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levedb-mcpe-legacy/util/env.cc
Sanjay Ghemawat 1b7c4ce89d LevelDB now attempts to reuse the preceding MANIFEST and log file when re-opened.
(Based on a suggestion by cmumford.)

"open" benchmark on my workstation speeds up significantly since we
can now avoid three fdatasync calls and a compaction per open:

  Before: ~80000 microseconds
  After:    ~130 microseconds

Details:

(1) Added Options::reuse_logs (currently defaults to false) to control
new behavior.  The intention is to change the default to true after some
baking.

(2) Added Env::NewAppendableFile() whose default implementation returns
a not-supported error.

(3) VersionSet::Recovery attempts to reuse the MANIFEST from which
it is recovering.

(4) DBImpl recovery attempts to reuse the last log file and memtable.

(5) db_test.cc now tests a new configuration that sets reuse_logs to true.

(6) fault_injection_test also tests a reuse_logs==true config.

(7) Added a new recovery_test.
2016-04-07 17:45:03 +02:00

101 lines
2.2 KiB
C++

// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#include "leveldb/env.h"
namespace leveldb {
Env::~Env() {
}
Status Env::NewAppendableFile(const std::string& fname, WritableFile** result) {
return Status::NotSupported("NewAppendableFile", fname);
}
SequentialFile::~SequentialFile() {
}
RandomAccessFile::~RandomAccessFile() {
}
WritableFile::~WritableFile() {
}
Logger::~Logger() {
}
FileLock::~FileLock() {
}
void Log(Logger* info_log, const char* format, ...) {
if (info_log != NULL) {
va_list ap;
va_start(ap, format);
info_log->Logv(format, ap);
va_end(ap);
}
}
static Status DoWriteStringToFile(Env* env, const Slice& data,
const std::string& fname,
bool should_sync) {
WritableFile* file;
Status s = env->NewWritableFile(fname, &file);
if (!s.ok()) {
return s;
}
s = file->Append(data);
if (s.ok() && should_sync) {
s = file->Sync();
}
if (s.ok()) {
s = file->Close();
}
delete file; // Will auto-close if we did not close above
if (!s.ok()) {
env->DeleteFile(fname);
}
return s;
}
Status WriteStringToFile(Env* env, const Slice& data,
const std::string& fname) {
return DoWriteStringToFile(env, data, fname, false);
}
Status WriteStringToFileSync(Env* env, const Slice& data,
const std::string& fname) {
return DoWriteStringToFile(env, data, fname, true);
}
Status ReadFileToString(Env* env, const std::string& fname, std::string* data) {
data->clear();
SequentialFile* file;
Status s = env->NewSequentialFile(fname, &file);
if (!s.ok()) {
return s;
}
static const int kBufferSize = 8192;
char* space = new char[kBufferSize];
while (true) {
Slice fragment;
s = file->Read(kBufferSize, &fragment, space);
if (!s.ok()) {
break;
}
data->append(fragment.data(), fragment.size());
if (fragment.empty()) {
break;
}
}
delete[] space;
delete file;
return s;
}
EnvWrapper::~EnvWrapper() {
}
} // namespace leveldb