Change the way options.compression_per_level is used when...

Change the way options.compression_per_level is used when options.level_compaction_dynamic_level_bytes=true

Summary:
Change the way options.compression_per_level is used when options.level_compaction_dynamic_level_bytes=true so that options.compression_per_level[1] determines compression for the level L0 is merged to, options.compression_per_level[2] to the level after that, etc.

Test Plan: run all tests

Reviewers: rven, yhchiang, kradhakrishnan, igor

Reviewed By: igor

Subscribers: yoshinorim, leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D34431

db/compaction_picker.cc

@@ -37,9 +37,9 @@ uint64_t TotalCompensatedFileSize(const std::vector<FileMetaData*>& files) {
 // If enable_compression is false, then compression is always disabled no
 // matter what the values of the other two parameters are.
 // Otherwise, the compression type is determined based on options and level.
-CompressionType GetCompressionType(
-    const ImmutableCFOptions& ioptions, int level,
-    const bool enable_compression = true) {
+CompressionType GetCompressionType(const ImmutableCFOptions& ioptions,
+                                   int level, int base_level,
+                                   const bool enable_compression = true) {
   if (!enable_compression) {
     // disable compression
     return kNoCompression;
@@ -47,13 +47,16 @@ CompressionType GetCompressionType(
   // If the use has specified a different compression level for each level,
   // then pick the compression for that level.
   if (!ioptions.compression_per_level.empty()) {
+    assert(level == 0 || level >= base_level);
+    int idx = (level == 0) ? 0 : level - base_level + 1;
+
     const int n = static_cast<int>(ioptions.compression_per_level.size()) - 1;
     // It is possible for level_ to be -1; in that case, we use level
     // 0's compression.  This occurs mostly in backwards compatibility
     // situations when the builder doesn't know what level the file
     // belongs to.  Likewise, if level is beyond the end of the
     // specified compression levels, use the last value.
-    return ioptions.compression_per_level[std::max(0, std::min(level, n))];
+    return ioptions.compression_per_level[std::max(0, std::min(idx, n))];
   } else {
     return ioptions.compression;
   }
@@ -417,7 +420,8 @@ Compaction* CompactionPicker::CompactRange(
       vstorage->num_levels(), input_level, output_level,
       mutable_cf_options.MaxFileSizeForLevel(output_level),
       mutable_cf_options.MaxGrandParentOverlapBytes(input_level),
-      output_path_id, GetCompressionType(ioptions_, output_level));
+      output_path_id,
+      GetCompressionType(ioptions_, output_level, vstorage->base_level()));
 
   c->inputs_[0].files = inputs;
   if (ExpandWhileOverlapping(cf_name, vstorage, c) == false) {
@@ -828,11 +832,12 @@ Compaction* LevelCompactionPicker::PickCompactionBySize(
   }
   assert(output_level < NumberLevels());
 
-  c = new Compaction(vstorage->num_levels(), level, output_level,
-                     mutable_cf_options.MaxFileSizeForLevel(output_level),
-                     mutable_cf_options.MaxGrandParentOverlapBytes(level),
-                     GetPathId(ioptions_, mutable_cf_options, output_level),
-                     GetCompressionType(ioptions_, output_level));
+  c = new Compaction(
+      vstorage->num_levels(), level, output_level,
+      mutable_cf_options.MaxFileSizeForLevel(output_level),
+      mutable_cf_options.MaxGrandParentOverlapBytes(level),
+      GetPathId(ioptions_, mutable_cf_options, output_level),
+      GetCompressionType(ioptions_, output_level, vstorage->base_level()));
   c->score_ = score;
 
   // Pick the largest file in this level that is not already
@@ -1160,7 +1165,7 @@ Compaction* UniversalCompactionPicker::PickCompactionUniversalReadAmp(
   Compaction* c = new Compaction(
       vstorage->num_levels(), kLevel0, kLevel0,
       mutable_cf_options.MaxFileSizeForLevel(kLevel0), LLONG_MAX, path_id,
-      GetCompressionType(ioptions_, kLevel0, enable_compression));
+      GetCompressionType(ioptions_, kLevel0, 1, enable_compression));
   c->score_ = score;
 
   for (unsigned int i = start_index; i < first_index_after; i++) {
@@ -1280,7 +1285,7 @@ Compaction* UniversalCompactionPicker::PickCompactionUniversalSizeAmp(
   Compaction* c =
       new Compaction(vstorage->num_levels(), kLevel, kLevel,
                      mutable_cf_options.MaxFileSizeForLevel(kLevel), LLONG_MAX,
-                     path_id, GetCompressionType(ioptions_, kLevel));
+                     path_id, GetCompressionType(ioptions_, kLevel, 1));
   c->score_ = score;
   for (unsigned int loop = start_index; loop < files.size(); loop++) {
     f = files[loop];

db/db_test.cc

@@ -39,6 +39,7 @@
 #include "rocksdb/utilities/checkpoint.h"
 #include "rocksdb/utilities/convenience.h"
 #include "table/block_based_table_factory.h"
+#include "table/mock_table.h"
 #include "table/plain_table_factory.h"
 #include "util/hash.h"
 #include "util/hash_linklist_rep.h"
@@ -10455,6 +10456,11 @@ TEST(DBTest, DynamicLevelMaxBytesBase) {
       options.max_background_compactions = max_background_compactions;
       options.num_levels = 5;
 
+      options.compression_per_level.resize(3);
+      options.compression_per_level[0] = kNoCompression;
+      options.compression_per_level[1] = kLZ4Compression;
+      options.compression_per_level[2] = kSnappyCompression;
+
       DestroyAndReopen(options);
 
       for (int i = 0; i < kNKeys; i++) {
@@ -10642,6 +10648,171 @@ TEST(DBTest, DynamicLevelMaxBytesBase2) {
   ASSERT_EQ(1U, int_prop);
 }
 
+TEST(DBTest, DynamicLevelCompressionPerLevel) {
+  const int kNKeys = 120;
+  int keys[kNKeys];
+  for (int i = 0; i < kNKeys; i++) {
+    keys[i] = i;
+  }
+  std::random_shuffle(std::begin(keys), std::end(keys));
+
+  Random rnd(301);
+  Options options;
+  options.create_if_missing = true;
+  options.db_write_buffer_size = 20480;
+  options.write_buffer_size = 20480;
+  options.max_write_buffer_number = 2;
+  options.level0_file_num_compaction_trigger = 2;
+  options.level0_slowdown_writes_trigger = 2;
+  options.level0_stop_writes_trigger = 2;
+  options.target_file_size_base = 2048;
+  options.level_compaction_dynamic_level_bytes = true;
+  options.max_bytes_for_level_base = 102400;
+  options.max_bytes_for_level_multiplier = 4;
+  options.max_background_compactions = 1;
+  options.num_levels = 5;
+
+  options.compression_per_level.resize(3);
+  options.compression_per_level[0] = kNoCompression;
+  options.compression_per_level[1] = kNoCompression;
+  options.compression_per_level[2] = kSnappyCompression;
+
+  DestroyAndReopen(options);
+
+  // Insert more than 80K. L4 should be base level. Neither L0 nor L4 should
+  // be compressed, so total data size should be more than 80K.
+  for (int i = 0; i < 20; i++) {
+    ASSERT_OK(Put(Key(keys[i]), CompressibleString(&rnd, 4000)));
+  }
+  Flush();
+  dbfull()->TEST_WaitForCompact();
+
+  ASSERT_EQ(NumTableFilesAtLevel(1), 0);
+  ASSERT_EQ(NumTableFilesAtLevel(2), 0);
+  ASSERT_EQ(NumTableFilesAtLevel(3), 0);
+  ASSERT_GT(SizeAtLevel(0) + SizeAtLevel(4), 20U * 4000U);
+
+  // Insert 400KB. Some data will be compressed
+  for (int i = 21; i < 120; i++) {
+    ASSERT_OK(Put(Key(keys[i]), CompressibleString(&rnd, 4000)));
+  }
+  Flush();
+  dbfull()->TEST_WaitForCompact();
+  ASSERT_EQ(NumTableFilesAtLevel(1), 0);
+  ASSERT_EQ(NumTableFilesAtLevel(2), 0);
+  ASSERT_LT(SizeAtLevel(0) + SizeAtLevel(3) + SizeAtLevel(4), 120U * 4000U);
+  // Make sure data in files in L3 is not compacted by removing all files
+  // in L4 and calculate number of rows
+  ASSERT_OK(dbfull()->SetOptions({
+      {"disable_auto_compactions", "true"},
+  }));
+  ColumnFamilyMetaData cf_meta;
+  db_->GetColumnFamilyMetaData(&cf_meta);
+  for (auto file : cf_meta.levels[4].files) {
+    ASSERT_OK(dbfull()->DeleteFile(file.name));
+  }
+  int num_keys = 0;
+  std::unique_ptr<Iterator> iter(db_->NewIterator(ReadOptions()));
+  for (iter->SeekToFirst(); iter->Valid(); iter->Next()) {
+    num_keys++;
+  }
+  ASSERT_OK(iter->status());
+  ASSERT_GT(SizeAtLevel(0) + SizeAtLevel(3), num_keys * 4000U);
+}
+
+TEST(DBTest, DynamicLevelCompressionPerLevel2) {
+  const int kNKeys = 500;
+  int keys[kNKeys];
+  for (int i = 0; i < kNKeys; i++) {
+    keys[i] = i;
+  }
+  std::random_shuffle(std::begin(keys), std::end(keys));
+
+  Random rnd(301);
+  Options options;
+  options.create_if_missing = true;
+  options.db_write_buffer_size = 6000;
+  options.write_buffer_size = 6000;
+  options.max_write_buffer_number = 2;
+  options.level0_file_num_compaction_trigger = 2;
+  options.level0_slowdown_writes_trigger = 2;
+  options.level0_stop_writes_trigger = 2;
+  options.hard_rate_limit = 1.1;
+
+  // Use file size to distinguish levels
+  // L1: 10, L2: 20, L3 40, L4 80
+  // L0 is less than 30
+  options.target_file_size_base = 10;
+  options.target_file_size_multiplier = 2;
+
+  options.level_compaction_dynamic_level_bytes = true;
+  options.max_bytes_for_level_base = 200;
+  options.max_bytes_for_level_multiplier = 8;
+  options.max_background_compactions = 1;
+  options.num_levels = 5;
+  std::shared_ptr<mock::MockTableFactory> mtf(new mock::MockTableFactory);
+  options.table_factory = mtf;
+
+  options.compression_per_level.resize(3);
+  options.compression_per_level[0] = kNoCompression;
+  options.compression_per_level[1] = kLZ4Compression;
+  options.compression_per_level[2] = kZlibCompression;
+
+  DestroyAndReopen(options);
+  // When base level is L4, L4 is LZ4.
+  std::atomic<bool> seen_lz4(false);
+  std::function<void(const CompressionType&, uint64_t)> cb1 =
+      [&](const CompressionType& ct, uint64_t size) {
+    ASSERT_TRUE(size <= 30 || ct == kLZ4Compression);
+    if (ct == kLZ4Compression) {
+      seen_lz4.store(true);
+    }
+  };
+  mock::MockTableBuilder::finish_cb_ = &cb1;
+  for (int i = 0; i < 100; i++) {
+    ASSERT_OK(Put(Key(keys[i]), RandomString(&rnd, 200)));
+  }
+  Flush();
+  dbfull()->TEST_WaitForCompact();
+  ASSERT_TRUE(seen_lz4.load());
+
+  ASSERT_EQ(NumTableFilesAtLevel(1), 0);
+  ASSERT_EQ(NumTableFilesAtLevel(2), 0);
+  ASSERT_EQ(NumTableFilesAtLevel(3), 0);
+
+  // After base level turn L4->L3, L3 becomes LZ4 and L4 becomes Zlib
+  std::atomic<bool> seen_zlib(false);
+  std::function<void(const CompressionType&, uint64_t)> cb2 =
+      [&](const CompressionType& ct, uint64_t size) {
+    ASSERT_TRUE(size <= 30 || ct != kNoCompression);
+    if (ct == kZlibCompression) {
+      if (!seen_zlib.load()) {
+        seen_lz4.store(false);
+      }
+      seen_zlib.store(true);
+    }
+    // Make sure after making L4 the base level, L4 is LZ4.
+    if (seen_zlib.load()) {
+      if (ct == kLZ4Compression && size < 80) {
+        seen_lz4.store(true);
+      }
+    }
+  };
+  mock::MockTableBuilder::finish_cb_ = &cb2;
+  for (int i = 101; i < 500; i++) {
+    ASSERT_OK(Put(Key(keys[i]), RandomString(&rnd, 200)));
+    if (i % 100 == 99) {
+      Flush();
+      dbfull()->TEST_WaitForCompact();
+    }
+  }
+  ASSERT_TRUE(seen_lz4.load());
+  ASSERT_TRUE(seen_zlib.load());
+  ASSERT_EQ(NumTableFilesAtLevel(1), 0);
+  ASSERT_EQ(NumTableFilesAtLevel(2), 0);
+  mock::MockTableBuilder::finish_cb_ = nullptr;
+}
+
 TEST(DBTest, DynamicCompactionOptions) {
   // minimum write buffer size is enforced at 64KB
   const uint64_t k32KB = 1 << 15;

include/rocksdb/options.h

@@ -255,6 +255,20 @@ struct ColumnFamilyOptions {
   // be slower. This array, if non-empty, should have an entry for
   // each level of the database; these override the value specified in
   // the previous field 'compression'.
+  //
+  // NOTICE if level_compaction_dynamic_level_bytes=true,
+  // compression_per_level[0] still determines L0, but other elements
+  // of the array are based on base level (the level L0 files are merged
+  // to), and may not match the level users see from info log for metadata.
+  // If L0 files are merged to level-n, then, for i>0, compression_per_level[i]
+  // determines compaction type for level n+i-1.
+  // For example, if we have three 5 levels, and we determine to merge L0
+  // data to L4 (which means L1..L3 will be empty), then the new files go to
+  // L4 uses compression type compression_per_level[1].
+  // If now L0 is merged to L2. Data goes to L2 will be compressed
+  // according to compression_per_level[1], L3 using compression_per_level[2]
+  // and L4 using compression_per_level[3]. Compaction for each level can
+  // change when data grows.
   std::vector<CompressionType> compression_per_level;
 
   // different options for compression algorithms

table/mock_table.cc

@@ -61,6 +61,9 @@ Status MockTableFactory::NewTableReader(
   return Status::OK();
 }
 
+std::function<void(const CompressionType&, uint64_t)>*
+    MockTableBuilder::finish_cb_ = nullptr;
+
 TableBuilder* MockTableFactory::NewTableBuilder(
     const ImmutableCFOptions& ioptions,
     const InternalKeyComparator& internal_key, WritableFile* file,
@@ -68,7 +71,7 @@ TableBuilder* MockTableFactory::NewTableBuilder(
     const CompressionOptions& compression_opts, const bool skip_filters) const {
   uint32_t id = GetAndWriteNextID(file);
 
-  return new MockTableBuilder(id, &file_system_);
+  return new MockTableBuilder(id, &file_system_, compression_type);
 }
 
 Status MockTableFactory::CreateMockTable(Env* env, const std::string& fname,

table/mock_table.h

@@ -97,8 +97,11 @@ class MockTableIterator : public Iterator {
 
 class MockTableBuilder : public TableBuilder {
  public:
-  MockTableBuilder(uint32_t id, MockTableFileSystem* file_system)
-      : id_(id), file_system_(file_system) {}
+  MockTableBuilder(uint32_t id, MockTableFileSystem* file_system,
+                   CompressionType compression_type)
+      : id_(id),
+        file_system_(file_system),
+        compression_type_(compression_type) {}
 
   // REQUIRES: Either Finish() or Abandon() has been called.
   ~MockTableBuilder() {}
@@ -114,6 +117,9 @@ class MockTableBuilder : public TableBuilder {
   Status status() const override { return Status::OK(); }
 
   Status Finish() override {
+    if (finish_cb_ != nullptr) {
+      (*finish_cb_)(compression_type_, FileSize());
+    }
     MutexLock lock_guard(&file_system_->mutex);
     file_system_->files.insert({id_, table_});
     return Status::OK();
@@ -125,10 +131,13 @@ class MockTableBuilder : public TableBuilder {
 
   uint64_t FileSize() const override { return table_.size(); }
 
+  static std::function<void(const CompressionType&, uint64_t)>* finish_cb_;
+
  private:
   uint32_t id_;
   MockTableFileSystem* file_system_;
   MockFileContents table_;
+  CompressionType compression_type_;
 };
 
 class MockTableFactory : public TableFactory {