mirror of https://github.com/facebook/rocksdb.git
93 lines
3.3 KiB
C++
93 lines
3.3 KiB
C++
// 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/merge_operator.h"
|
|
#include "rocksdb/slice.h"
|
|
#include "utilities/merge_operators.h"
|
|
|
|
namespace { // anonymous namespace
|
|
|
|
using ROCKSDB_NAMESPACE::Logger;
|
|
using ROCKSDB_NAMESPACE::MergeOperator;
|
|
using ROCKSDB_NAMESPACE::Slice;
|
|
|
|
// A merge operator that mimics Put semantics
|
|
// Since this merge-operator will not be used in production,
|
|
// it is implemented as a non-associative merge operator to illustrate the
|
|
// new interface and for testing purposes. (That is, we inherit from
|
|
// the MergeOperator class rather than the AssociativeMergeOperator
|
|
// which would be simpler in this case).
|
|
//
|
|
// From the client-perspective, semantics are the same.
|
|
class PutOperator : public MergeOperator {
|
|
public:
|
|
bool FullMerge(const Slice& /*key*/, const Slice* /*existing_value*/,
|
|
const std::deque<std::string>& operand_sequence,
|
|
std::string* new_value, Logger* /*logger*/) const override {
|
|
// Put basically only looks at the current/latest value
|
|
assert(!operand_sequence.empty());
|
|
assert(new_value != nullptr);
|
|
new_value->assign(operand_sequence.back());
|
|
return true;
|
|
}
|
|
|
|
bool PartialMerge(const Slice& /*key*/, const Slice& /*left_operand*/,
|
|
const Slice& right_operand, std::string* new_value,
|
|
Logger* /*logger*/) const override {
|
|
new_value->assign(right_operand.data(), right_operand.size());
|
|
return true;
|
|
}
|
|
|
|
using MergeOperator::PartialMergeMulti;
|
|
bool PartialMergeMulti(const Slice& /*key*/,
|
|
const std::deque<Slice>& operand_list,
|
|
std::string* new_value,
|
|
Logger* /*logger*/) const override {
|
|
new_value->assign(operand_list.back().data(), operand_list.back().size());
|
|
return true;
|
|
}
|
|
|
|
static const char* kClassName() { return "PutOperator"; }
|
|
static const char* kNickName() { return "put_v1"; }
|
|
const char* Name() const override { return kClassName(); }
|
|
const char* NickName() const override { return kNickName(); }
|
|
};
|
|
|
|
class PutOperatorV2 : public PutOperator {
|
|
bool FullMerge(const Slice& /*key*/, const Slice* /*existing_value*/,
|
|
const std::deque<std::string>& /*operand_sequence*/,
|
|
std::string* /*new_value*/,
|
|
Logger* /*logger*/) const override {
|
|
assert(false);
|
|
return false;
|
|
}
|
|
|
|
bool FullMergeV2(const MergeOperationInput& merge_in,
|
|
MergeOperationOutput* merge_out) const override {
|
|
// Put basically only looks at the current/latest value
|
|
assert(!merge_in.operand_list.empty());
|
|
merge_out->existing_operand = merge_in.operand_list.back();
|
|
return true;
|
|
}
|
|
|
|
static const char* kNickName() { return "put"; }
|
|
const char* NickName() const override { return kNickName(); }
|
|
};
|
|
|
|
} // end of anonymous namespace
|
|
|
|
namespace ROCKSDB_NAMESPACE {
|
|
|
|
std::shared_ptr<MergeOperator> MergeOperators::CreateDeprecatedPutOperator() {
|
|
return std::make_shared<PutOperator>();
|
|
}
|
|
|
|
std::shared_ptr<MergeOperator> MergeOperators::CreatePutOperator() {
|
|
return std::make_shared<PutOperatorV2>();
|
|
}
|
|
} // namespace ROCKSDB_NAMESPACE
|