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