| // 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). |
| |
| #include <memory> |
| |
| #include "rocksdb/env.h" |
| #include "rocksdb/merge_operator.h" |
| #include "rocksdb/slice.h" |
| #include "util/coding.h" |
| #include "util/logging.h" |
| #include "utilities/merge_operators.h" |
| |
| using namespace rocksdb; |
| |
| namespace { // anonymous namespace |
| |
| // A 'model' merge operator with uint64 addition semantics |
| // Implemented as an AssociativeMergeOperator for simplicity and example. |
| class UInt64AddOperator : public AssociativeMergeOperator { |
| public: |
| virtual bool Merge(const Slice& key, |
| const Slice* existing_value, |
| const Slice& value, |
| std::string* new_value, |
| Logger* logger) const override { |
| uint64_t orig_value = 0; |
| if (existing_value){ |
| orig_value = DecodeInteger(*existing_value, logger); |
| } |
| uint64_t operand = DecodeInteger(value, logger); |
| |
| assert(new_value); |
| new_value->clear(); |
| PutFixed64(new_value, orig_value + operand); |
| |
| return true; // Return true always since corruption will be treated as 0 |
| } |
| |
| virtual const char* Name() const override { |
| return "UInt64AddOperator"; |
| } |
| |
| private: |
| // Takes the string and decodes it into a uint64_t |
| // On error, prints a message and returns 0 |
| uint64_t DecodeInteger(const Slice& value, Logger* logger) const { |
| uint64_t result = 0; |
| |
| if (value.size() == sizeof(uint64_t)) { |
| result = DecodeFixed64(value.data()); |
| } else if (logger != nullptr) { |
| // If value is corrupted, treat it as 0 |
| ROCKS_LOG_ERROR(logger, "uint64 value corruption, size: %" ROCKSDB_PRIszt |
| " > %" ROCKSDB_PRIszt, |
| value.size(), sizeof(uint64_t)); |
| } |
| |
| return result; |
| } |
| |
| }; |
| |
| } |
| |
| namespace rocksdb { |
| |
| std::shared_ptr<MergeOperator> MergeOperators::CreateUInt64AddOperator() { |
| return std::make_shared<UInt64AddOperator>(); |
| } |
| |
| } |