Allow users to migrate to options.level_compaction_dynamic_level_bytes=true using CompactRange()

Summary: In DB::CompactRange(), change parameter "reduce_level" to "change_level". Users can compact all data to the last level if needed. By doing it, users can migrate the DB to options.level_compaction_dynamic_level_bytes=true.

Test Plan: Add a unit test for it.

Reviewers: yhchiang, anthony, kradhakrishnan, igor, rven

Reviewed By: rven

Subscribers: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D39099

HISTORY.md

@@ -7,6 +7,7 @@
 * DB::GetDbIdentity() is now a const function.  If this function is overridden in your application, be sure to also make GetDbIdentity() const to avoid compile error.
 * Move listeners from ColumnFamilyOptions to DBOptions.
 * Add max_write_buffer_number_to_maintain option
+* DB::CompactRange()'s parameter reduce_level is changed to change_level, to allow users to move levels to lower levels if allowed. It can be used to migrate a DB from options.level_compaction_dynamic_level_bytes=false to options.level_compaction_dynamic_level_bytes.true.
 
 ## 3.11.0 (5/19/2015)
 ### New Features

db/db_impl.cc

@@ -1299,7 +1299,7 @@ void DBImpl::NotifyOnFlushCompleted(
 
 Status DBImpl::CompactRange(ColumnFamilyHandle* column_family,
                             const Slice* begin, const Slice* end,
-                            bool reduce_level, int target_level,
+                            bool change_level, int target_level,
                             uint32_t target_path_id) {
   if (target_path_id >= db_options_.db_paths.size()) {
     return Status::InvalidArgument("Invalid target path ID");
@@ -1364,7 +1364,7 @@ Status DBImpl::CompactRange(ColumnFamilyHandle* column_family,
     return s;
   }
 
-  if (reduce_level) {
+  if (change_level) {
     s = ReFitLevel(cfd, max_level_with_files, target_level);
   }
   LogFlush(db_options_.info_log);
@@ -1658,6 +1658,9 @@ int DBImpl::FindMinimumEmptyLevelFitting(ColumnFamilyData* cfd,
 
 Status DBImpl::ReFitLevel(ColumnFamilyData* cfd, int level, int target_level) {
   assert(level < cfd->NumberLevels());
+  if (target_level >= cfd->NumberLevels()) {
+    return Status::InvalidArgument("Target level exceeds number of levels");
+  }
 
   SuperVersion* superversion_to_free = nullptr;
   SuperVersion* new_superversion = new SuperVersion();
@@ -1691,17 +1694,29 @@ Status DBImpl::ReFitLevel(ColumnFamilyData* cfd, int level, int target_level) {
     to_level = FindMinimumEmptyLevelFitting(cfd, mutable_cf_options, level);
   }
 
-  assert(to_level <= level);
-
   Status status;
-  if (to_level < level) {
+  auto* vstorage = cfd->current()->storage_info();
+  if (to_level > level) {
+    if (level == 0) {
+      return Status::NotSupported(
+          "Cannot change from level 0 to other levels.");
+    }
+    // Check levels are empty for a trivial move
+    for (int l = level + 1; l <= to_level; l++) {
+      if (vstorage->NumLevelFiles(l) > 0) {
+        return Status::NotSupported(
+            "Levels between source and target are not empty for a move.");
+      }
+    }
+  }
+  if (to_level != level) {
     Log(InfoLogLevel::DEBUG_LEVEL, db_options_.info_log,
         "[%s] Before refitting:\n%s",
         cfd->GetName().c_str(), cfd->current()->DebugString().data());
 
     VersionEdit edit;
     edit.SetColumnFamily(cfd->GetID());
-    for (const auto& f : cfd->current()->storage_info()->LevelFiles(level)) {
+    for (const auto& f : vstorage->LevelFiles(level)) {
       edit.DeleteFile(level, f->fd.GetNumber());
       edit.AddFile(to_level, f->fd.GetNumber(), f->fd.GetPathId(),
                    f->fd.GetFileSize(), f->smallest, f->largest,

db/db_impl.h

@@ -125,7 +125,7 @@ class DBImpl : public DB {
   using DB::CompactRange;
   virtual Status CompactRange(ColumnFamilyHandle* column_family,
                               const Slice* begin, const Slice* end,
-                              bool reduce_level = false, int target_level = -1,
+                              bool change_level = false, int target_level = -1,
                               uint32_t target_path_id = 0) override;
 
   using DB::CompactFiles;

db/db_test.cc

@@ -11313,6 +11313,83 @@ TEST_F(DBTest, DynamicLevelMaxBytesBaseInc) {
   env_->SetBackgroundThreads(1, Env::HIGH);
 }
 
+TEST_F(DBTest, MigrateToDynamicLevelMaxBytesBase) {
+  Random rnd(301);
+  const int kMaxKey = 2000;
+
+  Options options;
+  options.create_if_missing = true;
+  options.db_write_buffer_size = 2048;
+  options.write_buffer_size = 2048;
+  options.max_write_buffer_number = 8;
+  options.level0_file_num_compaction_trigger = 4;
+  options.level0_slowdown_writes_trigger = 4;
+  options.level0_stop_writes_trigger = 8;
+  options.target_file_size_base = 2048;
+  options.level_compaction_dynamic_level_bytes = false;
+  options.max_bytes_for_level_base = 10240;
+  options.max_bytes_for_level_multiplier = 4;
+  options.hard_rate_limit = 1.1;
+  options.num_levels = 8;
+
+  DestroyAndReopen(options);
+
+  auto verify_func = [&](int num_keys) {
+    for (int i = 0; i < num_keys; i++) {
+      ASSERT_NE("NOT_FOUND", Get(Key(kMaxKey + i)));
+      if (i < num_keys / 10) {
+        ASSERT_EQ("NOT_FOUND", Get(Key(i)));
+      } else {
+        ASSERT_NE("NOT_FOUND", Get(Key(i)));
+      }
+    }
+  };
+
+  int total_keys = 1000;
+  for (int i = 0; i < total_keys; i++) {
+    ASSERT_OK(Put(Key(i), RandomString(&rnd, 102)));
+    ASSERT_OK(Put(Key(kMaxKey + i), RandomString(&rnd, 102)));
+    ASSERT_OK(Delete(Key(i / 10)));
+  }
+  verify_func(total_keys);
+  dbfull()->TEST_WaitForCompact();
+
+  options.level_compaction_dynamic_level_bytes = true;
+  options.disable_auto_compactions = true;
+  Reopen(options);
+  verify_func(total_keys);
+
+  std::atomic_bool compaction_finished(false);
+  // Issue manual compaction in one thread and still verify DB state
+  // in main thread.
+  std::thread t([&]() {
+    dbfull()->CompactRange(nullptr, nullptr, true, options.num_levels - 1);
+    compaction_finished.store(true);
+  });
+  do {
+    verify_func(total_keys);
+  } while (!compaction_finished.load());
+  t.join();
+
+  ASSERT_OK(dbfull()->SetOptions({
+      {"disable_auto_compactions", "false"},
+  }));
+
+  int total_keys2 = 2000;
+  for (int i = total_keys; i < total_keys2; i++) {
+    ASSERT_OK(Put(Key(i), RandomString(&rnd, 102)));
+    ASSERT_OK(Put(Key(kMaxKey + i), RandomString(&rnd, 102)));
+    ASSERT_OK(Delete(Key(i / 10)));
+  }
+
+  verify_func(total_keys2);
+  dbfull()->TEST_WaitForCompact();
+  verify_func(total_keys2);
+
+  // Base level is not level 1
+  ASSERT_EQ(NumTableFilesAtLevel(1), 0);
+  ASSERT_EQ(NumTableFilesAtLevel(2), 0);
+}
 
 TEST_F(DBTest, DynamicLevelCompressionPerLevel) {
   if (!Snappy_Supported()) {

db/version_set.cc

@@ -973,8 +973,8 @@ void VersionStorageInfo::ComputeCompensatedSizes() {
         // shape of LSM tree.
         if (file_meta->num_deletions * 2 >= file_meta->num_entries) {
           file_meta->compensated_file_size +=
-              (file_meta->num_deletions * 2 - file_meta->num_entries)
-              * average_value_size * kDeletionWeightOnCompaction;
+              (file_meta->num_deletions * 2 - file_meta->num_entries) *
+              average_value_size * kDeletionWeightOnCompaction;
         }
       }
     }

include/rocksdb/db.h

@@ -417,20 +417,20 @@ class DB {
   // Note that after the entire database is compacted, all data are pushed
   // down to the last level containing any data. If the total data size
   // after compaction is reduced, that level might not be appropriate for
-  // hosting all the files. In this case, client could set reduce_level
+  // hosting all the files. In this case, client could set change_level
   // to true, to move the files back to the minimum level capable of holding
   // the data set or a given level (specified by non-negative target_level).
   // Compaction outputs should be placed in options.db_paths[target_path_id].
   // Behavior is undefined if target_path_id is out of range.
   virtual Status CompactRange(ColumnFamilyHandle* column_family,
                               const Slice* begin, const Slice* end,
-                              bool reduce_level = false, int target_level = -1,
+                              bool change_level = false, int target_level = -1,
                               uint32_t target_path_id = 0) = 0;
   virtual Status CompactRange(const Slice* begin, const Slice* end,
-                              bool reduce_level = false, int target_level = -1,
+                              bool change_level = false, int target_level = -1,
                               uint32_t target_path_id = 0) {
-    return CompactRange(DefaultColumnFamily(), begin, end, reduce_level,
-                        target_level, target_path_id);
+    return CompactRange(DefaultColumnFamily(), begin, end, change_level,
+                        change_level, target_path_id);
   }
   virtual Status SetOptions(ColumnFamilyHandle* column_family,
       const std::unordered_map<std::string, std::string>& new_options) {

include/rocksdb/utilities/stackable_db.h

@@ -129,9 +129,9 @@ class StackableDB : public DB {
   using DB::CompactRange;
   virtual Status CompactRange(ColumnFamilyHandle* column_family,
                               const Slice* begin, const Slice* end,
-                              bool reduce_level = false, int target_level = -1,
+                              bool change_level = false, int target_level = -1,
                               uint32_t target_path_id = 0) override {
-    return db_->CompactRange(column_family, begin, end, reduce_level,
+    return db_->CompactRange(column_family, begin, end, change_level,
                              target_level, target_path_id);
   }
 

utilities/compacted_db/compacted_db_impl.h

@@ -56,7 +56,7 @@ class CompactedDBImpl : public DBImpl {
   using DBImpl::CompactRange;
   virtual Status CompactRange(ColumnFamilyHandle* column_family,
                               const Slice* begin, const Slice* end,
-                              bool reduce_level = false, int target_level = -1,
+                              bool change_level = false, int target_level = -1,
                               uint32_t target_path_id = 0) override {
     return Status::NotSupported("Not supported in compacted db mode.");
   }