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ce76cec964
Throughout the Git codebase we're using the typedeffed version of `z_stream`, which maps to `struct z_stream_s`. By using a typedef instead of the struct it becomes somewhat harder to predeclare the symbol so that headers depending on the struct can do so without having to pull in "zlib-compat.h". We don't yet have users that would really care about this: the only users that declare `z_stream` as a pointer are in "reftable/block.h", which is a header that is internal to the reftable library. But in the next step we're going to expose the `struct reftable_block` publicly, and that struct does contain a pointer to `z_stream`. And as the public header shouldn't depend on "reftable/system.h", which is an internal implementation detail, we won't have the typedef for `z_stream` readily available. Prepare for this change by using `struct z_stream_s` throughout our code base. In case zlib-ng is used we use a define to map from `z_stream_s` to `zng_stream_s`. Drop the pre-declaration of `struct z_stream` while at it. This struct does not exist in the first place, and the declaration wasn't needed because "reftable/block.h" already includes "reftable/basics.h" which transitively includes "reftable/system.h" and thus "git-zlib.h". Signed-off-by: Patrick Steinhardt <ps@pks.im> Signed-off-by: Junio C Hamano <gitster@pobox.com>
153 lines
4.2 KiB
C
153 lines
4.2 KiB
C
/*
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* Copyright 2020 Google LLC
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*
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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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struct z_stream_s *zstream;
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unsigned char *compressed;
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size_t compressed_cap;
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uint8_t *block;
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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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uint16_t restart_interval;
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uint32_t 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 reftable_buf last_key;
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/* Scratch buffer used to avoid allocations. */
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struct reftable_buf scratch;
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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 `block` as temporary
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* storage. `block` is not owned by the block_writer. */
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int block_writer_init(struct block_writer *bw, uint8_t typ, uint8_t *block,
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uint32_t block_size, uint32_t header_off, uint32_t 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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/*
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* A block part of a reftable. Contains records as well as some metadata
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* describing them.
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*/
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struct reftable_block {
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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_data block_data;
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uint32_t hash_size;
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/* Uncompressed data for log entries. */
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struct z_stream_s *zstream;
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unsigned char *uncompressed_data;
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size_t uncompressed_cap;
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/*
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* Restart point data. Restart points are located after the block's
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* record data.
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*/
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uint16_t restart_count;
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uint32_t restart_off;
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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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uint8_t block_type;
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};
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/*
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* Initialize a reftable block from the given block source.
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*/
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int reftable_block_init(struct reftable_block *b,
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struct reftable_block_source *source,
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uint32_t offset, uint32_t header_size,
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uint32_t table_block_size, uint32_t hash_size);
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void reftable_block_release(struct reftable_block *b);
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/* Returns the block type (eg. 'r' for refs) */
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uint8_t reftable_block_type(const struct reftable_block *b);
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/* Decodes the first key in the block */
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int reftable_block_first_key(const struct reftable_block *b, struct reftable_buf *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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uint32_t hash_size;
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/* key for last entry we read. */
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struct reftable_buf last_key;
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struct reftable_buf scratch;
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};
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#define BLOCK_ITER_INIT { \
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.last_key = REFTABLE_BUF_INIT, \
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.scratch = REFTABLE_BUF_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 reftable_block *block);
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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 reftable_block *block,
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struct reftable_buf *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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size_t header_size(int version);
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/* size of file footer, depending on format version */
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size_t footer_size(int version);
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#endif
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