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/*
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;
struct strbuf key;
};
#define BLOCK_ITER_INIT { \
.last_key = STRBUF_INIT, \
.key = STRBUF_INIT, \
}
/* 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
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