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// Copyright 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 <map>
#include <memory>
#include <string>
#include "base/callback.h"
#include "base/callback_helpers.h"
#include "base/macros.h"
#include "base/memory/ref_counted.h"
#include "base/synchronization/lock.h"
#include "base/synchronization/waitable_event.h"
#include "components/sync/base/model_type.h"
#include "components/sync/base/syncer_error.h"
namespace base {
class DictionaryValue;
} // namespace base
namespace syncer {
using WorkCallback = base::OnceCallback<SyncerError(void)>;
enum ModelSafeGroup {
GROUP_PASSIVE = 0, // Models that are just "passively" being synced; e.g.
// changes to these models don't need to be pushed to a
// native model.
GROUP_UI, // Models that live on UI thread and are being synced.
GROUP_DB, // Models that live on DB thread and are being synced.
GROUP_FILE, // Models that live on FILE thread and are being synced.
GROUP_HISTORY, // Models that live on history thread and are being
// synced.
GROUP_PASSWORD, // Models that live on the password thread and are
// being synced. On windows and linux, this runs on the
// DB thread.
GROUP_NON_BLOCKING, // Models that correspond to non-blocking types. These
// models always stay in GROUP_NON_BLOCKING; changes are
// forwarded to these models without ModelSafeWorker/
// SyncBackendRegistrar involvement.
std::string ModelSafeGroupToString(ModelSafeGroup group);
// The Syncer uses a ModelSafeWorker for all tasks that could potentially
// modify syncable entries (e.g under a WriteTransaction). The ModelSafeWorker
// only knows how to do one thing, and that is take some work (in a fully
// pre-bound callback) and have it performed (as in Run()) from a thread which
// is guaranteed to be "model-safe", where "safe" refers to not allowing us to
// cause an embedding application model to fall out of sync with the
// syncable::Directory due to a race. Each ModelSafeWorker is affiliated with
// a thread and does actual work on that thread.
class ModelSafeWorker : public base::RefCountedThreadSafe<ModelSafeWorker> {
// If not stopped, calls ScheduleWork() to schedule |work| and waits until it
// is done or abandoned. Otherwise, returns CANNOT_DO_WORK.
SyncerError DoWorkAndWaitUntilDone(WorkCallback work);
// Soft stop worker by setting stopped_ flag. Called when sync is disabled
// or browser is shutting down. Called on UI loop.
virtual void RequestStop();
virtual ModelSafeGroup GetModelSafeGroup() = 0;
// Returns true if called on the sequence this worker works on.
virtual bool IsOnModelSequence() = 0;
virtual ~ModelSafeWorker();
friend class base::RefCountedThreadSafe<ModelSafeWorker>;
// Schedules |work| on the appropriate sequence.
virtual void ScheduleWork(base::OnceClosure work) = 0;
void DoWork(WorkCallback work,
base::ScopedClosureRunner scoped_closure_runner,
SyncerError* error,
bool* did_run);
// Synchronizes access to all members.
base::Lock lock_;
// Signaled when DoWorkAndWaitUntilDone() can return, either because the work
// is done, the work has been abandoned or RequestStop() was called while no
// work was running. Reset at the beginning of DoWorkAndWaitUntilDone().
base::WaitableEvent work_done_or_abandoned_;
// Whether a WorkCallback is currently running.
bool is_work_running_ = false;
// Whether the worker was stopped. No WorkCallback can start running when this
// is true.
bool stopped_ = false;
// A map that details which ModelSafeGroup each ModelType
// belongs to. Routing info can change in response to the user enabling /
// disabling sync for certain types, as well as model association completions.
using ModelSafeRoutingInfo = std::map<ModelType, ModelSafeGroup>;
// Caller takes ownership of return value.
std::unique_ptr<base::DictionaryValue> ModelSafeRoutingInfoToValue(
const ModelSafeRoutingInfo& routing_info);
std::string ModelSafeRoutingInfoToString(
const ModelSafeRoutingInfo& routing_info);
ModelTypeSet GetRoutingInfoTypes(const ModelSafeRoutingInfo& routing_info);
ModelSafeGroup GetGroupForModelType(const ModelType type,
const ModelSafeRoutingInfo& routes);
} // namespace syncer