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The reftable format is usually used with files for storage. However, we abstract away this using the blocksource data structure. This has two advantages: * log blocks are zlib compressed, and handling them is simplified if we can discard byte segments from within the block layer. * for unittests, it is useful to read and write in-memory. The blocksource allows us to abstract the data away from on-disk files. Signed-off-by: Han-Wen Nienhuys <hanwen@google.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>
50 lines
1.4 KiB
C
50 lines
1.4 KiB
C
/*
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Copyright 2020 Google LLC
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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 REFTABLE_BLOCKSOURCE_H
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#define REFTABLE_BLOCKSOURCE_H
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#include <stdint.h>
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/* block_source is a generic wrapper for a seekable readable file.
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*/
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struct reftable_block_source {
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struct reftable_block_source_vtable *ops;
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void *arg;
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};
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/* a contiguous segment of bytes. It keeps track of its generating block_source
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* so it can return itself into the pool. */
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struct reftable_block {
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uint8_t *data;
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int len;
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struct reftable_block_source source;
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};
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/* block_source_vtable are the operations that make up block_source */
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struct reftable_block_source_vtable {
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/* returns the size of a block source */
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uint64_t (*size)(void *source);
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/* reads a segment from the block source. It is an error to read
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beyond the end of the block */
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int (*read_block)(void *source, struct reftable_block *dest,
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uint64_t off, uint32_t size);
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/* mark the block as read; may return the data back to malloc */
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void (*return_block)(void *source, struct reftable_block *blockp);
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/* release all resources associated with the block source */
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void (*close)(void *source);
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};
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/* opens a file on the file system as a block_source */
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int reftable_block_source_from_file(struct reftable_block_source *block_src,
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const char *name);
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#endif
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