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Diffstat (limited to 'reftable/block.h')
| -rw-r--r-- | reftable/block.h | 115 |
1 files changed, 115 insertions, 0 deletions
diff --git a/reftable/block.h b/reftable/block.h new file mode 100644 index 0000000000..d6dfaae33e --- /dev/null +++ b/reftable/block.h @@ -0,0 +1,115 @@ +/* + * Copyright 2020 Google LLC + * + * Use of this source code is governed by a BSD-style + * license that can be found in the LICENSE file or at + * https://developers.google.com/open-source/licenses/bsd + */ + +#ifndef BLOCK_H +#define BLOCK_H + +#include "basics.h" +#include "record.h" +#include "reftable-block.h" +#include "reftable-blocksource.h" + +/* + * Writes reftable blocks. The block_writer is reused across blocks to minimize + * allocation overhead. + */ +struct block_writer { + struct z_stream_s *zstream; + unsigned char *compressed; + size_t compressed_cap; + + uint8_t *block; + uint32_t block_size; + + /* Offset of the global header. Nonzero in the first block only. */ + uint32_t header_off; + + /* How often to restart keys. */ + uint16_t restart_interval; + uint32_t hash_size; + + /* Offset of next uint8_t to write. */ + uint32_t next; + uint32_t *restarts; + uint32_t restart_len; + uint32_t restart_cap; + + struct reftable_buf last_key; + /* Scratch buffer used to avoid allocations. */ + struct reftable_buf scratch; + int entries; +}; + +/* + * initializes the blockwriter to write `typ` entries, using `block` as temporary + * storage. `block` is not owned by the block_writer. */ +int block_writer_init(struct block_writer *bw, uint8_t typ, uint8_t *block, + uint32_t block_size, uint32_t header_off, uint32_t hash_size); + +/* returns the block type (eg. 'r' for ref records. */ +uint8_t block_writer_type(struct block_writer *bw); + +/* Attempts to append the record. Returns 0 on success or error code on failure. */ +int block_writer_add(struct block_writer *w, struct reftable_record *rec); + +/* appends the key restarts, and compress the block if necessary. */ +int block_writer_finish(struct block_writer *w); + +/* clears out internally allocated block_writer members. */ +void block_writer_release(struct block_writer *bw); + +/* Iterator for records contained in a single block. */ +struct block_iter { + /* offset within the block of the next entry to read. */ + uint32_t next_off; + const struct reftable_block *block; + + /* key for last entry we read. */ + struct reftable_buf last_key; + struct reftable_buf scratch; +}; + +#define BLOCK_ITER_INIT { \ + .last_key = REFTABLE_BUF_INIT, \ + .scratch = REFTABLE_BUF_INIT, \ +} + +/* + * Initialize the block iterator with the given block. The iterator will be + * positioned at the first record contained in the block. The block must remain + * valid until the end of the iterator's lifetime. It is valid to re-initialize + * iterators multiple times. + */ +void block_iter_init(struct block_iter *it, const struct reftable_block *block); + +/* Position the initialized iterator at the first record of its block. */ +void block_iter_seek_start(struct block_iter *it); + +/* + * Position the initialized iterator at the desired record key. It is not an + * error in case the record cannot be found. If so, a subsequent call to + * `block_iter_next()` will indicate that the iterator is exhausted. + */ +int block_iter_seek_key(struct block_iter *it, struct reftable_buf *want); + +/* return < 0 for error, 0 for OK, > 0 for EOF. */ +int block_iter_next(struct block_iter *it, struct reftable_record *rec); + +/* Reset the block iterator to pristine state without releasing its memory. */ +void block_iter_reset(struct block_iter *it); + +/* deallocate memory for `it`. The block reader and its block is left intact. */ +void block_iter_close(struct block_iter *it); + +/* size of file header, depending on format version */ +size_t header_size(int version); + +/* size of file footer, depending on format version */ +size_t footer_size(int version); + +#endif |