rocksdb/utilities/merge_operators/uint64add.cc
Andres Notzli 1d20fa9d0f Fixed and simplified merge_helper
Summary:
MergeUntil was not reporting a success when merging an operand with
a Value/Deletion despite the comments in MergeHelper and CompactionJob
indicating otherwise. This lead to operands being written to the compaction
output unnecessarily:

M1 M2 M3 P M4 M5 --> (P+M1+M2+M3) M2 M3 M4 M5 (before the diff)
M1 M2 M3 P M4 M5 --> (P+M1+M2+M3) M4 M5 (after the diff)

In addition, the code handling Values/Deletion was basically identical.
This patch unifies the code. Finally, this patch also adds testing for
merge_helper.

Test Plan: make && make check

Reviewers: sdong, rven, yhchiang, tnovak, igor

Reviewed By: igor

Subscribers: tnovak, dhruba, leveldb

Differential Revision: https://reviews.facebook.net/D42351
2015-07-17 09:27:24 -07:00

74 lines
2.1 KiB
C++

// Copyright (c) 2013, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the root directory of this source tree. An additional grant
// of patent rights can be found in the PATENTS file in the same directory.
#include <memory>
#include "rocksdb/env.h"
#include "rocksdb/merge_operator.h"
#include "rocksdb/slice.h"
#include "util/coding.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
Log(InfoLogLevel::ERROR_LEVEL, 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>();
}
}