| 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-block.h" |
| 15 | #include "reftable-blocksource.h" |
| 16 | |
| 17 | /* |
| 18 | * Writes reftable blocks. The block_writer is reused across blocks to minimize |
| 19 | * allocation overhead. |
| 20 | */ |
| 21 | struct block_writer { |
| 22 | struct z_stream_s *zstream; |
| 23 | unsigned char *compressed; |
| 24 | size_t compressed_cap; |
| 25 | |
| 26 | uint8_t *block; |
| 27 | uint32_t block_size; |
| 28 | |
| 29 | /* Offset of the global header. Nonzero in the first block only. */ |
| 30 | uint32_t header_off; |
| 31 | |
| 32 | /* How often to restart keys. */ |
| 33 | uint16_t restart_interval; |
| 34 | uint32_t hash_size; |
| 35 | |
| 36 | /* Offset of next uint8_t to write. */ |
| 37 | uint32_t next; |
| 38 | uint32_t *restarts; |
| 39 | uint32_t restart_len; |
| 40 | uint32_t restart_cap; |
| 41 | |
| 42 | struct reftable_buf last_key; |
| 43 | /* Scratch buffer used to avoid allocations. */ |
| 44 | struct reftable_buf scratch; |
| 45 | int entries; |
| 46 | }; |
| 47 | |
| 48 | /* |
| 49 | * initializes the blockwriter to write `typ` entries, using `block` as temporary |
| 50 | * storage. `block` is not owned by the block_writer. */ |
| 51 | int block_writer_init(struct block_writer *bw, uint8_t typ, uint8_t *block, |
| 52 | uint32_t block_size, uint32_t header_off, uint32_t hash_size); |
| 53 | |
| 54 | /* returns the block type (eg. 'r' for ref records. */ |
| 55 | uint8_t block_writer_type(struct block_writer *bw); |
| 56 | |
| 57 | /* Attempts to append the record. Returns 0 on success or error code on failure. */ |
| 58 | int block_writer_add(struct block_writer *w, struct reftable_record *rec); |
| 59 | |
| 60 | /* appends the key restarts, and compress the block if necessary. */ |
| 61 | int block_writer_finish(struct block_writer *w); |
| 62 | |
| 63 | /* clears out internally allocated block_writer members. */ |
| 64 | void block_writer_release(struct block_writer *bw); |
| 65 | |
| 66 | /* Iterator for records contained in a single block. */ |
| 67 | struct block_iter { |
| 68 | /* offset within the block of the next entry to read. */ |
| 69 | uint32_t next_off; |
| 70 | const struct reftable_block *block; |
| 71 | |
| 72 | /* key for last entry we read. */ |
| 73 | struct reftable_buf last_key; |
| 74 | struct reftable_buf scratch; |
| 75 | }; |
| 76 | |
| 77 | #define BLOCK_ITER_INIT { \ |
| 78 | .last_key = REFTABLE_BUF_INIT, \ |
| 79 | .scratch = REFTABLE_BUF_INIT, \ |
| 80 | } |
| 81 | |
| 82 | /* |
| 83 | * Initialize the block iterator with the given block. The iterator will be |
| 84 | * positioned at the first record contained in the block. The block must remain |
| 85 | * valid until the end of the iterator's lifetime. It is valid to re-initialize |
| 86 | * iterators multiple times. |
| 87 | */ |
| 88 | void block_iter_init(struct block_iter *it, const struct reftable_block *block); |
| 89 | |
| 90 | /* Position the initialized iterator at the first record of its block. */ |
| 91 | void block_iter_seek_start(struct block_iter *it); |
| 92 | |
| 93 | /* |
| 94 | * Position the initialized iterator at the desired record key. It is not an |
| 95 | * error in case the record cannot be found. If so, a subsequent call to |
| 96 | * `block_iter_next()` will indicate that the iterator is exhausted. |
| 97 | */ |
| 98 | int block_iter_seek_key(struct block_iter *it, struct reftable_buf *want); |
| 99 | |
| 100 | /* return < 0 for error, 0 for OK, > 0 for EOF. */ |
| 101 | int block_iter_next(struct block_iter *it, struct reftable_record *rec); |
| 102 | |
| 103 | /* Reset the block iterator to pristine state without releasing its memory. */ |
| 104 | void block_iter_reset(struct block_iter *it); |
| 105 | |
| 106 | /* deallocate memory for `it`. The block reader and its block is left intact. */ |
| 107 | void block_iter_close(struct block_iter *it); |
| 108 | |
| 109 | /* size of file header, depending on format version */ |
| 110 | size_t header_size(int version); |
| 111 | |
| 112 | /* size of file footer, depending on format version */ |
| 113 | size_t footer_size(int version); |
| 114 | |
| 115 | #endif |