3f7984fbe66ea00c01e6e5c95090acbf07f634fc
[babeltrace.git] / include / babeltrace / iterator.h
1 #ifndef _BABELTRACE_ITERATOR_H
2 #define _BABELTRACE_ITERATOR_H
3
4 /*
5 * BabelTrace API Iterators
6 *
7 * Copyright 2010-2011 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
8 *
9 * Permission is hereby granted, free of charge, to any person obtaining a copy
10 * of this software and associated documentation files (the "Software"), to deal
11 * in the Software without restriction, including without limitation the rights
12 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
13 * copies of the Software, and to permit persons to whom the Software is
14 * furnished to do so, subject to the following conditions:
15 *
16 * The above copyright notice and this permission notice shall be included in
17 * all copies or substantial portions of the Software.
18 */
19
20 #include <babeltrace/format.h>
21 #include <babeltrace/context.h>
22
23 #ifdef __cplusplus
24 extern "C" {
25 #endif
26
27 /* Forward declarations */
28 struct bt_iter;
29 struct bt_saved_pos;
30
31 /*
32 * bt_iter is an abstract class, each format has to implement its own
33 * iterator derived from this parent class.
34 */
35
36 /*
37 * bt_iter_pos
38 *
39 * This structure represents the position where to set an iterator.
40 *
41 * type represents the type of seek to use.
42 * u is the argument of the seek if necessary :
43 * - seek_time is the real timestamp to seek to when using BT_SEEK_TIME, it
44 * is expressed in nanoseconds
45 * - restore is a position saved with bt_iter_get_pos, it is used with
46 * BT_SEEK_RESTORE.
47 *
48 * Note about BT_SEEK_LAST: if many events happen to be at the last
49 * timestamp, it is implementation-defined which event will be the last,
50 * and the order of events with the same timestamp may not be the same
51 * as normal iteration on the trace. Therefore, it is recommended to
52 * only use BT_SEEK_LAST to get the timestamp of the last event(s) in
53 * the trace.
54 */
55 struct bt_iter_pos {
56 enum {
57 BT_SEEK_TIME, /* uses u.seek_time */
58 BT_SEEK_RESTORE, /* uses u.restore */
59 BT_SEEK_CUR,
60 BT_SEEK_BEGIN,
61 BT_SEEK_LAST,
62 } type;
63 union {
64 uint64_t seek_time;
65 struct bt_saved_pos *restore;
66 } u;
67 };
68
69 /*
70 * bt_iter_next: Move trace collection position to the next event.
71 *
72 * Returns 0 on success, a negative value on error
73 */
74 int bt_iter_next(struct bt_iter *iter);
75
76 /*
77 * bt_iter_get_pos - Get the current iterator position.
78 *
79 * The position returned by this function needs to be freed by
80 * bt_iter_free_pos after use.
81 */
82 struct bt_iter_pos *bt_iter_get_pos(struct bt_iter *iter);
83
84 /*
85 * bt_iter_free_pos - Free the position.
86 */
87 void bt_iter_free_pos(struct bt_iter_pos *pos);
88
89 /*
90 * bt_iter_set_pos: move the iterator to a given position.
91 *
92 * On error, the stream_heap is reinitialized and returned empty.
93 *
94 * Return 0 for success.
95 *
96 * Return EOF if the position requested is after the last event of the
97 * trace collection.
98 * Return -EINVAL when called with invalid parameter.
99 * Return -ENOMEM if the stream_heap could not be properly initialized.
100 */
101 int bt_iter_set_pos(struct bt_iter *iter, const struct bt_iter_pos *pos);
102
103 /*
104 * bt_iter_create_time_pos: create a position based on time
105 *
106 * This function allocates and returns a new bt_iter_pos (which must be freed
107 * with bt_iter_free_pos) to be able to restore an iterator position based on a
108 * real timestamp.
109 */
110 struct bt_iter_pos *bt_iter_create_time_pos(struct bt_iter *iter,
111 uint64_t timestamp);
112
113 #ifdef __cplusplus
114 }
115 #endif
116
117 #endif /* _BABELTRACE_ITERATOR_H */
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