// 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).
//
// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file. See the AUTHORS file for names of contributors.
#pragma once
#include <vector>
#include <stdint.h>
#include "rocksdb/slice.h"
namespace rocksdb {
class BlockBuilder {
public:
BlockBuilder(const BlockBuilder&) = delete;
void operator=(const BlockBuilder&) = delete;
explicit BlockBuilder(int block_restart_interval,
bool use_delta_encoding = true);
// Reset the contents as if the BlockBuilder was just constructed.
void Reset();
// REQUIRES: Finish() has not been called since the last call to Reset().
// REQUIRES: key is larger than any previously added key
void Add(const Slice& key, const Slice& value);
// Finish building the block and return a slice that refers to the
// block contents. The returned slice will remain valid for the
// lifetime of this builder or until Reset() is called.
Slice Finish();
// Returns an estimate of the current (uncompressed) size of the block
// we are building.
inline size_t CurrentSizeEstimate() const { return estimate_; }
// Returns an estimated block size after appending key and value.
size_t EstimateSizeAfterKV(const Slice& key, const Slice& value) const;
// Return true iff no entries have been added since the last Reset()
bool empty() const {
return buffer_.empty();
}
private:
const int block_restart_interval_;
const bool use_delta_encoding_;
std::string buffer_; // Destination buffer
std::vector<uint32_t> restarts_; // Restart points
size_t estimate_;
int counter_; // Number of entries emitted since restart
bool finished_; // Has Finish() been called?
std::string last_key_;
};
} // namespace rocksdb