bloom hit/miss stats for SST and memtable

Summary:
	hit and miss bloom filter stats for memtable and SST
	stats added to perf_context struct
	key matches and prefix matches combined into one stat

Test Plan: unit test veryfing the functionality added, see BloomStatsTest in db_test.cc for details

Reviewers: yhchiang, igor, sdong

Reviewed By: sdong

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D47859

db/db_test.cc

@@ -131,6 +131,46 @@ class DBTestWithParam : public DBTest,
   uint32_t max_subcompactions_;
 };
 
+class BloomStatsTestWithParam
+    : public DBTest,
+      public testing::WithParamInterface<std::tuple<bool, bool>> {
+ public:
+  BloomStatsTestWithParam() {
+    use_block_table_ = std::get<0>(GetParam());
+    use_block_based_builder_ = std::get<1>(GetParam());
+
+    options_.create_if_missing = true;
+    options_.prefix_extractor.reset(rocksdb::NewFixedPrefixTransform(4));
+    options_.memtable_prefix_bloom_bits = 8 * 1024;
+    if (use_block_table_) {
+      BlockBasedTableOptions table_options;
+      table_options.hash_index_allow_collision = false;
+      table_options.filter_policy.reset(
+          NewBloomFilterPolicy(10, use_block_based_builder_));
+      options_.table_factory.reset(NewBlockBasedTableFactory(table_options));
+    } else {
+      PlainTableOptions table_options;
+      options_.table_factory.reset(NewPlainTableFactory(table_options));
+    }
+
+    perf_context.Reset();
+    DestroyAndReopen(options_);
+  }
+
+  ~BloomStatsTestWithParam() {
+    perf_context.Reset();
+    Destroy(options_);
+  }
+
+  // Required if inheriting from testing::WithParamInterface<>
+  static void SetUpTestCase() {}
+  static void TearDownTestCase() {}
+
+  bool use_block_table_;
+  bool use_block_based_builder_;
+  Options options_;
+};
+
 TEST_F(DBTest, Empty) {
   do {
     Options options;
@@ -9709,6 +9749,119 @@ TEST_F(DBTest, PauseBackgroundWorkTest) {
   ASSERT_EQ(true, done.load());
 }
 
+// 1 Insert 2 K-V pairs into DB
+// 2 Call Get() for both keys - expext memtable bloom hit stat to be 2
+// 3 Call Get() for nonexisting key - expect memtable bloom miss stat to be 1
+// 4 Call Flush() to create SST
+// 5 Call Get() for both keys - expext SST bloom hit stat to be 2
+// 6 Call Get() for nonexisting key - expect SST bloom miss stat to be 1
+// Test both: block and plain SST
+TEST_P(BloomStatsTestWithParam, BloomStatsTest) {
+  std::string key1("AAAA");
+  std::string key2("RXDB");  // not in DB
+  std::string key3("ZBRA");
+  std::string value1("Value1");
+  std::string value3("Value3");
+
+  ASSERT_OK(Put(key1, value1, WriteOptions()));
+  ASSERT_OK(Put(key3, value3, WriteOptions()));
+
+  // check memtable bloom stats
+  ASSERT_EQ(value1, Get(key1));
+  ASSERT_EQ(1, perf_context.bloom_memtable_hit_count);
+  ASSERT_EQ(value3, Get(key3));
+  ASSERT_EQ(2, perf_context.bloom_memtable_hit_count);
+  ASSERT_EQ(0, perf_context.bloom_memtable_miss_count);
+
+  ASSERT_EQ("NOT_FOUND", Get(key2));
+  ASSERT_EQ(1, perf_context.bloom_memtable_miss_count);
+  ASSERT_EQ(2, perf_context.bloom_memtable_hit_count);
+
+  // sanity checks
+  ASSERT_EQ(0, perf_context.bloom_sst_hit_count);
+  ASSERT_EQ(0, perf_context.bloom_sst_miss_count);
+
+  Flush();
+
+  // sanity checks
+  ASSERT_EQ(0, perf_context.bloom_sst_hit_count);
+  ASSERT_EQ(0, perf_context.bloom_sst_miss_count);
+
+  // check SST bloom stats
+  // NOTE: hits per get differs because of code paths differences
+  // in BlockBasedTable::Get()
+  int hits_per_get = use_block_table_ && !use_block_based_builder_ ? 2 : 1;
+  ASSERT_EQ(value1, Get(key1));
+  ASSERT_EQ(hits_per_get, perf_context.bloom_sst_hit_count);
+  ASSERT_EQ(value3, Get(key3));
+  ASSERT_EQ(2 * hits_per_get, perf_context.bloom_sst_hit_count);
+
+  ASSERT_EQ("NOT_FOUND", Get(key2));
+  ASSERT_EQ(1, perf_context.bloom_sst_miss_count);
+}
+
+// Same scenario as in BloomStatsTest but using an iterator
+TEST_P(BloomStatsTestWithParam, BloomStatsTestWithIter) {
+  std::string key1("AAAA");
+  std::string key2("RXDB");  // not in DB
+  std::string key3("ZBRA");
+  std::string value1("Value1");
+  std::string value3("Value3");
+
+  ASSERT_OK(Put(key1, value1, WriteOptions()));
+  ASSERT_OK(Put(key3, value3, WriteOptions()));
+
+  unique_ptr<Iterator> iter(dbfull()->NewIterator(ReadOptions()));
+
+  // check memtable bloom stats
+  iter->Seek(key1);
+  ASSERT_OK(iter->status());
+  ASSERT_TRUE(iter->Valid());
+  ASSERT_EQ(value1, iter->value().ToString());
+  ASSERT_EQ(1, perf_context.bloom_memtable_hit_count);
+  ASSERT_EQ(0, perf_context.bloom_memtable_miss_count);
+
+  iter->Seek(key3);
+  ASSERT_OK(iter->status());
+  ASSERT_TRUE(iter->Valid());
+  ASSERT_EQ(value3, iter->value().ToString());
+  ASSERT_EQ(2, perf_context.bloom_memtable_hit_count);
+  ASSERT_EQ(0, perf_context.bloom_memtable_miss_count);
+
+  iter->Seek(key2);
+  ASSERT_OK(iter->status());
+  ASSERT_TRUE(!iter->Valid());
+  ASSERT_EQ(1, perf_context.bloom_memtable_miss_count);
+  ASSERT_EQ(2, perf_context.bloom_memtable_hit_count);
+
+  Flush();
+
+  iter.reset(dbfull()->NewIterator(ReadOptions()));
+
+  // check SST bloom stats
+  iter->Seek(key1);
+  ASSERT_OK(iter->status());
+  ASSERT_TRUE(iter->Valid());
+  ASSERT_EQ(value1, iter->value().ToString());
+  ASSERT_EQ(1, perf_context.bloom_sst_hit_count);
+
+  iter->Seek(key3);
+  ASSERT_OK(iter->status());
+  ASSERT_TRUE(iter->Valid());
+  ASSERT_EQ(value3, iter->value().ToString());
+  ASSERT_EQ(2, perf_context.bloom_sst_hit_count);
+
+  iter->Seek(key2);
+  ASSERT_OK(iter->status());
+  ASSERT_TRUE(!iter->Valid());
+  ASSERT_EQ(1, perf_context.bloom_sst_miss_count);
+  ASSERT_EQ(2, perf_context.bloom_sst_hit_count);
+}
+
+INSTANTIATE_TEST_CASE_P(BloomStatsTestWithParam, BloomStatsTestWithParam,
+                        ::testing::Values(std::make_tuple(true, true),
+                                          std::make_tuple(true, false),
+                                          std::make_tuple(false, false)));
 }  // namespace rocksdb
 
 #endif

db/memtable.cc

@@ -230,10 +230,15 @@ class MemTableIterator: public Iterator {
   virtual void Seek(const Slice& k) override {
     PERF_TIMER_GUARD(seek_on_memtable_time);
     PERF_COUNTER_ADD(seek_on_memtable_count, 1);
-    if (bloom_ != nullptr &&
-        !bloom_->MayContain(prefix_extractor_->Transform(ExtractUserKey(k)))) {
-      valid_ = false;
-      return;
+    if (bloom_ != nullptr) {
+      if (!bloom_->MayContain(
+              prefix_extractor_->Transform(ExtractUserKey(k)))) {
+        PERF_COUNTER_ADD(bloom_memtable_miss_count, 1);
+        valid_ = false;
+        return;
+      } else {
+        PERF_COUNTER_ADD(bloom_memtable_hit_count, 1);
+      }
     }
     iter_->Seek(k, nullptr);
     valid_ = iter_->Valid();
@@ -508,12 +513,18 @@ bool MemTable::Get(const LookupKey& key, std::string* value, Status* s,
   Slice user_key = key.user_key();
   bool found_final_value = false;
   bool merge_in_progress = s->IsMergeInProgress();
-
-  if (prefix_bloom_ &&
-      !prefix_bloom_->MayContain(prefix_extractor_->Transform(user_key))) {
+  bool const may_contain =
+      nullptr == prefix_bloom_
+          ? false
+          : prefix_bloom_->MayContain(prefix_extractor_->Transform(user_key));
+  if (prefix_bloom_ && !may_contain) {
     // iter is null if prefix bloom says the key does not exist
+    PERF_COUNTER_ADD(bloom_memtable_miss_count, 1);
     *seq = kMaxSequenceNumber;
   } else {
+    if (prefix_bloom_) {
+      PERF_COUNTER_ADD(bloom_memtable_hit_count, 1);
+    }
     Saver saver;
     saver.status = s;
     saver.found_final_value = &found_final_value;

include/rocksdb/perf_context.h

@@ -83,6 +83,14 @@ struct PerfContext {
   uint64_t block_seek_nanos;
   // Time spent on finding or creating a table reader
   uint64_t find_table_nanos;
+  // total number of mem table bloom hits
+  uint64_t bloom_memtable_hit_count;
+  // total number of mem table bloom misses
+  uint64_t bloom_memtable_miss_count;
+  // total number of SST table bloom hits
+  uint64_t bloom_sst_hit_count;
+  // total number of SST table bloom misses
+  uint64_t bloom_sst_miss_count;
 };
 
 #if defined(NPERF_CONTEXT) || defined(IOS_CROSS_COMPILE)

table/block_based_filter_block.cc

@@ -7,12 +7,13 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file. See the AUTHORS file for names of contributors.
 
-#include <algorithm>
 #include "table/block_based_filter_block.h"
+#include <algorithm>
 
 #include "db/dbformat.h"
 #include "rocksdb/filter_policy.h"
 #include "util/coding.h"
+#include "util/perf_context_imp.h"
 #include "util/string_util.h"
 
 namespace rocksdb {
@@ -219,7 +220,14 @@ bool BlockBasedFilterBlockReader::MayMatch(const Slice& entry,
     uint32_t limit = DecodeFixed32(offset_ + index * 4 + 4);
     if (start <= limit && limit <= (uint32_t)(offset_ - data_)) {
       Slice filter = Slice(data_ + start, limit - start);
-      return policy_->KeyMayMatch(entry, filter);
+      bool const may_match = policy_->KeyMayMatch(entry, filter);
+      if (may_match) {
+        PERF_COUNTER_ADD(bloom_sst_hit_count, 1);
+        return true;
+      } else {
+        PERF_COUNTER_ADD(bloom_sst_miss_count, 1);
+        return false;
+      }
     } else if (start == limit) {
       // Empty filters do not match any entries
       return false;

table/full_filter_block.cc

@@ -8,6 +8,7 @@
 #include "rocksdb/filter_policy.h"
 #include "port/port.h"
 #include "util/coding.h"
+#include "util/perf_context_imp.h"
 
 namespace rocksdb {
 
@@ -89,7 +90,13 @@ bool FullFilterBlockReader::PrefixMayMatch(const Slice& prefix,
 
 bool FullFilterBlockReader::MayMatch(const Slice& entry) {
   if (contents_.size() != 0)  {
-    return filter_bits_reader_->MayMatch(entry);
+    if (filter_bits_reader_->MayMatch(entry)) {
+      PERF_COUNTER_ADD(bloom_sst_hit_count, 1);
+      return true;
+    } else {
+      PERF_COUNTER_ADD(bloom_sst_miss_count, 1);
+      return false;
+    }
   }
   return true;  // remain the same with block_based filter
 }

table/plain_table_reader.cc

@@ -488,7 +488,17 @@ Status PlainTableReader::GetOffset(const Slice& target, const Slice& prefix,
 }
 
 bool PlainTableReader::MatchBloom(uint32_t hash) const {
-  return !enable_bloom_ || bloom_.MayContainHash(hash);
+  if (!enable_bloom_) {
+    return true;
+  }
+
+  if (bloom_.MayContainHash(hash)) {
+    PERF_COUNTER_ADD(bloom_sst_hit_count, 1);
+    return true;
+  } else {
+    PERF_COUNTER_ADD(bloom_sst_miss_count, 1);
+    return false;
+  }
 }
 
 Status PlainTableReader::Next(PlainTableKeyDecoder* decoder, uint32_t* offset,

util/perf_context.cc

@@ -54,6 +54,10 @@ void PerfContext::Reset() {
   new_table_iterator_nanos = 0;
   block_seek_nanos = 0;
   find_table_nanos = 0;
+  bloom_memtable_hit_count = 0;
+  bloom_memtable_miss_count = 0;
+  bloom_sst_hit_count = 0;
+  bloom_sst_miss_count = 0;
 #endif
 }
 
@@ -80,7 +84,9 @@ std::string PerfContext::ToString() const {
      << OUTPUT(merge_operator_time_nanos) << OUTPUT(write_delay_time)
      << OUTPUT(read_index_block_nanos) << OUTPUT(read_filter_block_nanos)
      << OUTPUT(new_table_block_iter_nanos) << OUTPUT(new_table_iterator_nanos)
-     << OUTPUT(block_seek_nanos) << OUTPUT(find_table_nanos);
+     << OUTPUT(block_seek_nanos) << OUTPUT(find_table_nanos)
+     << OUTPUT(bloom_memtable_hit_count) << OUTPUT(bloom_memtable_miss_count)
+     << OUTPUT(bloom_sst_hit_count) << OUTPUT(bloom_sst_miss_count);
   return ss.str();
 #endif
 }