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Revision a661c0d2085b6de1ff745eb83f056a87801985b4 authored by Maysam Yabandeh on 27 February 2019, 00:52:20 UTC, committed by Facebook Github Bot on 27 February 2019, 00:56:19 UTC 
WritePrepared: optimize read path by avoiding virtual (#5018)
 
Summary:
The read path includes a callback function, ReadCallback, which would eventually calls IsInSnapshot to figure if a particular seq is in the reading snapshot or not. This callback is virtual, which adds the cost of multiple virtual function call to each read. The first few checks in IsInSnapshot, however, are quite trivial and take care of majority of the cases. The patch moves those to a non-virtual function in the the parent class, ReadCallback, to lower the virtual callback cost.
Pull Request resolved: https://github.com/facebook/rocksdb/pull/5018

Differential Revision: D14226562

Pulled By: maysamyabandeh

fbshipit-source-id: 6feed5b34f3b082e52092c5ef143e29b49c46b44
1 parent bb474e9
Raw File
merge_operators.h 
//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
//  This source code is licensed under both the GPLv2 (found in the
//  COPYING file in the root directory) and Apache 2.0 License
//  (found in the LICENSE.Apache file in the root directory).
//
#pragma once
#include "rocksdb/merge_operator.h"

#include <stdio.h>

#include <memory>
#include <string>

namespace rocksdb {

class MergeOperators {
 public:
  static std::shared_ptr<MergeOperator> CreatePutOperator();
  static std::shared_ptr<MergeOperator> CreateDeprecatedPutOperator();
  static std::shared_ptr<MergeOperator> CreateUInt64AddOperator();
  static std::shared_ptr<MergeOperator> CreateStringAppendOperator();
  static std::shared_ptr<MergeOperator> CreateStringAppendOperator(char delim_char);
  static std::shared_ptr<MergeOperator> CreateStringAppendTESTOperator();
  static std::shared_ptr<MergeOperator> CreateMaxOperator();
  static std::shared_ptr<MergeOperator> CreateBytesXOROperator();

  // Will return a different merge operator depending on the string.
  // TODO: Hook the "name" up to the actual Name() of the MergeOperators?
  static std::shared_ptr<MergeOperator> CreateFromStringId(
      const std::string& name) {
    if (name == "put") {
      return CreatePutOperator();
    } else if (name == "put_v1") {
      return CreateDeprecatedPutOperator();
    } else if ( name == "uint64add") {
      return CreateUInt64AddOperator();
    } else if (name == "stringappend") {
      return CreateStringAppendOperator();
    } else if (name == "stringappendtest") {
      return CreateStringAppendTESTOperator();
    } else if (name == "max") {
      return CreateMaxOperator();
    } else if (name == "bytesxor") {
      return CreateBytesXOROperator();
    } else {
      // Empty or unknown, just return nullptr
      return nullptr;
    }
  }
};

}  // namespace rocksdb
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