1 files changed, 164 insertions, 0 deletions
diff --git a/reftable/record.h b/reftable/record.h
new file mode 100644
index 0000000000..7953f352a3
--- /dev/null
+++ b/reftable/record.h
@@ -0,0 +1,164 @@
+/*
+ * 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 "basics.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. */
+static inline void string_view_consume(struct string_view *s, int n)
+{
+	s->buf += n;
+	s->len -= n;
+}
+
+/*
+ * Decode and encode a varint. Returns the number of bytes read/written, or a
+ * negative value in case encoding/decoding the varint has failed.
+ */
+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 reftable_buf. */
+	int (*key)(const void *rec, struct reftable_buf *dest);
+
+	/* The record type of ('r' for ref). */
+	uint8_t type;
+
+	int (*copy_from)(void *dest, const void *src, uint32_t 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, uint32_t hash_size);
+
+	/* decode data from `src` into the record. */
+	int (*decode)(void *rec, struct reftable_buf key, uint8_t extra,
+		      struct string_view src, uint32_t hash_size,
+		      struct reftable_buf *scratch);
+
+	/* deallocate and null the record. */
+	void (*release)(void *rec);
+
+	/* is this a tombstone? */
+	int (*is_deletion)(const void *rec);
+
+	/* Are two records equal? This assumes they have the same type. Returns 0 for non-equal. */
+	int (*equal)(const void *a, const void *b, uint32_t hash_size);
+
+	/*
+	 * Compare keys of two records with each other. The records must have
+	 * the same type.
+	 */
+	int (*cmp)(const void *a, const void *b);
+};
+
+/* returns true for recognized block types. Block start with the block type. */
+int reftable_is_block_type(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 reftable_buf prev_key, struct reftable_buf key,
+			uint8_t extra);
+
+/* Decode a record's key lengths. */
+int reftable_decode_keylen(struct string_view in,
+			   uint64_t *prefix_len,
+			   uint64_t *suffix_len,
+			   uint8_t *extra);
+
+/*
+ * Decode into `last_key` and `extra` from `in`. `last_key` is expected to
+ * contain the decoded key of the preceding record, if any.
+ */
+int reftable_decode_key(struct reftable_buf *last_key, uint8_t *extra,
+			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 reftable_buf 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;
+};
+
+/* record is a generic wrapper for different types of records. It is normally
+ * created on the stack, or embedded within another struct. If the type is
+ * known, a fresh instance can be initialized explicitly. Otherwise, use
+ * `reftable_record_init()` to initialize generically (as the index_record is
+ * not valid as 0-initialized structure)
+ */
+struct reftable_record {
+	uint8_t type;
+	union {
+		struct reftable_ref_record ref;
+		struct reftable_log_record log;
+		struct reftable_obj_record obj;
+		struct reftable_index_record idx;
+	} u;
+};
+
+/* Initialize the reftable record for the given type. */
+int reftable_record_init(struct reftable_record *rec, uint8_t typ);
+
+/* see struct record_vtable */
+int reftable_record_cmp(struct reftable_record *a, struct reftable_record *b, int *cmp);
+int reftable_record_equal(struct reftable_record *a, struct reftable_record *b, uint32_t hash_size);
+int reftable_record_key(struct reftable_record *rec, struct reftable_buf *dest);
+int reftable_record_copy_from(struct reftable_record *rec,
+			      struct reftable_record *src, uint32_t hash_size);
+uint8_t reftable_record_val_type(struct reftable_record *rec);
+int reftable_record_encode(struct reftable_record *rec, struct string_view dest,
+			   uint32_t hash_size);
+int reftable_record_decode(struct reftable_record *rec, struct reftable_buf key,
+			   uint8_t extra, struct string_view src,
+			   uint32_t hash_size, struct reftable_buf *scratch);
+int reftable_record_is_deletion(struct reftable_record *rec);
+
+static inline uint8_t reftable_record_type(struct reftable_record *rec)
+{
+	return rec->type;
+}
+
+/* frees and zeroes out the embedded record */
+void reftable_record_release(struct reftable_record *rec);
+
+/* 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