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[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 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
20 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
21 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
22 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
23 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
24 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
25 * SOFTWARE.
26 */
27
28 #include <babeltrace/format.h>
29 #include <babeltrace/context.h>
30
31 #ifdef __cplusplus
32 extern "C" {
33 #endif
34
35 /* Flags for the iterator read_event */
36 enum {
37 BT_ITER_FLAG_LOST_EVENTS = (1 << 0),
38 };
39
40 /* Forward declarations */
41 struct bt_iter;
42 struct bt_saved_pos;
43
44 /*
45 * bt_iter is an abstract class, each format has to implement its own
46 * iterator derived from this parent class.
47 */
48
49 /*
50 * bt_iter_pos
51 *
52 * This structure represents the position where to set an iterator.
53 *
54 * type represents the type of seek to use.
55 * u is the argument of the seek if necessary :
56 * - seek_time is the real timestamp to seek to when using BT_SEEK_TIME, it
57 * is expressed in nanoseconds
58 * - restore is a position saved with bt_iter_get_pos, it is used with
59 * BT_SEEK_RESTORE.
60 *
61 * Note about BT_SEEK_LAST: if many events happen to be at the last
62 * timestamp, it is implementation-defined which event will be the last,
63 * and the order of events with the same timestamp may not be the same
64 * as normal iteration on the trace. Therefore, it is recommended to
65 * only use BT_SEEK_LAST to get the timestamp of the last event(s) in
66 * the trace.
67 */
68 struct bt_iter_pos {
69 enum {
70 BT_SEEK_TIME, /* uses u.seek_time */
71 BT_SEEK_RESTORE, /* uses u.restore */
72 BT_SEEK_CUR,
73 BT_SEEK_BEGIN,
74 BT_SEEK_LAST,
75 } type;
76 union {
77 uint64_t seek_time;
78 struct bt_saved_pos *restore;
79 } u;
80 };
81
82 /*
83 * bt_iter_next: Move trace collection position to the next event.
84 *
85 * Returns 0 on success, a negative value on error
86 */
87 int bt_iter_next(struct bt_iter *iter);
88
89 /*
90 * bt_iter_get_pos - Get the current iterator position.
91 *
92 * The position returned by this function needs to be freed by
93 * bt_iter_free_pos after use.
94 */
95 struct bt_iter_pos *bt_iter_get_pos(struct bt_iter *iter);
96
97 /*
98 * bt_iter_free_pos - Free the position.
99 */
100 void bt_iter_free_pos(struct bt_iter_pos *pos);
101
102 /*
103 * bt_iter_set_pos: move the iterator to a given position.
104 *
105 * On error, the stream_heap is reinitialized and returned empty.
106 *
107 * Return 0 for success.
108 *
109 * Return EOF if the position requested is after the last event of the
110 * trace collection.
111 * Return -EINVAL when called with invalid parameter.
112 * Return -ENOMEM if the stream_heap could not be properly initialized.
113 */
114 int bt_iter_set_pos(struct bt_iter *iter, const struct bt_iter_pos *pos);
115
116 /*
117 * bt_iter_create_time_pos: create a position based on time
118 *
119 * This function allocates and returns a new bt_iter_pos (which must be freed
120 * with bt_iter_free_pos) to be able to restore an iterator position based on a
121 * real timestamp.
122 */
123 struct bt_iter_pos *bt_iter_create_time_pos(struct bt_iter *iter,
124 uint64_t timestamp);
125
126 #ifdef __cplusplus
127 }
128 #endif
129
130 #endif /* _BABELTRACE_ITERATOR_H */
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