reftable: write reftable files

Signed-off-by: Han-Wen Nienhuys <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: hanwen

Makefile

@@ -2463,6 +2463,7 @@ REFTABLE_OBJS += reftable/blocksource.o
 REFTABLE_OBJS += reftable/publicbasics.o
 REFTABLE_OBJS += reftable/record.o
 REFTABLE_OBJS += reftable/tree.o
+REFTABLE_OBJS += reftable/writer.o
 
 REFTABLE_TEST_OBJS += reftable/basics_test.o
 REFTABLE_TEST_OBJS += reftable/block_test.o

reftable/reftable-writer.h

@@ -0,0 +1,148 @@
+/*
+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