// Copyright 2015 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.

syntax = "proto2";

option optimize_for = LITE_RUNTIME;
option retain_unknown_fields = true;

package sync_pb;

// Sync proto to store entity metadata in model type storage.
message EntityMetadata {
  // A hash based on the client tag and model type.
  // Used for various map lookups. Should always be available.
  // Sent to the server as SyncEntity::client_defined_unique_tag.
  optional string client_tag_hash = 1;

  // The entity's server-assigned ID.
  //
  // Prior to the item's first commit, we leave this value as an empty string.
  // The initial ID for a newly created item has to meet certain uniqueness
  // requirements, and we handle those on the sync thread.
  optional string server_id = 2;

  // Whether or not the entity is deleted.
  optional bool is_deleted = 3;

  // A version number used to track in-progress commits. Each local change
  // increments this number.
  optional int64 sequence_number = 4;

  // The sequence number of the last item known to be successfully committed.
  optional int64 acked_sequence_number = 5;

  // The server version on which this item is based.
  //
  // If there are no local changes, this is the version of the entity as we see
  // it here.
  //
  // If there are local changes, this is the version of the entity on which
  // those changes are based.
  optional int64 server_version = 6 [default = -1];

  // Entity creation and modification timestamps.
  // Assigned by the client and synced by the server, though the server usually
  // doesn't bother to inspect their values.
  optional int64 creation_time = 7;
  optional int64 modification_time = 8;

  // A hash of the current entity specifics value. Used to detect whether
  // entity's specifics value has changed without having to keep specifics in
  // memory.
  optional string specifics_hash = 9;
}