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 bt_saved_pos;
  26
  27 struct bt_iter_pos {
  28         enum {
  29                 BT_SEEK_TIME,           /* uses u.seek_time */
  30                 BT_SEEK_RESTORE,        /* uses u.restore */
  31                 BT_SEEK_CUR,
  32                 BT_SEEK_BEGIN,
  33                 BT_SEEK_END,
  34         } type;
  35         union {
  36                 uint64_t seek_time;
  37                 struct bt_saved_pos *restore;
  38         } u;
  39 };
  40
  41 /*
  42  * bt_iter_create - Allocate a trace collection iterator.
  43  *
  44  * begin_pos and end_pos are optional parameters to specify the position
  45  * at which the trace collection should be seeked upon iterator
  46  * creation, and the position at which iteration will start returning
  47  * "EOF".
  48  *
  49  * By default, if begin_pos is NULL, a BT_SEEK_CUR is performed at
  50  * creation. By default, if end_pos is NULL, a BT_SEEK_END (end of
  51  * trace) is the EOF criterion.
  52  */
  53 struct bt_iter *bt_iter_create(struct bt_context *ctx,
  54                 struct bt_iter_pos *begin_pos,
  55                 struct bt_iter_pos *end_pos);
  56
  57 /*
  58  * bt_iter_destroy - Free a trace collection iterator.
  59  */
  60 void bt_iter_destroy(struct bt_iter *iter);
  61
  62 /*
  63  * bt_iter_next: Move trace collection position to the next event.
  64  *
  65  * Returns 0 on success, a negative value on error
  66  */
  67 int bt_iter_next(struct bt_iter *iter);
  68
  69 /*
  70  * bt_iter_get_pos - Get the current iterator position.
  71  *
  72  * The position returned by this function needs to be freed by
  73  * bt_iter_free_pos after use.
  74  */
  75 struct bt_iter_pos *
  76         bt_iter_get_pos(struct bt_iter *iter);
  77
  78 /*
  79  * bt_iter_free_pos - Free the position.
  80  */
  81 void bt_iter_free_pos(struct bt_iter_pos *pos);
  82
  83 /*
  84  * bt_iter_set_pos: move the iterator to a given position.
  85  *
  86  * On error, the stream_heap is reinitialized and returned empty.
  87  *
  88  * Return 0 for success.
  89  *
  90  * Return EOF if the position requested is after the last event of the
  91  * trace collection.
  92  * Return -EINVAL when called with invalid parameter.
  93  * Return -ENOMEM if the stream_heap could not be properly initialized.
  94  */
  95 int bt_iter_set_pos(struct bt_iter *iter, const struct bt_iter_pos *pos);
  96
  97 /*
  98  * bt_iter_create_time_pos: create a position based on time
  99  *
 100  * This function allocates and returns a new bt_iter_pos (which must be freed
 101  * with bt_iter_free_pos) to be able to restore an iterator position based on a
 102  * timestamp.
 103  */
 104 struct bt_iter_pos *bt_iter_create_time_pos(struct bt_iter *iter,
 105                 uint64_t timestamp);
 106
 107 #endif /* _BABELTRACE_ITERATOR_H */