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Diffstat (limited to 'reftable/block.h')
| -rw-r--r-- | reftable/block.h | 127 |
1 files changed, 127 insertions, 0 deletions
diff --git a/reftable/block.h b/reftable/block.h new file mode 100644 index 0000000000..87c77539b5 --- /dev/null +++ b/reftable/block.h @@ -0,0 +1,127 @@ +/* +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-blocksource.h" + +/* + * Writes reftable blocks. The block_writer is reused across blocks to minimize + * allocation overhead. + */ +struct block_writer { + uint8_t *buf; + uint32_t block_size; + + /* Offset of the global header. Nonzero in the first block only. */ + uint32_t header_off; + + /* How often to restart keys. */ + int restart_interval; + int hash_size; + + /* Offset of next uint8_t to write. */ + uint32_t next; + uint32_t *restarts; + uint32_t restart_len; + uint32_t restart_cap; + + struct strbuf last_key; + int entries; +}; + +/* + * initializes the blockwriter to write `typ` entries, using `buf` as temporary + * storage. `buf` is not owned by the block_writer. */ +void block_writer_init(struct block_writer *bw, uint8_t typ, uint8_t *buf, + uint32_t block_size, uint32_t header_off, int hash_size); + +/* returns the block type (eg. 'r' for ref records. */ +uint8_t block_writer_type(struct block_writer *bw); + +/* appends the record, or -1 if it doesn't fit. */ +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); + +/* Read a block. */ +struct block_reader { + /* offset of the block header; nonzero for the first block in a + * reftable. */ + uint32_t header_off; + + /* the memory block */ + struct reftable_block block; + int hash_size; + + /* size of the data, excluding restart data. */ + uint32_t block_len; + uint8_t *restart_bytes; + uint16_t restart_count; + + /* size of the data in the file. For log blocks, this is the compressed + * size. */ + uint32_t full_block_size; +}; + +/* Iterate over entries in a block */ +struct block_iter { + /* offset within the block of the next entry to read. */ + uint32_t next_off; + struct block_reader *br; + + /* key for last entry we read. */ + struct strbuf last_key; +}; + +/* initializes a block reader. */ +int block_reader_init(struct block_reader *br, struct reftable_block *bl, + uint32_t header_off, uint32_t table_block_size, + int hash_size); + +/* Position `it` at start of the block */ +void block_reader_start(struct block_reader *br, struct block_iter *it); + +/* Position `it` to the `want` key in the block */ +int block_reader_seek(struct block_reader *br, struct block_iter *it, + struct strbuf *want); + +/* Returns the block type (eg. 'r' for refs) */ +uint8_t block_reader_type(struct block_reader *r); + +/* Decodes the first key in the block */ +int block_reader_first_key(struct block_reader *br, struct strbuf *key); + +void block_iter_copy_from(struct block_iter *dest, struct block_iter *src); + +/* return < 0 for error, 0 for OK, > 0 for EOF. */ +int block_iter_next(struct block_iter *it, struct reftable_record *rec); + +/* Seek to `want` with in the block pointed to by `it` */ +int block_iter_seek(struct block_iter *it, struct strbuf *want); + +/* 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 */ +int header_size(int version); + +/* size of file footer, depending on format version */ +int footer_size(int version); + +/* returns a block to its source. */ +void reftable_block_done(struct reftable_block *ret); + +#endif |