reftable-table.h · leroysheep/Socializer

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1	/*
2	* Copyright 2020 Google LLC
3	*
4	* Use of this source code is governed by a BSD-style
5	* license that can be found in the LICENSE file or at
6	* https://developers.google.com/open-source/licenses/bsd
7	*/
8
9	#ifndef REFTABLE_TABLE_H
10	#define REFTABLE_TABLE_H
11
12	#include "reftable-system.h"
13	#include "reftable-iterator.h"
14	#include "reftable-block.h"
15	#include "reftable-blocksource.h"
16
17	/*
18	* Reading single tables
19	*
20	* The follow routines are for reading single files. For an
21	* application-level interface, skip ahead to struct
22	* reftable_merged_table and struct reftable_stack.
23	*/
24
25	/* Metadata for a block type. */
26	struct reftable_table_offsets {
27	int is_present;
28	uint64_t offset;
29	uint64_t index_offset;
30	};
31
32	/* The table struct is a handle to an open reftable file. */
33	struct reftable_table {
34	/* for convenience, associate a name with the instance. */
35	char *name;
36	struct reftable_block_source source;
37
38	/* Size of the file, excluding the footer. */
39	uint64_t size;
40
41	/* The hash function used for ref records. */
42	enum reftable_hash hash_id;
43
44	uint32_t block_size;
45	uint64_t min_update_index;
46	uint64_t max_update_index;
47	/* Length of the OID keys in the 'o' section */
48	int object_id_len;
49	int version;
50
51	struct reftable_table_offsets ref_offsets;
52	struct reftable_table_offsets obj_offsets;
53	struct reftable_table_offsets log_offsets;
54
55	uint64_t refcount;
56	};
57
58	/* reftable_table_new opens a reftable for reading. If successful,
59	* returns 0 code and sets pp. The name is used for creating a
60	* stack. Typically, it is the basename of the file. The block source
61	* `src` is owned by the table, and is closed on calling
62	* reftable_table_destroy(). On error, the block source `src` is
63	* closed as well.
64	*/
65	int reftable_table_new(struct reftable_table **out,
66	struct reftable_block_source src, const char name);
67
68	/*
69	* Manage the reference count of the reftable table. A newly initialized
70	* table starts with a refcount of 1 and will be deleted once the refcount has
71	* reached 0.
72	*
73	* This is required because tables may have longer lifetimes than the stack
74	* they belong to. The stack may for example be reloaded while the old tables
75	* are still being accessed by an iterator.
76	*/
77	void reftable_table_incref(struct reftable_table *table);
78	void reftable_table_decref(struct reftable_table *table);
79
80	/* Initialize a reftable iterator for reading refs. */
81	int reftable_table_init_ref_iterator(struct reftable_table *t,
82	struct reftable_iterator *it);
83
84	/* Initialize a reftable iterator for reading logs. */
85	int reftable_table_init_log_iterator(struct reftable_table *t,
86	struct reftable_iterator *it);
87
88	/* returns the hash ID used in this table. */
89	enum reftable_hash reftable_table_hash_id(struct reftable_table *t);
90
91	/* return an iterator for the refs pointing to `oid`. */
92	int reftable_table_refs_for(struct reftable_table *t,
93	struct reftable_iterator it, uint8_t oid);
94
95	/* return the max_update_index for a table */
96	uint64_t reftable_table_max_update_index(struct reftable_table *t);
97
98	/* return the min_update_index for a table */
99	uint64_t reftable_table_min_update_index(struct reftable_table *t);
100
101	/*
102	* An iterator that iterates through the blocks contained in a given table.
103	*/
104	struct reftable_table_iterator {
105	void *iter_arg;
106	};
107
108	int reftable_table_iterator_init(struct reftable_table_iterator *it,
109	struct reftable_table *t);
110
111	void reftable_table_iterator_release(struct reftable_table_iterator *it);
112
113	int reftable_table_iterator_next(struct reftable_table_iterator *it,
114	const struct reftable_block **out);
115
116	#endif