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-rw-r--r--reftable/block.h127
1 files changed, 127 insertions, 0 deletions
diff --git a/reftable/block.h b/reftable/block.h
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--- /dev/null
+++ b/reftable/block.h
@@ -0,0 +1,127 @@
+/*
+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