blob: 23c882afd9f60408ad1a781812c682ec85f9dc88 [file] [log] [blame]
// Copyright (c) 2012 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 <stdint.h>
#include <memory>
#include <set>
#include <string>
#include "base/callback_forward.h"
#include "base/compiler_specific.h"
#include "base/files/file_path.h"
#include "base/files/important_file_writer.h"
#include "base/gtest_prod_util.h"
#include "base/macros.h"
#include "base/memory/weak_ptr.h"
#include "base/observer_list.h"
#include "base/sequence_checker.h"
#include "base/task/post_task.h"
#include "components/prefs/persistent_pref_store.h"
#include "components/prefs/pref_filter.h"
#include "components/prefs/prefs_export.h"
class PrefFilter;
namespace base {
class DictionaryValue;
class FilePath;
class JsonPrefStoreCallbackTest;
class JsonPrefStoreLossyWriteTest;
class SequencedTaskRunner;
class WriteCallbacksObserver;
class Value;
} // namespace base
// A writable PrefStore implementation that is used for user preferences.
: public PersistentPrefStore,
public base::ImportantFileWriter::DataSerializer,
public base::SupportsWeakPtr<JsonPrefStore> {
struct ReadResult;
// A pair of callbacks to call before and after the preference file is written
// to disk.
using OnWriteCallbackPair =
std::pair<base::Closure, base::Callback<void(bool success)>>;
// |pref_filename| is the path to the file to read prefs from. It is incorrect
// to create multiple JsonPrefStore with the same |pref_filename|.
// |file_task_runner| is used for asynchronous reads and writes. It must
// have the base::TaskShutdownBehavior::BLOCK_SHUTDOWN and base::MayBlock()
// traits. Unless external tasks need to run on the same sequence as
// JsonPrefStore tasks, keep the default value.
// The initial read is done synchronously, the TaskPriority is thus only used
// for flushes to disks and BEST_EFFORT is therefore appropriate. Priority of
// remaining BEST_EFFORT+BLOCK_SHUTDOWN tasks is bumped by the ThreadPool on
// shutdown. However, some shutdown use cases happen without
// ThreadPoolInstance::Shutdown() (e.g. ChromeRestartRequest::Start() and
// BrowserProcessImpl::EndSession()) and we must thus unfortunately make this
// USER_VISIBLE until we solve to allow bumping
// priority of a sequence on demand.
JsonPrefStore(const base::FilePath& pref_filename,
std::unique_ptr<PrefFilter> pref_filter = nullptr,
scoped_refptr<base::SequencedTaskRunner> file_task_runner =
{base::MayBlock(), base::TaskPriority::USER_VISIBLE,
// PrefStore overrides:
bool GetValue(const std::string& key,
const base::Value** result) const override;
std::unique_ptr<base::DictionaryValue> GetValues() const override;
void AddObserver(PrefStore::Observer* observer) override;
void RemoveObserver(PrefStore::Observer* observer) override;
bool HasObservers() const override;
bool IsInitializationComplete() const override;
// PersistentPrefStore overrides:
bool GetMutableValue(const std::string& key, base::Value** result) override;
void SetValue(const std::string& key,
std::unique_ptr<base::Value> value,
uint32_t flags) override;
void SetValueSilently(const std::string& key,
std::unique_ptr<base::Value> value,
uint32_t flags) override;
void RemoveValue(const std::string& key, uint32_t flags) override;
bool ReadOnly() const override;
PrefReadError GetReadError() const override;
// Note this method may be asynchronous if this instance has a |pref_filter_|
// See details in pref_filter.h.
PrefReadError ReadPrefs() override;
void ReadPrefsAsync(ReadErrorDelegate* error_delegate) override;
void CommitPendingWrite(
base::OnceClosure reply_callback = base::OnceClosure(),
base::OnceClosure synchronous_done_callback =
base::OnceClosure()) override;
void SchedulePendingLossyWrites() override;
void ReportValueChanged(const std::string& key, uint32_t flags) override;
// Just like RemoveValue(), but doesn't notify observers. Used when doing some
// cleanup that shouldn't otherwise alert observers.
void RemoveValueSilently(const std::string& key, uint32_t flags);
// Registers |on_next_successful_write_reply| to be called once, on the next
// successful write event of |writer_|.
// |on_next_successful_write_reply| will be called on the thread from which
// this method is called and does not need to be thread safe.
void RegisterOnNextSuccessfulWriteReply(
const base::Closure& on_next_successful_write_reply);
void ClearMutableValues() override;
void OnStoreDeletionFromDisk() override;
friend class base::JsonPrefStoreCallbackTest;
friend class base::JsonPrefStoreLossyWriteTest;
friend class base::WriteCallbacksObserver;
~JsonPrefStore() override;
// If |write_success| is true, runs |on_next_successful_write_|.
// Otherwise, re-registers |on_next_successful_write_|.
void RunOrScheduleNextSuccessfulWriteCallback(bool write_success);
// Handles the result of a write with result |write_success|. Runs
// |on_next_write_callback| on the current thread and posts
// |on_next_write_reply| on |reply_task_runner|.
static void PostWriteCallback(
const base::Callback<void(bool success)>& on_next_write_callback,
const base::Callback<void(bool success)>& on_next_write_reply,
scoped_refptr<base::SequencedTaskRunner> reply_task_runner,
bool write_success);
// Registers the |callbacks| pair to be called once synchronously before and
// after, respectively, the next write event of |writer_|.
// Both callbacks must be thread-safe.
void RegisterOnNextWriteSynchronousCallbacks(OnWriteCallbackPair callbacks);
// This method is called after the JSON file has been read. It then hands
// |value| (or an empty dictionary in some read error cases) to the
// |pref_filter| if one is set. It also gives a callback pointing at
// FinalizeFileRead() to that |pref_filter_| which is then responsible for
// invoking it when done. If there is no |pref_filter_|, FinalizeFileRead()
// is invoked directly.
void OnFileRead(std::unique_ptr<ReadResult> read_result);
// ImportantFileWriter::DataSerializer overrides:
bool SerializeData(std::string* output) override;
// This method is called after the JSON file has been read and the result has
// potentially been intercepted and modified by |pref_filter_|.
// |initialization_successful| is pre-determined by OnFileRead() and should
// be used when reporting OnInitializationCompleted().
// |schedule_write| indicates whether a write should be immediately scheduled
// (typically because the |pref_filter_| has already altered the |prefs|) --
// this will be ignored if this store is read-only.
void FinalizeFileRead(bool initialization_successful,
std::unique_ptr<base::DictionaryValue> prefs,
bool schedule_write);
// Schedule a write with the file writer as long as |flags| doesn't contain
// WriteablePrefStore::LOSSY_PREF_WRITE_FLAG.
void ScheduleWrite(uint32_t flags);
const base::FilePath path_;
const scoped_refptr<base::SequencedTaskRunner> file_task_runner_;
std::unique_ptr<base::DictionaryValue> prefs_;
bool read_only_;
// Helper for safely writing pref data.
base::ImportantFileWriter writer_;
std::unique_ptr<PrefFilter> pref_filter_;
base::ObserverList<PrefStore::Observer, true>::Unchecked observers_;
std::unique_ptr<ReadErrorDelegate> error_delegate_;
bool initialized_;
bool filtering_in_progress_;
bool pending_lossy_write_;
PrefReadError read_error_;
std::set<std::string> keys_need_empty_value_;
bool has_pending_write_reply_ = true;
base::Closure on_next_successful_write_reply_;