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 | |
13 | namespace leveldb { |
14 | |
15 | struct Options; |
16 | |
17 | class 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 | |