// 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.

syntax = "proto2";

option optimize_for = LITE_RUNTIME;
option retain_unknown_fields = true;

package attachment_store_pb;

// Metadata for leveldb attachment store database.
message StoreMetadata {
  // |schema_version| indicates format in which data is written in attachment
  // store. Needed for upgrade and to prevent newer data from being loaded by
  // older code that doesn't understand it.
  optional int32 schema_version = 1;
}

// Metadata for attachment in attachment store. Storing metadata in separate
// record from actual data allows us to enumerate attachments in the store
// without incurring cost to read actual data. It also allows us to update
// attachment metadata independent of the data.
message RecordMetadata {
  // Size of attachment data. Useful for attachment store space management.
  optional int64 attachment_size = 1;
  // Crc32c of attachment data.
  optional fixed32 crc32c = 2;

  // Component enum mirrors values of AttachmentStore::Component.
  enum Component {
    UNKNOWN = 0;
    MODEL_TYPE = 1;
    SYNC = 2;
  }
  // Set of components that reference this attachment.
  repeated Component component = 3;
}