lib/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 enum bt_iter_pos_type {
  69         BT_SEEK_TIME,           /* uses u.seek_time */
  70         BT_SEEK_RESTORE,        /* uses u.restore */
  71         BT_SEEK_CUR,
  72         BT_SEEK_BEGIN,
  73         BT_SEEK_LAST,
  74 };
  75
  76 struct bt_iter_pos {
  77         enum bt_iter_pos_type type;
  78         union {
  79                 uint64_t seek_time;
  80                 struct bt_saved_pos *restore;
  81         } u;
  82 };
  83
  84 /*
  85  * bt_iter_next: Move trace collection position to the next event.
  86  *
  87  * Returns 0 on success, a negative value on error
  88  */
  89 int bt_iter_next(struct bt_iter *iter);
  90
  91 /*
  92  * bt_iter_get_pos - Get the current iterator position.
  93  *
  94  * The position returned by this function needs to be freed by
  95  * bt_iter_free_pos after use.
  96  */
  97 struct bt_iter_pos *bt_iter_get_pos(struct bt_iter *iter);
  98
  99 /*
 100  * bt_iter_free_pos - Free the position.
 101  */
 102 void bt_iter_free_pos(struct bt_iter_pos *pos);
 103
 104 /*
 105  * bt_iter_set_pos: move the iterator to a given position.
 106  *
 107  * On error, the stream_heap is reinitialized and returned empty.
 108  *
 109  * Return 0 for success.
 110  *
 111  * Return EOF if the position requested is after the last event of the
 112  * trace collection.
 113  * Return -EINVAL when called with invalid parameter.
 114  * Return -ENOMEM if the stream_heap could not be properly initialized.
 115  */
 116 int bt_iter_set_pos(struct bt_iter *iter, const struct bt_iter_pos *pos);
 117
 118 /*
 119  * bt_iter_create_time_pos: create a position based on time
 120  *
 121  * This function allocates and returns a new bt_iter_pos (which must be freed
 122  * with bt_iter_free_pos) to be able to restore an iterator position based on a
 123  * real timestamp.
 124  */
 125 struct bt_iter_pos *bt_iter_create_time_pos(struct bt_iter *iter,
 126                 uint64_t timestamp);
 127
 128 #ifdef __cplusplus
 129 }
 130 #endif
 131
 132 #endif /* _BABELTRACE_ITERATOR_H */