git/reftable/reftable-writer.h
Han-Wen Nienhuys f14bd71934 reftable: write reftable files
Signed-off-by: Han-Wen Nienhuys <hanwen@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2021-10-08 10:45:48 -07:00

149 lines
4.5 KiB
C

/*
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 REFTABLE_WRITER_H
#define REFTABLE_WRITER_H
#include "reftable-record.h"
#include <stdint.h>
#include <unistd.h> /* ssize_t */
/* Writing single reftables */
/* reftable_write_options sets options for writing a single reftable. */
struct reftable_write_options {
/* boolean: do not pad out blocks to block size. */
unsigned unpadded : 1;
/* the blocksize. Should be less than 2^24. */
uint32_t block_size;
/* boolean: do not generate a SHA1 => ref index. */
unsigned skip_index_objects : 1;
/* how often to write complete keys in each block. */
int restart_interval;
/* 4-byte identifier ("sha1", "s256") of the hash.
* Defaults to SHA1 if unset
*/
uint32_t hash_id;
/* boolean: do not check ref names for validity or dir/file conflicts.
*/
unsigned skip_name_check : 1;
/* boolean: copy log messages exactly. If unset, check that the message
* is a single line, and add '\n' if missing.
*/
unsigned exact_log_message : 1;
};
/* reftable_block_stats holds statistics for a single block type */
struct reftable_block_stats {
/* total number of entries written */
int entries;
/* total number of key restarts */
int restarts;
/* total number of blocks */
int blocks;
/* total number of index blocks */
int index_blocks;
/* depth of the index */
int max_index_level;
/* offset of the first block for this type */
uint64_t offset;
/* offset of the top level index block for this type, or 0 if not
* present */
uint64_t index_offset;
};
/* stats holds overall statistics for a single reftable */
struct reftable_stats {
/* total number of blocks written. */
int blocks;
/* stats for ref data */
struct reftable_block_stats ref_stats;
/* stats for the SHA1 to ref map. */
struct reftable_block_stats obj_stats;
/* stats for index blocks */
struct reftable_block_stats idx_stats;
/* stats for log blocks */
struct reftable_block_stats log_stats;
/* disambiguation length of shortened object IDs. */
int object_id_len;
};
/* reftable_new_writer creates a new writer */
struct reftable_writer *
reftable_new_writer(ssize_t (*writer_func)(void *, const void *, size_t),
void *writer_arg, struct reftable_write_options *opts);
/* Set the range of update indices for the records we will add. When writing a
table into a stack, the min should be at least
reftable_stack_next_update_index(), or REFTABLE_API_ERROR is returned.
For transactional updates to a stack, typically min==max, and the
update_index can be obtained by inspeciting the stack. When converting an
existing ref database into a single reftable, this would be a range of
update-index timestamps.
*/
void reftable_writer_set_limits(struct reftable_writer *w, uint64_t min,
uint64_t max);
/*
Add a reftable_ref_record. The record should have names that come after
already added records.
The update_index must be within the limits set by
reftable_writer_set_limits(), or REFTABLE_API_ERROR is returned. It is an
REFTABLE_API_ERROR error to write a ref record after a log record.
*/
int reftable_writer_add_ref(struct reftable_writer *w,
struct reftable_ref_record *ref);
/*
Convenience function to add multiple reftable_ref_records; the function sorts
the records before adding them, reordering the records array passed in.
*/
int reftable_writer_add_refs(struct reftable_writer *w,
struct reftable_ref_record *refs, int n);
/*
adds reftable_log_records. Log records are keyed by (refname, decreasing
update_index). The key for the record added must come after the already added
log records.
*/
int reftable_writer_add_log(struct reftable_writer *w,
struct reftable_log_record *log);
/*
Convenience function to add multiple reftable_log_records; the function sorts
the records before adding them, reordering records array passed in.
*/
int reftable_writer_add_logs(struct reftable_writer *w,
struct reftable_log_record *logs, int n);
/* reftable_writer_close finalizes the reftable. The writer is retained so
* statistics can be inspected. */
int reftable_writer_close(struct reftable_writer *w);
/* writer_stats returns the statistics on the reftable being written.
This struct becomes invalid when the writer is freed.
*/
const struct reftable_stats *writer_stats(struct reftable_writer *w);
/* reftable_writer_free deallocates memory for the writer */
void reftable_writer_free(struct reftable_writer *w);
#endif