74 lines
2.1 KiB
C++
74 lines
2.1 KiB
C++
// Copyright (c) 2011-present, Facebook, Inc. All rights reserved.
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// This source code is licensed under the BSD-style license found in the
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// LICENSE file in the root directory of this source tree. An additional grant
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// of patent rights can be found in the PATENTS file in the same directory.
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#include <memory>
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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;
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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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virtual bool Merge(const Slice& key,
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const Slice* existing_value,
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const Slice& value,
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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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virtual const char* Name() const override {
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return "UInt64AddOperator";
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}
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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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Log(InfoLogLevel::ERROR_LEVEL, logger,
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"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 {
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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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}
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