Implement lossy pref behavior for JsonPrefStore.

base/files/important_file_writer.cc

 // Copyright (c) 2011 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 "base/files/important_file_writer.h"
 
 #include <stdio.h>
 
 #include <string>
 
@@ skipping 36 matching lines @@
                 const std::string& message) {
   UMA_HISTOGRAM_ENUMERATION("ImportantFile.TempFileFailures", failure_code,
                             TEMP_FILE_FAILURE_MAX);
   DPLOG(WARNING) << "temp file failure: " << path.value().c_str()
                  << " : " << message;
 }
 
 // Helper function to call WriteFileAtomically() with a scoped_ptr<std::string>.
 bool WriteScopedStringToFileAtomically(const FilePath& path,
                                        scoped_ptr<std::string> data) {
-  return ImportantFileWriter::WriteFileAtomically(path, *data);
+  return ImportantFileWriterImpl::WriteFileAtomically(path, *data);
 }
 
 }  // namespace
 
 // static
-bool ImportantFileWriter::WriteFileAtomically(const FilePath& path,
-                                              const std::string& data) {
+bool ImportantFileWriterImpl::WriteFileAtomically(const FilePath& path,
+                                                  const std::string& data) {
 #if defined(OS_CHROMEOS)
   // On Chrome OS, chrome gets killed when it cannot finish shutdown quickly,
   // and this function seems to be one of the slowest shutdown steps.
   // Include some info to the report for investigation. crbug.com/418627
   // TODO(hashimoto): Remove this.
   struct {
     size_t data_size;
     char path[128];
   } file_info;
   file_info.data_size = data.size();
@@ skipping 39 matching lines @@
 
   if (!base::ReplaceFile(tmp_file_path, path, NULL)) {
     LogFailure(path, FAILED_RENAMING, "could not rename temporary file");
     base::DeleteFile(tmp_file_path, false);
     return false;
   }
 
   return true;
 }
 
-ImportantFileWriter::ImportantFileWriter(
+ImportantFileWriterImpl::ImportantFileWriterImpl(
     const FilePath& path,
     const scoped_refptr<base::SequencedTaskRunner>& task_runner)
     : path_(path),
       task_runner_(task_runner),
       serializer_(NULL),
       commit_interval_(TimeDelta::FromMilliseconds(kDefaultCommitIntervalMs)),
       weak_factory_(this) {
   DCHECK(CalledOnValidThread());
   DCHECK(task_runner_);
 }
 
-ImportantFileWriter::~ImportantFileWriter() {
+ImportantFileWriterImpl::~ImportantFileWriterImpl() {
   // 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 {
+bool ImportantFileWriterImpl::HasPendingWrite() const {
   DCHECK(CalledOnValidThread());
   return timer_.IsRunning();
 }
 
-void ImportantFileWriter::WriteNow(scoped_ptr<std::string> data) {
+void ImportantFileWriterImpl::WriteNow(scoped_ptr<std::string> data) {
   DCHECK(CalledOnValidThread());
   if (data->length() > static_cast<size_t>(kint32max)) {
     NOTREACHED();
     return;
   }
 
   if (HasPendingWrite())
     timer_.Stop();
 
   auto task = Bind(&WriteScopedStringToFileAtomically, path_, Passed(&data));
   if (!PostWriteTask(task)) {
     // Posting the task to background message loop is not expected
     // to fail, but if it does, avoid losing data and just hit the disk
     // on the current thread.
     NOTREACHED();
 
     task.Run();
   }
 }
 
-void ImportantFileWriter::ScheduleWrite(DataSerializer* serializer) {
+void ImportantFileWriterImpl::ScheduleWrite(DataSerializer* serializer) {
   DCHECK(CalledOnValidThread());
 
   DCHECK(serializer);
   serializer_ = serializer;
 
   if (!timer_.IsRunning()) {
     timer_.Start(FROM_HERE, commit_interval_, this,
-                 &ImportantFileWriter::DoScheduledWrite);
+                 &ImportantFileWriterImpl::DoScheduledWrite);
   }
 }
 
-void ImportantFileWriter::DoScheduledWrite() {
+void ImportantFileWriterImpl::DoScheduledWrite() {
   DCHECK(serializer_);
   scoped_ptr<std::string> data(new std::string);
   if (serializer_->SerializeData(data.get())) {
     WriteNow(data.Pass());
   } else {
     DLOG(WARNING) << "failed to serialize data to be saved in "
                   << path_.value().c_str();
   }
   serializer_ = NULL;
 }
 
-void ImportantFileWriter::RegisterOnNextSuccessfulWriteCallback(
+void ImportantFileWriterImpl::RegisterOnNextSuccessfulWriteCallback(
     const base::Closure& on_next_successful_write) {
   DCHECK(on_next_successful_write_.is_null());
   on_next_successful_write_ = on_next_successful_write;
 }
 
-bool ImportantFileWriter::PostWriteTask(const Callback<bool()>& task) {
+TimeDelta ImportantFileWriterImpl::CommitInterval() const {
+  return commit_interval_;
+}
+
+bool ImportantFileWriterImpl::PostWriteTask(const Callback<bool()>& task) {
   // TODO(gab): This code could always use PostTaskAndReplyWithResult and let
   // ForwardSuccessfulWrite() no-op if |on_next_successful_write_| is null, but
   // PostTaskAndReply causes memory leaks in tests (crbug.com/371974) and
   // suppressing all of those is unrealistic hence we avoid most of them by
   // using PostTask() in the typical scenario below.
   if (!on_next_successful_write_.is_null()) {
     return base::PostTaskAndReplyWithResult(
-        task_runner_.get(),
-        FROM_HERE,
-        MakeCriticalClosure(task),
-        Bind(&ImportantFileWriter::ForwardSuccessfulWrite,
+        task_runner_.get(), FROM_HERE, MakeCriticalClosure(task),
+        Bind(&ImportantFileWriterImpl::ForwardSuccessfulWrite,
              weak_factory_.GetWeakPtr()));
   }
   return task_runner_->PostTask(
       FROM_HERE,
       MakeCriticalClosure(base::Bind(IgnoreResult(task))));
 }
 
-void ImportantFileWriter::ForwardSuccessfulWrite(bool result) {
+void ImportantFileWriterImpl::ForwardSuccessfulWrite(bool result) {
   DCHECK(CalledOnValidThread());
   if (result && !on_next_successful_write_.is_null()) {
     on_next_successful_write_.Run();
     on_next_successful_write_.Reset();
   }
 }
 
 }  // namespace base