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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;

};

/* 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