7eb3c5ebc4c34ffea7232afd80f8fd041fb739de
[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 /* Flags for the iterator read_event */
28 enum {
29 BT_ITER_FLAG_LOST_EVENTS = (1 << 0),
30 };
31
32 /* Forward declarations */
33 struct bt_iter;
34 struct bt_saved_pos;
35
36 /*
37 * bt_iter is an abstract class, each format has to implement its own
38 * iterator derived from this parent class.
39 */
40
41 /*
42 * bt_iter_pos
43 *
44 * This structure represents the position where to set an iterator.
45 *
46 * type represents the type of seek to use.
47 * u is the argument of the seek if necessary :
48 * - seek_time is the real timestamp to seek to when using BT_SEEK_TIME, it
49 * is expressed in nanoseconds
50 * - restore is a position saved with bt_iter_get_pos, it is used with
51 * BT_SEEK_RESTORE.
52 *
53 * Note about BT_SEEK_LAST: if many events happen to be at the last
54 * timestamp, it is implementation-defined which event will be the last,
55 * and the order of events with the same timestamp may not be the same
56 * as normal iteration on the trace. Therefore, it is recommended to
57 * only use BT_SEEK_LAST to get the timestamp of the last event(s) in
58 * the trace.
59 */
60 struct bt_iter_pos {
61 enum {
62 BT_SEEK_TIME, /* uses u.seek_time */
63 BT_SEEK_RESTORE, /* uses u.restore */
64 BT_SEEK_CUR,
65 BT_SEEK_BEGIN,
66 BT_SEEK_LAST,
67 } type;
68 union {
69 uint64_t seek_time;
70 struct bt_saved_pos *restore;
71 } u;
72 };
73
74 /*
75 * bt_iter_next: Move trace collection position to the next event.
76 *
77 * Returns 0 on success, a negative value on error
78 */
79 int bt_iter_next(struct bt_iter *iter);
80
81 /*
82 * bt_iter_get_pos - Get the current iterator position.
83 *
84 * The position returned by this function needs to be freed by
85 * bt_iter_free_pos after use.
86 */
87 struct bt_iter_pos *bt_iter_get_pos(struct bt_iter *iter);
88
89 /*
90 * bt_iter_free_pos - Free the position.
91 */
92 void bt_iter_free_pos(struct bt_iter_pos *pos);
93
94 /*
95 * bt_iter_set_pos: move the iterator to a given position.
96 *
97 * On error, the stream_heap is reinitialized and returned empty.
98 *
99 * Return 0 for success.
100 *
101 * Return EOF if the position requested is after the last event of the
102 * trace collection.
103 * Return -EINVAL when called with invalid parameter.
104 * Return -ENOMEM if the stream_heap could not be properly initialized.
105 */
106 int bt_iter_set_pos(struct bt_iter *iter, const struct bt_iter_pos *pos);
107
108 /*
109 * bt_iter_create_time_pos: create a position based on time
110 *
111 * This function allocates and returns a new bt_iter_pos (which must be freed
112 * with bt_iter_free_pos) to be able to restore an iterator position based on a
113 * real timestamp.
114 */
115 struct bt_iter_pos *bt_iter_create_time_pos(struct bt_iter *iter,
116 uint64_t timestamp);
117
118 #ifdef __cplusplus
119 }
120 #endif
121
122 #endif /* _BABELTRACE_ITERATOR_H */
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