// Copyright 2011 Google Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// Author: abliss@google.com (Adam Bliss)

// Protobuf to encapsulate custom metadata about a resource (not including real
// HTTP Headers).

syntax = "proto2";

package net_instaweb;

// Info about the input resource that was used to create a CachedResult.
// Next free tag: 10.
message InputInfo {
  // Generally, URLs of inputs are not kept in the protobufs, only the indices.
  // The intended usage is the URLs of inputs will be used to construct
  // the key to a cache entry, and the cache value will be an
  // encoded OutputPartitions.
  //
  // One caveat to this is that in case of a file-loaded input we store its
  // filename. This is because it's otherwise too hard to determine the name
  // when we need to do cache validation of things like nested
  // rewrites, and to keep this information accurate across caching
  // of such inner jobs.
  optional int32 index = 1;

  // This type affects how we check that CachedResults are up-to-date.
  enum Type {
    // Cached resources are valid until the expiration_time_ms.
    CACHED = 1;
    // File based resources are valid as long as the file has not changed.
    // We stat the file and compare it's mtime to last_modified_time_ms
    // to decide if the file has changed or not.
    FILE_BASED = 2;
    // E.g. data: URL resources never expire or change.
    ALWAYS_VALID = 3;
  }
  required Type type = 2;
  // An identifying timestamp which can be used to decide if a resource has
  // been updated or not. For web-based resources, we use Last-Modified headers.
  // For file-based resources, we use mtime.
  optional int64 last_modified_time_ms = 3;

  // For CACHED resources, keeps track of when the input expires, as taken
  // from the headers returned when it was fetched.
  optional int64 expiration_time_ms = 4;

  // For FILE_BASED resources, the file this was loaded from.
  optional string filename = 5;

  // For CACHED resources, we keep track of the original fetch time so we
  // can freshen.
  optional int64 date_ms = 6;

  // For CACHED and FILE_BASED resources, we store a hash of the input, so
  // that we can reuse optimization results if it did not change, even if it
  // has expired from the HTTP cache.
  optional string input_content_hash = 7;

  // If true, no later filters should process the same input.
  optional bool disable_further_processing = 8;

  // To support invalidation by exact URL, we keep the URL in the metadata.
  // This bloats the size a bit, but enables fast invalidation.  Compressing
  // the metadata cache helps.
  optional string url = 9;
}