mirror of https://github.com/facebook/rocksdb.git
70 lines
2.1 KiB
C++
70 lines
2.1 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under both the GPLv2 (found in the
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// COPYING file in the root directory) and Apache 2.0 License
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// (found in the LICENSE.Apache file in the root directory).
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#include <memory>
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#include "logging/logging.h"
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#include "rocksdb/env.h"
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#include "rocksdb/merge_operator.h"
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#include "rocksdb/slice.h"
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#include "util/coding.h"
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#include "utilities/merge_operators.h"
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using namespace ROCKSDB_NAMESPACE;
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namespace { // anonymous namespace
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// A 'model' merge operator with uint64 addition semantics
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// Implemented as an AssociativeMergeOperator for simplicity and example.
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class UInt64AddOperator : public AssociativeMergeOperator {
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public:
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bool Merge(const Slice& /*key*/, const Slice* existing_value,
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const Slice& value, std::string* new_value,
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Logger* logger) const override {
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uint64_t orig_value = 0;
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if (existing_value){
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orig_value = DecodeInteger(*existing_value, logger);
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}
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uint64_t operand = DecodeInteger(value, logger);
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assert(new_value);
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new_value->clear();
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PutFixed64(new_value, orig_value + operand);
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return true; // Return true always since corruption will be treated as 0
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}
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const char* Name() const override { return "UInt64AddOperator"; }
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private:
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// Takes the string and decodes it into a uint64_t
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// On error, prints a message and returns 0
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uint64_t DecodeInteger(const Slice& value, Logger* logger) const {
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uint64_t result = 0;
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if (value.size() == sizeof(uint64_t)) {
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result = DecodeFixed64(value.data());
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} else if (logger != nullptr) {
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// If value is corrupted, treat it as 0
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ROCKS_LOG_ERROR(logger, "uint64 value corruption, size: %" ROCKSDB_PRIszt
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" > %" ROCKSDB_PRIszt,
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value.size(), sizeof(uint64_t));
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}
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return result;
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}
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};
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}
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namespace ROCKSDB_NAMESPACE {
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std::shared_ptr<MergeOperator> MergeOperators::CreateUInt64AddOperator() {
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return std::make_shared<UInt64AddOperator>();
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}
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} // namespace ROCKSDB_NAMESPACE
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