Fixed a bug of CompactionStats in multi-level universal compaction case

Summary:
Universal compaction can involves in multiple levels.  However,
the current implementation of bytes_readn and bytes_readnp1
(and some other stats with postfix `n` and `np1`) assumes compaction
can only have two levels.

This patch fixes this bug and redefines bytes_readn and bytes_readnp1:
* bytes_readnp1: the number of bytes read in the compaction output level.
* bytes_readn: the total number of bytes read minus bytes_readnp1

Test Plan: Add a test in compaction_job_stats_test

Reviewers: igor, sdong, rven, anthony, kradhakrishnan, IslamAbdelRahman

Reviewed By: IslamAbdelRahman

Subscribers: dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D40239

db/compaction_job.cc

@@ -491,10 +491,6 @@ Status CompactionJob::Run() {
   }
 
   compaction_stats_.micros = env_->NowMicros() - start_micros - imm_micros;
-  compaction_stats_.files_in_leveln =
-      static_cast<int>(compact_->compaction->num_input_files(0));
-  compaction_stats_.files_in_levelnp1 =
-      static_cast<int>(compact_->compaction->num_input_files(1));
   MeasureTime(stats_, COMPACTION_TIME, compaction_stats_.micros);
 
   size_t num_output_files = compact_->outputs.size();
@@ -503,19 +499,9 @@ Status CompactionJob::Run() {
     assert(num_output_files > 0);
     --num_output_files;
   }
-  compaction_stats_.files_out_levelnp1 = static_cast<int>(num_output_files);
+  compaction_stats_.num_output_files = static_cast<int>(num_output_files);
 
-  for (size_t i = 0; i < compact_->compaction->num_input_files(0); i++) {
+  UpdateCompactionInputStats();
-    compaction_stats_.bytes_readn +=
-        compact_->compaction->input(0, i)->fd.GetFileSize();
-    compaction_stats_.num_input_records +=
-        static_cast<uint64_t>(compact_->compaction->input(0, i)->num_entries);
-  }
-
-  for (size_t i = 0; i < compact_->compaction->num_input_files(1); i++) {
-    compaction_stats_.bytes_readnp1 +=
-        compact_->compaction->input(1, i)->fd.GetFileSize();
-  }
 
   for (size_t i = 0; i < num_output_files; i++) {
     compaction_stats_.bytes_written += compact_->outputs[i].file_size;
@@ -548,22 +534,28 @@ void CompactionJob::Install(Status* status,
   VersionStorageInfo::LevelSummaryStorage tmp;
   auto vstorage = cfd->current()->storage_info();
   const auto& stats = compaction_stats_;
-  LogToBuffer(log_buffer_,
+  LogToBuffer(
+      log_buffer_,
       "[%s] compacted to: %s, MB/sec: %.1f rd, %.1f wr, level %d, "
       "files in(%d, %d) out(%d) "
       "MB in(%.1f, %.1f) out(%.1f), read-write-amplify(%.1f) "
       "write-amplify(%.1f) %s, records in: %d, records dropped: %d\n",
       cfd->GetName().c_str(), vstorage->LevelSummary(&tmp),
-              (stats.bytes_readn + stats.bytes_readnp1) /
+      (stats.bytes_read_non_output_levels + stats.bytes_read_output_level) /
           static_cast<double>(stats.micros),
       stats.bytes_written / static_cast<double>(stats.micros),
-              compact_->compaction->output_level(), stats.files_in_leveln,
+      compact_->compaction->output_level(),
-              stats.files_in_levelnp1, stats.files_out_levelnp1,
+      stats.num_input_files_in_non_output_levels,
-              stats.bytes_readn / 1048576.0, stats.bytes_readnp1 / 1048576.0,
+      stats.num_input_files_in_output_level,
+      stats.num_output_files,
+      stats.bytes_read_non_output_levels / 1048576.0,
+      stats.bytes_read_output_level / 1048576.0,
       stats.bytes_written / 1048576.0,
-              (stats.bytes_written + stats.bytes_readnp1 + stats.bytes_readn) /
+      (stats.bytes_written + stats.bytes_read_output_level +
-                  static_cast<double>(stats.bytes_readn),
+       stats.bytes_read_non_output_levels) /
-              stats.bytes_written / static_cast<double>(stats.bytes_readn),
+          static_cast<double>(stats.bytes_read_non_output_levels),
+      stats.bytes_written /
+          static_cast<double>(stats.bytes_read_non_output_levels),
       status->ToString().c_str(), stats.num_input_records,
       stats.num_dropped_records);
 
@@ -574,9 +566,9 @@ void CompactionJob::Install(Status* status,
          << "compaction_finished"
          << "output_level" << compact_->compaction->output_level()
          << "num_output_files" << compact_->outputs.size()
-         << "total_output_size" << compact_->total_bytes << "num_input_records"
+         << "total_output_size" << compact_->total_bytes
-         << compact_->num_input_records << "num_output_records"
+         << "num_input_records" << compact_->num_input_records
-         << compact_->num_output_records;
+         << "num_output_records" << compact_->num_output_records;
   stream << "lsm_state";
   stream.StartArray();
   for (int level = 0; level < vstorage->num_levels(); ++level) {
@@ -1245,6 +1237,42 @@ void CopyPrefix(
 
 #endif  // !ROCKSDB_LITE
 
+void CompactionJob::UpdateCompactionInputStats() {
+  Compaction* compaction = compact_->compaction;
+  compaction_stats_.num_input_files_in_non_output_levels = 0;
+  compaction_stats_.num_input_files_in_output_level = 0;
+  for (int input_level = 0;
+       input_level < static_cast<int>(compaction->num_input_levels());
+       ++input_level) {
+    if (compaction->start_level() + input_level
+        != compaction->output_level()) {
+      UpdateCompactionInputStatsHelper(
+          &compaction_stats_.num_input_files_in_non_output_levels,
+          &compaction_stats_.bytes_read_non_output_levels,
+          input_level);
+    } else {
+      UpdateCompactionInputStatsHelper(
+          &compaction_stats_.num_input_files_in_output_level,
+          &compaction_stats_.bytes_read_output_level,
+          input_level);
+    }
+  }
+}
+
+void CompactionJob::UpdateCompactionInputStatsHelper(
+    int* num_files, uint64_t* bytes_read, int input_level) {
+  const Compaction* compaction = compact_->compaction;
+  auto num_input_files = compaction->num_input_files(input_level);
+  *num_files += static_cast<int>(num_input_files);
+
+  for (size_t i = 0; i < num_input_files; ++i) {
+    const auto* file_meta = compaction->input(input_level, i);
+    *bytes_read += file_meta->fd.GetFileSize();
+    compaction_stats_.num_input_records +=
+        static_cast<uint64_t>(file_meta->num_entries);
+  }
+}
+
 void CompactionJob::UpdateCompactionJobStats(
     const InternalStats::CompactionStats& stats) const {
 #ifndef ROCKSDB_LITE
@@ -1253,18 +1281,21 @@ void CompactionJob::UpdateCompactionJobStats(
 
     // input information
     compaction_job_stats_->total_input_bytes =
-        stats.bytes_readn + stats.bytes_readnp1;
+        stats.bytes_read_non_output_levels +
-    compaction_job_stats_->num_input_records = compact_->num_input_records;
+        stats.bytes_read_output_level;
+    compaction_job_stats_->num_input_records =
+        compact_->num_input_records;
     compaction_job_stats_->num_input_files =
-        stats.files_in_leveln + stats.files_in_levelnp1;
+        stats.num_input_files_in_non_output_levels +
+        stats.num_input_files_in_output_level;
     compaction_job_stats_->num_input_files_at_output_level =
-        stats.files_in_levelnp1;
+        stats.num_input_files_in_output_level;
 
     // output information
     compaction_job_stats_->total_output_bytes = stats.bytes_written;
     compaction_job_stats_->num_output_records =
         compact_->num_output_records;
-    compaction_job_stats_->num_output_files = stats.files_out_levelnp1;
+    compaction_job_stats_->num_output_files = stats.num_output_files;
 
     if (compact_->outputs.size() > 0U) {
       CopyPrefix(

db/compaction_job.h

@@ -105,6 +105,10 @@ class CompactionJob {
                          int64_t* key_drop_newer_entry,
                          int64_t* key_drop_obsolete);
 
+  void UpdateCompactionInputStats();
+  void UpdateCompactionInputStatsHelper(
+      int* num_files, uint64_t* bytes_read, int input_level);
+
   int job_id_;
 
   // CompactionJob state

db/compaction_job_stats_test.cc

@@ -475,7 +475,8 @@ CompactionJobStats NewManualCompactionJobStats(
     size_t num_input_files, size_t num_input_files_at_output_level,
     uint64_t num_input_records, size_t key_size, size_t value_size,
     size_t num_output_files, uint64_t num_output_records,
-    double compression_ratio, uint64_t num_records_replaced) {
+    double compression_ratio, uint64_t num_records_replaced,
+    bool is_manual = true) {
   CompactionJobStats stats;
   stats.Reset();
 
@@ -499,7 +500,7 @@ CompactionJobStats NewManualCompactionJobStats(
   stats.total_input_raw_value_bytes =
       num_input_records * value_size;
 
-  stats.is_manual_compaction = true;
+  stats.is_manual_compaction = is_manual;
 
   stats.num_records_replaced = num_records_replaced;
 
@@ -671,7 +672,7 @@ TEST_F(CompactionJobStatsTest, CompactionJobStatsTest) {
     stats_checker->AddExpectedStats(
         NewManualCompactionJobStats(
             smallest_key, largest_key,
-            4, 0, num_keys_per_L0_file * 8,
+            4, 4, num_keys_per_L0_file * 8,
             kKeySize, kValueSize,
             1, num_keys_per_L0_file * 8,
             compression_ratio, 0));
@@ -688,6 +689,90 @@ TEST_F(CompactionJobStatsTest, CompactionJobStatsTest) {
   ASSERT_EQ(stats_checker->NumberOfUnverifiedStats(), 0U);
 }
 
+namespace {
+int GetUniversalCompactionInputUnits(uint32_t num_flushes) {
+  uint32_t compaction_input_units;
+  for (compaction_input_units = 1;
+       num_flushes >= compaction_input_units;
+       compaction_input_units *= 2) {
+    if ((num_flushes & compaction_input_units) != 0) {
+      return compaction_input_units > 1 ? compaction_input_units : 0;
+    }
+  }
+  return 0;
+}
+}  // namespace
+
+TEST_F(CompactionJobStatsTest, UniversalCompactionTest) {
+  Random rnd(301);
+  uint64_t key_base = 100000000l;
+  // Note: key_base must be multiple of num_keys_per_L0_file
+  int num_keys_per_table = 100;
+  const uint32_t kTestScale = 8;
+  const int kKeySize = 10;
+  const int kValueSize = 900;
+  double compression_ratio = 1.0;
+  uint64_t key_interval = key_base / num_keys_per_table;
+
+  auto* stats_checker = new CompactionJobStatsChecker();
+  Options options;
+  options.listeners.emplace_back(stats_checker);
+  options.create_if_missing = true;
+  options.max_background_flushes = 0;
+  options.max_mem_compaction_level = 0;
+  options.num_levels = 3;
+  options.compression = kNoCompression;
+  options.level0_file_num_compaction_trigger = 2;
+  options.target_file_size_base = num_keys_per_table * 1000;
+  options.compaction_style = kCompactionStyleUniversal;
+  options.compaction_options_universal.size_ratio = 1;
+  options.compaction_options_universal.max_size_amplification_percent = 1000;
+  DestroyAndReopen(options);
+  CreateAndReopenWithCF({"pikachu"}, options);
+
+  // Generates the expected CompactionJobStats for each compaction
+  for (uint32_t num_flushes = 2; num_flushes <= kTestScale; num_flushes++) {
+    // Here we treat one newly flushed file as an unit.
+    //
+    // For example, if a newly flushed file is 100k, and a compaction has
+    // 4 input units, then this compaction inputs 400k.
+    uint32_t num_input_units = GetUniversalCompactionInputUnits(num_flushes);
+    if (num_input_units == 0) {
+      continue;
+    }
+    // The following statement determines the expected smallest key
+    // based on whether it is a full compaction.  A full compaction only
+    // happens when the number of flushes equals to the number of compaction
+    // input runs.
+    uint64_t smallest_key =
+        (num_flushes == num_input_units) ?
+            key_base : key_base * (num_flushes - 1);
+
+    stats_checker->AddExpectedStats(
+        NewManualCompactionJobStats(
+            Key(smallest_key, 10),
+            Key(smallest_key + key_base * num_input_units - key_interval, 10),
+            num_input_units,
+            num_input_units > 2 ? num_input_units / 2 : 0,
+            num_keys_per_table * num_input_units,
+            kKeySize, kValueSize,
+            num_input_units,
+            num_keys_per_table * num_input_units,
+            1.0, 0, false));
+  }
+  ASSERT_EQ(stats_checker->NumberOfUnverifiedStats(), 4U);
+
+  for (uint64_t start_key = key_base;
+                start_key <= key_base * kTestScale;
+                start_key += key_base) {
+    MakeTableWithKeyValues(
+        &rnd, start_key, start_key + key_base - 1,
+        kKeySize, kValueSize, key_interval,
+        compression_ratio, 1);
+  }
+  ASSERT_EQ(stats_checker->NumberOfUnverifiedStats(), 0U);
+}
+
 }  // namespace rocksdb
 
 int main(int argc, char** argv) {

db/db_impl.cc

@@ -1215,7 +1215,7 @@ Status DBImpl::WriteLevel0TableForRecovery(int job_id, ColumnFamilyData* cfd,
   InternalStats::CompactionStats stats(1);
   stats.micros = env_->NowMicros() - start_micros;
   stats.bytes_written = meta.fd.GetFileSize();
-  stats.files_out_levelnp1 = 1;
+  stats.num_output_files = 1;
   cfd->internal_stats()->AddCompactionStats(level, stats);
   cfd->internal_stats()->AddCFStats(
       InternalStats::BYTES_FLUSHED, meta.fd.GetFileSize());

db/internal_stats.cc

@@ -45,8 +45,10 @@ void PrintLevelStats(char* buf, size_t len, const std::string& name,
     int num_files, int being_compacted, double total_file_size, double score,
     double w_amp, uint64_t stalls,
     const InternalStats::CompactionStats& stats) {
-  uint64_t bytes_read = stats.bytes_readn + stats.bytes_readnp1;
+  uint64_t bytes_read =
-  int64_t bytes_new = stats.bytes_written - stats.bytes_readnp1;
+      stats.bytes_read_non_output_levels + stats.bytes_read_output_level;
+  int64_t bytes_new =
+      stats.bytes_written - stats.bytes_read_output_level;
   double elapsed = (stats.micros + 1) / 1000000.0;
   std::string num_input_records = NumberToHumanString(stats.num_input_records);
   std::string num_dropped_records =
@@ -71,8 +73,8 @@ void PrintLevelStats(char* buf, size_t len, const std::string& name,
            "%7s "   /* KeyIn */
            "%6s\n", /* KeyDrop */
            name.c_str(), num_files, being_compacted, total_file_size / kMB,
-           score, bytes_read / kGB, stats.bytes_readn / kGB,
+           score, bytes_read / kGB, stats.bytes_read_non_output_levels / kGB,
-           stats.bytes_readnp1 / kGB, stats.bytes_written / kGB,
+           stats.bytes_read_output_level / kGB, stats.bytes_written / kGB,
            bytes_new / kGB, stats.bytes_moved / kGB,
            w_amp, bytes_read / kMB / elapsed,
            stats.bytes_written / kMB / elapsed, stats.micros / 1000000.0,
@@ -440,8 +442,8 @@ void InternalStats::DumpDBStats(std::string* value) {
   value->append(buf);
   // Compact
   for (int level = 0; level < number_levels_; level++) {
-    compact_bytes_read += comp_stats_[level].bytes_readnp1 +
+    compact_bytes_read += comp_stats_[level].bytes_read_output_level +
-                          comp_stats_[level].bytes_readn;
+                          comp_stats_[level].bytes_read_non_output_levels;
     compact_bytes_write += comp_stats_[level].bytes_written;
     compact_micros += comp_stats_[level].micros;
   }
@@ -598,9 +600,10 @@ void InternalStats::DumpCFStats(std::string* value) {
       total_stall_count += stalls;
       total_slowdown_count_soft += stall_leveln_slowdown_count_soft_[level];
       total_slowdown_count_hard += stall_leveln_slowdown_count_hard_[level];
-      double w_amp = (comp_stats_[level].bytes_readn == 0) ? 0.0
+      double w_amp =
-          : comp_stats_[level].bytes_written /
+          (comp_stats_[level].bytes_read_non_output_levels == 0) ? 0.0
-            static_cast<double>(comp_stats_[level].bytes_readn);
+          : static_cast<double>(comp_stats_[level].bytes_written) /
+            comp_stats_[level].bytes_read_non_output_levels;
       PrintLevelStats(buf, sizeof(buf), "L" + ToString(level), files,
                       files_being_compacted[level],
                       vstorage->NumLevelBytes(level), compaction_score[level],

db/internal_stats.h

@@ -120,26 +120,26 @@ class InternalStats {
   struct CompactionStats {
     uint64_t micros;
 
-    // Bytes read from level N during compaction between levels N and N+1
+    // The number of bytes read from all non-output levels
-    uint64_t bytes_readn;
+    uint64_t bytes_read_non_output_levels;
 
-    // Bytes read from level N+1 during compaction between levels N and N+1
+    // The number of bytes read from the compaction output level.
-    uint64_t bytes_readnp1;
+    uint64_t bytes_read_output_level;
 
-    // Total bytes written during compaction between levels N and N+1
+    // Total number of bytes written during compaction
     uint64_t bytes_written;
 
-    // Total bytes moved to this level
+    // Total number of bytes moved to the output level
     uint64_t bytes_moved;
 
-    // Files read from level N during compaction between levels N and N+1
+    // The number of compaction input files in all non-output levels.
-    int files_in_leveln;
+    int num_input_files_in_non_output_levels;
 
-    // Files read from level N+1 during compaction between levels N and N+1
+    // The number of compaction input files in the output level.
-    int files_in_levelnp1;
+    int num_input_files_in_output_level;
 
-    // Files written during compaction between levels N and N+1
+    // The number of compaction output files.
-    int files_out_levelnp1;
+    int num_output_files;
 
     // Total incoming entries during compaction between levels N and N+1
     uint64_t num_input_records;
@@ -153,39 +153,43 @@ class InternalStats {
 
     explicit CompactionStats(int _count = 0)
         : micros(0),
-          bytes_readn(0),
+          bytes_read_non_output_levels(0),
-          bytes_readnp1(0),
+          bytes_read_output_level(0),
           bytes_written(0),
           bytes_moved(0),
-          files_in_leveln(0),
+          num_input_files_in_non_output_levels(0),
-          files_in_levelnp1(0),
+          num_input_files_in_output_level(0),
-          files_out_levelnp1(0),
+          num_output_files(0),
           num_input_records(0),
           num_dropped_records(0),
           count(_count) {}
 
     explicit CompactionStats(const CompactionStats& c)
         : micros(c.micros),
-          bytes_readn(c.bytes_readn),
+          bytes_read_non_output_levels(c.bytes_read_non_output_levels),
-          bytes_readnp1(c.bytes_readnp1),
+          bytes_read_output_level(c.bytes_read_output_level),
           bytes_written(c.bytes_written),
           bytes_moved(c.bytes_moved),
-          files_in_leveln(c.files_in_leveln),
+          num_input_files_in_non_output_levels(
-          files_in_levelnp1(c.files_in_levelnp1),
+              c.num_input_files_in_non_output_levels),
-          files_out_levelnp1(c.files_out_levelnp1),
+          num_input_files_in_output_level(
+              c.num_input_files_in_output_level),
+          num_output_files(c.num_output_files),
           num_input_records(c.num_input_records),
           num_dropped_records(c.num_dropped_records),
           count(c.count) {}
 
     void Add(const CompactionStats& c) {
       this->micros += c.micros;
-      this->bytes_readn += c.bytes_readn;
+      this->bytes_read_non_output_levels += c.bytes_read_non_output_levels;
-      this->bytes_readnp1 += c.bytes_readnp1;
+      this->bytes_read_output_level += c.bytes_read_output_level;
       this->bytes_written += c.bytes_written;
       this->bytes_moved += c.bytes_moved;
-      this->files_in_leveln += c.files_in_leveln;
+      this->num_input_files_in_non_output_levels +=
-      this->files_in_levelnp1 += c.files_in_levelnp1;
+          c.num_input_files_in_non_output_levels;
-      this->files_out_levelnp1 += c.files_out_levelnp1;
+      this->num_input_files_in_output_level +=
+          c.num_input_files_in_output_level;
+      this->num_output_files += c.num_output_files;
       this->num_input_records += c.num_input_records;
       this->num_dropped_records += c.num_dropped_records;
       this->count += c.count;
@@ -193,13 +197,15 @@ class InternalStats {
 
     void Subtract(const CompactionStats& c) {
       this->micros -= c.micros;
-      this->bytes_readn -= c.bytes_readn;
+      this->bytes_read_non_output_levels -= c.bytes_read_non_output_levels;
-      this->bytes_readnp1 -= c.bytes_readnp1;
+      this->bytes_read_output_level -= c.bytes_read_output_level;
       this->bytes_written -= c.bytes_written;
       this->bytes_moved -= c.bytes_moved;
-      this->files_in_leveln -= c.files_in_leveln;
+      this->num_input_files_in_non_output_levels -=
-      this->files_in_levelnp1 -= c.files_in_levelnp1;
+          c.num_input_files_in_non_output_levels;
-      this->files_out_levelnp1 -= c.files_out_levelnp1;
+      this->num_input_files_in_output_level -=
+          c.num_input_files_in_output_level;
+      this->num_output_files -= c.num_output_files;
       this->num_input_records -= c.num_input_records;
       this->num_dropped_records -= c.num_dropped_records;
       this->count -= c.count;
@@ -352,13 +358,13 @@ class InternalStats {
 
   struct CompactionStats {
     uint64_t micros;
-    uint64_t bytes_readn;
+    uint64_t bytes_read_non_output_levels;
-    uint64_t bytes_readnp1;
+    uint64_t bytes_read_output_level;
     uint64_t bytes_written;
     uint64_t bytes_moved;
-    int files_in_leveln;
+    int num_input_files_in_non_output_levels;
-    int files_in_levelnp1;
+    int num_input_files_in_output_level;
-    int files_out_levelnp1;
+    int num_output_files;
     uint64_t num_input_records;
     uint64_t num_dropped_records;
     int count;