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// 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.
#ifndef COMPONENTS_SYNC_ENGINE_IMPL_SYNCER_H_
#define COMPONENTS_SYNC_ENGINE_IMPL_SYNCER_H_
#include <stdint.h>
#include <vector>
#include "base/gtest_prod_util.h"
#include "base/macros.h"
#include "components/sync/base/model_type.h"
#include "components/sync/base/syncer_error.h"
#include "components/sync/protocol/sync.pb.h"
namespace syncer {
class CancelationSignal;
class CommitProcessor;
class GetUpdatesDelegate;
class NudgeTracker;
class SyncCycle;
// A Syncer provides a control interface for driving the sync cycle. These
// cycles consist of downloading updates, parsing the response (aka. process
// updates), applying updates while resolving conflicts, and committing local
// changes. Some of these steps may be skipped if they're deemed to be
// unnecessary.
//
// A Syncer instance expects to run on a dedicated thread. Calls to SyncShare()
// may take an unbounded amount of time because it may block on network I/O, on
// lock contention, or on tasks posted to other threads.
class Syncer {
public:
explicit Syncer(CancelationSignal* cancelation_signal);
virtual ~Syncer();
// Whether the syncer is in the middle of a sync cycle.
bool IsSyncing() const;
// Fetches and applies updates, resolves conflicts and commits local changes
// for |request_types| as necessary until client and server states are in
// sync. The |nudge_tracker| contains state that describes why the client is
// out of sync and what must be done to bring it back into sync.
// Returns: false if an error occurred and retries should backoff, true
// otherwise.
virtual bool NormalSyncShare(ModelTypeSet request_types,
NudgeTracker* nudge_tracker,
SyncCycle* cycle);
// Performs an initial download for the |request_types|. It is assumed that
// the specified types have no local state, and that their associated change
// processors are in "passive" mode, so none of the downloaded updates will be
// applied to the model. The |source| is sent up to the server for debug
// purposes. It describes the reson for performing this initial download.
// Returns: false if an error occurred and retries should backoff, true
// otherwise.
virtual bool ConfigureSyncShare(const ModelTypeSet& request_types,
sync_pb::SyncEnums::GetUpdatesOrigin origin,
SyncCycle* cycle);
// Requests to download updates for the |request_types|. For a well-behaved
// client with a working connection to the invalidations server, this should
// be unnecessary. It may be invoked periodically to try to keep the client
// in sync despite bugs or transient failures.
// Returns: false if an error occurred and retries should backoff, true
// otherwise.
virtual bool PollSyncShare(ModelTypeSet request_types, SyncCycle* cycle);
// Posts a ClearServerData command.
// Returns: false if an error occurred and retries should backoff, true
// otherwise.
virtual bool PostClearServerData(SyncCycle* cycle);
private:
bool DownloadAndApplyUpdates(ModelTypeSet* request_types,
SyncCycle* cycle,
const GetUpdatesDelegate& delegate);
// This function will commit batches of unsynced items to the server until the
// number of unsynced and ready to commit items reaches zero or an error is
// encountered. A request to exit early will be treated as an error and will
// abort any blocking operations.
SyncerError BuildAndPostCommits(const ModelTypeSet& request_types,
NudgeTracker* nudge_tracker,
SyncCycle* cycle,
CommitProcessor* commit_processor);
// Whether an early exist was requested due to a cancelation signal.
bool ExitRequested();
bool HandleCycleEnd(SyncCycle* cycle,
sync_pb::SyncEnums::GetUpdatesOrigin origin);
CancelationSignal* const cancelation_signal_;
// Whether the syncer is in the middle of a sync attempt.
bool is_syncing_;
DISALLOW_COPY_AND_ASSIGN(Syncer);
};
} // namespace syncer
#endif // COMPONENTS_SYNC_ENGINE_IMPL_SYNCER_H_