1 // Copyright 2014 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #ifndef SYNC_ENGINE_ENTITY_TRACKER_H_ 6 #define SYNC_ENGINE_ENTITY_TRACKER_H_ 7 8 #include <string> 9 10 #include "base/basictypes.h" 11 #include "base/memory/scoped_ptr.h" 12 #include "base/time/time.h" 13 #include "sync/base/sync_export.h" 14 #include "sync/internal_api/public/non_blocking_sync_common.h" 15 #include "sync/protocol/sync.pb.h" 16 17 namespace syncer { 18 19 // Manages the pending commit and update state for an entity on the sync 20 // thread. 21 // 22 // It should be considered a helper class internal to the 23 // ModelTypeSyncWorker. 24 // 25 // Maintains the state associated with a particular sync entity which is 26 // necessary for decision-making on the sync thread. It can track pending 27 // commit state, received update state, and can detect conflicts. 28 // 29 // This object may or may not contain state associated with a pending commit. 30 // If no commit is pending, the |is_commit_pending_| flag will be set to false 31 // and many of this object's fields will be cleared. 32 class SYNC_EXPORT EntityTracker { 33 public: 34 ~EntityTracker(); 35 36 // Initialize a new entity based on an update response. 37 static EntityTracker* FromServerUpdate(const std::string& id_string, 38 const std::string& client_tag_hash, 39 int64 version); 40 41 // Initialize a new entity based on a commit request. 42 static EntityTracker* FromCommitRequest( 43 const std::string& id_string, 44 const std::string& client_tag_hash, 45 int64 sequence_number, 46 int64 base_version, 47 base::Time ctime, 48 base::Time mtime, 49 const std::string& non_unique_name, 50 bool deleted, 51 const sync_pb::EntitySpecifics& specifics); 52 53 // Returns true if this entity should be commited to the server. 54 bool IsCommitPending() const; 55 56 // Populates a sync_pb::SyncEntity for a commit. Also sets the 57 // |sequence_number|, so we can track it throughout the commit process. 58 void PrepareCommitProto(sync_pb::SyncEntity* commit_entity, 59 int64* sequence_number) const; 60 61 // Updates this entity with data from the latest version that the 62 // model asked us to commit. May clobber state related to the 63 // model's previous commit attempt(s). 64 void RequestCommit(const std::string& id, 65 const std::string& client_tag_hash, 66 int64 sequence_number, 67 int64 base_version, 68 base::Time ctime, 69 base::Time mtime, 70 const std::string& non_unique_name, 71 bool deleted, 72 const sync_pb::EntitySpecifics& specifics); 73 74 // Handles the receipt of a commit response. 75 // 76 // Since commits happen entirely on the sync thread, we can safely assume 77 // that our item's state at the end of the commit is the same as it was at 78 // the start. 79 void ReceiveCommitResponse(const std::string& response_id, 80 int64 response_version, 81 int64 sequence_number); 82 83 // Handles receipt of an update from the server. 84 void ReceiveUpdate(int64 version); 85 86 // Handles the receipt of an pending update from the server. 87 // 88 // Returns true if the tracker decides this item is worth keeping. Returns 89 // false if the item is discarded, which could happen if the version number 90 // is out of date. 91 bool ReceivePendingUpdate(const UpdateResponseData& data); 92 93 // Functions to fetch the latest pending update. 94 bool HasPendingUpdate() const; 95 UpdateResponseData GetPendingUpdate() const; 96 97 // Clears the pending update. Allows us to resume regular commit behavior. 98 void ClearPendingUpdate(); 99 100 private: 101 // Initializes received update state. Does not initialize state related to 102 // pending commits and sets |is_commit_pending_| to false. 103 EntityTracker(const std::string& id, 104 const std::string& client_tag_hash, 105 int64 highest_commit_response_version, 106 int64 highest_gu_response_version); 107 108 // Initializes all fields. Sets |is_commit_pending_| to true. 109 EntityTracker(const std::string& id, 110 const std::string& client_tag_hash, 111 int64 highest_commit_response_version, 112 int64 highest_gu_response_version, 113 bool is_commit_pending, 114 int64 sequence_number, 115 int64 base_version, 116 base::Time ctime, 117 base::Time mtime, 118 const std::string& non_unique_name, 119 bool deleted, 120 const sync_pb::EntitySpecifics& specifics); 121 122 // Checks if the current state indicates a conflict. 123 // 124 // This can be true only while a call to this object is in progress. 125 // Conflicts are always cleared before the method call ends. 126 bool IsInConflict() const; 127 128 // Checks if the server knows about this item. 129 bool IsServerKnown() const; 130 131 // Clears flag and optionally clears state associated with a pending commit. 132 void ClearPendingCommit(); 133 134 // The ID for this entry. May be empty if the entry has never been committed. 135 std::string id_; 136 137 // The hashed client tag for this entry. 138 std::string client_tag_hash_; 139 140 // The highest version seen in a commit response for this entry. 141 int64 highest_commit_response_version_; 142 143 // The highest version seen in a GU response for this entry. 144 int64 highest_gu_response_version_; 145 146 // Flag that indicates whether or not we're waiting for a chance to commit 147 // this item. 148 bool is_commit_pending_; 149 150 // Used to track in-flight commit requests on the model thread. All we need 151 // to do here is return it back to the model thread when the pending commit 152 // is completed and confirmed. Not valid if no commit is pending. 153 int64 sequence_number_; 154 155 // The following fields are valid only when a commit is pending. 156 // This is where we store the data that is to be sent up to the server 157 // at the next possible opportunity. 158 int64 base_version_; 159 base::Time ctime_; 160 base::Time mtime_; 161 std::string non_unique_name_; 162 bool deleted_; 163 sync_pb::EntitySpecifics specifics_; 164 165 // An update for this item which can't be applied right now. The presence of 166 // an pending update prevents commits. As of this writing, the only source 167 // of pending updates is updates we can't decrypt right now. 168 scoped_ptr<UpdateResponseData> pending_update_; 169 170 DISALLOW_COPY_AND_ASSIGN(EntityTracker); 171 }; 172 173 } // namespace syncer 174 175 #endif // SYNC_ENGINE_ENTITY_TRACKER_H_ 176
