143 lines
3.8 KiB
C
143 lines
3.8 KiB
C
/*
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Copyright 2020 Google LLC
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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-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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uint8_t *buf;
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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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int restart_interval;
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int 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 strbuf last_key;
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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 `buf` as temporary
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* storage. `buf` is not owned by the block_writer. */
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void block_writer_init(struct block_writer *bw, uint8_t typ, uint8_t *buf,
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uint32_t block_size, uint32_t header_off, int 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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/* appends the record, or -1 if it doesn't fit. */
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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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struct z_stream;
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/* Read a block. */
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struct block_reader {
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/* offset of the block header; nonzero for the first block in a
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* reftable. */
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uint32_t header_off;
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/* the memory block */
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struct reftable_block block;
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int hash_size;
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/* Uncompressed data for log entries. */
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z_stream *zstream;
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unsigned char *uncompressed_data;
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size_t uncompressed_cap;
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/* size of the data, excluding restart data. */
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uint32_t block_len;
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uint8_t *restart_bytes;
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uint16_t restart_count;
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/* size of the data in the file. For log blocks, this is the compressed
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* size. */
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uint32_t full_block_size;
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};
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/* initializes a block reader. */
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int block_reader_init(struct block_reader *br, struct reftable_block *bl,
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uint32_t header_off, uint32_t table_block_size,
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int hash_size);
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void block_reader_release(struct block_reader *br);
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/* Returns the block type (eg. 'r' for refs) */
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uint8_t block_reader_type(const struct block_reader *r);
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/* Decodes the first key in the block */
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int block_reader_first_key(const struct block_reader *br, struct strbuf *key);
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/* Iterate over entries in a 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 unsigned char *block;
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size_t block_len;
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int hash_size;
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/* key for last entry we read. */
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struct strbuf last_key;
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struct strbuf scratch;
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};
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#define BLOCK_ITER_INIT { \
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.last_key = STRBUF_INIT, \
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.scratch = STRBUF_INIT, \
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}
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/* Position `it` at start of the block */
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void block_iter_seek_start(struct block_iter *it, const struct block_reader *br);
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/* Position `it` to the `want` key in the block */
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int block_iter_seek_key(struct block_iter *it, const struct block_reader *br,
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struct strbuf *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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int header_size(int version);
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/* size of file footer, depending on format version */
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int footer_size(int version);
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/* returns a block to its source. */
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void reftable_block_done(struct reftable_block *ret);
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#endif
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