ceph/src/rocksdb/utilities/merge_operators/uint64add.cc

   1 // Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
   2 // This source code is licensed under the BSD-style license found in the
   3 // LICENSE file in the root directory of this source tree. An additional grant
   4 // of patent rights can be found in the PATENTS file in the same directory.
   5
   6 #include <memory>
   7
   8 #include "rocksdb/env.h"
   9 #include "rocksdb/merge_operator.h"
  10 #include "rocksdb/slice.h"
  11 #include "util/coding.h"
  12 #include "util/logging.h"
  13 #include "utilities/merge_operators.h"
  14
  15 using namespace rocksdb;
  16
  17 namespace { // anonymous namespace
  18
  19 // A 'model' merge operator with uint64 addition semantics
  20 // Implemented as an AssociativeMergeOperator for simplicity and example.
  21 class UInt64AddOperator : public AssociativeMergeOperator {
  22  public:
  23   virtual bool Merge(const Slice& key,
  24                      const Slice* existing_value,
  25                      const Slice& value,
  26                      std::string* new_value,
  27                      Logger* logger) const override {
  28     uint64_t orig_value = 0;
  29     if (existing_value){
  30       orig_value = DecodeInteger(*existing_value, logger);
  31     }
  32     uint64_t operand = DecodeInteger(value, logger);
  33
  34     assert(new_value);
  35     new_value->clear();
  36     PutFixed64(new_value, orig_value + operand);
  37
  38     return true;  // Return true always since corruption will be treated as 0
  39   }
  40
  41   virtual const char* Name() const override {
  42     return "UInt64AddOperator";
  43   }
  44
  45  private:
  46   // Takes the string and decodes it into a uint64_t
  47   // On error, prints a message and returns 0
  48   uint64_t DecodeInteger(const Slice& value, Logger* logger) const {
  49     uint64_t result = 0;
  50
  51     if (value.size() == sizeof(uint64_t)) {
  52       result = DecodeFixed64(value.data());
  53     } else if (logger != nullptr) {
  54       // If value is corrupted, treat it as 0
  55       ROCKS_LOG_ERROR(logger, "uint64 value corruption, size: %" ROCKSDB_PRIszt
  56                               " > %" ROCKSDB_PRIszt,
  57                       value.size(), sizeof(uint64_t));
  58     }
  59
  60     return result;
  61   }
  62
  63 };
  64
  65 }
  66
  67 namespace rocksdb {
  68
  69 std::shared_ptr<MergeOperator> MergeOperators::CreateUInt64AddOperator() {
  70   return std::make_shared<UInt64AddOperator>();
  71 }
  72
  73 }