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 both the GPLv2 (found in the
   3 //  COPYING file in the root directory) and Apache 2.0 License
   4 //  (found in the LICENSE.Apache file in the root directory).
   5
   6 #include <memory>
   7
   8 #include "logging/logging.h"
   9 #include "rocksdb/env.h"
  10 #include "rocksdb/merge_operator.h"
  11 #include "rocksdb/slice.h"
  12 #include "util/coding.h"
  13 #include "utilities/merge_operators.h"
  14
  15 namespace {  // anonymous namespace
  16
  17 using ROCKSDB_NAMESPACE::AssociativeMergeOperator;
  18 using ROCKSDB_NAMESPACE::InfoLogLevel;
  19 using ROCKSDB_NAMESPACE::Logger;
  20 using ROCKSDB_NAMESPACE::Slice;
  21
  22 // A 'model' merge operator with uint64 addition semantics
  23 // Implemented as an AssociativeMergeOperator for simplicity and example.
  24 class UInt64AddOperator : public AssociativeMergeOperator {
  25  public:
  26   bool Merge(const Slice& /*key*/, const Slice* existing_value,
  27              const Slice& value, std::string* new_value,
  28              Logger* logger) const override {
  29     uint64_t orig_value = 0;
  30     if (existing_value) {
  31       orig_value = DecodeInteger(*existing_value, logger);
  32     }
  33     uint64_t operand = DecodeInteger(value, logger);
  34
  35     assert(new_value);
  36     new_value->clear();
  37     ROCKSDB_NAMESPACE::PutFixed64(new_value, orig_value + operand);
  38
  39     return true;  // Return true always since corruption will be treated as 0
  40   }
  41
  42   static const char* kClassName() { return "UInt64AddOperator"; }
  43   static const char* kNickName() { return "uint64add"; }
  44   const char* Name() const override { return kClassName(); }
  45   const char* NickName() const override { return kNickName(); }
  46
  47  private:
  48   // Takes the string and decodes it into a uint64_t
  49   // On error, prints a message and returns 0
  50   uint64_t DecodeInteger(const Slice& value, Logger* logger) const {
  51     uint64_t result = 0;
  52
  53     if (value.size() == sizeof(uint64_t)) {
  54       result = ROCKSDB_NAMESPACE::DecodeFixed64(value.data());
  55     } else if (logger != nullptr) {
  56       // If value is corrupted, treat it as 0
  57       ROCKS_LOG_ERROR(logger,
  58                       "uint64 value corruption, size: %" ROCKSDB_PRIszt
  59                       " > %" ROCKSDB_PRIszt,
  60                       value.size(), sizeof(uint64_t));
  61     }
  62
  63     return result;
  64   }
  65 };
  66
  67 }  // anonymous namespace
  68
  69 namespace ROCKSDB_NAMESPACE {
  70
  71 std::shared_ptr<MergeOperator> MergeOperators::CreateUInt64AddOperator() {
  72   return std::make_shared<UInt64AddOperator>();
  73 }
  74
  75 }  // namespace ROCKSDB_NAMESPACE