rocksdb/db/db_impl_readonly.cc
Lei Jin 5b3b6549d6 use super_version in NewIterator() and MultiGet() function
Summary:
Use super_version insider NewIterator to avoid Ref() each component
separately under mutex
The new added bench shows NewIterator QPS increases from 515K to 719K
No meaningful improvement for multiget I guess due to its relatively small
cost comparing to 90 keys fetch in the test.

Test Plan: unit test and db_bench

Reviewers: igor, sdong

Reviewed By: igor

CC: leveldb, dhruba

Differential Revision: https://reviews.facebook.net/D15609
2014-02-03 13:13:36 -08:00

103 lines
3.0 KiB
C++

// Copyright (c) 2013, 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.
//
// 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 "db/db_impl.h"
#include <algorithm>
#include <set>
#include <string>
#include <stdint.h>
#include <stdio.h>
#include <vector>
#include <algorithm>
#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"
namespace rocksdb {
DBImplReadOnly::DBImplReadOnly(const Options& options,
const std::string& dbname)
: DBImpl(options, dbname) {
Log(options_.info_log, "Opening the db in read only mode");
}
DBImplReadOnly::~DBImplReadOnly() {
}
// Implementations of the DB interface
Status DBImplReadOnly::Get(const ReadOptions& options,
const Slice& key,
std::string* value) {
Status s;
SequenceNumber snapshot = versions_->LastSequence();
SuperVersion* super_version = GetSuperVersion();
MergeContext merge_context;
LookupKey lkey(key, snapshot);
if (super_version->mem->Get(lkey, value, &s, merge_context, options_)) {
} else {
Version::GetStats stats;
super_version->current->Get(options, lkey, value, &s, &merge_context,
&stats, options_);
}
return s;
}
Iterator* DBImplReadOnly::NewIterator(const ReadOptions& options) {
SequenceNumber latest_snapshot;
Iterator* internal_iter = NewInternalIterator(options, &latest_snapshot);
return NewDBIterator(
&dbname_, env_, options_, user_comparator(),internal_iter,
(options.snapshot != nullptr
? reinterpret_cast<const SnapshotImpl*>(options.snapshot)->number_
: latest_snapshot));
}
Status DB::OpenForReadOnly(const Options& options, const std::string& dbname,
DB** dbptr, bool error_if_log_file_exist) {
*dbptr = nullptr;
DBImplReadOnly* impl = new DBImplReadOnly(options, dbname);
impl->mutex_.Lock();
Status s = impl->Recover(true /* read only */, error_if_log_file_exist);
if (s.ok()) {
delete impl->InstallSuperVersion(new DBImpl::SuperVersion());
}
impl->mutex_.Unlock();
if (s.ok()) {
*dbptr = impl;
} else {
delete impl;
}
return s;
}
}