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 /* Forward declarations */
  24 struct bt_iter;
  25 struct ctf_stream_event;
  26 struct ctf_stream;
  27 struct bt_saved_pos;
  28
  29 struct bt_iter_pos {
  30         enum {
  31                 BT_SEEK_TIME,           /* uses u.seek_time */
  32                 BT_SEEK_RESTORE,        /* uses u.restore */
  33                 BT_SEEK_CUR,
  34                 BT_SEEK_BEGIN,
  35                 BT_SEEK_END,
  36         } type;
  37         union {
  38                 uint64_t seek_time;
  39                 struct bt_saved_pos *restore;
  40         } u;
  41 };
  42
  43 /*
  44  * bt_iter_create - Allocate a trace collection iterator.
  45  *
  46  * begin_pos and end_pos are optional parameters to specify the position
  47  * at which the trace collection should be seeked upon iterator
  48  * creation, and the position at which iteration will start returning
  49  * "EOF".
  50  *
  51  * By default, if begin_pos is NULL, a BT_SEEK_CUR is performed at
  52  * creation. By default, if end_pos is NULL, a BT_SEEK_END (end of
  53  * trace) is the EOF criterion.
  54  */
  55 struct bt_iter *bt_iter_create(struct bt_context *ctx,
  56                 struct bt_iter_pos *begin_pos,
  57                 struct bt_iter_pos *end_pos);
  58
  59 /*
  60  * bt_iter_destroy - Free a trace collection iterator.
  61  */
  62 void bt_iter_destroy(struct bt_iter *iter);
  63
  64 /*
  65  * bt_iter_next: Move trace collection position to the next event.
  66  *
  67  * Returns 0 on success, a negative value on error
  68  */
  69 int bt_iter_next(struct bt_iter *iter);
  70
  71 /*
  72  * bt_iter_save_pos - Save the current trace collection position.
  73  *
  74  * The position returned by this function needs to be freed by
  75  * bt_iter_free_pos after use.
  76  */
  77 struct bt_iter_pos *
  78         bt_iter_save_pos(struct bt_iter *iter);
  79
  80 /*
  81  * bt_iter_free_pos - Free the position.
  82  */
  83 void bt_iter_free_pos(struct bt_iter_pos *pos);
  84
  85 /*
  86  * bt_iter_seek: seek iterator to given position.
  87  *
  88  * Return EOF if position is after the last event of the trace collection.
  89  * Return other negative value for other errors.
  90  * Return 0 for success.
  91  */
  92 int bt_iter_seek(struct bt_iter *iter,
  93                 const struct bt_iter_pos *pos);
  94
  95 /*
  96  * bt_iter_read_event: Read the iterator's current event data.
  97  *
  98  * @iter: trace collection iterator (input)
  99  * @stream: stream containing event at current position (output)
 100  * @event: current event (output)
 101  * Return 0 on success, negative error value on error.
 102  */
 103 int bt_iter_read_event(struct bt_iter *iter,
 104                 struct ctf_stream **stream,
 105                 struct ctf_stream_event **event);
 106
 107 #endif /* _BABELTRACE_ITERATOR_H */