include/proxy/ParentConsistentHash.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.
 */

/*****************************************************************************
 *
 *  ParentConsistentHash.h - Interface to Parent Consistent Hash.
 *
 ****************************************************************************/

#pragma once

#include "tscore/HashSip.h"
#include "proxy/ParentSelection.h"

//
//  Implementation of round robin based upon consistent hash of the URL,
//  ParentRR_t = ParentRR_t::CONSISTENT_HASH.
//
class ParentConsistentHash : public ParentSelectionStrategy
{
  std::unique_ptr<ATSHash64>         hash[2];
  std::unique_ptr<ATSConsistentHash> chash[2];
  pRecord                           *parents[2];
  bool                               ignore_query;
  int                                secondary_mode;
  ParentHashAlgorithm                selected_algorithm;
  uint64_t                           hash_seed0;
  uint64_t                           hash_seed1;

public:
  static const int PRIMARY   = 0;
  static const int SECONDARY = 1;
  ParentConsistentHash(ParentRecord *_parent_record);
  ~ParentConsistentHash() override;
  pRecord *
  getParents(ParentResult *result) override
  {
    return parents[result->last_lookup];
  }
  uint64_t getPathHash(HttpRequestData *hrdata, ATSHash64 *h);
  void     selectParent(bool firstCall, ParentResult *result, RequestData *rdata, unsigned int fail_threshold,
                        unsigned int retry_time) override;
  void     markParentDown(ParentResult *result, unsigned int fail_threshold, unsigned int retry_time);
  uint32_t numParents(ParentResult *result) const override;
  void     markParentUp(ParentResult *result);
};