BlobDB: Implement DisableFileDeletions (#4314)

Summary:
`DB::DiableFileDeletions` and `DB::EnableFileDeletions` are used for applications to stop RocksDB background jobs to delete files while they are doing replication. Implement these methods for BlobDB. `DeleteObsolteFiles` now needs to check `disable_file_deletions_` before starting, and will hold `delete_file_mutex_` the whole time while it is running. `DisableFileDeletions` needs to wait on `delete_file_mutex_` for running `DeleteObsolteFiles` job and set `disable_file_deletions_` flag.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/4314

Differential Revision: D9501373

Pulled By: yiwu-arbug

fbshipit-source-id: 81064c1228f1724eff46da22b50ff765b16292cd

CMakeLists.txt

@@ -612,6 +612,7 @@ set(SOURCES
         utilities/blob_db/blob_compaction_filter.cc
         utilities/blob_db/blob_db.cc
         utilities/blob_db/blob_db_impl.cc
+        utilities/blob_db/blob_db_impl_filesnapshot.cc
         utilities/blob_db/blob_dump_tool.cc
         utilities/blob_db/blob_file.cc
         utilities/blob_db/blob_log_reader.cc

TARGETS

@@ -233,6 +233,7 @@ cpp_library(
         "utilities/blob_db/blob_compaction_filter.cc",
         "utilities/blob_db/blob_db.cc",
         "utilities/blob_db/blob_db_impl.cc",
+        "utilities/blob_db/blob_db_impl_filesnapshot.cc",
         "utilities/blob_db/blob_dump_tool.cc",
         "utilities/blob_db/blob_file.cc",
         "utilities/blob_db/blob_log_format.cc",
@@ -376,11 +377,6 @@ ROCKS_TESTS = [
         "table/block_based_filter_block_test.cc",
         "serial",
     ],
-    [
-        "data_block_hash_index_test",
-        "table/data_block_hash_index_test.cc",
-        "serial",
-    ],
     [
         "block_test",
         "table/block_test.cc",
@@ -506,6 +502,11 @@ ROCKS_TESTS = [
         "table/cuckoo_table_reader_test.cc",
         "serial",
     ],
+    [
+        "data_block_hash_index_test",
+        "table/data_block_hash_index_test.cc",
+        "serial",
+    ],
     [
         "date_tiered_test",
         "utilities/date_tiered/date_tiered_test.cc",
@@ -956,11 +957,6 @@ ROCKS_TESTS = [
         "tools/sst_dump_test.cc",
         "serial",
     ],
-    [
-        "trace_analyzer_test",
-        "tools/trace_analyzer_test.cc",
-        "serial",
-    ],
     [
         "statistics_test",
         "monitoring/statistics_test.cc",
@@ -996,6 +992,11 @@ ROCKS_TESTS = [
         "util/timer_queue_test.cc",
         "serial",
     ],
+    [
+        "trace_analyzer_test",
+        "tools/trace_analyzer_test.cc",
+        "serial",
+    ],
     [
         "transaction_test",
         "utilities/transactions/transaction_test.cc",
@@ -1094,3 +1095,4 @@ if not is_opt_mode:
           deps = [":" + test_bin],
           command = [TEST_RUNNER, BUCK_BINS + test_bin]
         )
+

src.mk

@@ -122,6 +122,7 @@ LIB_SOURCES =                                                   \
   table/plain_table_reader.cc                                   \
   table/sst_file_writer.cc                                      \
   table/table_properties.cc                                     \
+  tools/trace_analyzer_tool.cc                                  \
   table/two_level_iterator.cc                                   \
   tools/dump/db_dump_tool.cc                                    \
   util/arena.cc                                                 \
@@ -161,6 +162,7 @@ LIB_SOURCES =                                                   \
   utilities/blob_db/blob_compaction_filter.cc                   \
   utilities/blob_db/blob_db.cc                                  \
   utilities/blob_db/blob_db_impl.cc                             \
+  utilities/blob_db/blob_db_impl_filesnapshot.cc                \
   utilities/blob_db/blob_file.cc                                \
   utilities/blob_db/blob_log_format.cc                          \
   utilities/blob_db/blob_log_reader.cc                          \

utilities/blob_db/blob_db_impl.cc

@@ -621,39 +621,6 @@ Status BlobDBImpl::Write(const WriteOptions& options, WriteBatch* updates) {
   return db_->Write(options, blob_inserter.batch());
 }
 
-Status BlobDBImpl::GetLiveFiles(std::vector<std::string>& ret,
-                                uint64_t* manifest_file_size,
-                                bool flush_memtable) {
-  // Hold a lock in the beginning to avoid updates to base DB during the call
-  ReadLock rl(&mutex_);
-  Status s = db_->GetLiveFiles(ret, manifest_file_size, flush_memtable);
-  if (!s.ok()) {
-    return s;
-  }
-  ret.reserve(ret.size() + blob_files_.size());
-  for (auto bfile_pair : blob_files_) {
-    auto blob_file = bfile_pair.second;
-    ret.emplace_back(blob_file->PathName());
-  }
-  return Status::OK();
-}
-
-void BlobDBImpl::GetLiveFilesMetaData(std::vector<LiveFileMetaData>* metadata) {
-  // Hold a lock in the beginning to avoid updates to base DB during the call
-  ReadLock rl(&mutex_);
-  db_->GetLiveFilesMetaData(metadata);
-  for (auto bfile_pair : blob_files_) {
-    auto blob_file = bfile_pair.second;
-    LiveFileMetaData filemetadata;
-    filemetadata.size = blob_file->GetFileSize();
-    filemetadata.name = blob_file->PathName();
-    auto cfh =
-        reinterpret_cast<ColumnFamilyHandleImpl*>(DefaultColumnFamily());
-    filemetadata.column_family_name = cfh->GetName();
-    metadata->emplace_back(filemetadata);
-  }
-}
-
 Status BlobDBImpl::Put(const WriteOptions& options, const Slice& key,
                        const Slice& value) {
   return PutUntil(options, key, value, kNoExpiration);
@@ -1684,16 +1651,21 @@ Status BlobDBImpl::GCFileAndUpdateLSM(const std::shared_ptr<BlobFile>& bfptr,
 }
 
 std::pair<bool, int64_t> BlobDBImpl::DeleteObsoleteFiles(bool aborted) {
-  if (aborted) return std::make_pair(false, -1);
+  if (aborted) {
+    return std::make_pair(false, -1);
+  }
 
-  {
-    ReadLock rl(&mutex_);
-    if (obsolete_files_.empty()) return std::make_pair(true, -1);
+  MutexLock delete_file_lock(&delete_file_mutex_);
+  if (disable_file_deletions_ > 0) {
+    return std::make_pair(true, -1);
   }
 
   std::list<std::shared_ptr<BlobFile>> tobsolete;
   {
     WriteLock wl(&mutex_);
+    if (obsolete_files_.empty()) {
+      return std::make_pair(true, -1);
+    }
     tobsolete.swap(obsolete_files_);
   }
 

utilities/blob_db/blob_db_impl.h

@@ -155,12 +155,6 @@ class BlobDBImpl : public BlobDB {
 
   virtual Status Close() override;
 
-  virtual Status GetLiveFiles(std::vector<std::string>&,
-                              uint64_t* manifest_file_size,
-                              bool flush_memtable = true) override;
-  virtual void GetLiveFilesMetaData(
-      std::vector<LiveFileMetaData>* ) override;
-
   using BlobDB::PutWithTTL;
   Status PutWithTTL(const WriteOptions& options, const Slice& key,
                     const Slice& value, uint64_t ttl) override;
@@ -175,6 +169,15 @@ class BlobDBImpl : public BlobDB {
              const DBOptions& db_options,
              const ColumnFamilyOptions& cf_options);
 
+  virtual Status DisableFileDeletions() override;
+
+  virtual Status EnableFileDeletions(bool force) override;
+
+  virtual Status GetLiveFiles(std::vector<std::string>&,
+                              uint64_t* manifest_file_size,
+                              bool flush_memtable = true) override;
+  virtual void GetLiveFilesMetaData(std::vector<LiveFileMetaData>*) override;
+
   ~BlobDBImpl();
 
   Status Open(std::vector<ColumnFamilyHandle*>* handles);
@@ -408,6 +411,26 @@ class BlobDBImpl : public BlobDB {
 
   std::list<std::shared_ptr<BlobFile>> obsolete_files_;
 
+  // DeleteObsoleteFiles, DiableFileDeletions and EnableFileDeletions block
+  // on the mutex to avoid contention.
+  //
+  // While DeleteObsoleteFiles hold both mutex_ and delete_file_mutex_, note
+  // the difference. mutex_ only needs to be held when access the
+  // data-structure, and delete_file_mutex_ needs to be held the whole time
+  // during DeleteObsoleteFiles to avoid being run simultaneously with
+  // DisableFileDeletions.
+  //
+  // If both of mutex_ and delete_file_mutex_ needs to be held, it is adviced
+  // to hold delete_file_mutex_ first to avoid deadlock.
+  mutable port::Mutex delete_file_mutex_;
+
+  // Each call of DisableFileDeletions will increase disable_file_deletion_
+  // by 1. EnableFileDeletions will either decrease the count by 1 or reset
+  // it to zeor, depending on the force flag.
+  //
+  // REQUIRES: access with delete_file_mutex_ held.
+  int disable_file_deletions_ = 0;
+
   uint32_t debug_level_;
 };
 

utilities/blob_db/blob_db_impl_filesnapshot.cc

@@ -0,0 +1,97 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+
+#ifndef ROCKSDB_LITE
+
+#include "utilities/blob_db/blob_db_impl.h"
+
+#include "util/logging.h"
+#include "util/mutexlock.h"
+
+// BlobDBImpl methods to get snapshot of files, e.g. for replication.
+
+namespace rocksdb {
+namespace blob_db {
+
+Status BlobDBImpl::DisableFileDeletions() {
+  // Disable base DB file deletions.
+  Status s = db_impl_->DisableFileDeletions();
+  if (!s.ok()) {
+    return s;
+  }
+
+  int count = 0;
+  {
+    // Hold delete_file_mutex_ to make sure no DeleteObsoleteFiles job
+    // is running.
+    MutexLock l(&delete_file_mutex_);
+    count = ++disable_file_deletions_;
+  }
+
+  ROCKS_LOG_INFO(db_options_.info_log,
+                 "Disalbed blob file deletions. count: %d", count);
+  return Status::OK();
+}
+
+Status BlobDBImpl::EnableFileDeletions(bool force) {
+  // Enable base DB file deletions.
+  Status s = db_impl_->EnableFileDeletions(force);
+  if (!s.ok()) {
+    return s;
+  }
+
+  int count = 0;
+  {
+    MutexLock l(&delete_file_mutex_);
+    if (force) {
+      disable_file_deletions_ = 0;
+    } else if (disable_file_deletions_ > 0) {
+      count = --disable_file_deletions_;
+    }
+    assert(count >= 0);
+  }
+
+  ROCKS_LOG_INFO(db_options_.info_log, "Enabled blob file deletions. count: %d",
+                 count);
+  // Consider trigger DeleteobsoleteFiles once after re-enabled, if we are to
+  // make DeleteobsoleteFiles re-run interval configuration.
+  return Status::OK();
+}
+
+Status BlobDBImpl::GetLiveFiles(std::vector<std::string>& ret,
+                                uint64_t* manifest_file_size,
+                                bool flush_memtable) {
+  // Hold a lock in the beginning to avoid updates to base DB during the call
+  ReadLock rl(&mutex_);
+  Status s = db_->GetLiveFiles(ret, manifest_file_size, flush_memtable);
+  if (!s.ok()) {
+    return s;
+  }
+  ret.reserve(ret.size() + blob_files_.size());
+  for (auto bfile_pair : blob_files_) {
+    auto blob_file = bfile_pair.second;
+    ret.emplace_back(blob_file->PathName());
+  }
+  return Status::OK();
+}
+
+void BlobDBImpl::GetLiveFilesMetaData(std::vector<LiveFileMetaData>* metadata) {
+  // Hold a lock in the beginning to avoid updates to base DB during the call
+  ReadLock rl(&mutex_);
+  db_->GetLiveFilesMetaData(metadata);
+  for (auto bfile_pair : blob_files_) {
+    auto blob_file = bfile_pair.second;
+    LiveFileMetaData filemetadata;
+    filemetadata.size = blob_file->GetFileSize();
+    filemetadata.name = blob_file->PathName();
+    auto cfh = reinterpret_cast<ColumnFamilyHandleImpl*>(DefaultColumnFamily());
+    filemetadata.column_family_name = cfh->GetName();
+    metadata->emplace_back(filemetadata);
+  }
+}
+
+}  // namespace blob_db
+}  // namespace rocksdb
+#endif  // !ROCKSDB_LITE

utilities/blob_db/blob_db_test.cc

@@ -1415,6 +1415,47 @@ TEST_F(BlobDBTest, EvictExpiredFile) {
   ASSERT_EQ(0, blob_db_impl()->TEST_GetObsoleteFiles().size());
 }
 
+TEST_F(BlobDBTest, DisableFileDeletions) {
+  BlobDBOptions bdb_options;
+  bdb_options.disable_background_tasks = true;
+  Open(bdb_options);
+  std::map<std::string, std::string> data;
+  for (bool force : {true, false}) {
+    ASSERT_OK(Put("foo", "v", &data));
+    auto blob_files = blob_db_impl()->TEST_GetBlobFiles();
+    ASSERT_EQ(1, blob_files.size());
+    auto blob_file = blob_files[0];
+    ASSERT_OK(blob_db_impl()->TEST_CloseBlobFile(blob_file));
+    blob_db_impl()->TEST_ObsoleteBlobFile(blob_file);
+    ASSERT_EQ(1, blob_db_impl()->TEST_GetBlobFiles().size());
+    ASSERT_EQ(1, blob_db_impl()->TEST_GetObsoleteFiles().size());
+    // Call DisableFileDeletions twice.
+    ASSERT_OK(blob_db_->DisableFileDeletions());
+    ASSERT_OK(blob_db_->DisableFileDeletions());
+    // File deletions should be disabled.
+    blob_db_impl()->TEST_DeleteObsoleteFiles();
+    ASSERT_EQ(1, blob_db_impl()->TEST_GetBlobFiles().size());
+    ASSERT_EQ(1, blob_db_impl()->TEST_GetObsoleteFiles().size());
+    VerifyDB(data);
+    // Enable file deletions once. If force=true, file deletion is enabled.
+    // Otherwise it needs to enable it for a second time.
+    ASSERT_OK(blob_db_->EnableFileDeletions(force));
+    blob_db_impl()->TEST_DeleteObsoleteFiles();
+    if (!force) {
+      ASSERT_EQ(1, blob_db_impl()->TEST_GetBlobFiles().size());
+      ASSERT_EQ(1, blob_db_impl()->TEST_GetObsoleteFiles().size());
+      VerifyDB(data);
+      // Call EnableFileDeletions a second time.
+      ASSERT_OK(blob_db_->EnableFileDeletions(false));
+      blob_db_impl()->TEST_DeleteObsoleteFiles();
+    }
+    // Regardless of value of `force`, file should be deleted by now.
+    ASSERT_EQ(0, blob_db_impl()->TEST_GetBlobFiles().size());
+    ASSERT_EQ(0, blob_db_impl()->TEST_GetObsoleteFiles().size());
+    VerifyDB({});
+  }
+}
+
 }  //  namespace blob_db
 }  //  namespace rocksdb