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1 | // Copyright (c) 2011-present, Facebook, Inc. All rights reserved. |
2 | // This source code is licensed under both the GPLv2 (found in the | |
3 | // COPYING file in the root directory) and Apache 2.0 License | |
4 | // (found in the LICENSE.Apache file in the root directory). | |
5 | // | |
6 | #pragma once | |
7 | ||
8 | #include <memory> | |
9 | ||
10 | #include "db/blob/blob_log_format.h" | |
11 | #include "rocksdb/slice.h" | |
12 | ||
1e59de90 TL |
13 | #define MAX_HEADER_SIZE(a, b, c) (a > b ? (a > c ? a : c) : (b > c ? b : c)) |
14 | ||
20effc67 TL |
15 | namespace ROCKSDB_NAMESPACE { |
16 | ||
17 | class RandomAccessFileReader; | |
18 | class Env; | |
19 | class Statistics; | |
20 | class Status; | |
1e59de90 | 21 | class SystemClock; |
20effc67 TL |
22 | |
23 | /** | |
24 | * BlobLogSequentialReader is a general purpose log stream reader | |
25 | * implementation. The actual job of reading from the device is implemented by | |
26 | * the RandomAccessFileReader interface. | |
27 | * | |
28 | * Please see BlobLogWriter for details on the file and record layout. | |
29 | */ | |
30 | ||
31 | class BlobLogSequentialReader { | |
32 | public: | |
33 | enum ReadLevel { | |
34 | kReadHeader, | |
35 | kReadHeaderKey, | |
36 | kReadHeaderKeyBlob, | |
37 | }; | |
38 | ||
39 | // Create a reader that will return log records from "*file_reader". | |
40 | BlobLogSequentialReader(std::unique_ptr<RandomAccessFileReader>&& file_reader, | |
1e59de90 | 41 | SystemClock* clock, Statistics* statistics); |
20effc67 TL |
42 | |
43 | // No copying allowed | |
44 | BlobLogSequentialReader(const BlobLogSequentialReader&) = delete; | |
45 | BlobLogSequentialReader& operator=(const BlobLogSequentialReader&) = delete; | |
46 | ||
47 | ~BlobLogSequentialReader(); | |
48 | ||
49 | Status ReadHeader(BlobLogHeader* header); | |
50 | ||
51 | // Read the next record into *record. Returns true if read | |
52 | // successfully, false if we hit end of the input. The contents filled in | |
53 | // *record will only be valid until the next mutating operation on this | |
54 | // reader. | |
55 | // If blob_offset is non-null, return offset of the blob through it. | |
56 | Status ReadRecord(BlobLogRecord* record, ReadLevel level = kReadHeader, | |
57 | uint64_t* blob_offset = nullptr); | |
58 | ||
59 | Status ReadFooter(BlobLogFooter* footer); | |
60 | ||
61 | void ResetNextByte() { next_byte_ = 0; } | |
62 | ||
63 | uint64_t GetNextByte() const { return next_byte_; } | |
64 | ||
65 | private: | |
66 | Status ReadSlice(uint64_t size, Slice* slice, char* buf); | |
67 | ||
68 | const std::unique_ptr<RandomAccessFileReader> file_; | |
1e59de90 TL |
69 | SystemClock* clock_; |
70 | ||
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71 | Statistics* statistics_; |
72 | ||
73 | Slice buffer_; | |
1e59de90 TL |
74 | char header_buf_[MAX_HEADER_SIZE(BlobLogHeader::kSize, BlobLogFooter::kSize, |
75 | BlobLogRecord::kHeaderSize)]; | |
20effc67 TL |
76 | |
77 | // which byte to read next | |
78 | uint64_t next_byte_; | |
79 | }; | |
80 | ||
81 | } // namespace ROCKSDB_NAMESPACE | |
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82 | |
83 | #undef MAX_HEADER_SIZE |