[Sync] Move //sync to //components/sync.

sync/engine/model_type_worker.h

-// Copyright 2014 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 SYNC_ENGINE_MODEL_TYPE_WORKER_H_
-#define SYNC_ENGINE_MODEL_TYPE_WORKER_H_
-
-#include <stddef.h>
-
-#include <map>
-#include <memory>
-#include <string>
-
-#include "base/memory/weak_ptr.h"
-#include "base/threading/non_thread_safe.h"
-#include "sync/base/sync_export.h"
-#include "sync/engine/commit_contributor.h"
-#include "sync/engine/commit_queue.h"
-#include "sync/engine/nudge_handler.h"
-#include "sync/engine/update_handler.h"
-#include "sync/internal_api/public/base/model_type.h"
-#include "sync/internal_api/public/non_blocking_sync_common.h"
-#include "sync/internal_api/public/sync_encryption_handler.h"
-#include "sync/protocol/data_type_state.pb.h"
-#include "sync/protocol/sync.pb.h"
-#include "sync/util/cryptographer.h"
-
-namespace base {
-class SingleThreadTaskRunner;
-}
-
-namespace syncer_v2 {
-
-class ModelTypeProcessor;
-class WorkerEntityTracker;
-
-// A smart cache for sync types that use message passing (rather than
-// transactions and the syncable::Directory) to communicate with the sync
-// thread.
-//
-// When the non-blocking sync type wants to talk with the sync server, it will
-// send a message from its thread to this object on the sync thread. This
-// object ensures the appropriate sync server communication gets scheduled and
-// executed. The response, if any, will be returned to the non-blocking sync
-// type's thread eventually.
-//
-// This object also has a role to play in communications in the opposite
-// direction. Sometimes the sync thread will receive changes from the sync
-// server and deliver them here. This object will post this information back to
-// the appropriate component on the model type's thread.
-//
-// This object does more than just pass along messages. It understands the sync
-// protocol, and it can make decisions when it sees conflicting messages. For
-// example, if the sync server sends down an update for a sync entity that is
-// currently pending for commit, this object will detect this condition and
-// cancel the pending commit.
-class SYNC_EXPORT ModelTypeWorker : public syncer::UpdateHandler,
-                                    public syncer::CommitContributor,
-                                    public CommitQueue,
-                                    public base::NonThreadSafe {
- public:
-  ModelTypeWorker(syncer::ModelType type,
-                  const sync_pb::DataTypeState& initial_state,
-                  std::unique_ptr<syncer::Cryptographer> cryptographer,
-                  syncer::NudgeHandler* nudge_handler,
-                  std::unique_ptr<ModelTypeProcessor> model_type_processor);
-  ~ModelTypeWorker() override;
-
-  syncer::ModelType GetModelType() const;
-
-  bool IsEncryptionRequired() const;
-  void UpdateCryptographer(
-      std::unique_ptr<syncer::Cryptographer> cryptographer);
-
-  // UpdateHandler implementation.
-  bool IsInitialSyncEnded() const override;
-  void GetDownloadProgress(
-      sync_pb::DataTypeProgressMarker* progress_marker) const override;
-  void GetDataTypeContext(sync_pb::DataTypeContext* context) const override;
-  syncer::SyncerError ProcessGetUpdatesResponse(
-      const sync_pb::DataTypeProgressMarker& progress_marker,
-      const sync_pb::DataTypeContext& mutated_context,
-      const SyncEntityList& applicable_updates,
-      syncer::sessions::StatusController* status) override;
-  void ApplyUpdates(syncer::sessions::StatusController* status) override;
-  void PassiveApplyUpdates(syncer::sessions::StatusController* status) override;
-
-  // CommitQueue implementation.
-  void EnqueueForCommit(const CommitRequestDataList& request_list) override;
-
-  // CommitContributor implementation.
-  std::unique_ptr<syncer::CommitContribution> GetContribution(
-      size_t max_entries) override;
-
-  // Callback for when our contribution gets a response.
-  void OnCommitResponse(CommitResponseDataList* response_list);
-
-  base::WeakPtr<ModelTypeWorker> AsWeakPtr();
-
- private:
-  using EntityMap = std::map<std::string, std::unique_ptr<WorkerEntityTracker>>;
-
-  // Helper function to actually send |pending_updates_| to the processor.
-  void ApplyPendingUpdates();
-
-  // Returns true if this type has successfully fetched all available updates
-  // from the server at least once. Our state may or may not be stale, but at
-  // least we know that it was valid at some point in the past.
-  bool IsTypeInitialized() const;
-
-  // Returns true if this type is prepared to commit items. Currently, this
-  // depends on having downloaded the initial data and having the encryption
-  // settings in a good state.
-  bool CanCommitItems() const;
-
-  // Takes |commit_entity| populated from fields of WorkerEntityTracker and
-  // adjusts some fields before committing to server. Adjustments include
-  // generating client-assigned ID, encrypting data, etc.
-  void AdjustCommitProto(sync_pb::SyncEntity* commit_entity);
-
-  // Attempts to decrypt encrypted updates stored in the EntityMap. If
-  // successful, will remove the update from the its tracker and forward
-  // it to the processor for application. Will forward any new encryption
-  // keys to the processor to trigger re-encryption if necessary.
-  void OnCryptographerUpdated();
-
-  // Attempts to decrypt the given specifics and return them in the |out|
-  // parameter. Assumes cryptographer->CanDecrypt(specifics) returned true.
-  //
-  // Returns false if the decryption failed. There are no guarantees about the
-  // contents of |out| when that happens.
-  //
-  // In theory, this should never fail. Only corrupt or invalid entries could
-  // cause this to fail, and no clients are known to create such entries. The
-  // failure case is an attempt to be defensive against bad input.
-  static bool DecryptSpecifics(syncer::Cryptographer* cryptographer,
-                               const sync_pb::EntitySpecifics& in,
-                               sync_pb::EntitySpecifics* out);
-
-  // Returns the entity tracker for the given |tag_hash|, or nullptr.
-  WorkerEntityTracker* GetEntityTracker(const std::string& tag_hash);
-
-  // Creates an entity tracker in the map using the given |data| and returns a
-  // pointer to it. Requires that one doesn't exist for data.client_tag_hash.
-  WorkerEntityTracker* CreateEntityTracker(const EntityData& data);
-
-  // Gets the entity tracker for |data| or creates one if it doesn't exist.
-  WorkerEntityTracker* GetOrCreateEntityTracker(const EntityData& data);
-
-  syncer::ModelType type_;
-
-  // State that applies to the entire model type.
-  sync_pb::DataTypeState data_type_state_;
-
-  // Pointer to the ModelTypeProcessor associated with this worker. Never null.
-  std::unique_ptr<ModelTypeProcessor> model_type_processor_;
-
-  // A private copy of the most recent cryptographer known to sync.
-  // Initialized at construction time and updated with UpdateCryptographer().
-  // NULL if encryption is not enabled for this type.
-  std::unique_ptr<syncer::Cryptographer> cryptographer_;
-
-  // Interface used to access and send nudges to the sync scheduler. Not owned.
-  syncer::NudgeHandler* nudge_handler_;
-
-  // A map of per-entity information known to this object.
-  //
-  // When commits are pending, their information is stored here. This
-  // information is dropped from memory when the commit succeeds or gets
-  // cancelled.
-  //
-  // This also stores some information related to received server state in
-  // order to implement reflection blocking and conflict detection. This
-  // information is kept in memory indefinitely. With a bit more coordination
-  // with the model thread, we could optimize this to reduce memory usage in
-  // the steady state.
-  EntityMap entities_;
-
-  // Accumulates all the updates from a single GetUpdates cycle in memory so
-  // they can all be sent to the processor at once.
-  UpdateResponseDataList pending_updates_;
-
-  base::WeakPtrFactory<ModelTypeWorker> weak_ptr_factory_;
-};
-
-}  // namespace syncer_v2
-
-#endif  // SYNC_ENGINE_MODEL_TYPE_WORKER_H_