projects / thirdparty / git.git / blame
| Commit | Line | Data |
|---|---|---|
| e581fd72 HWN |
1 | /* |
| 2 | Copyright 2020 Google LLC | |
| 3 | ||
| 4 | Use of this source code is governed by a BSD-style | |
| 5 | license that can be found in the LICENSE file or at | |
| 6 | https://developers.google.com/open-source/licenses/bsd | |
| 7 | */ | |
| 8 | ||
| 9 | #ifndef BLOCK_H | |
| 10 | #define BLOCK_H | |
| 11 | ||
| 12 | #include "basics.h" | |
| 13 | #include "record.h" | |
| 14 | #include "reftable-blocksource.h" | |
| 15 | ||
| 16 | /* | |
| 17 | * Writes reftable blocks. The block_writer is reused across blocks to minimize | |
| 18 | * allocation overhead. | |
| 19 | */ | |
| 20 | struct block_writer { | |
| 21 | uint8_t *buf; | |
| 22 | uint32_t block_size; | |
| 23 | ||
| 019bd340 | 24 | /* Offset of the global header. Nonzero in the first block only. */ |
| e581fd72 HWN |
25 | uint32_t header_off; |
| 26 | ||
| 27 | /* How often to restart keys. */ | |
| 28 | int restart_interval; | |
| 29 | int hash_size; | |
| 30 | ||
| 31 | /* Offset of next uint8_t to write. */ | |
| 32 | uint32_t next; | |
| 33 | uint32_t *restarts; | |
| 34 | uint32_t restart_len; | |
| 35 | uint32_t restart_cap; | |
| 36 | ||
| 37 | struct strbuf last_key; | |
| 38 | int entries; | |
| 39 | }; | |
| 40 | ||
| 41 | /* | |
| 42 | * initializes the blockwriter to write `typ` entries, using `buf` as temporary | |
| 43 | * storage. `buf` is not owned by the block_writer. */ | |
| 44 | void block_writer_init(struct block_writer *bw, uint8_t typ, uint8_t *buf, | |
| 45 | uint32_t block_size, uint32_t header_off, int hash_size); | |
| 46 | ||
| 47 | /* returns the block type (eg. 'r' for ref records. */ | |
| 48 | uint8_t block_writer_type(struct block_writer *bw); | |
| 49 | ||
| 50 | /* appends the record, or -1 if it doesn't fit. */ | |
| 51 | int block_writer_add(struct block_writer *w, struct reftable_record *rec); | |
| 52 | ||
| 53 | /* appends the key restarts, and compress the block if necessary. */ | |
| 54 | int block_writer_finish(struct block_writer *w); | |
| 55 | ||
| 56 | /* clears out internally allocated block_writer members. */ | |
| 57 | void block_writer_release(struct block_writer *bw); | |
| 58 | ||
| 59 | /* Read a block. */ | |
| 60 | struct block_reader { | |
| 61 | /* offset of the block header; nonzero for the first block in a | |
| 62 | * reftable. */ | |
| 63 | uint32_t header_off; | |
| 64 | ||
| 65 | /* the memory block */ | |
| 66 | struct reftable_block block; | |
| 67 | int hash_size; | |
| 68 | ||
| 69 | /* size of the data, excluding restart data. */ | |
| 70 | uint32_t block_len; | |
| 71 | uint8_t *restart_bytes; | |
| 72 | uint16_t restart_count; | |
| 73 | ||
| 74 | /* size of the data in the file. For log blocks, this is the compressed | |
| 75 | * size. */ | |
| 76 | uint32_t full_block_size; | |
| 77 | }; | |
| 78 | ||
| 79 | /* Iterate over entries in a block */ | |
| 80 | struct block_iter { | |
| 81 | /* offset within the block of the next entry to read. */ | |
| 82 | uint32_t next_off; | |
| 83 | struct block_reader *br; | |
| 84 | ||
| 85 | /* key for last entry we read. */ | |
| 86 | struct strbuf last_key; | |
| 87 | }; | |
| 88 | ||
| 89 | /* initializes a block reader. */ | |
| 90 | int block_reader_init(struct block_reader *br, struct reftable_block *bl, | |
| 91 | uint32_t header_off, uint32_t table_block_size, | |
| 92 | int hash_size); | |
| 93 | ||
| 94 | /* Position `it` at start of the block */ | |
| 95 | void block_reader_start(struct block_reader *br, struct block_iter *it); | |
| 96 | ||
| 97 | /* Position `it` to the `want` key in the block */ | |
| 98 | int block_reader_seek(struct block_reader *br, struct block_iter *it, | |
| 99 | struct strbuf *want); | |
| 100 | ||
| 101 | /* Returns the block type (eg. 'r' for refs) */ | |
| 102 | uint8_t block_reader_type(struct block_reader *r); | |
| 103 | ||
| 104 | /* Decodes the first key in the block */ | |
| 105 | int block_reader_first_key(struct block_reader *br, struct strbuf *key); | |
| 106 | ||
| 107 | void block_iter_copy_from(struct block_iter *dest, struct block_iter *src); | |
| 108 | ||
| 109 | /* return < 0 for error, 0 for OK, > 0 for EOF. */ | |
| 110 | int block_iter_next(struct block_iter *it, struct reftable_record *rec); | |
| 111 | ||
| 112 | /* Seek to `want` with in the block pointed to by `it` */ | |
| 113 | int block_iter_seek(struct block_iter *it, struct strbuf *want); | |
| 114 | ||
| 115 | /* deallocate memory for `it`. The block reader and its block is left intact. */ | |
| 116 | void block_iter_close(struct block_iter *it); | |
| 117 | ||
| 118 | /* size of file header, depending on format version */ | |
| 119 | int header_size(int version); | |
| 120 | ||
| 121 | /* size of file footer, depending on format version */ | |
| 122 | int footer_size(int version); | |
| 123 | ||
| 124 | /* returns a block to its source. */ | |
| 125 | void reftable_block_done(struct reftable_block *ret); | |
| 126 | ||
| 127 | #endif |