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// Copyright (c) 2010 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "chrome/common/important_file_writer.h"
#include <stdio.h>
#include <string>
#include "base/file_path.h"
#include "base/file_util.h"
#include "base/logging.h"
#include "base/message_loop_proxy.h"
#include "base/string_number_conversions.h"
#include "base/task.h"
#include "base/thread.h"
#include "base/time.h"
using base::TimeDelta;
namespace {
const int kDefaultCommitIntervalMs = 10000;
class WriteToDiskTask : public Task {
public:
WriteToDiskTask(const FilePath& path, const std::string& data)
: path_(path),
data_(data) {
}
virtual void Run() {
// Write the data to a temp file then rename to avoid data loss if we crash
// while writing the file. Ensure that the temp file is on the same volume
// as target file, so it can be moved in one step, and that the temp file
// is securely created.
FilePath tmp_file_path;
FILE* tmp_file = file_util::CreateAndOpenTemporaryFileInDir(
path_.DirName(), &tmp_file_path);
if (!tmp_file) {
LogFailure("could not create temporary file");
return;
}
size_t bytes_written = fwrite(data_.data(), 1, data_.length(), tmp_file);
if (!file_util::CloseFile(tmp_file)) {
LogFailure("failed to close temporary file");
file_util::Delete(tmp_file_path, false);
return;
}
if (bytes_written < data_.length()) {
LogFailure("error writing, bytes_written=" +
base::Uint64ToString(bytes_written));
file_util::Delete(tmp_file_path, false);
return;
}
if (!file_util::ReplaceFile(tmp_file_path, path_)) {
LogFailure("could not rename temporary file");
file_util::Delete(tmp_file_path, false);
return;
}
}
private:
void LogFailure(const std::string& message) {
PLOG(WARNING) << "failed to write " << path_.value()
<< ": " << message;
}
const FilePath path_;
const std::string data_;
DISALLOW_COPY_AND_ASSIGN(WriteToDiskTask);
};
} // namespace
ImportantFileWriter::ImportantFileWriter(
const FilePath& path, base::MessageLoopProxy* file_message_loop_proxy)
: path_(path),
file_message_loop_proxy_(file_message_loop_proxy),
serializer_(NULL),
commit_interval_(TimeDelta::FromMilliseconds(
kDefaultCommitIntervalMs)) {
DCHECK(CalledOnValidThread());
DCHECK(file_message_loop_proxy_.get());
}
ImportantFileWriter::~ImportantFileWriter() {
// We're usually a member variable of some other object, which also tends
// to be our serializer. It may not be safe to call back to the parent object
// being destructed.
DCHECK(!HasPendingWrite());
}
bool ImportantFileWriter::HasPendingWrite() const {
DCHECK(CalledOnValidThread());
return timer_.IsRunning();
}
void ImportantFileWriter::WriteNow(const std::string& data) {
DCHECK(CalledOnValidThread());
if (HasPendingWrite())
timer_.Stop();
// TODO(sanjeevr): Add a DCHECK for the return value of PostTask.
// (Some tests fail if we add the DCHECK and they need to be fixed first).
file_message_loop_proxy_->PostTask(FROM_HERE,
new WriteToDiskTask(path_, data));
}
void ImportantFileWriter::ScheduleWrite(DataSerializer* serializer) {
DCHECK(CalledOnValidThread());
DCHECK(serializer);
serializer_ = serializer;
if (!MessageLoop::current()) {
// Happens in unit tests.
DoScheduledWrite();
return;
}
if (!timer_.IsRunning()) {
timer_.Start(commit_interval_, this,
&ImportantFileWriter::DoScheduledWrite);
}
}
void ImportantFileWriter::DoScheduledWrite() {
DCHECK(serializer_);
std::string data;
if (serializer_->SerializeData(&data)) {
WriteNow(data);
} else {
LOG(WARNING) << "failed to serialize data to be saved in "
<< path_.value();
}
serializer_ = NULL;
}
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