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-rw-r--r--reftable/record.h139
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diff --git a/reftable/record.h b/reftable/record.h
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+/*
+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 RECORD_H
+#define RECORD_H
+
+#include "system.h"
+
+#include <stdint.h>
+
+#include "reftable-record.h"
+
+/*
+ * A substring of existing string data. This structure takes no responsibility
+ * for the lifetime of the data it points to.
+ */
+struct string_view {
+ uint8_t *buf;
+ size_t len;
+};
+
+/* Advance `s.buf` by `n`, and decrease length. */
+void string_view_consume(struct string_view *s, int n);
+
+/* utilities for de/encoding varints */
+
+int get_var_int(uint64_t *dest, struct string_view *in);
+int put_var_int(struct string_view *dest, uint64_t val);
+
+/* Methods for records. */
+struct reftable_record_vtable {
+ /* encode the key of to a uint8_t strbuf. */
+ void (*key)(const void *rec, struct strbuf *dest);
+
+ /* The record type of ('r' for ref). */
+ uint8_t type;
+
+ void (*copy_from)(void *dest, const void *src, int hash_size);
+
+ /* a value of [0..7], indicating record subvariants (eg. ref vs. symref
+ * vs ref deletion) */
+ uint8_t (*val_type)(const void *rec);
+
+ /* encodes rec into dest, returning how much space was used. */
+ int (*encode)(const void *rec, struct string_view dest, int hash_size);
+
+ /* decode data from `src` into the record. */
+ int (*decode)(void *rec, struct strbuf key, uint8_t extra,
+ struct string_view src, int hash_size);
+
+ /* deallocate and null the record. */
+ void (*release)(void *rec);
+
+ /* is this a tombstone? */
+ int (*is_deletion)(const void *rec);
+};
+
+/* record is a generic wrapper for different types of records. */
+struct reftable_record {
+ void *data;
+ struct reftable_record_vtable *ops;
+};
+
+/* returns true for recognized block types. Block start with the block type. */
+int reftable_is_block_type(uint8_t typ);
+
+/* creates a malloced record of the given type. Dispose with record_destroy */
+struct reftable_record reftable_new_record(uint8_t typ);
+
+/* Encode `key` into `dest`. Sets `is_restart` to indicate a restart. Returns
+ * number of bytes written. */
+int reftable_encode_key(int *is_restart, struct string_view dest,
+ struct strbuf prev_key, struct strbuf key,
+ uint8_t extra);
+
+/* Decode into `key` and `extra` from `in` */
+int reftable_decode_key(struct strbuf *key, uint8_t *extra,
+ struct strbuf last_key, struct string_view in);
+
+/* reftable_index_record are used internally to speed up lookups. */
+struct reftable_index_record {
+ uint64_t offset; /* Offset of block */
+ struct strbuf last_key; /* Last key of the block. */
+};
+
+/* reftable_obj_record stores an object ID => ref mapping. */
+struct reftable_obj_record {
+ uint8_t *hash_prefix; /* leading bytes of the object ID */
+ int hash_prefix_len; /* number of leading bytes. Constant
+ * across a single table. */
+ uint64_t *offsets; /* a vector of file offsets. */
+ int offset_len;
+};
+
+/* see struct record_vtable */
+
+void reftable_record_key(struct reftable_record *rec, struct strbuf *dest);
+uint8_t reftable_record_type(struct reftable_record *rec);
+void reftable_record_copy_from(struct reftable_record *rec,
+ struct reftable_record *src, int hash_size);
+uint8_t reftable_record_val_type(struct reftable_record *rec);
+int reftable_record_encode(struct reftable_record *rec, struct string_view dest,
+ int hash_size);
+int reftable_record_decode(struct reftable_record *rec, struct strbuf key,
+ uint8_t extra, struct string_view src,
+ int hash_size);
+int reftable_record_is_deletion(struct reftable_record *rec);
+
+/* zeroes out the embedded record */
+void reftable_record_release(struct reftable_record *rec);
+
+/* clear and deallocate embedded record, and zero `rec`. */
+void reftable_record_destroy(struct reftable_record *rec);
+
+/* initialize generic records from concrete records. The generic record should
+ * be zeroed out. */
+void reftable_record_from_obj(struct reftable_record *rec,
+ struct reftable_obj_record *objrec);
+void reftable_record_from_index(struct reftable_record *rec,
+ struct reftable_index_record *idxrec);
+void reftable_record_from_ref(struct reftable_record *rec,
+ struct reftable_ref_record *refrec);
+void reftable_record_from_log(struct reftable_record *rec,
+ struct reftable_log_record *logrec);
+struct reftable_ref_record *reftable_record_as_ref(struct reftable_record *ref);
+struct reftable_log_record *reftable_record_as_log(struct reftable_record *ref);
+
+/* for qsort. */
+int reftable_ref_record_compare_name(const void *a, const void *b);
+
+/* for qsort. */
+int reftable_log_record_compare_key(const void *a, const void *b);
+
+#endif