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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-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