Merge branch 'master' into performance

Conflicts:
	db/version_set.cc
	include/leveldb/options.h
	util/options.cc

Makefile

@@ -90,8 +90,8 @@ SHARED3 = $(SHARED1)
 SHARED = $(SHARED1)
 else
 # Update db.h if you change these.
-SHARED_MAJOR = 1
+SHARED_MAJOR = 2
-SHARED_MINOR = 5
+SHARED_MINOR = 0
 SHARED1 = libleveldb.$(PLATFORM_SHARED_EXT)
 SHARED2 = $(SHARED1).$(SHARED_MAJOR)
 SHARED3 = $(SHARED1).$(SHARED_MAJOR).$(SHARED_MINOR)

db/db_bench.cc

@@ -302,18 +302,12 @@ static uint64_t FLAGS_WAL_ttl_seconds = 0;
 // Allow buffered io using OS buffers
 static bool FLAGS_use_os_buffer;
 
-// Allow filesystem to do read-aheads
-static bool FLAGS_use_fsreadahead;
-
 // Allow reads to occur via mmap-ing files
 static bool FLAGS_use_mmap_reads;
 
 // Allow writes to occur via mmap-ing files
 static bool FLAGS_use_mmap_writes;
 
-// Allow readaheads to occur for compactions
-static bool FLAGS_use_readahead_compactions;
-
 // Advise random access on table file open
 static bool FLAGS_advise_random_on_open =
   leveldb::Options().advise_random_on_open;
@@ -343,6 +337,9 @@ static auto FLAGS_use_adaptive_mutex =
 static auto FLAGS_bytes_per_sync =
   leveldb::Options().bytes_per_sync;
 
+// On true, deletes use bloom-filter and drop the delete if key not present
+static bool FLAGS_deletes_check_filter_first = false;
+
 namespace leveldb {
 
 // Helper for quickly generating random data.
@@ -1131,6 +1128,7 @@ unique_ptr<char []> GenerateKeyFromInt(int v, const char* suffix = "")
     options.max_bytes_for_level_base = FLAGS_max_bytes_for_level_base;
     options.max_bytes_for_level_multiplier =
         FLAGS_max_bytes_for_level_multiplier;
+    options.deletes_check_filter_first = FLAGS_deletes_check_filter_first;
     if (FLAGS_max_bytes_for_level_multiplier_additional.size() > 0) {
       if (FLAGS_max_bytes_for_level_multiplier_additional.size() !=
           (unsigned int)FLAGS_num_levels) {
@@ -1172,7 +1170,6 @@ unique_ptr<char []> GenerateKeyFromInt(int v, const char* suffix = "")
 
     // fill storage options
     options.allow_os_buffer = FLAGS_use_os_buffer;
-    options.allow_readahead = FLAGS_use_fsreadahead;
     options.allow_mmap_reads = FLAGS_use_mmap_reads;
     options.allow_mmap_writes = FLAGS_use_mmap_writes;
     options.advise_random_on_open = FLAGS_advise_random_on_open;
@@ -2106,12 +2103,6 @@ int main(int argc, char** argv) {
     } else if (sscanf(argv[i], "--mmap_write=%d%c", &n, &junk) == 1 &&
                (n == 0 || n == 1)) {
       FLAGS_use_mmap_writes = n;
-    } else if (sscanf(argv[i], "--readahead=%d%c", &n, &junk) == 1 &&
-               (n == 0 || n == 1)) {
-      FLAGS_use_fsreadahead = n;
-    } else if (sscanf(argv[i], "--readahead_compactions=%d%c", &n, &junk) == 1&&
-               (n == 0 || n == 1)) {
-      FLAGS_use_readahead_compactions = n;
     } else if (sscanf(argv[i], "--statistics=%d%c", &n, &junk) == 1 &&
                (n == 0 || n == 1)) {
       if (n == 1) {
@@ -2255,6 +2246,9 @@ int main(int argc, char** argv) {
       FLAGS_keys_per_multiget = n;
     }  else if (sscanf(argv[i], "--bytes_per_sync=%ld%c", &l, &junk) == 1) {
       FLAGS_bytes_per_sync = l;
+    } else if (sscanf(argv[i], "--deletes_check_filter_first=%d%c", &n, &junk)
+               == 1 && (n == 0 || n ==1 )) {
+      FLAGS_deletes_check_filter_first = n;
     } else {
       fprintf(stderr, "Invalid flag '%s'\n", argv[i]);
       exit(1);

db/db_impl.cc

@@ -10,6 +10,7 @@
 #include <set>
 #include <string>
 #include <stdint.h>
+#include <stdexcept>
 #include <vector>
 #include <unordered_set>
 
@@ -2015,6 +2016,16 @@ int64_t DBImpl::TEST_MaxNextLevelOverlappingBytes() {
 Status DBImpl::Get(const ReadOptions& options,
                    const Slice& key,
                    std::string* value) {
+  return GetImpl(options, key, value);
+}
+
+// If no_IO is true, then returns Status::NotFound if key is not in memtable,
+// immutable-memtable and bloom-filters can guarantee that key is not in db,
+// "value" is garbage string if no_IO is true
+Status DBImpl::GetImpl(const ReadOptions& options,
+                       const Slice& key,
+                       std::string* value,
+                       const bool no_IO) {
   Status s;
 
   StopWatch sw(env_, options_.statistics, DB_GET);
@@ -2043,12 +2054,12 @@ Status DBImpl::Get(const ReadOptions& options,
   // s is both in/out. When in, s could either be OK or MergeInProgress.
   // value will contain the current merge operand in the latter case.
   LookupKey lkey(key, snapshot);
-  if (mem->Get(lkey, value, &s, options_)) {
+  if (mem->Get(lkey, value, &s, options_, no_IO)) {
     // Done
-  } else if (imm.Get(lkey, value, &s, options_)) {
+  } else if (imm.Get(lkey, value, &s, options_, no_IO)) {
     // Done
   } else {
-    current->Get(options, lkey, value, &s, &stats, options_);
+    current->Get(options, lkey, value, &s, &stats, options_, no_IO);
     have_stat_update = true;
   }
   mutex_.Lock();
@@ -2138,6 +2149,12 @@ std::vector<Status> DBImpl::MultiGet(const ReadOptions& options,
   return statList;
 }
 
+bool DBImpl::KeyMayExist(const Slice& key) {
+  std::string value;
+  const Status s = GetImpl(ReadOptions(), key, &value, true);
+  return !s.IsNotFound();
+}
+
 Iterator* DBImpl::NewIterator(const ReadOptions& options) {
   SequenceNumber latest_snapshot;
   Iterator* internal_iter = NewInternalIterator(options, &latest_snapshot);
@@ -2173,6 +2190,10 @@ Status DBImpl::Merge(const WriteOptions& o, const Slice& key,
 }
 
 Status DBImpl::Delete(const WriteOptions& options, const Slice& key) {
+  if (options_.deletes_check_filter_first && !KeyMayExist(key)) {
+    RecordTick(options_.statistics, NUMBER_FILTERED_DELETES);
+    return Status::OK();
+  }
   return DB::Delete(options, key);
 }
 
@@ -2232,13 +2253,19 @@ Status DBImpl::Write(const WriteOptions& options, WriteBatch* my_batch) {
       }
       if (status.ok()) {
         status = WriteBatchInternal::InsertInto(updates, mem_);
+        if (!status.ok()) {
+          // Panic for in-memory corruptions
+          // Note that existing logic was not sound. Any partial failure writing
+          // into the memtable would result in a state that some write ops might
+          // have succeeded in memtable but Status reports error for all writes.
+          throw std::runtime_error("In memory WriteBatch corruption!");
+        }
+        versions_->SetLastSequence(last_sequence);
+        last_flushed_sequence_ = current_sequence;
       }
       mutex_.Lock();
     }
-    last_flushed_sequence_ = current_sequence;
     if (updates == &tmp_batch_) tmp_batch_.Clear();
-
-    versions_->SetLastSequence(last_sequence);
   }
 
   while (true) {

db/db_impl.h

@@ -48,6 +48,10 @@ class DBImpl : public DB {
   virtual std::vector<Status> MultiGet(const ReadOptions& options,
                                        const std::vector<Slice>& keys,
                                        std::vector<std::string>* values);
+
+  // Returns false if key can't exist- based on memtable, immutable-memtable and
+  // bloom-filters; true otherwise. No IO is performed
+  virtual bool KeyMayExist(const Slice& key);
   virtual Iterator* NewIterator(const ReadOptions&);
   virtual const Snapshot* GetSnapshot();
   virtual void ReleaseSnapshot(const Snapshot* snapshot);
@@ -379,6 +383,12 @@ class DBImpl : public DB {
     SequenceNumber in,
     std::vector<SequenceNumber>& snapshots,
     SequenceNumber* prev_snapshot);
+
+  // Function that Get and KeyMayExist call with no_IO true or false
+  Status GetImpl(const ReadOptions& options,
+                 const Slice& key,
+                 std::string* value,
+                 const bool no_IO = false);
 };
 
 // Sanitize db options.  The caller should delete result.info_log if

db/db_test.cc

@@ -218,6 +218,7 @@ class DBTest {
     kManifestFileSize,
     kCompactOnFlush,
     kPerfOptions,
+    kDeletesFilterFirst,
     kEnd
   };
   int option_config_;
@@ -289,6 +290,9 @@ class DBTest {
         options.rate_limit_delay_milliseconds = 2;
         // TODO -- test more options
         break;
+      case kDeletesFilterFirst:
+        options.deletes_check_filter_first = true;
+        break;
       default:
         break;
     }
@@ -768,6 +772,39 @@ TEST(DBTest, GetEncountersEmptyLevel) {
   } while (ChangeOptions());
 }
 
+// KeyMayExist-API returns false if memtable(s) and in-memory bloom-filters can
+// guarantee that the key doesn't exist in the db, else true. This can lead to
+// a few false positives, but not false negatives. To make test deterministic,
+// use a much larger number of bits per key-20 than bits in the key, so
+// that false positives are eliminated
+TEST(DBTest, KeyMayExist) {
+  do {
+    Options options = CurrentOptions();
+    options.filter_policy = NewBloomFilterPolicy(20);
+    Reopen(&options);
+
+    ASSERT_TRUE(!db_->KeyMayExist("a"));
+
+    ASSERT_OK(db_->Put(WriteOptions(), "a", "b"));
+    ASSERT_TRUE(db_->KeyMayExist("a"));
+
+    dbfull()->Flush(FlushOptions());
+    ASSERT_TRUE(db_->KeyMayExist("a"));
+
+    ASSERT_OK(db_->Delete(WriteOptions(), "a"));
+    ASSERT_TRUE(!db_->KeyMayExist("a"));
+
+    dbfull()->Flush(FlushOptions());
+    dbfull()->CompactRange(nullptr, nullptr);
+    ASSERT_TRUE(!db_->KeyMayExist("a"));
+
+    ASSERT_OK(db_->Delete(WriteOptions(), "c"));
+    ASSERT_TRUE(!db_->KeyMayExist("c"));
+
+    delete options.filter_policy;
+  } while (ChangeOptions());
+}
+
 TEST(DBTest, IterEmpty) {
   Iterator* iter = db_->NewIterator(ReadOptions());
 
@@ -1403,7 +1440,7 @@ class DeleteFilter : public CompactionFilter {
 
 class ChangeFilter : public CompactionFilter {
  public:
-  ChangeFilter(int argv) : argv_(argv) {}
+  explicit ChangeFilter(int argv) : argv_(argv) {}
 
   virtual bool Filter(int level, const Slice& key,
                       const Slice& value, std::string* new_value,
@@ -2970,6 +3007,9 @@ class ModelDB: public DB {
                           Status::NotSupported("Not implemented."));
     return s;
   }
+  virtual bool KeyMayExist(const Slice& key) {
+    return true; // Not Supported directly
+  }
   virtual Iterator* NewIterator(const ReadOptions& options) {
     if (options.snapshot == nullptr) {
       KVMap* saved = new KVMap;

db/memtable.cc

@@ -119,7 +119,7 @@ void MemTable::Add(SequenceNumber s, ValueType type,
 }
 
 bool MemTable::Get(const LookupKey& key, std::string* value, Status* s,
-                  const Options& options) {
+                  const Options& options, const bool check_presence_only) {
   Slice memkey = key.memtable_key();
   Table::Iterator iter(&table_);
   iter.Seek(memkey.data());
@@ -164,6 +164,10 @@ bool MemTable::Get(const LookupKey& key, std::string* value, Status* s,
           return true;
         }
         case kTypeMerge: {
+          if (check_presence_only) {
+            *s = Status::OK();
+            return true;
+          }
           Slice v = GetLengthPrefixedSlice(key_ptr + key_length);
           if (merge_in_progress) {
             merge_operator->Merge(key.user_key(), &v, operand,

db/memtable.h

@@ -63,12 +63,13 @@ class MemTable {
   // If memtable contains a deletion for key, store a NotFound() error
   // in *status and return true.
   // If memtable contains Merge operation as the most recent entry for a key,
-  //   and the merge process does not stop (not reaching a value or delete),
+  //   and if check_presence_only is set, return true with Status::OK,
+  //   else if the merge process does not stop (not reaching a value or delete),
   //   store the current merged result in value and MergeInProgress in s.
   //   return false
   // Else, return false.
   bool Get(const LookupKey& key, std::string* value, Status* s,
-          const Options& options);
+          const Options& options, const bool check_presence_only = false);
 
   // Returns the edits area that is needed for flushing the memtable
   VersionEdit* GetEdits() { return &edit_; }

db/memtablelist.cc

@@ -194,10 +194,10 @@ size_t MemTableList::ApproximateMemoryUsage() {
 // Search all the memtables starting from the most recent one.
 // Return the most recent value found, if any.
 bool MemTableList::Get(const LookupKey& key, std::string* value, Status* s,
-                      const Options& options ) {
+                      const Options& options, const bool check_presence_only) {
   for (list<MemTable*>::iterator it = memlist_.begin();
        it != memlist_.end(); ++it) {
-    if ((*it)->Get(key, value, s, options)) {
+    if ((*it)->Get(key, value, s, options, check_presence_only)) {
       return true;
     }
   }

db/memtablelist.h

@@ -71,7 +71,7 @@ class MemTableList {
   // Search all the memtables starting from the most recent one.
   // Return the most recent value found, if any.
   bool Get(const LookupKey& key, std::string* value, Status* s,
-           const Options& options);
+           const Options& options, const bool check_presence_only = false);
 
   // Returns the list of underlying memtables.
   void GetMemTables(std::vector<MemTable*>* list);

db/table_cache.cc

@@ -112,14 +112,16 @@ Status TableCache::Get(const ReadOptions& options,
                        const Slice& k,
                        void* arg,
                        bool (*saver)(void*, const Slice&, const Slice&, bool),
-                       bool* tableIO) {
+                       bool* tableIO,
+                       void (*mark_key_may_exist)(void*),
+                       const bool no_IO) {
   Cache::Handle* handle = nullptr;
   Status s = FindTable(storage_options_, file_number, file_size,
                        &handle, tableIO);
   if (s.ok()) {
     Table* t =
       reinterpret_cast<Table*>(cache_->Value(handle));
-    s = t->InternalGet(options, k, arg, saver);
+    s = t->InternalGet(options, k, arg, saver, mark_key_may_exist, no_IO);
     cache_->Release(handle);
   }
   return s;

db/table_cache.h

@@ -48,7 +48,9 @@ class TableCache {
              const Slice& k,
              void* arg,
              bool (*handle_result)(void*, const Slice&, const Slice&, bool),
-             bool* tableIO);
+             bool* tableIO,
+             void (*mark_key_may_exist)(void*) = nullptr,
+             const bool no_IO = false);
 
   // Evict any entry for the specified file number
   void Evict(uint64_t file_number);

db/version_set.cc

@@ -245,6 +245,16 @@ struct Saver {
   bool didIO;    // did we do any disk io?
 };
 }
+
+// Called from TableCache::Get when bloom-filters can't guarantee that key does
+// not exist and Get is not permitted to do IO to read the data-block and be
+// certain.
+// Set the key as Found and let the caller know that key-may-exist
+static void MarkKeyMayExist(void* arg) {
+  Saver* s = reinterpret_cast<Saver*>(arg);
+  s->state = kFound;
+}
+
 static bool SaveValue(void* arg, const Slice& ikey, const Slice& v, bool didIO){
   Saver* s = reinterpret_cast<Saver*>(arg);
   ParsedInternalKey parsed_key;
@@ -337,7 +347,8 @@ void Version::Get(const ReadOptions& options,
                   std::string* value,
                   Status *status,
                   GetStats* stats,
-                  const Options& db_options) {
+                  const Options& db_options,
+                  const bool no_IO) {
   Slice ikey = k.internal_key();
   Slice user_key = k.user_key();
   const Comparator* ucmp = vset_->icmp_.user_comparator();
@@ -346,6 +357,9 @@ void Version::Get(const ReadOptions& options,
   auto logger = db_options.info_log;
 
   assert(status->ok() || status->IsMergeInProgress());
+  if (no_IO) {
+    assert(status->ok());
+  }
   Saver saver;
   saver.state = status->ok()? kNotFound : kMerge;
   saver.ucmp = ucmp;
@@ -417,7 +431,8 @@ void Version::Get(const ReadOptions& options,
       FileMetaData* f = files[i];
       bool tableIO = false;
       *status = vset_->table_cache_->Get(options, f->number, f->file_size,
-                                         ikey, &saver, SaveValue, &tableIO);
+                                         ikey, &saver, SaveValue, &tableIO,
+                                         MarkKeyMayExist, no_IO);
       // TODO: examine the behavior for corrupted key
       if (!status->ok()) {
         return;
@@ -2199,7 +2214,7 @@ Compaction* VersionSet::PickCompactionBySize(int level, double score) {
 
   assert(level >= 0);
   assert(level+1 < NumberLevels());
-  c = new Compaction(level, level+1, MaxFileSizeForLevel(level),
+  c = new Compaction(level, level+1, MaxFileSizeForLevel(level+1),
       MaxGrandParentOverlapBytes(level), NumberLevels());
   c->score_ = score;
 
@@ -2304,7 +2319,7 @@ Compaction* VersionSet::PickCompaction() {
     if (level != 0 || compactions_in_progress_[0].empty()) {
       if(!ParentRangeInCompaction(&f->smallest, &f->largest, level,
                                   &parent_index)) {
-        c = new Compaction(level, level, MaxFileSizeForLevel(level),
+        c = new Compaction(level, level, MaxFileSizeForLevel(level+1),
                 MaxGrandParentOverlapBytes(level), NumberLevels(), true);
         c->inputs_[0].push_back(f);
         c->parent_index_ = parent_index;
@@ -2481,7 +2496,7 @@ Compaction* VersionSet::CompactRange(
   int out_level = (options_->compaction_style == kCompactionStyleUniversal) ?
                   level : level+1;
 
-  Compaction* c = new Compaction(level, out_level, MaxFileSizeForLevel(level),
+  Compaction* c = new Compaction(level, out_level, MaxFileSizeForLevel(out_level),
     MaxGrandParentOverlapBytes(level), NumberLevels());
   c->input_version_ = current_;
   c->input_version_->Ref();

db/version_set.h

@@ -74,7 +74,8 @@ class Version {
     int seek_file_level;
   };
   void Get(const ReadOptions&, const LookupKey& key, std::string* val,
-           Status* status, GetStats* stats,  const Options& db_option);
+           Status* status, GetStats* stats,  const Options& db_option,
+           const bool no_IO = false);
 
   // Adds "stats" into the current state.  Returns true if a new
   // compaction may need to be triggered, false otherwise.

include/leveldb/db.h

@@ -19,8 +19,8 @@ namespace leveldb {
 using std::unique_ptr;
 
 // Update Makefile if you change these
-static const int kMajorVersion = 1;
+static const int kMajorVersion = 2;
-static const int kMinorVersion = 5;
+static const int kMinorVersion = 0;
 
 struct Options;
 struct ReadOptions;
@@ -120,6 +120,11 @@ class DB {
                                        const std::vector<Slice>& keys,
                                        std::vector<std::string>* values) = 0;
 
+  // If the key definitely does not exist in the database, then this method
+  // returns false. Otherwise return true. This check is potentially
+  // lighter-weight than invoking DB::Get(). No IO is performed
+  virtual bool KeyMayExist(const Slice& key) = 0;
+
   // Return a heap-allocated iterator over the contents of the database.
   // The result of NewIterator() is initially invalid (caller must
   // call one of the Seek methods on the iterator before using it).

include/leveldb/options.h

@@ -422,17 +422,6 @@ struct Options {
   // Default: true
   bool allow_os_buffer;
 
-  // Reading a single block from a file can cause the OS/FS to start
-  // readaheads of other blocks from the file. Default: true
-  // Note: Deprecated
-  bool allow_readahead;
-
-  // The reads triggered by compaction allows data to be readahead
-  // by the OS/FS. This overrides the setting of 'allow_readahead'
-  // for compaction-reads. Default: true
-  // Note: Deprecated
-  bool allow_readahead_compactions;
-
   // Allow the OS to mmap file for reading sst tables. Default: false
   bool allow_mmap_reads;
 
@@ -487,6 +476,15 @@ struct Options {
 
   // The options needed to support Universal Style compactions
   CompactionOptionsUniversal compaction_options_universal;
+
+  // Use bloom-filter for deletes when this is true.
+  // db->Delete first calls KeyMayExist which checks memtable,immutable-memtable
+  // and bloom-filters to determine if the key does not exist in the database.
+  // If the key definitely does not exist, then the delete is a noop.KeyMayExist
+  // only incurs in-memory look up. This optimization avoids writing the delete
+  // to storage when appropriate.
+  // Default: false
+  bool deletes_check_filter_first;
 };
 
 // Options that control read operations

include/leveldb/statistics.h

@@ -58,7 +58,9 @@ enum Tickers {
   NUMBER_MULTIGET_KEYS_READ = 19,
   NUMBER_MULTIGET_BYTES_READ = 20,
 
-  TICKER_ENUM_MAX = 21
+  NUMBER_FILTERED_DELETES = 21,
+
+  TICKER_ENUM_MAX = 22
 };
 
 const std::vector<std::pair<Tickers, std::string>> TickersNameMap = {
@@ -82,7 +84,8 @@ const std::vector<std::pair<Tickers, std::string>> TickersNameMap = {
   { NO_ITERATORS, "rocksdb.num.iterators" },
   { NUMBER_MULTIGET_CALLS, "rocksdb.number.multiget.get" },
   { NUMBER_MULTIGET_KEYS_READ, "rocksdb.number.multiget.keys.read" },
-  { NUMBER_MULTIGET_BYTES_READ, "rocksdb.number.multiget.bytes.read" }
+  { NUMBER_MULTIGET_BYTES_READ, "rocksdb.number.multiget.bytes.read" },
+  { NUMBER_FILTERED_DELETES, "rocksdb.number.deletes.filtered" }
 };
 
 /**

table/table.cc

@@ -322,7 +322,9 @@ Iterator* Table::NewIterator(const ReadOptions& options) const {
 Status Table::InternalGet(const ReadOptions& options, const Slice& k,
                           void* arg,
                           bool (*saver)(void*, const Slice&, const Slice&,
-                                        bool)) {
+                                        bool),
+                          void (*mark_key_may_exist)(void*),
+                          const bool no_IO) {
   Status s;
   Iterator* iiter = rep_->index_block->NewIterator(rep_->options.comparator);
   bool done = false;
@@ -338,6 +340,11 @@ Status Table::InternalGet(const ReadOptions& options, const Slice& k,
       // cross one data block, we should be fine.
       RecordTick(rep_->options.statistics, BLOOM_FILTER_USEFUL);
       break;
+    } else if (no_IO) {
+        // Update Saver.state to Found because we are only looking for whether
+        // bloom-filter can guarantee the key is not there when "no_IO"
+        (*mark_key_may_exist)(arg);
+        done = true;
     } else {
       bool didIO = false;
       Iterator* block_iter = BlockReader(this, options, iiter->value(),

table/table.h

@@ -86,7 +86,9 @@ class Table {
   Status InternalGet(
       const ReadOptions&, const Slice& key,
       void* arg,
-      bool (*handle_result)(void* arg, const Slice& k, const Slice& v, bool));
+      bool (*handle_result)(void* arg, const Slice& k, const Slice& v, bool),
+      void (*mark_key_may_exist)(void*) = nullptr,
+      const bool no_IO = false);
 
 
   void ReadMeta(const Footer& footer);

tools/db_stress.cc

@@ -183,6 +183,9 @@ static uint32_t FLAGS_log2_keys_per_lock = 2; // implies 2^2 keys per lock
 // Percentage of times we want to purge redundant keys in memory before flushing
 static uint32_t FLAGS_purge_redundant_percent = 50;
 
+// On true, deletes use bloom-filter and drop the delete if key not present
+static bool FLAGS_deletes_check_filter_first = false;
+
 // Level0 compaction start trigger
 static int FLAGS_level0_file_num_compaction_trigger = 0;
 
@@ -901,8 +904,10 @@ class StressTest {
     fprintf(stdout, "Num times DB reopens: %d\n", FLAGS_reopen);
     fprintf(stdout, "Batches/snapshots   : %d\n",
             FLAGS_test_batches_snapshots);
-    fprintf(stdout, "Purge redundant %%   : %d\n",
+    fprintf(stdout, "Purge redundant %%  : %d\n",
             FLAGS_purge_redundant_percent);
+    fprintf(stdout, "Deletes use filter  : %d\n",
+            FLAGS_deletes_check_filter_first);
     fprintf(stdout, "Num keys per lock   : %d\n",
             1 << FLAGS_log2_keys_per_lock);
 
@@ -959,6 +964,7 @@ class StressTest {
     options.delete_obsolete_files_period_micros =
       FLAGS_delete_obsolete_files_period_micros;
     options.max_manifest_file_size = 1024;
+    options.deletes_check_filter_first = FLAGS_deletes_check_filter_first;
     static Random purge_percent(1000); // no benefit from non-determinism here
     if (purge_percent.Uniform(100) < FLAGS_purge_redundant_percent - 1) {
       options.purge_redundant_kvs_while_flush = false;
@@ -998,10 +1004,7 @@ class StressTest {
 
   void PrintStatistics() {
     if (dbstats) {
-      fprintf(stdout, "File opened:%ld closed:%ld errors:%ld\n",
+      fprintf(stdout, "STATISTICS:\n%s\n", dbstats->ToString().c_str());
-              dbstats->getTickerCount(NO_FILE_OPENS),
-              dbstats->getTickerCount(NO_FILE_CLOSES),
-              dbstats->getTickerCount(NO_FILE_ERRORS));
     }
   }
 
@@ -1165,6 +1168,9 @@ int main(int argc, char** argv) {
     } else if (sscanf(argv[i], "--purge_redundant_percent=%d%c", &n, &junk) == 1
         && (n >= 0 && n <= 100)) {
       FLAGS_purge_redundant_percent = n;
+    } else if (sscanf(argv[i], "--deletes_check_filter_first=%d%c", &n, &junk)
+        == 1 && (n == 0 || n == 1)) {
+      FLAGS_deletes_check_filter_first = n;
     } else {
       fprintf(stderr, "Invalid flag '%s'\n", argv[i]);
       exit(1);

util/ldb_cmd.cc

@@ -5,6 +5,7 @@
 #include "util/ldb_cmd.h"
 
 #include "db/dbformat.h"
+#include "db/db_impl.h"
 #include "db/log_reader.h"
 #include "db/filename.h"
 #include "db/write_batch_internal.h"
@@ -45,7 +46,7 @@ const char* LDBCommand::DELIM = " ==> ";
 LDBCommand* LDBCommand::InitFromCmdLineArgs(
   int argc,
   char** argv,
-  Options options
+  const Options& options
 ) {
   vector<string> args;
   for (int i = 1; i < argc; i++) {
@@ -66,7 +67,7 @@ LDBCommand* LDBCommand::InitFromCmdLineArgs(
  */
 LDBCommand* LDBCommand::InitFromCmdLineArgs(
   const vector<string>& args,
-  Options options
+  const Options& options
 ) {
   // --x=y command line arguments are added as x->y map entries.
   map<string, string> option_map;
@@ -80,9 +81,7 @@ LDBCommand* LDBCommand::InitFromCmdLineArgs(
 
   const string OPTION_PREFIX = "--";
 
-  for (vector<string>::const_iterator itr = args.begin();
+  for (const auto& arg : args) {
-      itr != args.end(); itr++) {
-    string arg = *itr;
     if (arg[0] == '-' && arg[1] == '-'){
       vector<string> splits = stringSplit(arg, '=');
       if (splits.size() == 2) {
@@ -93,7 +92,7 @@ LDBCommand* LDBCommand::InitFromCmdLineArgs(
         flags.push_back(optionKey);
       }
     } else {
-      cmdTokens.push_back(string(arg));
+      cmdTokens.push_back(arg);
     }
   }
 
@@ -119,9 +118,9 @@ LDBCommand* LDBCommand::InitFromCmdLineArgs(
 
 LDBCommand* LDBCommand::SelectCommand(
     const std::string& cmd,
-    vector<string>& cmdParams,
+    const vector<string>& cmdParams,
-    map<string, string>& option_map,
+    const map<string, string>& option_map,
-    vector<string>& flags
+    const vector<string>& flags
   ) {
 
   if (cmd == GetCommand::Name()) {
@@ -150,6 +149,8 @@ LDBCommand* LDBCommand::SelectCommand(
     return new DBLoaderCommand(cmdParams, option_map, flags);
   } else if (cmd == ManifestDumpCommand::Name()) {
     return new ManifestDumpCommand(cmdParams, option_map, flags);
+  } else if (cmd == InternalDumpCommand::Name()) {
+    return new InternalDumpCommand(cmdParams, option_map, flags);
   }
   return nullptr;
 }
@@ -163,7 +164,8 @@ LDBCommand* LDBCommand::SelectCommand(
  * updated.
  */
 bool LDBCommand::ParseIntOption(const map<string, string>& options,
-    string option, int& value, LDBCommandExecuteResult& exec_state) {
+                                const string& option, int& value,
+                                LDBCommandExecuteResult& exec_state) {
 
   map<string, string>::const_iterator itr = option_map_.find(option);
   if (itr != option_map_.end()) {
@@ -181,6 +183,21 @@ bool LDBCommand::ParseIntOption(const map<string, string>& options,
   return false;
 }
 
+/**
+ * Parses the specified option and fills in the value.
+ * Returns true if the option is found.
+ * Returns false otherwise.
+ */
+bool LDBCommand::ParseStringOption(const map<string, string>& options,
+                                   const string& option, string* value) {
+  auto itr = option_map_.find(option);
+  if (itr != option_map_.end()) {
+    *value = itr->second;
+    return true;
+  }
+  return false;
+}
+
 Options LDBCommand::PrepareOptionsForOpenDB() {
 
   Options opt = options_;
@@ -453,7 +470,7 @@ void ManifestDumpCommand::Help(string& ret) {
 ManifestDumpCommand::ManifestDumpCommand(const vector<string>& params,
       const map<string, string>& options, const vector<string>& flags) :
     LDBCommand(options, flags, false,
-               BuildCmdLineOptions({ARG_VERBOSE,ARG_PATH})),
+               BuildCmdLineOptions({ARG_VERBOSE, ARG_PATH, ARG_HEX})),
     verbose_(false),
     path_("")
 {
@@ -559,6 +576,115 @@ void PrintBucketCounts(const vector<uint64_t>& bucket_counts, int ttl_start,
           ReadableTime(ttl_end).c_str(), bucket_counts[num_buckets - 1]);
 }
 
+const string InternalDumpCommand::ARG_COUNT_ONLY = "count_only";
+const string InternalDumpCommand::ARG_STATS = "stats";
+
+InternalDumpCommand::InternalDumpCommand(const vector<string>& params,
+                                         const map<string, string>& options,
+                                         const vector<string>& flags) :
+    LDBCommand(options, flags, true,
+               BuildCmdLineOptions({ ARG_HEX, ARG_KEY_HEX, ARG_VALUE_HEX,
+                                     ARG_FROM, ARG_TO, ARG_MAX_KEYS,
+                                     ARG_COUNT_ONLY, ARG_STATS})),
+    has_from_(false),
+    has_to_(false),
+    max_keys_(-1),
+    count_only_(false),
+    print_stats_(false) {
+
+  has_from_ = ParseStringOption(options, ARG_FROM, &from_);
+  has_to_ = ParseStringOption(options, ARG_TO, &to_);
+
+  ParseIntOption(options, ARG_MAX_KEYS, max_keys_, exec_state_);
+
+  print_stats_ = IsFlagPresent(flags, ARG_STATS);
+  count_only_ = IsFlagPresent(flags, ARG_COUNT_ONLY);
+
+  if (is_key_hex_) {
+    if (has_from_) {
+      from_ = HexToString(from_);
+    }
+    if (has_to_) {
+      to_ = HexToString(to_);
+    }
+  }
+}
+
+void InternalDumpCommand::Help(string& ret) {
+  ret.append("  ");
+  ret.append(InternalDumpCommand::Name());
+  ret.append(HelpRangeCmdArgs());
+  ret.append(" [--" + ARG_MAX_KEYS + "=<N>]");
+  ret.append(" [--" + ARG_COUNT_ONLY + "]");
+  ret.append(" [--" + ARG_STATS + "]");
+  ret.append("\n");
+}
+
+void InternalDumpCommand::DoCommand() {
+  if (!db_) {
+    return;
+  }
+
+  if (print_stats_) {
+    string stats;
+    if (db_->GetProperty("leveldb.stats", &stats)) {
+      fprintf(stdout, "%s\n", stats.c_str());
+    }
+  }
+
+  // Cast as DBImpl to get internal iterator
+  DBImpl* idb = dynamic_cast<DBImpl*>(db_);
+  if (!idb) {
+    exec_state_ = LDBCommandExecuteResult::FAILED("DB is not DBImpl");
+    return;
+  }
+
+  // Setup internal key iterator
+  auto iter = unique_ptr<Iterator>(idb->TEST_NewInternalIterator());
+  Status st = iter->status();
+  if (!st.ok()) {
+    exec_state_ = LDBCommandExecuteResult::FAILED("Iterator error:"
+                                                  + st.ToString());
+  }
+
+  if (has_from_) {
+    InternalKey ikey(from_, kMaxSequenceNumber, kValueTypeForSeek);
+    iter->Seek(ikey.Encode());
+  } else {
+    iter->SeekToFirst();
+  }
+
+  long long count = 0;
+  for (; iter->Valid(); iter->Next()) {
+    ParsedInternalKey ikey;
+    if (!ParseInternalKey(iter->key(), &ikey)) {
+      fprintf(stderr, "Internal Key [%s] parse error!\n",
+              iter->key().ToString(true /* in hex*/).data());
+      // TODO: add error counter
+      continue;
+    }
+
+    // If end marker was specified, we stop before it
+    if (has_to_ && options_.comparator->Compare(ikey.user_key, to_) >= 0) {
+      break;
+    }
+
+    ++count;
+
+    if (!count_only_) {
+      string key = ikey.DebugString(is_key_hex_);
+      string value = iter->value().ToString(is_value_hex_);
+      fprintf(stdout, "%s => %s\n", key.data(), value.data());
+    }
+
+    // Terminate if maximum number of keys have been dumped
+    if (max_keys_ > 0 && count >= max_keys_) break;
+  }
+
+  fprintf(stdout, "Internal keys in range: %lld\n", (long long) count);
+}
+
+
 const string DBDumperCommand::ARG_COUNT_ONLY = "count_only";
 const string DBDumperCommand::ARG_STATS = "stats";
 const string DBDumperCommand::ARG_TTL_BUCKET = "bucket";

util/ldb_cmd.h

@@ -55,13 +55,13 @@ public:
 
   static LDBCommand* InitFromCmdLineArgs(
     const vector<string>& args,
-    Options options = Options()
+    const Options& options = Options()
   );
 
   static LDBCommand* InitFromCmdLineArgs(
     int argc,
     char** argv,
-    Options options = Options()
+    const Options& options = Options()
   );
 
   bool ValidateCmdLineOptions();
@@ -230,6 +230,8 @@ protected:
       string msg = st.ToString();
       exec_state_ = LDBCommandExecuteResult::FAILED(msg);
     }
+
+    options_ = opt;
   }
 
   void CloseDB () {
@@ -281,13 +283,16 @@ protected:
     return ret;
   }
 
-  bool ParseIntOption(const map<string, string>& options, string option,
+  bool ParseIntOption(const map<string, string>& options, const string& option,
-      int& value, LDBCommandExecuteResult& exec_state);
+                      int& value, LDBCommandExecuteResult& exec_state);
 
-private:
+  bool ParseStringOption(const map<string, string>& options,
+                         const string& option, string* value);
 
   Options options_;
 
+private:
+
   /**
    * Interpret command line options and flags to determine if the key
    * should be input/output in hex.
@@ -347,9 +352,9 @@ private:
 
   static LDBCommand* SelectCommand(
     const string& cmd,
-    vector<string>& cmdParams,
+    const vector<string>& cmdParams,
-    map<string, string>& option_map,
+    const map<string, string>& option_map,
-    vector<string>& flags
+    const vector<string>& flags
   );
 
 };
@@ -397,6 +402,31 @@ private:
   static const string ARG_TTL_BUCKET;
 };
 
+class InternalDumpCommand: public LDBCommand {
+public:
+  static string Name() { return "idump"; }
+
+  InternalDumpCommand(const vector<string>& params,
+                      const map<string, string>& options,
+                      const vector<string>& flags);
+
+  static void Help(string& ret);
+
+  virtual void DoCommand();
+
+private:
+  bool has_from_;
+  string from_;
+  bool has_to_;
+  string to_;
+  int max_keys_;
+  bool count_only_;
+  bool print_stats_;
+
+  static const string ARG_COUNT_ONLY;
+  static const string ARG_STATS;
+};
+
 class DBLoaderCommand: public LDBCommand {
 public:
   static string Name() { return "load"; }

util/ldb_tool.cc

@@ -59,6 +59,7 @@ public:
     DBDumperCommand::Help(ret);
     DBLoaderCommand::Help(ret);
     ManifestDumpCommand::Help(ret);
+    InternalDumpCommand::Help(ret);
 
     fprintf(stderr, "%s\n", ret.c_str());
   }

util/options.cc

@@ -65,8 +65,6 @@ Options::Options()
       manifest_preallocation_size(4 * 1024 * 1024),
       purge_redundant_kvs_while_flush(true),
       allow_os_buffer(true),
-      allow_readahead(true),
-      allow_readahead_compactions(true),
       allow_mmap_reads(false),
       allow_mmap_writes(true),
       is_fd_close_on_exec(true),
@@ -78,6 +76,7 @@ Options::Options()
       use_adaptive_mutex(false),
       bytes_per_sync(0),
       compaction_style(kCompactionStyleLevel) {
+      deletes_check_filter_first(false) {
 }
 
 static const char* const access_hints[] = {
@@ -127,13 +126,10 @@ Options::Dump(Logger* log) const
     Log(log," Options.db_stats_log_interval: %d",
         db_stats_log_interval);
     Log(log,"       Options.allow_os_buffer: %d", allow_os_buffer);
-    Log(log,"       Options.allow_readahead: %d", allow_readahead);
     Log(log,"      Options.allow_mmap_reads: %d", allow_mmap_reads);
     Log(log,"     Options.allow_mmap_writes: %d", allow_mmap_writes);
     Log(log,"       Options.min_write_buffer_number_to_merge: %d",
         min_write_buffer_number_to_merge);
-    Log(log,"            Options.allow_readahead_compactions: %d",
-        allow_readahead_compactions);
     Log(log,"        Options.purge_redundant_kvs_while_flush: %d",
          purge_redundant_kvs_while_flush);
     Log(log,"           Options.compression_opts.window_bits: %d",
@@ -194,10 +190,6 @@ Options::Dump(Logger* log) const
         purge_redundant_kvs_while_flush);
     Log(log,"                         Options.allow_os_buffer: %d",
         allow_os_buffer);
-    Log(log,"                         Options.allow_readahead: %d",
-        allow_readahead);
-    Log(log,"             Options.allow_readahead_compactions: %d",
-        allow_readahead_compactions);
     Log(log,"                        Options.allow_mmap_reads: %d",
         allow_mmap_reads);
     Log(log,"                       Options.allow_mmap_writes: %d",
@@ -220,6 +212,8 @@ Options::Dump(Logger* log) const
         bytes_per_sync);
     Log(log,"                        Options.compaction_style: %d",
         compaction_style);
+    Log(log,"              Options.deletes_check_filter_first: %d",
+        deletes_check_filter_first);
     Log(log,"        Options.compaction_options_universal.size_ratio: %d",
         compaction_options_universal.size_ratio);
     Log(log,"   Options.compaction_options_universal.min_merge_width: %d",

utilities/ttl/db_ttl.cc

@@ -158,6 +158,10 @@ std::vector<Status> DBWithTTL::MultiGet(const ReadOptions& options,
                                supported with TTL"));
 }
 
+bool DBWithTTL::KeyMayExist(const Slice& key) {
+  return db_->KeyMayExist(key);
+}
+
 Status DBWithTTL::Delete(const WriteOptions& wopts, const Slice& key) {
   return db_->Delete(wopts, key);
 }

utilities/ttl/db_ttl.h

@@ -33,6 +33,8 @@ class DBWithTTL : public DB, CompactionFilter {
                                        const std::vector<Slice>& keys,
                                        std::vector<std::string>* values);
 
+  virtual bool KeyMayExist(const Slice& key);
+
   virtual Status Delete(const WriteOptions& wopts, const Slice& key);
 
   virtual Status Merge(const WriteOptions& options,