proxy/http/HttpTransactCache.h

/** @file

  A brief file description

  @section license License

  Licensed to the Apache Software Foundation (ASF) under one
  or more contributor license agreements.  See the NOTICE file
  distributed with this work for additional information
  regarding copyright ownership.  The ASF licenses this file
  to you 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.
 */

/****************************************************************************

   HttpTransactCache.h --
   Created On      : Thu Mar 26 17:19:35 1998


 ****************************************************************************/
#pragma once

#include "tscore/ink_platform.h"
#include "HttpConfig.h"

// This is needed since txn_conf->cache_guaranteed_max_lifetime is currently not
// readily available in the cache. ToDo: We should fix this with TS-1919
static const time_t CacheHighAgeWatermark = UINT_MAX;
struct CacheHTTPInfoVector;

enum Variability_t {
  VARIABILITY_NONE = 0,
  VARIABILITY_SOME,
  VARIABILITY_ALL,
};

class HttpTransactCache
{
public:
  /////////////////////////////////
  // content negotiation support //
  /////////////////////////////////

  static int SelectFromAlternates(CacheHTTPInfoVector *cache_vector_data, HTTPHdr *client_request,
                                  const OverridableHttpConfigParams *cache_lookup_http_config_params);

  static float calculate_quality_of_match(const OverridableHttpConfigParams *http_config_params, HTTPHdr *client_request,
                                          HTTPHdr *obj_client_request, HTTPHdr *obj_origin_server_response);

  static float calculate_quality_of_accept_match(MIMEField *accept_field, MIMEField *content_field);

  static float calculate_quality_of_accept_charset_match(MIMEField *accept_field, MIMEField *content_field,
                                                         MIMEField *cached_accept_field = nullptr);

  static float calculate_quality_of_accept_encoding_match(MIMEField *accept_field, MIMEField *content_field,
                                                          MIMEField *cached_accept_field = nullptr);

  // 'encoding_identifier' is a nul-terminated string.
  static bool match_content_encoding(MIMEField *accept_field, const char *encoding_identifier);

  static float calculate_quality_of_accept_language_match(MIMEField *accept_field, MIMEField *content_field,
                                                          MIMEField *cached_accept_field = nullptr);

  ///////////////////////////////////////////////
  // variability & server negotiation routines //
  ///////////////////////////////////////////////

  static Variability_t CalcVariability(const OverridableHttpConfigParams *http_config_params, HTTPHdr *client_request,
                                       HTTPHdr *obj_client_request, HTTPHdr *obj_origin_server_response);

  static HTTPStatus match_response_to_request_conditionals(HTTPHdr *ua_request, HTTPHdr *c_response,
                                                           ink_time_t response_received_time);
};