CompactedDBImpl

Summary:
Add a CompactedDBImpl that will enabled when calling OpenForReadOnly()
and the DB only has one level (>0) of files. As a performan comparison,
CuckooTable performs 2.1M/s with CompactedDBImpl vs. 1.78M/s with
ReadOnlyDBImpl.

Test Plan: db_bench

Reviewers: yhchiang, igor, sdong

Reviewed By: sdong

Subscribers: leveldb

Differential Revision: https://reviews.facebook.net/D23553

db/db_bench.cc

@@ -1262,6 +1262,8 @@ class Benchmark {
         method = &Benchmark::ReadReverse;
       } else if (name == Slice("readrandom")) {
         method = &Benchmark::ReadRandom;
+      } else if (name == Slice("readrandomfast")) {
+        method = &Benchmark::ReadRandomFast;
       } else if (name == Slice("multireadrandom")) {
         method = &Benchmark::MultiReadRandom;
       } else if (name == Slice("readmissing")) {
@@ -2071,6 +2073,44 @@ class Benchmark {
     thread->stats.AddBytes(bytes);
   }
 
+  void ReadRandomFast(ThreadState* thread) {
+    int64_t read = 0;
+    int64_t found = 0;
+    ReadOptions options(FLAGS_verify_checksum, true);
+    Slice key = AllocateKey();
+    std::unique_ptr<const char[]> key_guard(key.data());
+    std::string value;
+    DB* db = SelectDBWithCfh(thread)->db;
+
+    int64_t pot = 1;
+    while (pot < FLAGS_num) {
+      pot <<= 1;
+    }
+
+    Duration duration(FLAGS_duration, reads_);
+    do {
+      for (int i = 0; i < 100; ++i) {
+        int64_t key_rand = thread->rand.Next() & (pot - 1);
+        GenerateKeyFromInt(key_rand, FLAGS_num, &key);
+        ++read;
+        if (db->Get(options, key, &value).ok()) {
+          ++found;
+        }
+      }
+      thread->stats.FinishedOps(db, 100);
+    } while (!duration.Done(100));
+
+    char msg[100];
+    snprintf(msg, sizeof(msg), "(%" PRIu64 " of %" PRIu64 " found)\n",
+             found, read);
+
+    thread->stats.AddMessage(msg);
+
+    if (FLAGS_perf_level > 0) {
+      thread->stats.AddMessage(perf_context.ToString());
+    }
+  }
+
   void ReadRandom(ThreadState* thread) {
     int64_t read = 0;
     int64_t found = 0;

db/db_impl.h

@@ -325,6 +325,7 @@ class DBImpl : public DB {
   friend class ForwardIterator;
 #endif
   friend struct SuperVersion;
+  friend class CompactedDBImpl;
   struct CompactionState;
 
   struct WriteContext;

db/db_impl_readonly.cc

@@ -2,42 +2,12 @@
 //  This source code is licensed under the BSD-style license found in the
 //  LICENSE file in the root directory of this source tree. An additional grant
 //  of patent rights can be found in the PATENTS file in the same directory.
-//
-// Copyright (c) 2012 Facebook. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
 
 #include "db/db_impl_readonly.h"
+#include "utilities/compacted_db/compacted_db_impl.h"
 #include "db/db_impl.h"
-
-#include <algorithm>
-#include <set>
-#include <string>
-#include <stdint.h>
-#include <stdio.h>
-#include <vector>
-#include "db/db_iter.h"
-#include "db/dbformat.h"
-#include "db/filename.h"
-#include "db/log_reader.h"
-#include "db/log_writer.h"
-#include "db/memtable.h"
 #include "db/merge_context.h"
-#include "db/table_cache.h"
-#include "db/version_set.h"
-#include "db/write_batch_internal.h"
-#include "rocksdb/db.h"
-#include "rocksdb/env.h"
-#include "rocksdb/status.h"
-#include "rocksdb/table.h"
-#include "rocksdb/merge_operator.h"
-#include "port/port.h"
-#include "table/block.h"
-#include "table/merger.h"
-#include "table/two_level_iterator.h"
-#include "util/coding.h"
-#include "util/logging.h"
-#include "util/build_version.h"
+#include "db/db_iter.h"
 
 namespace rocksdb {
 
@@ -120,6 +90,15 @@ Status DB::OpenForReadOnly(const Options& options, const std::string& dbname,
                            DB** dbptr, bool error_if_log_file_exist) {
   *dbptr = nullptr;
 
+  // Try to first open DB as fully compacted DB
+  Status s;
+#ifndef ROCKSDB_LITE
+  s = CompactedDBImpl::Open(options, dbname, dbptr);
+  if (s.ok()) {
+    return s;
+  }
+#endif
+
   DBOptions db_options(options);
   ColumnFamilyOptions cf_options(options);
   std::vector<ColumnFamilyDescriptor> column_families;
@@ -127,8 +106,7 @@ Status DB::OpenForReadOnly(const Options& options, const std::string& dbname,
       ColumnFamilyDescriptor(kDefaultColumnFamilyName, cf_options));
   std::vector<ColumnFamilyHandle*> handles;
 
-  Status s =
-      DB::OpenForReadOnly(db_options, dbname, column_families, &handles, dbptr);
+  s = DB::OpenForReadOnly(db_options, dbname, column_families, &handles, dbptr);
   if (s.ok()) {
     assert(handles.size() == 1);
     // i can delete the handle since DBImpl is always holding a

db/db_impl_readonly.h

@@ -2,24 +2,11 @@
 //  This source code is licensed under the BSD-style license found in the
 //  LICENSE file in the root directory of this source tree. An additional grant
 //  of patent rights can be found in the PATENTS file in the same directory.
-//
-// Copyright (c) 2012 Facebook. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
 
 #pragma once
 #include "db/db_impl.h"
-
-#include <deque>
-#include <set>
 #include <vector>
 #include <string>
-#include "db/dbformat.h"
-#include "db/log_writer.h"
-#include "db/snapshot.h"
-#include "rocksdb/db.h"
-#include "rocksdb/env.h"
-#include "port/port.h"
 
 namespace rocksdb {
 

db/db_test.cc

@@ -1270,6 +1270,80 @@ TEST(DBTest, ReadOnlyDB) {
   ASSERT_EQ("v2", Get("bar"));
 }
 
+TEST(DBTest, CompactedDB) {
+  const uint64_t kFileSize = 1 << 20;
+  Options options;
+  options.disable_auto_compactions = true;
+  options.max_mem_compaction_level = 0;
+  options.write_buffer_size = kFileSize;
+  options.target_file_size_base = kFileSize;
+  options.max_bytes_for_level_base = 1 << 30;
+  options.compression = kNoCompression;
+  Reopen(&options);
+  // 1 L0 file, use CompactedDB if max_open_files = -1
+  ASSERT_OK(Put("aaa", DummyString(kFileSize / 2, '1')));
+  Flush();
+  Close();
+  ASSERT_OK(ReadOnlyReopen(&options));
+  Status s = Put("new", "value");
+  ASSERT_EQ(s.ToString(),
+            "Not implemented: Not supported operation in read only mode.");
+  ASSERT_EQ(DummyString(kFileSize / 2, '1'), Get("aaa"));
+  Close();
+  options.max_open_files = -1;
+  ASSERT_OK(ReadOnlyReopen(&options));
+  s = Put("new", "value");
+  ASSERT_EQ(s.ToString(),
+            "Not implemented: Not supported in compacted db mode.");
+  ASSERT_EQ(DummyString(kFileSize / 2, '1'), Get("aaa"));
+  Close();
+  Reopen(&options);
+  // Add more L0 files
+  ASSERT_OK(Put("bbb", DummyString(kFileSize / 2, '2')));
+  Flush();
+  ASSERT_OK(Put("aaa", DummyString(kFileSize / 2, 'a')));
+  Flush();
+  ASSERT_OK(Put("bbb", DummyString(kFileSize / 2, 'b')));
+  Flush();
+  Close();
+
+  ASSERT_OK(ReadOnlyReopen(&options));
+  // Fallback to read-only DB
+  s = Put("new", "value");
+  ASSERT_EQ(s.ToString(),
+            "Not implemented: Not supported operation in read only mode.");
+  Close();
+
+  // Full compaction
+  Reopen(&options);
+  // Add more keys
+  ASSERT_OK(Put("eee", DummyString(kFileSize / 2, 'e')));
+  ASSERT_OK(Put("fff", DummyString(kFileSize / 2, 'f')));
+  ASSERT_OK(Put("hhh", DummyString(kFileSize / 2, 'h')));
+  ASSERT_OK(Put("iii", DummyString(kFileSize / 2, 'i')));
+  ASSERT_OK(Put("jjj", DummyString(kFileSize / 2, 'j')));
+  db_->CompactRange(nullptr, nullptr);
+  ASSERT_EQ(3, NumTableFilesAtLevel(1));
+  Close();
+
+  // CompactedDB
+  ASSERT_OK(ReadOnlyReopen(&options));
+  s = Put("new", "value");
+  ASSERT_EQ(s.ToString(),
+            "Not implemented: Not supported in compacted db mode.");
+  ASSERT_EQ("NOT_FOUND", Get("abc"));
+  ASSERT_EQ(DummyString(kFileSize / 2, 'a'), Get("aaa"));
+  ASSERT_EQ(DummyString(kFileSize / 2, 'b'), Get("bbb"));
+  ASSERT_EQ("NOT_FOUND", Get("ccc"));
+  ASSERT_EQ(DummyString(kFileSize / 2, 'e'), Get("eee"));
+  ASSERT_EQ(DummyString(kFileSize / 2, 'f'), Get("fff"));
+  ASSERT_EQ("NOT_FOUND", Get("ggg"));
+  ASSERT_EQ(DummyString(kFileSize / 2, 'h'), Get("hhh"));
+  ASSERT_EQ(DummyString(kFileSize / 2, 'i'), Get("iii"));
+  ASSERT_EQ(DummyString(kFileSize / 2, 'j'), Get("jjj"));
+  ASSERT_EQ("NOT_FOUND", Get("kkk"));
+}
+
 // Make sure that when options.block_cache is set, after a new table is
 // created its index/filter blocks are added to block cache.
 TEST(DBTest, IndexAndFilterBlocksOfNewTableAddedToCache) {

db/version_set.cc

@@ -626,46 +626,23 @@ void Version::AddIterators(const ReadOptions& read_options,
   }
 }
 
-// Callback from TableCache::Get()
-enum SaverState {
-  kNotFound,
-  kFound,
-  kDeleted,
-  kCorrupt,
-  kMerge // saver contains the current merge result (the operands)
-};
-
-namespace version_set {
-struct Saver {
-  SaverState state;
-  const Comparator* ucmp;
-  Slice user_key;
-  bool* value_found; // Is value set correctly? Used by KeyMayExist
-  std::string* value;
-  const MergeOperator* merge_operator;
-  // the merge operations encountered;
-  MergeContext* merge_context;
-  Logger* logger;
-  Statistics* statistics;
-};
-} // namespace version_set
 
 // Called from TableCache::Get and Table::Get when file/block in which
 // key may  exist are not there in TableCache/BlockCache respectively. In this
 // case we  can't guarantee that key does not exist and are not permitted to do
 // IO to be  certain.Set the status=kFound and value_found=false to let the
 // caller know that key may exist but is not there in memory
-static void MarkKeyMayExist(void* arg) {
-  version_set::Saver* s = reinterpret_cast<version_set::Saver*>(arg);
-  s->state = kFound;
+void MarkKeyMayExist(void* arg) {
+  Version::Saver* s = reinterpret_cast<Version::Saver*>(arg);
+  s->state = Version::kFound;
   if (s->value_found != nullptr) {
     *(s->value_found) = false;
   }
 }
 
-static bool SaveValue(void* arg, const ParsedInternalKey& parsed_key,
+bool SaveValue(void* arg, const ParsedInternalKey& parsed_key,
                const Slice& v) {
-  version_set::Saver* s = reinterpret_cast<version_set::Saver*>(arg);
+  Version::Saver* s = reinterpret_cast<Version::Saver*>(arg);
   MergeContext* merge_contex = s->merge_context;
   std::string merge_result;  // temporary area for merge results later
 
@@ -676,17 +653,17 @@ static bool SaveValue(void* arg, const ParsedInternalKey& parsed_key,
     // Key matches. Process it
     switch (parsed_key.type) {
       case kTypeValue:
-        if (kNotFound == s->state) {
-          s->state = kFound;
+        if (Version::kNotFound == s->state) {
+          s->state = Version::kFound;
           s->value->assign(v.data(), v.size());
-        } else if (kMerge == s->state) {
+        } else if (Version::kMerge == s->state) {
           assert(s->merge_operator != nullptr);
-          s->state = kFound;
+          s->state = Version::kFound;
           if (!s->merge_operator->FullMerge(s->user_key, &v,
                                             merge_contex->GetOperands(),
                                             s->value, s->logger)) {
             RecordTick(s->statistics, NUMBER_MERGE_FAILURES);
-            s->state = kCorrupt;
+            s->state = Version::kCorrupt;
           }
         } else {
           assert(false);
@@ -694,15 +671,15 @@ static bool SaveValue(void* arg, const ParsedInternalKey& parsed_key,
         return false;
 
       case kTypeDeletion:
-        if (kNotFound == s->state) {
-          s->state = kDeleted;
-        } else if (kMerge == s->state) {
-          s->state = kFound;
+        if (Version::kNotFound == s->state) {
+          s->state = Version::kDeleted;
+        } else if (Version::kMerge == s->state) {
+          s->state = Version::kFound;
           if (!s->merge_operator->FullMerge(s->user_key, nullptr,
                                             merge_contex->GetOperands(),
                                             s->value, s->logger)) {
             RecordTick(s->statistics, NUMBER_MERGE_FAILURES);
-            s->state = kCorrupt;
+            s->state = Version::kCorrupt;
           }
         } else {
           assert(false);
@@ -710,8 +687,8 @@ static bool SaveValue(void* arg, const ParsedInternalKey& parsed_key,
         return false;
 
       case kTypeMerge:
-        assert(s->state == kNotFound || s->state == kMerge);
-        s->state = kMerge;
+        assert(s->state == Version::kNotFound || s->state == Version::kMerge);
+        s->state = Version::kMerge;
         merge_contex->PushOperand(v);
         return true;
 
@@ -779,7 +756,7 @@ void Version::Get(const ReadOptions& options,
   Slice user_key = k.user_key();
 
   assert(status->ok() || status->IsMergeInProgress());
-  version_set::Saver saver;
+  Saver saver;
   saver.state = status->ok()? kNotFound : kMerge;
   saver.ucmp = user_comparator_;
   saver.user_key = user_key;

db/version_set.h

@@ -241,10 +241,33 @@ class Version {
     FileMetaData* file;
   };
 
+  enum SaverState {
+    kNotFound,
+    kFound,
+    kDeleted,
+    kCorrupt,
+    kMerge  // saver contains the current merge result (the operands)
+  };
+
+  // Callback from TableCache::Get()
+  struct Saver {
+    SaverState state;
+    const Comparator* ucmp;
+    Slice user_key;
+    bool* value_found;  // Is value set correctly? Used by KeyMayExist
+    std::string* value;
+    const MergeOperator* merge_operator;
+    // the merge operations encountered;
+    MergeContext* merge_context;
+    Logger* logger;
+    Statistics* statistics;
+  };
+
  private:
   friend class Compaction;
   friend class VersionSet;
   friend class DBImpl;
+  friend class CompactedDBImpl;
   friend class ColumnFamilyData;
   friend class CompactionPicker;
   friend class LevelCompactionPicker;

utilities/compacted_db/compacted_db_impl.cc

@@ -0,0 +1,132 @@
+//  Copyright (c) 2014, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under the BSD-style license found in the
+//  LICENSE file in the root directory of this source tree. An additional grant
+//  of patent rights can be found in the PATENTS file in the same directory.
+
+#ifndef ROCKSDB_LITE
+#include "utilities/compacted_db/compacted_db_impl.h"
+#include "db/db_impl.h"
+#include "db/version_set.h"
+#include "db/merge_context.h"
+
+namespace rocksdb {
+
+extern void MarkKeyMayExist(void* arg);
+extern bool SaveValue(void* arg, const ParsedInternalKey& parsed_key,
+                      const Slice& v);
+
+CompactedDBImpl::CompactedDBImpl(
+  const DBOptions& options, const std::string& dbname)
+  : DBImpl(options, dbname) {
+}
+
+CompactedDBImpl::~CompactedDBImpl() {
+}
+
+Status CompactedDBImpl::Get(const ReadOptions& options,
+     ColumnFamilyHandle*, const Slice& key, std::string* value) {
+  size_t left = 0;
+  size_t right = files_.num_files - 1;
+  while (left < right) {
+    size_t mid = (left + right) >> 1;
+    const FdWithKeyRange& f = files_.files[mid];
+    if (user_comparator_->Compare(ExtractUserKey(f.largest_key), key) < 0) {
+      // Key at "mid.largest" is < "target".  Therefore all
+      // files at or before "mid" are uninteresting.
+      left = mid + 1;
+    } else {
+      // Key at "mid.largest" is >= "target".  Therefore all files
+      // after "mid" are uninteresting.
+      right = mid;
+    }
+  }
+  const FdWithKeyRange& f = files_.files[right];
+
+  bool value_found;
+  MergeContext merge_context;
+  Version::Saver saver;
+  saver.state = Version::kNotFound;
+  saver.ucmp = user_comparator_;
+  saver.user_key = key;
+  saver.value_found = &value_found;
+  saver.value = value;
+  saver.merge_operator = nullptr;
+  saver.merge_context = &merge_context;
+  saver.logger = info_log_;
+  saver.statistics = statistics_;
+  LookupKey lkey(key, kMaxSequenceNumber);
+  f.fd.table_reader->Get(options, lkey.internal_key(),
+                         reinterpret_cast<void*>(&saver), SaveValue,
+                         MarkKeyMayExist);
+  if (saver.state == Version::kFound) {
+    return Status::OK();
+  }
+  return Status::NotFound();
+}
+
+Status CompactedDBImpl::Init(const Options& options) {
+  mutex_.Lock();
+  ColumnFamilyDescriptor cf(kDefaultColumnFamilyName,
+                            ColumnFamilyOptions(options));
+  Status s = Recover({ cf }, true /* read only */, false);
+  if (s.ok()) {
+    cfd_ = reinterpret_cast<ColumnFamilyHandleImpl*>(
+              DefaultColumnFamily())->cfd();
+    delete cfd_->InstallSuperVersion(new SuperVersion(), &mutex_);
+  }
+  mutex_.Unlock();
+  if (!s.ok()) {
+    return s;
+  }
+  version_ = cfd_->GetSuperVersion()->current;
+  user_comparator_ = cfd_->user_comparator();
+  statistics_ = cfd_->ioptions()->statistics;
+  info_log_ = cfd_->ioptions()->info_log;
+  // L0 should not have files
+  if (version_->file_levels_[0].num_files > 1) {
+    return Status::NotSupported("L0 contain more than 1 file");
+  }
+  if (version_->file_levels_[0].num_files == 1) {
+    if (version_->num_non_empty_levels_ > 1) {
+      return Status::NotSupported("Both L0 and other level contain files");
+    }
+    files_ = version_->file_levels_[0];
+    return Status::OK();
+  }
+
+  for (int i = 1; i < version_->num_non_empty_levels_ - 1; ++i) {
+    if (version_->file_levels_[i].num_files > 0) {
+      return Status::NotSupported("Other levels also contain files");
+    }
+  }
+
+  int level = version_->num_non_empty_levels_ - 1;
+  if (version_->file_levels_[level].num_files > 0) {
+    files_ = version_->file_levels_[version_->num_non_empty_levels_ - 1];
+    return Status::OK();
+  }
+  return Status::NotSupported("no file exists");
+}
+
+Status CompactedDBImpl::Open(const Options& options,
+                             const std::string& dbname, DB** dbptr) {
+  *dbptr = nullptr;
+
+  if (options.max_open_files != -1) {
+    return Status::InvalidArgument("require max_open_files = -1");
+  }
+  if (options.merge_operator.get() != nullptr) {
+    return Status::InvalidArgument("merge operator is not supported");
+  }
+  DBOptions db_options(options);
+  std::unique_ptr<CompactedDBImpl> db(new CompactedDBImpl(db_options, dbname));
+  Status s = db->Init(options);
+  if (s.ok()) {
+    *dbptr = db.release();
+    Log(options.info_log, "Opened the db as fully compacted mode");
+  }
+  return s;
+}
+
+}   // namespace rocksdb
+#endif  // ROCKSDB_LITE

utilities/compacted_db/compacted_db_impl.h

@@ -0,0 +1,92 @@
+//  Copyright (c) 2014, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under the BSD-style license found in the
+//  LICENSE file in the root directory of this source tree. An additional grant
+//  of patent rights can be found in the PATENTS file in the same directory.
+
+#pragma once
+#ifndef ROCKSDB_LITE
+#include "db/db_impl.h"
+#include <vector>
+#include <string>
+
+namespace rocksdb {
+
+class CompactedDBImpl : public DBImpl {
+ public:
+  CompactedDBImpl(const DBOptions& options, const std::string& dbname);
+  virtual ~CompactedDBImpl();
+
+  static Status Open(const Options& options, const std::string& dbname,
+                     DB** dbptr);
+
+  // Implementations of the DB interface
+  using DB::Get;
+  virtual Status Get(const ReadOptions& options,
+                     ColumnFamilyHandle* column_family, const Slice& key,
+                     std::string* value) override;
+
+  using DBImpl::Put;
+  virtual Status Put(const WriteOptions& options,
+                     ColumnFamilyHandle* column_family, const Slice& key,
+                     const Slice& value) override {
+    return Status::NotSupported("Not supported in compacted db mode.");
+  }
+  using DBImpl::Merge;
+  virtual Status Merge(const WriteOptions& options,
+                       ColumnFamilyHandle* column_family, const Slice& key,
+                       const Slice& value) override {
+    return Status::NotSupported("Not supported in compacted db mode.");
+  }
+  using DBImpl::Delete;
+  virtual Status Delete(const WriteOptions& options,
+                        ColumnFamilyHandle* column_family,
+                        const Slice& key) override {
+    return Status::NotSupported("Not supported in compacted db mode.");
+  }
+  virtual Status Write(const WriteOptions& options,
+                       WriteBatch* updates) override {
+    return Status::NotSupported("Not supported in compacted db mode.");
+  }
+  using DBImpl::CompactRange;
+  virtual Status CompactRange(ColumnFamilyHandle* column_family,
+                              const Slice* begin, const Slice* end,
+                              bool reduce_level = false, int target_level = -1,
+                              uint32_t target_path_id = 0) override {
+    return Status::NotSupported("Not supported in compacted db mode.");
+  }
+
+  virtual Status DisableFileDeletions() override {
+    return Status::NotSupported("Not supported in compacted db mode.");
+  }
+  virtual Status EnableFileDeletions(bool force) override {
+    return Status::NotSupported("Not supported in compacted db mode.");
+  }
+  virtual Status GetLiveFiles(std::vector<std::string>&,
+                              uint64_t* manifest_file_size,
+                              bool flush_memtable = true) override {
+    return Status::NotSupported("Not supported in compacted db mode.");
+  }
+  using DBImpl::Flush;
+  virtual Status Flush(const FlushOptions& options,
+                       ColumnFamilyHandle* column_family) override {
+    return Status::NotSupported("Not supported in compacted db mode.");
+  }
+
+ private:
+  friend class DB;
+  Status Init(const Options& options);
+
+  ColumnFamilyData* cfd_;
+  Version* version_;
+  const Comparator* user_comparator_;
+  FileLevel files_;
+
+  Statistics* statistics_;
+  Logger* info_log_;
+
+  // No copying allowed
+  CompactedDBImpl(const CompactedDBImpl&);
+  void operator=(const CompactedDBImpl&);
+};
+}
+#endif  // ROCKSDB_LITE