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_DB_LOG_WRITER_H_ |
6 | #define STORAGE_LEVELDB_DB_LOG_WRITER_H_ |
7 | |
8 | #include <cstdint> |
9 | |
10 | #include "db/log_format.h" |
11 | #include "leveldb/slice.h" |
12 | #include "leveldb/status.h" |
13 | |
14 | namespace leveldb { |
15 | |
16 | class WritableFile; |
17 | |
18 | namespace log { |
19 | |
20 | class Writer { |
21 | public: |
22 | // Create a writer that will append data to "*dest". |
23 | // "*dest" must be initially empty. |
24 | // "*dest" must remain live while this Writer is in use. |
25 | explicit Writer(WritableFile* dest); |
26 | |
27 | // Create a writer that will append data to "*dest". |
28 | // "*dest" must have initial length "dest_length". |
29 | // "*dest" must remain live while this Writer is in use. |
30 | Writer(WritableFile* dest, uint64_t dest_length); |
31 | |
32 | Writer(const Writer&) = delete; |
33 | Writer& operator=(const Writer&) = delete; |
34 | |
35 | ~Writer(); |
36 | |
37 | Status AddRecord(const Slice& slice); |
38 | |
39 | private: |
40 | Status EmitPhysicalRecord(RecordType type, const char* ptr, size_t length); |
41 | |
42 | WritableFile* dest_; |
43 | int block_offset_; // Current offset in block |
44 | |
45 | // crc32c values for all supported record types. These are |
46 | // pre-computed to reduce the overhead of computing the crc of the |
47 | // record type stored in the header. |
48 | uint32_t type_crc_[kMaxRecordType + 1]; |
49 | }; |
50 | |
51 | } // namespace log |
52 | } // namespace leveldb |
53 | |
54 | #endif // STORAGE_LEVELDB_DB_LOG_WRITER_H_ |
55 | |