1// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file. See the AUTHORS file for names of contributors.
4
5#ifndef STORAGE_LEVELDB_TABLE_BLOCK_BUILDER_H_
6#define STORAGE_LEVELDB_TABLE_BLOCK_BUILDER_H_
7
8#include <cstdint>
9#include <vector>
10
11#include "leveldb/slice.h"
12
13namespace leveldb {
14
15struct Options;
16
17class BlockBuilder {
18 public:
19 explicit BlockBuilder(const Options* options);
20
21 BlockBuilder(const BlockBuilder&) = delete;
22 BlockBuilder& operator=(const BlockBuilder&) = delete;
23
24 // Reset the contents as if the BlockBuilder was just constructed.
25 void Reset();
26
27 // REQUIRES: Finish() has not been called since the last call to Reset().
28 // REQUIRES: key is larger than any previously added key
29 void Add(const Slice& key, const Slice& value);
30
31 // Finish building the block and return a slice that refers to the
32 // block contents. The returned slice will remain valid for the
33 // lifetime of this builder or until Reset() is called.
34 Slice Finish();
35
36 // Returns an estimate of the current (uncompressed) size of the block
37 // we are building.
38 size_t CurrentSizeEstimate() const;
39
40 // Return true iff no entries have been added since the last Reset()
41 bool empty() const { return buffer_.empty(); }
42
43 private:
44 const Options* options_;
45 std::string buffer_; // Destination buffer
46 std::vector<uint32_t> restarts_; // Restart points
47 int counter_; // Number of entries emitted since restart
48 bool finished_; // Has Finish() been called?
49 std::string last_key_;
50};
51
52} // namespace leveldb
53
54#endif // STORAGE_LEVELDB_TABLE_BLOCK_BUILDER_H_
55