptr<SystemClock> clock;
+  SystemClock* clock;
 
   ReadCallback* callback_;
   bool* is_blob_index;

db/memtable.h

@@ -512,7 +512,7 @@ class MemTable {
 
   std::atomic<FlushStateEnum> flush_state_;
 
-  std::shared_ptr<SystemClock> clock_;
+  SystemClock* clock_;
 
   // Extract sequential insert prefixes.
   const SliceTransform* insert_with_hint_prefix_extractor_;

db/merge_helper.cc

@@ -29,7 +29,7 @@ MergeHelper::MergeHelper(Env* env, const Comparator* user_comparator,
                          Statistics* stats,
                          const std::atomic<bool>* shutting_down)
     : env_(env),
-      clock_(env->GetSystemClock()),
+      clock_(env->GetSystemClock().get()),
       user_comparator_(user_comparator),
       user_merge_operator_(user_merge_operator),
       compaction_filter_(compaction_filter),
@@ -50,11 +50,13 @@ MergeHelper::MergeHelper(Env* env, const Comparator* user_comparator,
   }
 }
 
-Status MergeHelper::TimedFullMerge(
-    const MergeOperator* merge_operator, const Slice& key, const Slice* value,
-    const std::vector<Slice>& operands, std::string* result, Logger* logger,
-    Statistics* statistics, const std::shared_ptr<SystemClock>& clock,
-    Slice* result_operand, bool update_num_ops_stats) {
+Status MergeHelper::TimedFullMerge(const MergeOperator* merge_operator,
+                                   const Slice& key, const Slice* value,
+                                   const std::vector<Slice>& operands,
+                                   std::string* result, Logger* logger,
+                                   Statistics* statistics, SystemClock* clock,
+                                   Slice* result_operand,
+                                   bool update_num_ops_stats) {
   assert(merge_operator != nullptr);
 
   if (operands.size() == 0) {

db/merge_helper.h

@@ -45,11 +45,13 @@ class MergeHelper {
   // Returns one of the following statuses:
   // - OK: Entries were successfully merged.
   // - Corruption: Merge operator reported unsuccessful merge.
-  static Status TimedFullMerge(
-      const MergeOperator* merge_operator, const Slice& key, const Slice* value,
-      const std::vector<Slice>& operands, std::string* result, Logger* logger,
-      Statistics* statistics, const std::shared_ptr<SystemClock>& clock,
-      Slice* result_operand = nullptr, bool update_num_ops_stats = false);
+  static Status TimedFullMerge(const MergeOperator* merge_operator,
+                               const Slice& key, const Slice* value,
+                               const std::vector<Slice>& operands,
+                               std::string* result, Logger* logger,
+                               Statistics* statistics, SystemClock* clock,
+                               Slice* result_operand = nullptr,
+                               bool update_num_ops_stats = false);
 
   // Merge entries until we hit
   //     - a corrupted key
@@ -139,7 +141,7 @@ class MergeHelper {
 
  private:
   Env* env_;
-  std::shared_ptr<SystemClock> clock_;
+  SystemClock* clock_;
   const Comparator* user_comparator_;
   const MergeOperator* user_merge_operator_;
   const CompactionFilter* compaction_filter_;

db/perf_context_test.cc

@@ -93,7 +93,7 @@ TEST_F(PerfContextTest, SeekIntoDeletion) {
     std::string value;
 
     get_perf_context()->Reset();
-    StopWatchNano timer(SystemClock::Default());
+    StopWatchNano timer(SystemClock::Default().get());
     timer.Start();
     auto status = db->Get(read_options, key, &value);
     auto elapsed_nanos = timer.ElapsedNanos();
@@ -112,7 +112,7 @@ TEST_F(PerfContextTest, SeekIntoDeletion) {
     std::unique_ptr<Iterator> iter(db->NewIterator(read_options));
 
     get_perf_context()->Reset();
-    StopWatchNano timer(SystemClock::Default(), true);
+    StopWatchNano timer(SystemClock::Default().get(), true);
     iter->SeekToFirst();
     hist_seek_to_first.Add(get_perf_context()->user_key_comparison_count);
     auto elapsed_nanos = timer.ElapsedNanos();
@@ -133,7 +133,7 @@ TEST_F(PerfContextTest, SeekIntoDeletion) {
     std::string key = "k" + ToString(i);
 
     get_perf_context()->Reset();
-    StopWatchNano timer(SystemClock::Default(), true);
+    StopWatchNano timer(SystemClock::Default().get(), true);
     iter->Seek(key);
     auto elapsed_nanos = timer.ElapsedNanos();
     hist_seek.Add(get_perf_context()->user_key_comparison_count);
@@ -147,7 +147,7 @@ TEST_F(PerfContextTest, SeekIntoDeletion) {
 
     get_perf_context()->Reset();
     ASSERT_TRUE(iter->Valid());
-    StopWatchNano timer2(SystemClock::Default(), true);
+    StopWatchNano timer2(SystemClock::Default().get(), true);
     iter->Next();
     auto elapsed_nanos2 = timer2.ElapsedNanos();
     if (FLAGS_verbose) {
@@ -166,7 +166,7 @@ TEST_F(PerfContextTest, StopWatchNanoOverhead) {
   const int kTotalIterations = 1000000;
   std::vector<uint64_t> timings(kTotalIterations);
 
-  StopWatchNano timer(SystemClock::Default(), true);
+  StopWatchNano timer(SystemClock::Default().get(), true);
   for (auto& timing : timings) {
     timing = timer.ElapsedNanos(true /* reset */);
   }
@@ -187,7 +187,7 @@ TEST_F(PerfContextTest, StopWatchOverhead) {
   uint64_t elapsed = 0;
   std::vector<uint64_t> timings(kTotalIterations);
 
-  StopWatch timer(SystemClock::Default(), nullptr, 0, &elapsed);
+  StopWatch timer(SystemClock::Default().get(), nullptr, 0, &elapsed);
   for (auto& timing : timings) {
     timing = elapsed;
   }
@@ -541,7 +541,7 @@ TEST_F(PerfContextTest, SeekKeyComparison) {
   HistogramImpl hist_time_diff;
 
   SetPerfLevel(kEnableTime);
-  StopWatchNano timer(SystemClock::Default());
+  StopWatchNano timer(SystemClock::Default().get());
   for (const int i : keys) {
     std::string key = "k" + ToString(i);
     std::string value = "v" + ToString(i);
@@ -594,7 +594,8 @@ TEST_F(PerfContextTest, DBMutexLockCounter) {
   for (PerfLevel perf_level_test :
        {PerfLevel::kEnableTimeExceptForMutex, PerfLevel::kEnableTime}) {
     for (int c = 0; c < 2; ++c) {
-      InstrumentedMutex mutex(nullptr, SystemClock::Default(), stats_code[c]);
+      InstrumentedMutex mutex(nullptr, SystemClock::Default().get(),
+                              stats_code[c]);
       mutex.Lock();
       ROCKSDB_NAMESPACE::port::Thread child_thread([&] {
         SetPerfLevel(perf_level_test);
@@ -621,7 +622,8 @@ TEST_F(PerfContextTest, FalseDBMutexWait) {
   SetPerfLevel(kEnableTime);
   int stats_code[] = {0, static_cast<int>(DB_MUTEX_WAIT_MICROS)};
   for (int c = 0; c < 2; ++c) {
-    InstrumentedMutex mutex(nullptr, SystemClock::Default(), stats_code[c]);
+    InstrumentedMutex mutex(nullptr, SystemClock::Default().get(),
+                            stats_code[c]);
     InstrumentedCondVar lock(&mutex);
     get_perf_context()->Reset();
     mutex.Lock();

db/periodic_work_scheduler.cc

@@ -13,7 +13,7 @@ namespace ROCKSDB_NAMESPACE {
 
 PeriodicWorkScheduler::PeriodicWorkScheduler(
     const std::shared_ptr<SystemClock>& clock) {
-  timer = std::unique_ptr<Timer>(new Timer(clock));
+  timer = std::unique_ptr<Timer>(new Timer(clock.get()));
 }
 
 void PeriodicWorkScheduler::Register(DBImpl* dbi,
@@ -87,7 +87,7 @@ PeriodicWorkTestScheduler* PeriodicWorkTestScheduler::Default(
         MutexLock timer_mu_guard(&scheduler.timer_mu_);
         scheduler.timer->Shutdown();
       }
-      scheduler.timer.reset(new Timer(clock));
+      scheduler.timer.reset(new Timer(clock.get()));
     }
   }
   return &scheduler;

db/prefix_test.cc

@@ -598,7 +598,6 @@ TEST_F(PrefixTest, DynamicPrefixIterator) {
 
     HistogramImpl hist_put_time;
     HistogramImpl hist_put_comparison;
-
     // insert x random prefix, each with y continuous element.
     for (auto prefix : prefixes) {
        for (uint64_t sorted = 0; sorted < FLAGS_items_per_prefix; sorted++) {
@@ -609,7 +608,7 @@ TEST_F(PrefixTest, DynamicPrefixIterator) {
         std::string value(FLAGS_value_size, 0);
 
         get_perf_context()->Reset();
-        StopWatchNano timer(SystemClock::Default(), true);
+        StopWatchNano timer(SystemClock::Default().get(), true);
         ASSERT_OK(db->Put(write_options, key, value));
         hist_put_time.Add(timer.ElapsedNanos());
         hist_put_comparison.Add(get_perf_context()->user_key_comparison_count);
@@ -632,7 +631,7 @@ TEST_F(PrefixTest, DynamicPrefixIterator) {
       std::string value = "v" + ToString(0);
 
       get_perf_context()->Reset();
-      StopWatchNano timer(SystemClock::Default(), true);
+      StopWatchNano timer(SystemClock::Default().get(), true);
       auto key_prefix = options.prefix_extractor->Transform(key);
       uint64_t total_keys = 0;
       for (iter->Seek(key);
@@ -666,7 +665,7 @@ TEST_F(PrefixTest, DynamicPrefixIterator) {
       Slice key = TestKeyToSlice(s, test_key);
 
       get_perf_context()->Reset();
-      StopWatchNano timer(SystemClock::Default(), true);
+      StopWatchNano timer(SystemClock::Default().get(), true);
       iter->Seek(key);
       hist_no_seek_time.Add(timer.ElapsedNanos());
       hist_no_seek_comparison.Add(get_perf_context()->user_key_comparison_count);

db/range_del_aggregator_bench.cc

@@ -171,6 +171,8 @@ int main(int argc, char** argv) {
   ParseCommandLineFlags(&argc, &argv, true);
 
   Stats stats;
+  ROCKSDB_NAMESPACE::SystemClock* clock =
+      ROCKSDB_NAMESPACE::SystemClock::Default().get();
   ROCKSDB_NAMESPACE::Random64 rnd(FLAGS_seed);
   std::default_random_engine random_gen(FLAGS_seed);
   std::normal_distribution<double> normal_dist(FLAGS_tombstone_width_mean,
@@ -219,7 +221,7 @@ int main(int argc, char** argv) {
                   ROCKSDB_NAMESPACE::kMaxSequenceNumber));
 
       ROCKSDB_NAMESPACE::StopWatchNano stop_watch_add_tombstones(
-          ROCKSDB_NAMESPACE::SystemClock::Default(), true /* auto_start */);
+          clock, true /* auto_start */);
       range_del_agg.AddTombstones(std::move(fragmented_range_del_iter));
       stats.time_add_tombstones += stop_watch_add_tombstones.ElapsedNanos();
     }
@@ -236,7 +238,7 @@ int main(int argc, char** argv) {
       parsed_key.user_key = key_string;
 
       ROCKSDB_NAMESPACE::StopWatchNano stop_watch_should_delete(
-          ROCKSDB_NAMESPACE::SystemClock::Default(), true /* auto_start */);
+          clock, true /* auto_start */);
       range_del_agg.ShouldDelete(parsed_key, mode);
       uint64_t call_time = stop_watch_should_delete.ElapsedNanos();
 

db/repair.cc

@@ -425,7 +425,8 @@ class Repairer {
       Arena arena;
       ScopedArenaIterator iter(mem->NewIterator(ro, &arena));
       int64_t _current_time = 0;
-      status = env_->GetCurrentTime(&_current_time);  // ignore error
+      immutable_db_options_.clock->GetCurrentTime(&_current_time)
+          .PermitUncheckedError();  // ignore error
       const uint64_t current_time = static_cast<uint64_t>(_current_time);
       SnapshotChecker* snapshot_checker = DisableGCSnapshotChecker::Instance();
 

db/table_cache.cc

@@ -106,15 +106,14 @@ Status TableCache::GetTableReader(
       TableFileName(ioptions_.cf_paths, fd.GetNumber(), fd.GetPathId());
   std::unique_ptr<FSRandomAccessFile> file;
   FileOptions fopts = file_options;
-  const auto& clock = ioptions_.env->GetSystemClock();
-  Status s = PrepareIOFromReadOptions(ro, clock, fopts.io_options);
+  Status s = PrepareIOFromReadOptions(ro, ioptions_.clock, fopts.io_options);
   if (s.ok()) {
     s = ioptions_.fs->NewRandomAccessFile(fname, fopts, &file, nullptr);
   }
   RecordTick(ioptions_.statistics, NO_FILE_OPENS);
   if (s.IsPathNotFound()) {
     fname = Rocks2LevelTableFileName(fname);
-    s = PrepareIOFromReadOptions(ro, clock, fopts.io_options);
+    s = PrepareIOFromReadOptions(ro, ioptions_.clock, fopts.io_options);
     if (s.ok()) {
       s = ioptions_.fs->NewRandomAccessFile(fname, file_options, &file,
                                             nullptr);
@@ -126,10 +125,10 @@ Status TableCache::GetTableReader(
     if (!sequential_mode && ioptions_.advise_random_on_open) {
       file->Hint(FSRandomAccessFile::kRandom);
     }
-    StopWatch sw(clock, ioptions_.statistics, TABLE_OPEN_IO_MICROS);
+    StopWatch sw(ioptions_.clock, ioptions_.statistics, TABLE_OPEN_IO_MICROS);
     std::unique_ptr<RandomAccessFileReader> file_reader(
         new RandomAccessFileReader(
-            std::move(file), fname, clock, io_tracer_,
+            std::move(file), fname, ioptions_.clock, io_tracer_,
             record_read_stats ? ioptions_.statistics : nullptr, SST_READ_MICROS,
             file_read_hist, ioptions_.rate_limiter, ioptions_.listeners));
     s = ioptions_.table_factory->NewTableReader(
@@ -162,8 +161,7 @@ Status TableCache::FindTable(const ReadOptions& ro,
                              HistogramImpl* file_read_hist, bool skip_filters,
                              int level, bool prefetch_index_and_filter_in_cache,
                              size_t max_file_size_for_l0_meta_pin) {
-  PERF_TIMER_GUARD_WITH_CLOCK(find_table_nanos,
-                              ioptions_.env->GetSystemClock());
+  PERF_TIMER_GUARD_WITH_CLOCK(find_table_nanos, ioptions_.clock);
   uint64_t number = fd.GetNumber();
   Slice key = GetSliceForFileNumber(&number);
   *handle = cache_->Lookup(key);

db/version_set.cc

@@ -1762,7 +1762,7 @@ Version::Version(ColumnFamilyData* column_family_data, VersionSet* vset,
                  const std::shared_ptr<IOTracer>& io_tracer,
                  uint64_t version_number)
     : env_(vset->env_),
-      clock_(env_->GetSystemClock()),
+      clock_(vset->clock_),
       cfd_(column_family_data),
       info_log_((cfd_ == nullptr) ? nullptr : cfd_->ioptions()->info_log),
       db_statistics_((cfd_ == nullptr) ? nullptr
@@ -2534,7 +2534,7 @@ uint32_t GetExpiredTtlFilesCount(const ImmutableCFOptions& ioptions,
   uint32_t ttl_expired_files_count = 0;
 
   int64_t _current_time;
-  auto status = ioptions.env->GetCurrentTime(&_current_time);
+  auto status = ioptions.clock->GetCurrentTime(&_current_time);
   if (status.ok()) {
     const uint64_t current_time = static_cast<uint64_t>(_current_time);
     for (FileMetaData* f : files) {
@@ -2703,7 +2703,7 @@ void VersionStorageInfo::ComputeExpiredTtlFiles(
   expired_ttl_files_.clear();
 
   int64_t _current_time;
-  auto status = ioptions.env->GetCurrentTime(&_current_time);
+  auto status = ioptions.clock->GetCurrentTime(&_current_time);
   if (!status.ok()) {
     return;
   }
@@ -2730,7 +2730,7 @@ void VersionStorageInfo::ComputeFilesMarkedForPeriodicCompaction(
   files_marked_for_periodic_compaction_.clear();
 
   int64_t temp_current_time;
-  auto status = ioptions.env->GetCurrentTime(&temp_current_time);
+  auto status = ioptions.clock->GetCurrentTime(&temp_current_time);
   if (!status.ok()) {
     return;
   }
@@ -3789,7 +3789,7 @@ VersionSet::VersionSet(const std::string& dbname,
       table_cache_(table_cache),
       env_(_db_options->env),
       fs_(_db_options->fs, io_tracer),
-      clock_(env_->GetSystemClock()),
+      clock_(_db_options->clock),
       dbname_(dbname),
       db_options_(_db_options),
       next_file_number_(2),
@@ -4176,7 +4176,7 @@ Status VersionSet::ProcessManifestWrites(
         }
       }
       if (s.ok()) {
-        io_s = SyncManifest(clock_, db_options_, descriptor_log_->file());
+        io_s = SyncManifest(db_options_, descriptor_log_->file());
         TEST_SYNC_POINT_CALLBACK(
             "VersionSet::ProcessManifestWrites:AfterSyncManifest", &io_s);
       }

db/version_set.h

@@ -794,7 +794,7 @@ class Version {
 
  private:
   Env* env_;
-  std::shared_ptr<SystemClock> clock_;
+  SystemClock* clock_;
 
   friend class ReactiveVersionSet;
   friend class VersionSet;
@@ -1345,7 +1345,7 @@ class VersionSet {
   Cache* table_cache_;
   Env* const env_;
   FileSystemPtr const fs_;
-  const std::shared_ptr<SystemClock> clock_;
+  SystemClock* const clock_;
   const std::string dbname_;
   std::string db_id_;
   const ImmutableDBOptions* const db_options_;

db/version_set_test.cc

@@ -2773,7 +2773,7 @@ class VersionSetTestMissingFiles : public VersionSetTestBase,
       Status s = fs_->NewWritableFile(fname, FileOptions(), &file, nullptr);
       ASSERT_OK(s);
       std::unique_ptr<WritableFileWriter> fwriter(new WritableFileWriter(
-          std::move(file), fname, FileOptions(), env_->GetSystemClock()));
+          std::move(file), fname, FileOptions(), env_->GetSystemClock().get()));
       std::vector<std::unique_ptr<IntTblPropCollectorFactory>>
           int_tbl_prop_collector_factories;
 

db/wal_manager.cc

@@ -140,8 +140,8 @@ void WalManager::PurgeObsoleteWALFiles() {
     return;
   }
 
-  int64_t current_time;
-  Status s = env_->GetCurrentTime(&current_time);
+  int64_t current_time = 0;
+  Status s = db_options_.clock->GetCurrentTime(&current_time);
   if (!s.ok()) {
     ROCKS_LOG_ERROR(db_options_.info_log, "Can't get current time: %s",
                     s.ToString().c_str());
@@ -171,7 +171,6 @@ void WalManager::PurgeObsoleteWALFiles() {
 
   size_t log_files_num = 0;
   uint64_t log_file_size = 0;
-
   for (auto& f : files) {
     uint64_t number;
     FileType type;

db/wal_manager_test.cc

@@ -49,6 +49,7 @@ class WalManagerTest : public testing::Test {
     db_options_.wal_dir = dbname_;
     db_options_.env = env_.get();
     db_options_.fs = env_->GetFileSystem();
+    db_options_.clock = env_->GetSystemClock().get();
 
     versions_.reset(
         new VersionSet(dbname_, &db_options_, env_options_, table_cache_.get(),

db/write_batch.cc

@@ -2041,7 +2041,8 @@ class MemTableInserter : public WriteBatch::Handler {
         std::string new_value;
         Status merge_status = MergeHelper::TimedFullMerge(
             merge_operator, key, &get_value_slice, {value}, &new_value,
-            moptions->info_log, moptions->statistics, SystemClock::Default());
+            moptions->info_log, moptions->statistics,
+            SystemClock::Default().get());
 
         if (!merge_status.ok()) {
           // Failed to merge!

db/write_controller.cc

@@ -43,8 +43,7 @@ bool WriteController::IsStopped() const {
 // If it turns out to be a performance issue, we can redesign the thread
 // synchronization model here.
 // The function trust caller will sleep micros returned.
-uint64_t WriteController::GetDelay(const std::shared_ptr<SystemClock>& clock,
-                                   uint64_t num_bytes) {
+uint64_t WriteController::GetDelay(SystemClock* clock, uint64_t num_bytes) {
   if (total_stopped_.load(std::memory_order_relaxed) > 0) {
     return 0;
   }
@@ -108,8 +107,7 @@ uint64_t WriteController::GetDelay(const std::shared_ptr<SystemClock>& clock,
   return sleep_amount;
 }
 
-uint64_t WriteController::NowMicrosMonotonic(
-    const std::shared_ptr<SystemClock>& clock) {
+uint64_t WriteController::NowMicrosMonotonic(SystemClock* clock) {
   return clock->NowNanos() / std::milli::den;
 }
 

db/write_controller.h

@@ -57,8 +57,7 @@ class WriteController {
   // return how many microseconds the caller needs to sleep after the call
   // num_bytes: how many number of bytes to put into the DB.
   // Prerequisite: DB mutex held.
-  uint64_t GetDelay(const std::shared_ptr<SystemClock>& clock,
-                    uint64_t num_bytes);
+  uint64_t GetDelay(SystemClock* clock, uint64_t num_bytes);
   void set_delayed_write_rate(uint64_t write_rate) {
     // avoid divide 0
     if (write_rate == 0) {
@@ -86,7 +85,7 @@ class WriteController {
   RateLimiter* low_pri_rate_limiter() { return low_pri_rate_limiter_.get(); }
 
  private:
-  uint64_t NowMicrosMonotonic(const std::shared_ptr<SystemClock>& clock);
+  uint64_t NowMicrosMonotonic(SystemClock* clock);
 
   friend class WriteControllerToken;
   friend class StopWriteToken;

db/write_controller_test.cc

@@ -32,21 +32,21 @@ TEST_F(WriteControllerTest, ChangeDelayRateTest) {
   auto delay_token_0 =
       controller.GetDelayToken(controller.delayed_write_rate());
   ASSERT_EQ(static_cast<uint64_t>(2000000),
-            controller.GetDelay(clock_, 20000000u));
+            controller.GetDelay(clock_.get(), 20000000u));
   auto delay_token_1 = controller.GetDelayToken(2000000u);
   ASSERT_EQ(static_cast<uint64_t>(10000000),
-            controller.GetDelay(clock_, 20000000u));
+            controller.GetDelay(clock_.get(), 20000000u));
   auto delay_token_2 = controller.GetDelayToken(1000000u);
   ASSERT_EQ(static_cast<uint64_t>(20000000),
-            controller.GetDelay(clock_, 20000000u));
+            controller.GetDelay(clock_.get(), 20000000u));
   auto delay_token_3 = controller.GetDelayToken(20000000u);
   ASSERT_EQ(static_cast<uint64_t>(1000000),
-            controller.GetDelay(clock_, 20000000u));
+            controller.GetDelay(clock_.get(), 20000000u));
   // This is more than max rate. Max delayed rate will be used.
   auto delay_token_4 =
       controller.GetDelayToken(controller.delayed_write_rate() * 3);
   ASSERT_EQ(static_cast<uint64_t>(500000),
-            controller.GetDelay(clock_, 20000000u));
+            controller.GetDelay(clock_.get(), 20000000u));
 }
 
 TEST_F(WriteControllerTest, SanityTest) {
@@ -62,69 +62,77 @@ TEST_F(WriteControllerTest, SanityTest) {
 
   auto delay_token_1 = controller.GetDelayToken(10000000u);
   ASSERT_EQ(static_cast<uint64_t>(2000000),
-            controller.GetDelay(clock_, 20000000u));
+            controller.GetDelay(clock_.get(), 20000000u));
 
   clock_->now_micros_ += 1999900u;  // sleep debt 1000
 
   auto delay_token_2 = controller.GetDelayToken(10000000u);
   // Rate reset after changing the token.
   ASSERT_EQ(static_cast<uint64_t>(2000000),
-            controller.GetDelay(clock_, 20000000u));
+            controller.GetDelay(clock_.get(), 20000000u));
 
   clock_->now_micros_ += 1999900u;  // sleep debt 1000
 
   // One refill: 10240 bytes allowed, 1000 used, 9240 left
-  ASSERT_EQ(static_cast<uint64_t>(1124), controller.GetDelay(clock_, 1000u));
+  ASSERT_EQ(static_cast<uint64_t>(1124),
+            controller.GetDelay(clock_.get(), 1000u));
   clock_->now_micros_ += 1124u;  // sleep debt 0
 
   delay_token_2.reset();
   // 1000 used, 8240 left
-  ASSERT_EQ(static_cast<uint64_t>(0), controller.GetDelay(clock_, 1000u));
+  ASSERT_EQ(static_cast<uint64_t>(0), controller.GetDelay(clock_.get(), 1000u));
 
   clock_->now_micros_ += 100u;  // sleep credit 100
   // 1000 used, 7240 left
-  ASSERT_EQ(static_cast<uint64_t>(0), controller.GetDelay(clock_, 1000u));
+  ASSERT_EQ(static_cast<uint64_t>(0), controller.GetDelay(clock_.get(), 1000u));
 
   clock_->now_micros_ += 100u;  // sleep credit 200
   // One refill: 10240 fileed, sleep credit generates 2000. 8000 used
   //             7240 + 10240 + 2000 - 8000 = 11480 left
-  ASSERT_EQ(static_cast<uint64_t>(1024u), controller.GetDelay(clock_, 8000u));
+  ASSERT_EQ(static_cast<uint64_t>(1024u),
+            controller.GetDelay(clock_.get(), 8000u));
 
   clock_->now_micros_ += 200u;  // sleep debt 824
   // 1000 used, 10480 left.
-  ASSERT_EQ(static_cast<uint64_t>(0), controller.GetDelay(clock_, 1000u));
+  ASSERT_EQ(static_cast<uint64_t>(0), controller.GetDelay(clock_.get(), 1000u));
 
   clock_->now_micros_ += 200u;  // sleep debt 624
   // Out of bound sleep, still 10480 left
   ASSERT_EQ(static_cast<uint64_t>(3000624u),
-            controller.GetDelay(clock_, 30000000u));
+            controller.GetDelay(clock_.get(), 30000000u));
 
   clock_->now_micros_ += 3000724u;  // sleep credit 100
   // 6000 used, 4480 left.
-  ASSERT_EQ(static_cast<uint64_t>(0), controller.GetDelay(clock_, 6000u));
+  ASSERT_EQ(static_cast<uint64_t>(0), controller.GetDelay(clock_.get(), 6000u));
 
   clock_->now_micros_ += 200u;  // sleep credit 300
   // One refill, credit 4480 balance + 3000 credit + 10240 refill
   // Use 8000, 9720 left
-  ASSERT_EQ(static_cast<uint64_t>(1024u), controller.GetDelay(clock_, 8000u));
+  ASSERT_EQ(static_cast<uint64_t>(1024u),
+            controller.GetDelay(clock_.get(), 8000u));
 
   clock_->now_micros_ += 3024u;  // sleep credit 2000
 
   // 1720 left
-  ASSERT_EQ(static_cast<uint64_t>(0u), controller.GetDelay(clock_, 8000u));
+  ASSERT_EQ(static_cast<uint64_t>(0u),
+            controller.GetDelay(clock_.get(), 8000u));
 
   // 1720 balance + 20000 credit = 20170 left
   // Use 8000, 12170 left
-  ASSERT_EQ(static_cast<uint64_t>(0u), controller.GetDelay(clock_, 8000u));
+  ASSERT_EQ(static_cast<uint64_t>(0u),
+            controller.GetDelay(clock_.get(), 8000u));
 
   // 4170 left
-  ASSERT_EQ(static_cast<uint64_t>(0u), controller.GetDelay(clock_, 8000u));
+  ASSERT_EQ(static_cast<uint64_t>(0u),
+            controller.GetDelay(clock_.get(), 8000u));
 
   // Need a refill
-  ASSERT_EQ(static_cast<uint64_t>(1024u), controller.GetDelay(clock_, 9000u));
+  ASSERT_EQ(static_cast<uint64_t>(1024u),
+            controller.GetDelay(clock_.get(), 9000u));
 
   delay_token_1.reset();
-  ASSERT_EQ(static_cast<uint64_t>(0), controller.GetDelay(clock_, 30000000u));
+  ASSERT_EQ(static_cast<uint64_t>(0),
+            controller.GetDelay(clock_.get(), 30000000u));
   delay_token_1.reset();
   ASSERT_FALSE(controller.IsStopped());
 }

db_stress_tool/db_stress_driver.cc

@@ -57,6 +57,7 @@ void ThreadBody(void* v) {
 }
 
 bool RunStressTest(StressTest* stress) {
+  SystemClock* clock = db_stress_env->GetSystemClock().get();
   stress->InitDb();
   SharedState shared(db_stress_env, stress);
   stress->FinishInitDb(&shared);
@@ -69,9 +70,9 @@ bool RunStressTest(StressTest* stress) {
 
   uint32_t n = shared.GetNumThreads();
 
-  uint64_t now = db_stress_env->NowMicros();
+  uint64_t now = clock->NowMicros();
   fprintf(stdout, "%s Initializing worker threads\n",
-          db_stress_env->TimeToString(now / 1000000).c_str());
+          clock->TimeToString(now / 1000000).c_str());
   std::vector<ThreadState*> threads(n);
   for (uint32_t i = 0; i < n; i++) {
     threads[i] = new ThreadState(i, &shared);
@@ -104,9 +105,9 @@ bool RunStressTest(StressTest* stress) {
       }
     }
 
-    now = db_stress_env->NowMicros();
+    now = clock->NowMicros();
     fprintf(stdout, "%s Starting database operations\n",
-            db_stress_env->TimeToString(now / 1000000).c_str());
+            clock->TimeToString(now / 1000000).c_str());
 
     shared.SetStart();
     shared.GetCondVar()->SignalAll();
@@ -114,16 +115,16 @@ bool RunStressTest(StressTest* stress) {
       shared.GetCondVar()->Wait();
     }
 
-    now = db_stress_env->NowMicros();
+    now = clock->NowMicros();
     if (FLAGS_test_batches_snapshots) {
       fprintf(stdout, "%s Limited verification already done during gets\n",
-              db_stress_env->TimeToString((uint64_t)now / 1000000).c_str());
+              clock->TimeToString((uint64_t)now / 1000000).c_str());
     } else if (FLAGS_skip_verifydb) {
       fprintf(stdout, "%s Verification skipped\n",
-              db_stress_env->TimeToString((uint64_t)now / 1000000).c_str());
+              clock->TimeToString((uint64_t)now / 1000000).c_str());
     } else {
       fprintf(stdout, "%s Starting verification\n",
-              db_stress_env->TimeToString((uint64_t)now / 1000000).c_str());
+              clock->TimeToString((uint64_t)now / 1000000).c_str());
     }
 
     shared.SetStartVerify();
@@ -142,11 +143,11 @@ bool RunStressTest(StressTest* stress) {
     delete threads[i];
     threads[i] = nullptr;
   }
-  now = db_stress_env->NowMicros();
+  now = clock->NowMicros();
   if (!FLAGS_skip_verifydb && !FLAGS_test_batches_snapshots &&
       !shared.HasVerificationFailedYet()) {
     fprintf(stdout, "%s Verification successful\n",
-            db_stress_env->TimeToString(now / 1000000).c_str());
+            clock->TimeToString(now / 1000000).c_str());
   }
   stress->PrintStatistics();
 

db_stress_tool/db_stress_stat.h

@@ -11,9 +11,9 @@
 
 #include "monitoring/histogram.h"
 #include "port/port.h"
-#include "rocksdb/env.h"
 #include "rocksdb/snapshot.h"
 #include "rocksdb/statistics.h"
+#include "rocksdb/system_clock.h"
 #include "util/gflags_compat.h"
 #include "util/random.h"
 
@@ -73,7 +73,7 @@ class Stats {
     seconds_ = 0;
     num_compact_files_succeed_ = 0;
     num_compact_files_failed_ = 0;
-    start_ = Env::Default()->NowMicros();
+    start_ = SystemClock::Default()->NowMicros();
     last_op_finish_ = start_;
     finish_ = start_;
   }
@@ -102,13 +102,13 @@ class Stats {
   }
 
   void Stop() {
-    finish_ = Env::Default()->NowMicros();
+    finish_ = SystemClock::Default()->NowMicros();
     seconds_ = (finish_ - start_) * 1e-6;
   }
 
   void FinishedSingleOp() {
     if (FLAGS_histogram) {
-      auto now = Env::Default()->NowMicros();
+      auto now = SystemClock::Default()->NowMicros();
       auto micros = now - last_op_finish_;
       hist_.Add(micros);
       if (micros > 20000) {

db_stress_tool/db_stress_test_base.cc

@@ -35,6 +35,7 @@ StressTest::StressTest()
 #ifndef ROCKSDB_LITE
       txn_db_(nullptr),
 #endif
+      clock_(db_stress_env->GetSystemClock().get()),
       new_column_family_name_(1),
       num_times_reopened_(0),
       db_preload_finished_(false),
@@ -226,9 +227,9 @@ bool StressTest::BuildOptionsTable() {
 }
 
 void StressTest::InitDb() {
-  uint64_t now = db_stress_env->NowMicros();
+  uint64_t now = clock_->NowMicros();
   fprintf(stdout, "%s Initializing db_stress\n",
-          db_stress_env->TimeToString(now / 1000000).c_str());
+          clock_->TimeToString(now / 1000000).c_str());
   PrintEnv();
   Open();
   BuildOptionsTable();
@@ -236,9 +237,9 @@ void StressTest::InitDb() {
 
 void StressTest::FinishInitDb(SharedState* shared) {
   if (FLAGS_read_only) {
-    uint64_t now = db_stress_env->NowMicros();
+    uint64_t now = clock_->NowMicros();
     fprintf(stdout, "%s Preloading db with %" PRIu64 " KVs\n",
-            db_stress_env->TimeToString(now / 1000000).c_str(), FLAGS_max_key);
+            clock_->TimeToString(now / 1000000).c_str(), FLAGS_max_key);
     PreloadDbAndReopenAsReadOnly(FLAGS_max_key, shared);
   }
   if (FLAGS_enable_compaction_filter) {
@@ -255,10 +256,9 @@ void StressTest::FinishInitDb(SharedState* shared) {
 bool StressTest::VerifySecondaries() {
 #ifndef ROCKSDB_LITE
   if (FLAGS_test_secondary) {
-    uint64_t now = db_stress_env->NowMicros();
-    fprintf(
-        stdout, "%s Start to verify secondaries against primary\n",
-        db_stress_env->TimeToString(static_cast<uint64_t>(now) / 1000000).c_str());
+    uint64_t now = clock_->NowMicros();
+    fprintf(stdout, "%s Start to verify secondaries against primary\n",
+            clock_->TimeToString(static_cast<uint64_t>(now) / 1000000).c_str());
   }
   for (size_t k = 0; k != secondaries_.size(); ++k) {
     Status s = secondaries_[k]->TryCatchUpWithPrimary();
@@ -300,10 +300,9 @@ bool StressTest::VerifySecondaries() {
     }
   }
   if (FLAGS_test_secondary) {
-    uint64_t now = db_stress_env->NowMicros();
-    fprintf(
-        stdout, "%s Verification of secondaries succeeded\n",
-        db_stress_env->TimeToString(static_cast<uint64_t>(now) / 1000000).c_str());
+    uint64_t now = clock_->NowMicros();
+    fprintf(stdout, "%s Verification of secondaries succeeded\n",
+            clock_->TimeToString(static_cast<uint64_t>(now) / 1000000).c_str());
   }
 #endif  // ROCKSDB_LITE
   return true;
@@ -462,9 +461,9 @@ void StressTest::PreloadDbAndReopenAsReadOnly(int64_t number_of_keys,
 #endif
 
     db_preload_finished_.store(true);
-    auto now = db_stress_env->NowMicros();
+    auto now = clock_->NowMicros();
     fprintf(stdout, "%s Reopening database in read-only\n",
-            db_stress_env->TimeToString(now / 1000000).c_str());
+            clock_->TimeToString(now / 1000000).c_str());
     // Reopen as read-only, can ignore all options related to updates
     Open();
   } else {
@@ -1724,7 +1723,7 @@ Status StressTest::TestPauseBackground(ThreadState* thread) {
   // 1 chance in 625 of pausing full 16s.)
   int pwr2_micros =
       std::min(thread->rand.Uniform(25), thread->rand.Uniform(25));
-  db_stress_env->SleepForMicroseconds(1 << pwr2_micros);
+  clock_->SleepForMicroseconds(1 << pwr2_micros);
   return db_->ContinueBackgroundWork();
 }
 
@@ -2487,10 +2486,9 @@ void StressTest::Reopen(ThreadState* thread) {
   secondaries_.clear();
 
   num_times_reopened_++;
-  auto now = db_stress_env->NowMicros();
+  auto now = clock_->NowMicros();
   fprintf(stdout, "%s Reopening database for the %dth time\n",
-          db_stress_env->TimeToString(now / 1000000).c_str(),
-          num_times_reopened_);
+          clock_->TimeToString(now / 1000000).c_str(), num_times_reopened_);
   Open();
 }
 }  // namespace ROCKSDB_NAMESPACE

db_stress_tool/db_stress_test_base.h

@@ -13,6 +13,7 @@
 #include "db_stress_tool/db_stress_shared_state.h"
 
 namespace ROCKSDB_NAMESPACE {
+class SystemClock;
 class Transaction;
 class TransactionDB;
 
@@ -218,6 +219,7 @@ class StressTest {
   TransactionDB* txn_db_;
 #endif
   Options options_;
+  SystemClock* clock_;
   std::vector<ColumnFamilyHandle*> column_families_;
   std::vector<std::string> column_family_names_;
   std::atomic<int> new_column_family_name_;

env/env_encryption.cc

@@ -15,6 +15,7 @@
 #include "env/env_encryption_ctr.h"
 #include "monitoring/perf_context_imp.h"
 #include "rocksdb/convenience.h"
+#include "rocksdb/system_clock.h"
 #include "util/aligned_buffer.h"
 #include "util/coding.h"
 #include "util/random.h"
@@ -1063,7 +1064,7 @@ Status CTREncryptionProvider::CreateNewPrefix(const std::string& /*fname*/,
     return Status::InvalidArgument("Encryption Cipher is missing");
   }
   // Create & seed rnd.
-  Random rnd((uint32_t)Env::Default()->NowMicros());
+  Random rnd((uint32_t)SystemClock::Default()->NowMicros());
   // Fill entire prefix block with random values.
   for (size_t i = 0; i < prefixLength; i++) {
     prefix[i] = rnd.Uniform(256) & 0xFF;

env/env_test.cc

@@ -2215,7 +2215,7 @@ TEST_F(EnvTest, IsDirectory) {
     std::unique_ptr<WritableFileWriter> fwriter;
     fwriter.reset(new WritableFileWriter(std::move(wfile), test_file_path,
                                          FileOptions(),
-                                         SystemClock::Default()));
+                                         SystemClock::Default().get()));
     constexpr char buf[] = "test";
     s = fwriter->Append(buf);
     ASSERT_OK(s);

env/file_system_tracer.h

@@ -23,7 +23,7 @@ class FileSystemTracingWrapper : public FileSystemWrapper {
                            const std::shared_ptr<IOTracer>& io_tracer)
       : FileSystemWrapper(t),
         io_tracer_(io_tracer),
-        clock_(SystemClock::Default()) {}
+        clock_(SystemClock::Default().get()) {}
 
   ~FileSystemTracingWrapper() override {}
 
@@ -86,7 +86,7 @@ class FileSystemTracingWrapper : public FileSystemWrapper {
 
  private:
   std::shared_ptr<IOTracer> io_tracer_;
-  std::shared_ptr<SystemClock> clock_;
+  SystemClock* clock_;
 };
 
 // The FileSystemPtr is a wrapper class that takes pointer to storage systems
@@ -138,7 +138,7 @@ class FSSequentialFileTracingWrapper : public FSSequentialFileWrapper {
                                  const std::string& file_name)
       : FSSequentialFileWrapper(t),
         io_tracer_(io_tracer),
-        clock_(SystemClock::Default()),
+        clock_(SystemClock::Default().get()),
         file_name_(file_name) {}
 
   ~FSSequentialFileTracingWrapper() override {}
@@ -154,7 +154,7 @@ class FSSequentialFileTracingWrapper : public FSSequentialFileWrapper {
 
  private:
   std::shared_ptr<IOTracer> io_tracer_;
-  std::shared_ptr<SystemClock> clock_;
+  SystemClock* clock_;
   std::string file_name_;
 };
 
@@ -210,7 +210,7 @@ class FSRandomAccessFileTracingWrapper : public FSRandomAccessFileWrapper {
                                    const std::string& file_name)
       : FSRandomAccessFileWrapper(t),
         io_tracer_(io_tracer),
-        clock_(SystemClock::Default()),
+        clock_(SystemClock::Default().get()),
         file_name_(file_name) {}
 
   ~FSRandomAccessFileTracingWrapper() override {}
@@ -229,7 +229,7 @@ class FSRandomAccessFileTracingWrapper : public FSRandomAccessFileWrapper {
 
  private:
   std::shared_ptr<IOTracer> io_tracer_;
-  std::shared_ptr<SystemClock> clock_;
+  SystemClock* clock_;
   // Stores file name instead of full path.
   std::string file_name_;
 };
@@ -285,7 +285,7 @@ class FSWritableFileTracingWrapper : public FSWritableFileWrapper {
                                const std::string& file_name)
       : FSWritableFileWrapper(t),
         io_tracer_(io_tracer),
-        clock_(SystemClock::Default()),
+        clock_(SystemClock::Default().get()),
         file_name_(file_name) {}
 
   ~FSWritableFileTracingWrapper() override {}
@@ -319,7 +319,7 @@ class FSWritableFileTracingWrapper : public FSWritableFileWrapper {
 
  private:
   std::shared_ptr<IOTracer> io_tracer_;
-  std::shared_ptr<SystemClock> clock_;
+  SystemClock* clock_;
   // Stores file name instead of full path.
   std::string file_name_;
 };
@@ -382,7 +382,7 @@ class FSRandomRWFileTracingWrapper : public FSRandomRWFileWrapper {
                                const std::string& file_name)
       : FSRandomRWFileWrapper(t),
         io_tracer_(io_tracer),
-        clock_(SystemClock::Default()),
+        clock_(SystemClock::Default().get()),
         file_name_(file_name) {}
 
   ~FSRandomRWFileTracingWrapper() override {}
@@ -404,7 +404,7 @@ class FSRandomRWFileTracingWrapper : public FSRandomRWFileWrapper {
 
  private:
   std::shared_ptr<IOTracer> io_tracer_;
-  std::shared_ptr<SystemClock> clock_;
+  SystemClock* clock_;
   // Stores file name instead of full path.
   std::string file_name_;
 };

env/fs_posix.cc

@@ -774,7 +774,9 @@ class PosixFileSystem : public FileSystem {
     LockHoldingInfo lhi;
     int64_t current_time = 0;
     // Ignore status code as the time is only used for error message.
-    Env::Default()->GetCurrentTime(&current_time).PermitUncheckedError();
+    SystemClock::Default()
+        ->GetCurrentTime(&current_time)
+        .PermitUncheckedError();
     lhi.acquire_time = current_time;
     lhi.acquiring_thread = Env::Default()->GetThreadID();
 

env/mock_env.cc

@@ -1033,26 +1033,43 @@ Status MockFileSystem::CorruptBuffer(const std::string& fname) {
   iter->second->CorruptBuffer();
   return Status::OK();
 }
+namespace {
+class MockSystemClock : public SystemClockWrapper {
+ public:
+  explicit MockSystemClock(const std::shared_ptr<SystemClock>& c)
+      : SystemClockWrapper(c), fake_sleep_micros_(0) {}
 
-MockEnv::MockEnv(Env* base_env)
-    : CompositeEnvWrapper(base_env, std::make_shared<MockFileSystem>(this)),
-      fake_sleep_micros_(0) {}
+  void FakeSleepForMicroseconds(int64_t micros) {
+    fake_sleep_micros_.fetch_add(micros);
+  }
+
+  const char* Name() const override { return "MockSystemClock"; }
 
-Status MockEnv::GetCurrentTime(int64_t* unix_time) {
-  auto s = CompositeEnvWrapper::GetCurrentTime(unix_time);
-  if (s.ok()) {
-    *unix_time += fake_sleep_micros_.load() / (1000 * 1000);
+  Status GetCurrentTime(int64_t* unix_time) override {
+    auto s = SystemClockWrapper::GetCurrentTime(unix_time);
+    if (s.ok()) {
+      auto fake_time = fake_sleep_micros_.load() / (1000 * 1000);
+      *unix_time += fake_time;
+    }
+    return s;
   }
-  return s;
-}
 
-uint64_t MockEnv::NowMicros() {
-  return CompositeEnvWrapper::NowMicros() + fake_sleep_micros_.load();
-}
+  uint64_t NowMicros() override {
+    return SystemClockWrapper::NowMicros() + fake_sleep_micros_.load();
+  }
 
-uint64_t MockEnv::NowNanos() {
-  return CompositeEnvWrapper::NowNanos() + fake_sleep_micros_.load() * 1000;
-}
+  uint64_t NowNanos() override {
+    return SystemClockWrapper::NowNanos() + fake_sleep_micros_.load() * 1000;
+  }
+
+ private:
+  std::atomic<int64_t> fake_sleep_micros_;
+};
+}  // namespace
+MockEnv::MockEnv(Env* base_env)
+    : CompositeEnvWrapper(
+          base_env, std::make_shared<MockFileSystem>(this),
+          std::make_shared<MockSystemClock>(base_env->GetSystemClock())) {}
 
 Status MockEnv::CorruptBuffer(const std::string& fname) {
   auto mock = static_cast_with_check<MockFileSystem>(GetFileSystem().get());
@@ -1060,7 +1077,8 @@ Status MockEnv::CorruptBuffer(const std::string& fname) {
 }
 
 void MockEnv::FakeSleepForMicroseconds(int64_t micros) {
-  fake_sleep_micros_.fetch_add(micros);
+  auto mock = static_cast_with_check<MockSystemClock>(GetSystemClock().get());
+  mock->FakeSleepForMicroseconds(micros);
 }
 
 #ifndef ROCKSDB_LITE

env/mock_env.h

@@ -23,11 +23,6 @@ class MockEnv : public CompositeEnvWrapper {
  public:
   explicit MockEnv(Env* base_env);
 
-  // Results of these can be affected by FakeSleepForMicroseconds()
-  Status GetCurrentTime(int64_t* unix_time) override;
-  uint64_t NowMicros() override;
-  uint64_t NowNanos() override;
-
   Status CorruptBuffer(const std::string& fname);
 
   // Doesn't really sleep, just affects output of GetCurrentTime(), NowMicros()
@@ -35,7 +30,6 @@ class MockEnv : public CompositeEnvWrapper {
   void FakeSleepForMicroseconds(int64_t micros);
 
  private:
-  std::atomic<int64_t> fake_sleep_micros_;
 };
 
 }  // namespace ROCKSDB_NAMESPACE

file/delete_scheduler.cc

@@ -22,9 +22,8 @@
 
 namespace ROCKSDB_NAMESPACE {
 
-DeleteScheduler::DeleteScheduler(const std::shared_ptr<SystemClock>& clock,
-                                 FileSystem* fs, int64_t rate_bytes_per_sec,
-                                 Logger* info_log,
+DeleteScheduler::DeleteScheduler(SystemClock* clock, FileSystem* fs,
+                                 int64_t rate_bytes_per_sec, Logger* info_log,
                                  SstFileManagerImpl* sst_file_manager,
                                  double max_trash_db_ratio,
                                  uint64_t bytes_max_delete_chunk)

file/delete_scheduler.h

@@ -34,7 +34,7 @@ class SystemClock;
 // case DeleteScheduler will delete files immediately.
 class DeleteScheduler {
  public:
-  DeleteScheduler(const std::shared_ptr<SystemClock>& clock, FileSystem* fs,
+  DeleteScheduler(SystemClock* clock, FileSystem* fs,
                   int64_t rate_bytes_per_sec, Logger* info_log,
                   SstFileManagerImpl* sst_file_manager,
                   double max_trash_db_ratio, uint64_t bytes_max_delete_chunk);
@@ -101,7 +101,7 @@ class DeleteScheduler {
 
   void MaybeCreateBackgroundThread();
 
-  const std::shared_ptr<SystemClock> clock_;
+  SystemClock* clock_;
   FileSystem* fs_;
 
   // total size of trash files

file/file_util.h

@@ -68,9 +68,8 @@ inline IOStatus GenerateOneFileChecksum(
       allow_mmap_reads, io_tracer);
 }
 
-inline IOStatus PrepareIOFromReadOptions(
-    const ReadOptions& ro, const std::shared_ptr<SystemClock>& clock,
-    IOOptions& opts) {
+inline IOStatus PrepareIOFromReadOptions(const ReadOptions& ro,
+                                         SystemClock* clock, IOOptions& opts) {
   if (ro.deadline.count()) {
     std::chrono::microseconds now =
         std::chrono::microseconds(clock->NowMicros());

file/filename.cc

@@ -419,11 +419,11 @@ Status SetIdentityFile(Env* env, const std::string& dbname,
   return s;
 }
 
-IOStatus SyncManifest(const std::shared_ptr<SystemClock>& clock,
-                      const ImmutableDBOptions* db_options,
+IOStatus SyncManifest(const ImmutableDBOptions* db_options,
                       WritableFileWriter* file) {
   TEST_KILL_RANDOM("SyncManifest:0", rocksdb_kill_odds * REDUCE_ODDS2);
-  StopWatch sw(clock, db_options->statistics.get(), MANIFEST_FILE_SYNC_MICROS);
+  StopWatch sw(db_options->clock, db_options->statistics.get(),
+               MANIFEST_FILE_SYNC_MICROS);
   return file->Sync(db_options->use_fsync);
 }
 

file/filename.h

@@ -167,8 +167,7 @@ extern Status SetIdentityFile(Env* env, const std::string& dbname,
                               const std::string& db_id = {});
 
 // Sync manifest file `file`.
-extern IOStatus SyncManifest(const std::shared_ptr<SystemClock>& clock,
-                             const ImmutableDBOptions* db_options,
+extern IOStatus SyncManifest(const ImmutableDBOptions* db_options,
                              WritableFileWriter* file);
 
 // Return list of file names of info logs in `file_names`.

file/random_access_file_reader.cc

@@ -326,10 +326,10 @@ Status RandomAccessFileReader::MultiRead(const IOOptions& opts,
 
 IOStatus RandomAccessFileReader::PrepareIOOptions(const ReadOptions& ro,
                                                   IOOptions& opts) {
-  if (clock_.get() != nullptr) {
+  if (clock_ != nullptr) {
     return PrepareIOFromReadOptions(ro, clock_, opts);
   } else {
-    return PrepareIOFromReadOptions(ro, SystemClock::Default(), opts);
+    return PrepareIOFromReadOptions(ro, SystemClock::Default().get(), opts);
   }
 }
 }  // namespace ROCKSDB_NAMESPACE

file/random_access_file_reader.h

@@ -67,7 +67,7 @@ class RandomAccessFileReader {
 
   FSRandomAccessFilePtr file_;
   std::string file_name_;
-  std::shared_ptr<SystemClock> clock_;
+  SystemClock* clock_;
   Statistics* stats_;
   uint32_t hist_type_;
   HistogramImpl* file_read_hist_;
@@ -77,7 +77,7 @@ class RandomAccessFileReader {
  public:
   explicit RandomAccessFileReader(
       std::unique_ptr<FSRandomAccessFile>&& raf, const std::string& _file_name,
-      const std::shared_ptr<SystemClock>& clock = nullptr,
+      SystemClock* clock = nullptr,
       const std::shared_ptr<IOTracer>& io_tracer = nullptr,
       Statistics* stats = nullptr, uint32_t hist_type = 0,
       HistogramImpl* file_read_hist = nullptr,

file/random_access_file_reader_test.cc

@@ -43,7 +43,7 @@ class RandomAccessFileReaderTest : public testing::Test {
     std::unique_ptr<FSRandomAccessFile> f;
     ASSERT_OK(fs_->NewRandomAccessFile(fpath, opts, &f, nullptr));
     (*reader).reset(new RandomAccessFileReader(std::move(f), fpath,
-                                               env_->GetSystemClock()));
+                                               env_->GetSystemClock().get()));
   }
 
   void AssertResult(const std::string& content,

file/sst_file_manager_impl.cc

@@ -31,8 +31,9 @@ SstFileManagerImpl::SstFileManagerImpl(
       compaction_buffer_size_(0),
       cur_compactions_reserved_size_(0),
       max_allowed_space_(0),
-      delete_scheduler_(clock_, fs_.get(), rate_bytes_per_sec, logger.get(),
-                        this, max_trash_db_ratio, bytes_max_delete_chunk),
+      delete_scheduler_(clock_.get(), fs_.get(), rate_bytes_per_sec,
+                        logger.get(), this, max_trash_db_ratio,
+                        bytes_max_delete_chunk),
       cv_(&mu_),
       closing_(false),
       bg_thread_(nullptr),

file/writable_file_writer.h

@@ -123,7 +123,7 @@ class WritableFileWriter {
 
   std::string file_name_;
   FSWritableFilePtr writable_file_;
-  std::shared_ptr<SystemClock> clock_;
+  SystemClock* clock_;
   AlignedBuffer buf_;
   size_t max_buffer_size_;
   // Actually written data size can be used for truncate
@@ -148,8 +148,7 @@ class WritableFileWriter {
  public:
   WritableFileWriter(
       std::unique_ptr<FSWritableFile>&& file, const std::string& _file_name,
-      const FileOptions& options,
-      const std::shared_ptr<SystemClock>& clock = nullptr,
+      const FileOptions& options, SystemClock* clock = nullptr,
       const std::shared_ptr<IOTracer>& io_tracer = nullptr,
       Statistics* stats = nullptr,
       const std::vector<std::shared_ptr<EventListener>>& listeners = {},

include/rocksdb/metadata.h

@@ -117,13 +117,13 @@ struct SstFileMetaData {
   // An SST file may be generated by compactions whose input files may
   // in turn be generated by earlier compactions. The creation time of the
   // oldest SST file that is the compaction ancester of this file.
-  // The timestamp is provided Env::GetCurrentTime().
+  // The timestamp is provided SystemClock::GetCurrentTime().
   // 0 if the information is not available.
   //
   // Note: for TTL blob files, it contains the start of the expiration range.
   uint64_t oldest_ancester_time;
-  // Timestamp when the SST file is created, provided by Env::GetCurrentTime().
-  // 0 if the information is not available.
+  // Timestamp when the SST file is created, provided by
+  // SystemClock::GetCurrentTime(). 0 if the information is not available.
   uint64_t file_creation_time;
 
   // The checksum of a SST file, the value is decided by the file content and

logging/env_logger.h

@@ -31,9 +31,10 @@ class EnvLogger : public Logger {
             const std::string& fname, const EnvOptions& options, Env* env,
             InfoLogLevel log_level = InfoLogLevel::ERROR_LEVEL)
       : Logger(log_level),
-        file_(std::move(writable_file), fname, options, env->GetSystemClock()),
-        last_flush_micros_(0),
         env_(env),
+        clock_(env_->GetSystemClock().get()),
+        file_(std::move(writable_file), fname, options, clock_),
+        last_flush_micros_(0),
         flush_pending_(false) {}
 
   ~EnvLogger() {
@@ -50,7 +51,7 @@ class EnvLogger : public Logger {
       flush_pending_ = false;
       file_.Flush().PermitUncheckedError();
     }
-    last_flush_micros_ = env_->NowMicros();
+    last_flush_micros_ = clock_->NowMicros();
   }
 
   void Flush() override {
@@ -136,7 +137,7 @@ class EnvLogger : public Logger {
       // We will ignore any error returned by Append().
       file_.Append(Slice(base, p - base)).PermitUncheckedError();
       flush_pending_ = true;
-      const uint64_t now_micros = env_->NowMicros();
+      const uint64_t now_micros = clock_->NowMicros();
       if (now_micros - last_flush_micros_ >= flush_every_seconds_ * 1000000) {
         FlushLocked();
       }
@@ -154,11 +155,12 @@ class EnvLogger : public Logger {
   }
 
  private:
+  Env* env_;
+  SystemClock* clock_;
   WritableFileWriter file_;
   mutable port::Mutex mutex_;  // Mutex to protect the shared variables below.
   const static uint64_t flush_every_seconds_ = 5;
   std::atomic_uint_fast64_t last_flush_micros_;
-  Env* env_;
   std::atomic<bool> flush_pending_;
 };
 

memtable/memtablerep_bench.cc

@@ -418,7 +418,7 @@ class Benchmark {
     uint64_t bytes_written = 0;
     uint64_t bytes_read = 0;
     uint64_t read_hits = 0;
-    StopWatchNano timer(SystemClock::Default(), true);
+    StopWatchNano timer(SystemClock::Default().get(), true);
     RunThreads(&threads, &bytes_written, &bytes_read, true, &read_hits);
     auto elapsed_time = static_cast<double>(timer.ElapsedNanos() / 1000);
     std::cout << "Elapsed time: " << static_cast<int>(elapsed_time) << " us"

monitoring/instrumented_mutex.cc

@@ -13,9 +13,8 @@
 namespace ROCKSDB_NAMESPACE {
 namespace {
 #ifndef NPERF_CONTEXT
-Statistics* stats_for_report(const std::shared_ptr<SystemClock>& clock,
-                             Statistics* stats) {
-  if (clock.get() != nullptr && stats != nullptr &&
+Statistics* stats_for_report(SystemClock* clock, Statistics* stats) {
+  if (clock != nullptr && stats != nullptr &&
       stats->get_stats_level() > kExceptTimeForMutex) {
     return stats;
   } else {

monitoring/instrumented_mutex.h

@@ -22,12 +22,10 @@ class InstrumentedMutex {
   explicit InstrumentedMutex(bool adaptive = false)
       : mutex_(adaptive), stats_(nullptr), clock_(nullptr), stats_code_(0) {}
 
-  explicit InstrumentedMutex(const std::shared_ptr<SystemClock>& clock,
-                             bool adaptive = false)
+  explicit InstrumentedMutex(SystemClock* clock, bool adaptive = false)
       : mutex_(adaptive), stats_(nullptr), clock_(clock), stats_code_(0) {}
 
-  InstrumentedMutex(Statistics* stats,
-                    const std::shared_ptr<SystemClock>& clock, int stats_code,
+  InstrumentedMutex(Statistics* stats, SystemClock* clock, int stats_code,
                     bool adaptive = false)
       : mutex_(adaptive),
         stats_(stats),
@@ -49,7 +47,7 @@ class InstrumentedMutex {
   friend class InstrumentedCondVar;
   port::Mutex mutex_;
   Statistics* stats_;
-  std::shared_ptr<SystemClock> clock_;
+  SystemClock* clock_;
   int stats_code_;
 };
 
@@ -96,7 +94,7 @@ class InstrumentedCondVar {
   bool TimedWaitInternal(uint64_t abs_time_us);
   port::CondVar cond_;
   Statistics* stats_;
-  const std::shared_ptr<SystemClock> clock_;
+  SystemClock* clock_;
   int stats_code_;
 };
 

monitoring/iostats_context_imp.h

@@ -40,7 +40,7 @@ extern __thread IOStatsContext iostats_context;
 // Declare and set start time of the timer
 #define IOSTATS_CPU_TIMER_GUARD(metric, clock)         \
   PerfStepTimer iostats_step_timer_##metric(           \
-      &(iostats_context.metric), clock.get(), true,    \
+      &(iostats_context.metric), clock, true,          \
       PerfLevel::kEnableTimeAndCPUTimeExceptForMutex); \
   iostats_step_timer_##metric.Start();
 

monitoring/perf_context_imp.h

@@ -46,14 +46,14 @@ extern thread_local PerfContext perf_context;
   perf_step_timer_##metric.Start();
 
 // Declare and set start time of the timer
-#define PERF_TIMER_GUARD_WITH_CLOCK(metric, clock)                             \
-  PerfStepTimer perf_step_timer_##metric(&(perf_context.metric), clock.get()); \
+#define PERF_TIMER_GUARD_WITH_CLOCK(metric, clock)                       \
+  PerfStepTimer perf_step_timer_##metric(&(perf_context.metric), clock); \
   perf_step_timer_##metric.Start();
 
 // Declare and set start time of the timer
 #define PERF_CPU_TIMER_GUARD(metric, clock)            \
   PerfStepTimer perf_step_timer_##metric(              \
-      &(perf_context.metric), clock.get(), true,       \
+      &(perf_context.metric), clock, true,             \
       PerfLevel::kEnableTimeAndCPUTimeExceptForMutex); \
   perf_step_timer_##metric.Start();
 

options/cf_options.cc

@@ -818,6 +818,7 @@ ImmutableCFOptions::ImmutableCFOptions(const ImmutableDBOptions& db_options,
       info_log_level(db_options.info_log_level),
       env(db_options.env),
       fs(db_options.fs.get()),
+      clock(db_options.clock),
       allow_mmap_reads(db_options.allow_mmap_reads),
       allow_mmap_writes(db_options.allow_mmap_writes),
       db_paths(db_options.db_paths),

options/cf_options.h

@@ -64,6 +64,8 @@ struct ImmutableCFOptions {
 
   FileSystem* fs;
 
+  SystemClock* clock;
+
   // Allow the OS to mmap file for reading sst tables. Default: false
   bool allow_mmap_reads;
 

options/db_options.cc

@@ -17,6 +17,7 @@
 #include "rocksdb/file_system.h"
 #include "rocksdb/rate_limiter.h"
 #include "rocksdb/sst_file_manager.h"
+#include "rocksdb/system_clock.h"
 #include "rocksdb/utilities/options_type.h"
 #include "rocksdb/wal_filter.h"
 #include "util/string_util.h"
@@ -582,6 +583,11 @@ ImmutableDBOptions::ImmutableDBOptions(const DBOptions& options)
       allow_data_in_errors(options.allow_data_in_errors),
       db_host_id(options.db_host_id),
       checksum_handoff_file_types(options.checksum_handoff_file_types) {
+  if (env != nullptr) {
+    clock = env->GetSystemClock().get();
+  } else {
+    clock = SystemClock::Default().get();
+  }
 }
 
 void ImmutableDBOptions::Dump(Logger* log) const {

options/db_options.h

@@ -11,6 +11,7 @@
 #include "rocksdb/options.h"
 
 namespace ROCKSDB_NAMESPACE {
+class SystemClock;
 
 struct ImmutableDBOptions {
   static const char* kName() { return "ImmutableDBOptions"; }
@@ -26,6 +27,7 @@ struct ImmutableDBOptions {
   bool track_and_verify_wals_in_manifest;
   Env* env;
   std::shared_ptr<FileSystem> fs;
+  SystemClock* clock;
   std::shared_ptr<RateLimiter> rate_limiter;
   std::shared_ptr<SstFileManager> sst_file_manager;
   std::shared_ptr<Logger> info_log;

port/win/env_win.cc

@@ -1059,7 +1059,7 @@ IOStatus WinFileSystem::NewLogger(const std::string& fname,
       // Set creation, last access and last write time to the same value
       SetFileTime(hFile, &ft, &ft, &ft);
     }
-    result->reset(new WinLogger(&WinEnvThreads::gettid, clock_, hFile));
+    result->reset(new WinLogger(&WinEnvThreads::gettid, clock_.get(), hFile));
   }
   return s;
 }

port/win/win_logger.cc

@@ -32,8 +32,7 @@ namespace ROCKSDB_NAMESPACE {
 
 namespace port {
 
-WinLogger::WinLogger(uint64_t (*gettid)(),
-                     const std::shared_ptr<SystemClock>& clock, HANDLE file,
+WinLogger::WinLogger(uint64_t (*gettid)(), SystemClock* clock, HANDLE file,
                      const InfoLogLevel log_level)
     : Logger(log_level),
       file_(file),

port/win/win_logger.h

@@ -26,8 +26,7 @@ class SystemClock;
 namespace port {
 class WinLogger : public ROCKSDB_NAMESPACE::Logger {
  public:
-  WinLogger(uint64_t (*gettid)(), const std::shared_ptr<SystemClock>& clock,
-            HANDLE file,
+  WinLogger(uint64_t (*gettid)(), SystemClock* clock, HANDLE file,
             const InfoLogLevel log_level = InfoLogLevel::ERROR_LEVEL);
 
   virtual ~WinLogger();
@@ -54,7 +53,7 @@ protected:
   uint64_t (*gettid_)();  // Return the thread id for the current thread
   std::atomic_size_t log_size_;
   std::atomic_uint_fast64_t last_flush_micros_;
-  std::shared_ptr<SystemClock> clock_;
+  SystemClock* clock_;
   bool flush_pending_;
 
   Status CloseInternal();

table/block_based/block_based_table_builder.cc

@@ -1083,7 +1083,7 @@ void BlockBasedTableBuilder::CompressAndVerifyBlock(
   bool abort_compression = false;
 
   StopWatchNano timer(
-      r->ioptions.env->GetSystemClock(),
+      r->ioptions.clock,
       ShouldReportDetailedTime(r->ioptions.env, r->ioptions.statistics));
 
   if (is_status_ok && raw_block_contents.size() < kCompressionSizeLimit) {
@@ -1177,7 +1177,7 @@ void BlockBasedTableBuilder::WriteRawBlock(const Slice& block_contents,
   Rep* r = rep_;
   Status s = Status::OK();
   IOStatus io_s = IOStatus::OK();
-  StopWatch sw(r->ioptions.env->GetSystemClock(), r->ioptions.statistics,
+  StopWatch sw(r->ioptions.clock, r->ioptions.statistics,
                WRITE_RAW_BLOCK_MICROS);
   handle->set_offset(r->get_offset());
   handle->set_size(block_contents.size());

table/block_based/block_based_table_reader.cc

@@ -1501,7 +1501,7 @@ Status BlockBasedTable::MaybeReadBlockAndLoadToCache(
       CompressionType raw_block_comp_type;
       BlockContents raw_block_contents;
       if (!contents) {
-        StopWatch sw(rep_->clock, statistics, READ_BLOCK_GET_MICROS);
+        StopWatch sw(rep_->ioptions.clock, statistics, READ_BLOCK_GET_MICROS);
         BlockFetcher block_fetcher(
             rep_->file.get(), prefetch_buffer, rep_->footer, ro, handle,
             &raw_block_contents, rep_->ioptions, do_uncompress,
@@ -1590,7 +1590,7 @@ Status BlockBasedTable::MaybeReadBlockAndLoadToCache(
       // Avoid making copy of block_key and cf_name when constructing the access
       // record.
       BlockCacheTraceRecord access_record(
-          rep_->clock->NowMicros(),
+          rep_->ioptions.clock->NowMicros(),
           /*block_key=*/"", trace_block_type,
           /*block_size=*/usage, rep_->cf_id_for_tracing(),
           /*cf_name=*/"", rep_->level_for_tracing(),
@@ -1935,7 +1935,8 @@ Status BlockBasedTable::RetrieveBlock(
   std::unique_ptr<TBlocklike> block;
 
   {
-    StopWatch sw(rep_->clock, rep_->ioptions.statistics, READ_BLOCK_GET_MICROS);
+    StopWatch sw(rep_->ioptions.clock, rep_->ioptions.statistics,
+                 READ_BLOCK_GET_MICROS);
     s = ReadBlockFromFile(
         rep_->file.get(), prefetch_buffer, rep_->footer, ro, handle, &block,
         rep_->ioptions, do_uncompress, maybe_compressed, block_type,
@@ -2427,7 +2428,7 @@ Status BlockBasedTable::Get(const ReadOptions& read_options, const Slice& key,
           referenced_key = key;
         }
         BlockCacheTraceRecord access_record(
-            rep_->clock->NowMicros(),
+            rep_->ioptions.clock->NowMicros(),
             /*block_key=*/"", lookup_data_block_context.block_type,
             lookup_data_block_context.block_size, rep_->cf_id_for_tracing(),
             /*cf_name=*/"", rep_->level_for_tracing(),
@@ -2763,7 +2764,7 @@ void BlockBasedTable::MultiGet(const ReadOptions& read_options,
             referenced_key = key;
           }
           BlockCacheTraceRecord access_record(
-              rep_->clock->NowMicros(),
+              rep_->ioptions.clock->NowMicros(),
               /*block_key=*/"", lookup_data_block_context.block_type,
               lookup_data_block_context.block_size, rep_->cf_id_for_tracing(),
               /*cf_name=*/"", rep_->level_for_tracing(),

table/block_based/block_based_table_reader.h

@@ -32,7 +32,6 @@ class Footer;
 class InternalKeyComparator;
 class Iterator;
 class FSRandomAccessFile;
-class SystemClock;
 class TableCache;
 class TableReader;
 class WritableFile;
@@ -521,7 +520,6 @@ struct BlockBasedTable::Rep {
         file_size(_file_size),
         level(_level),
         immortal_table(_immortal_table) {
-    clock = ioptions.env->GetSystemClock();
   }
   ~Rep() { status.PermitUncheckedError(); }
   const ImmutableCFOptions& ioptions;
@@ -529,7 +527,6 @@ struct BlockBasedTable::Rep {
   const BlockBasedTableOptions table_options;
   const FilterPolicy* const filter_policy;
   const InternalKeyComparator& internal_comparator;
-  std::shared_ptr<SystemClock> clock;
   Status status;
   std::unique_ptr<RandomAccessFileReader> file;
   char cache_key_prefix[kMaxCacheKeyPrefixSize];

table/block_based/block_based_table_reader_test.cc

@@ -135,8 +135,8 @@ class BlockBasedTableReaderTest
     std::string path = Path(filename);
     std::unique_ptr<FSRandomAccessFile> f;
     ASSERT_OK(fs_->NewRandomAccessFile(path, opt, &f, nullptr));
-    reader->reset(
-        new RandomAccessFileReader(std::move(f), path, env_->GetSystemClock()));
+    reader->reset(new RandomAccessFileReader(std::move(f), path,
+                                             env_->GetSystemClock().get()));
   }
 
   std::string ToInternalKey(const std::string& key) {

table/block_fetcher_test.cc

@@ -267,8 +267,8 @@ class BlockFetcherTest : public testing::Test {
     std::string path = Path(filename);
     std::unique_ptr<FSRandomAccessFile> f;
     ASSERT_OK(fs_->NewRandomAccessFile(path, opt, &f, nullptr));
-    reader->reset(
-        new RandomAccessFileReader(std::move(f), path, env_->GetSystemClock()));
+    reader->reset(new RandomAccessFileReader(std::move(f), path,
+                                             env_->GetSystemClock().get()));
   }
 
   void NewTableReader(const ImmutableCFOptions& ioptions,

table/format.cc

@@ -353,9 +353,8 @@ Status UncompressBlockContentsForCompressionType(
   assert(uncompression_info.type() != kNoCompression &&
          "Invalid compression type");
 
-  StopWatchNano timer(
-      ioptions.env->GetSystemClock(),
-      ShouldReportDetailedTime(ioptions.env, ioptions.statistics));
+  StopWatchNano timer(ioptions.clock, ShouldReportDetailedTime(
+                                          ioptions.env, ioptions.statistics));
   size_t uncompressed_size = 0;
   CacheAllocationPtr ubuf =
       UncompressData(uncompression_info, data, n, &uncompressed_size,

table/get_context.cc

@@ -44,10 +44,9 @@ GetContext::GetContext(
     Statistics* statistics, GetState init_state, const Slice& user_key,
     PinnableSlice* pinnable_val, std::string* timestamp, bool* value_found,
     MergeContext* merge_context, bool do_merge,
-    SequenceNumber* _max_covering_tombstone_seq,
-    const std::shared_ptr<SystemClock>& clock, SequenceNumber* seq,
-    PinnedIteratorsManager* _pinned_iters_mgr, ReadCallback* callback,
-    bool* is_blob_index, uint64_t tracing_get_id)
+    SequenceNumber* _max_covering_tombstone_seq, SystemClock* clock,
+    SequenceNumber* seq, PinnedIteratorsManager* _pinned_iters_mgr,
+    ReadCallback* callback, bool* is_blob_index, uint64_t tracing_get_id)
     : ucmp_(ucmp),
       merge_operator_(merge_operator),
       logger_(logger),
@@ -78,7 +77,7 @@ GetContext::GetContext(
     Statistics* statistics, GetState init_state, const Slice& user_key,
     PinnableSlice* pinnable_val, bool* value_found, MergeContext* merge_context,
     bool do_merge, SequenceNumber* _max_covering_tombstone_seq,
-    const std::shared_ptr<SystemClock>& clock, SequenceNumber* seq,
+    SystemClock* clock, SequenceNumber* seq,
     PinnedIteratorsManager* _pinned_iters_mgr, ReadCallback* callback,
     bool* is_blob_index, uint64_t tracing_get_id)
     : GetContext(ucmp, merge_operator, logger, statistics, init_state, user_key,

table/get_context.h

@@ -99,8 +99,7 @@ class GetContext {
              Logger* logger, Statistics* statistics, GetState init_state,
              const Slice& user_key, PinnableSlice* value, bool* value_found,
              MergeContext* merge_context, bool do_merge,
-             SequenceNumber* max_covering_tombstone_seq,
-             const std::shared_ptr<SystemClock>& clock,
+             SequenceNumber* max_covering_tombstone_seq, SystemClock* clock,
              SequenceNumber* seq = nullptr,
              PinnedIteratorsManager* _pinned_iters_mgr = nullptr,
              ReadCallback* callback = nullptr, bool* is_blob_index = nullptr,
@@ -110,8 +109,7 @@ class GetContext {
              const Slice& user_key, PinnableSlice* value,
              std::string* timestamp, bool* value_found,
              MergeContext* merge_context, bool do_merge,
-             SequenceNumber* max_covering_tombstone_seq,
-             const std::shared_ptr<SystemClock>& clock,
+             SequenceNumber* max_covering_tombstone_seq, SystemClock* clock,
              SequenceNumber* seq = nullptr,
              PinnedIteratorsManager* _pinned_iters_mgr = nullptr,
              ReadCallback* callback = nullptr, bool* is_blob_index = nullptr,
@@ -185,7 +183,7 @@ class GetContext {
   bool* value_found_;  // Is value set correctly? Used by KeyMayExist
   MergeContext* merge_context_;
   SequenceNumber* max_covering_tombstone_seq_;
-  std::shared_ptr<SystemClock> clock_;
+  SystemClock* clock_;
   // If a key is found, seq_ will be set to the SequenceNumber of most recent
   // write to the key or kMaxSequenceNumber if unknown
   SequenceNumber* seq_;

table/sst_file_writer.cc

@@ -259,9 +259,8 @@ Status SstFileWriter::Open(const std::string& file_path) {
       0 /* file_creation_time */, "SST Writer" /* db_id */, db_session_id);
   FileTypeSet tmp_set = r->ioptions.checksum_handoff_file_types;
   r->file_writer.reset(new WritableFileWriter(
-      std::move(sst_file), file_path, r->env_options,
-      r->ioptions.env->GetSystemClock(), nullptr /* io_tracer */,
-      nullptr /* stats */, r->ioptions.listeners,
+      std::move(sst_file), file_path, r->env_options, r->ioptions.clock,
+      nullptr /* io_tracer */, nullptr /* stats */, r->ioptions.listeners,
       r->ioptions.file_checksum_gen_factory,
       tmp_set.Contains(FileType::kTableFile)));
 

table/table_reader_bench.cc

@@ -51,8 +51,7 @@ static std::string MakeKey(int i, int j, bool through_db) {
   return key.Encode().ToString();
 }
 
-uint64_t Now(const std::shared_ptr<SystemClock>& clock,
-             bool measured_by_nanosecond) {
+uint64_t Now(SystemClock* clock, bool measured_by_nanosecond) {
   return measured_by_nanosecond ? clock->NowNanos() : clock->NowMicros();
 }
 }  // namespace
@@ -83,7 +82,7 @@ void TableReaderBenchmark(Options& opts, EnvOptions& env_options,
   std::string dbname = test::PerThreadDBPath("rocksdb_table_reader_bench_db");
   WriteOptions wo;
   Env* env = Env::Default();
-  const auto& clock = env->GetSystemClock();
+  auto* clock = env->GetSystemClock().get();
   TableBuilder* tb = nullptr;
   DB* db = nullptr;
   Status s;

table/table_test.cc

@@ -1140,7 +1140,8 @@ class BlockBasedTableTest
                                  &trace_writer));
     // Always return Status::OK().
     assert(c->block_cache_tracer_
-               .StartTrace(env_, trace_opt, std::move(trace_writer))
+               .StartTrace(env_->GetSystemClock().get(), trace_opt,
+                           std::move(trace_writer))
                .ok());
     {
       std::string user_key = "k01";

tools/block_cache_analyzer/block_cache_trace_analyzer.cc

@@ -19,6 +19,7 @@
 #include <sstream>
 
 #include "monitoring/histogram.h"
+#include "rocksdb/system_clock.h"
 #include "util/gflags_compat.h"
 #include "util/string_util.h"
 
@@ -1519,6 +1520,7 @@ Status BlockCacheTraceAnalyzer::RecordAccess(
 }
 
 Status BlockCacheTraceAnalyzer::Analyze() {
+  SystemClock* clock = env_->GetSystemClock().get();
   std::unique_ptr<BlockCacheTraceReader> reader;
   Status s = Status::OK();
   if (is_human_readable_trace_file_) {
@@ -1542,7 +1544,7 @@ Status BlockCacheTraceAnalyzer::Analyze() {
       return s;
     }
   }
-  uint64_t start = env_->NowMicros();
+  uint64_t start = clock->NowMicros();
   uint64_t time_interval = 0;
   while (s.ok()) {
     BlockCacheTraceRecord access;
@@ -1568,7 +1570,7 @@ Status BlockCacheTraceAnalyzer::Analyze() {
       cache_simulator_->Access(access);
     }
     access_sequence_number_++;
-    uint64_t now = env_->NowMicros();
+    uint64_t now = clock->NowMicros();
     uint64_t duration = (now - start) / kMicrosInSecond;
     if (duration > 10 * time_interval) {
       uint64_t trace_duration =
@@ -1582,7 +1584,7 @@ Status BlockCacheTraceAnalyzer::Analyze() {
       time_interval++;
     }
   }
-  uint64_t now = env_->NowMicros();
+  uint64_t now = clock->NowMicros();
   uint64_t duration = (now - start) / kMicrosInSecond;
   uint64_t trace_duration =
       trace_end_timestamp_in_seconds_ - trace_start_timestamp_in_seconds_;

tools/block_cache_analyzer/block_cache_trace_analyzer_test.cc

@@ -225,7 +225,9 @@ TEST_F(BlockCacheTracerTest, BlockCacheAnalyzer) {
     std::unique_ptr<TraceWriter> trace_writer;
     ASSERT_OK(NewFileTraceWriter(env_, env_options_, trace_file_path_,
                                  &trace_writer));
-    BlockCacheTraceWriter writer(env_, trace_opt, std::move(trace_writer));
+    const auto& clock = env_->GetSystemClock();
+    BlockCacheTraceWriter writer(clock.get(), trace_opt,
+                                 std::move(trace_writer));
     ASSERT_OK(writer.WriteHeader());
     WriteBlockAccess(&writer, 0, TraceType::kBlockTraceDataBlock, 50);
     ASSERT_OK(env_->FileExists(trace_file_path_));
@@ -610,9 +612,11 @@ TEST_F(BlockCacheTracerTest, MixedBlocks) {
     // kSSTStoringEvenKeys.
     TraceOptions trace_opt;
     std::unique_ptr<TraceWriter> trace_writer;
+    const auto& clock = env_->GetSystemClock();
     ASSERT_OK(NewFileTraceWriter(env_, env_options_, trace_file_path_,
                                  &trace_writer));
-    BlockCacheTraceWriter writer(env_, trace_opt, std::move(trace_writer));
+    BlockCacheTraceWriter writer(clock.get(), trace_opt,
+                                 std::move(trace_writer));
     ASSERT_OK(writer.WriteHeader());
     // Write blocks of different types.
     WriteBlockAccess(&writer, 0, TraceType::kBlockTraceUncompressionDictBlock,

tools/db_bench_tool.cc

@@ -1854,7 +1854,8 @@ class ReporterAgent {
  private:
   std::string Header() const { return "secs_elapsed,interval_qps"; }
   void SleepAndReport() {
-    auto time_started = env_->NowMicros();
+    auto* clock = env_->GetSystemClock().get();
+    auto time_started = clock->NowMicros();
     while (true) {
       {
         std::unique_lock<std::mutex> lk(mutex_);
@@ -1869,7 +1870,7 @@ class ReporterAgent {
       auto total_ops_done_snapshot = total_ops_done_.load();
       // round the seconds elapsed
       auto secs_elapsed =
-          (env_->NowMicros() - time_started + kMicrosInSecond / 2) /
+          (clock->NowMicros() - time_started + kMicrosInSecond / 2) /
           kMicrosInSecond;
       std::string report = ToString(secs_elapsed) + "," +
                            ToString(total_ops_done_snapshot - last_report_) +
@@ -1932,6 +1933,7 @@ static std::unordered_map<OperationType, std::string, std::hash<unsigned char>>
 class CombinedStats;
 class Stats {
  private:
+  SystemClock* clock_;
   int id_;
   uint64_t start_ = 0;
   uint64_t sine_interval_;
@@ -1951,7 +1953,7 @@ class Stats {
   friend class CombinedStats;
 
  public:
-  Stats() { Start(-1); }
+  Stats() : clock_(FLAGS_env->GetSystemClock().get()) { Start(-1); }
 
   void SetReporterAgent(ReporterAgent* reporter_agent) {
     reporter_agent_ = reporter_agent;
@@ -1966,8 +1968,8 @@ class Stats {
     last_report_done_ = 0;
     bytes_ = 0;
     seconds_ = 0;
-    start_ = FLAGS_env->NowMicros();
-    sine_interval_ = FLAGS_env->NowMicros();
+    start_ = clock_->NowMicros();
+    sine_interval_ = clock_->NowMicros();
     finish_ = start_;
     last_report_finish_ = start_;
     message_.clear();
@@ -1999,7 +2001,7 @@ class Stats {
   }
 
   void Stop() {
-    finish_ = FLAGS_env->NowMicros();
+    finish_ = clock_->NowMicros();
     seconds_ = (finish_ - start_) * 1e-6;
   }
 
@@ -2019,7 +2021,7 @@ class Stats {
         "ElapsedTime", "Stage", "State", "OperationProperties");
 
     int64_t current_time = 0;
-    FLAGS_env->GetCurrentTime(&current_time);
+    clock_->GetCurrentTime(&current_time).PermitUncheckedError();
     for (auto ts : thread_list) {
       fprintf(stderr, "%18" PRIu64 " %10s %12s %20s %13s %45s %12s",
           ts.thread_id,
@@ -2040,9 +2042,7 @@ class Stats {
     }
   }
 
-  void ResetSineInterval() {
-    sine_interval_ = FLAGS_env->NowMicros();
-  }
+  void ResetSineInterval() { sine_interval_ = clock_->NowMicros(); }
 
   uint64_t GetSineInterval() {
     return sine_interval_;
@@ -2054,7 +2054,7 @@ class Stats {
 
   void ResetLastOpTime() {
     // Set to now to avoid latency from calls to SleepForMicroseconds
-    last_op_finish_ = FLAGS_env->NowMicros();
+    last_op_finish_ = clock_->NowMicros();
   }
 
   void FinishedOps(DBWithColumnFamilies* db_with_cfh, DB* db, int64_t num_ops,
@@ -2063,7 +2063,7 @@ class Stats {
       reporter_agent_->ReportFinishedOps(num_ops);
     }
     if (FLAGS_histogram) {
-      uint64_t now = FLAGS_env->NowMicros();
+      uint64_t now = clock_->NowMicros();
       uint64_t micros = now - last_op_finish_;
 
       if (hist_.find(op_type) == hist_.end())
@@ -2092,7 +2092,7 @@ class Stats {
         else                            next_report_ += 100000;
         fprintf(stderr, "... finished %" PRIu64 " ops%30s\r", done_, "");
       } else {
-        uint64_t now = FLAGS_env->NowMicros();
+        uint64_t now = clock_->NowMicros();
         int64_t usecs_since_last = now - last_report_finish_;
 
         // Determine whether to print status where interval is either
@@ -2104,15 +2104,13 @@ class Stats {
           next_report_ += FLAGS_stats_interval;
 
         } else {
-
           fprintf(stderr,
-                  "%s ... thread %d: (%" PRIu64 ",%" PRIu64 ") ops and "
+                  "%s ... thread %d: (%" PRIu64 ",%" PRIu64
+                  ") ops and "
                   "(%.1f,%.1f) ops/second in (%.6f,%.6f) seconds\n",
-                  FLAGS_env->TimeToString(now/1000000).c_str(),
-                  id_,
+                  clock_->TimeToString(now / 1000000).c_str(), id_,
                   done_ - last_report_done_, done_,
-                  (done_ - last_report_done_) /
-                  (usecs_since_last / 1000000.0),
+                  (done_ - last_report_done_) / (usecs_since_last / 1000000.0),
                   done_ / ((now - start_) / 1000000.0),
                   (now - last_report_finish_) / 1000000.0,
                   (now - start_) / 1000000.0);

trace_replay/block_cache_tracer.cc

@@ -99,9 +99,9 @@ uint64_t BlockCacheTraceHelper::GetBlockOffsetInFile(
 }
 
 BlockCacheTraceWriter::BlockCacheTraceWriter(
-    Env* env, const TraceOptions& trace_options,
+    SystemClock* clock, const TraceOptions& trace_options,
     std::unique_ptr<TraceWriter>&& trace_writer)
-    : env_(env),
+    : clock_(clock),
       trace_options_(trace_options),
       trace_writer_(std::move(trace_writer)) {}
 
@@ -142,7 +142,7 @@ Status BlockCacheTraceWriter::WriteBlockAccess(
 
 Status BlockCacheTraceWriter::WriteHeader() {
   Trace trace;
-  trace.ts = env_->NowMicros();
+  trace.ts = clock_->NowMicros();
   trace.type = TraceType::kTraceBegin;
   PutLengthPrefixedSlice(&trace.payload, kTraceMagic);
   PutFixed32(&trace.payload, kMajorVersion);
@@ -444,7 +444,7 @@ BlockCacheTracer::BlockCacheTracer() { writer_.store(nullptr); }
 BlockCacheTracer::~BlockCacheTracer() { EndTrace(); }
 
 Status BlockCacheTracer::StartTrace(
-    Env* env, const TraceOptions& trace_options,
+    SystemClock* clock, const TraceOptions& trace_options,
     std::unique_ptr<TraceWriter>&& trace_writer) {
   InstrumentedMutexLock lock_guard(&trace_writer_mutex_);
   if (writer_.load()) {
@@ -453,7 +453,7 @@ Status BlockCacheTracer::StartTrace(
   get_id_counter_.store(1);
   trace_options_ = trace_options;
   writer_.store(
-      new BlockCacheTraceWriter(env, trace_options, std::move(trace_writer)));
+      new BlockCacheTraceWriter(clock, trace_options, std::move(trace_writer)));
   return writer_.load()->WriteHeader();
 }