include/babeltrace/babeltrace.h

   1 #ifndef _BABELTRACE_H
   2 #define _BABELTRACE_H
   3
   4 /*
   5  * BabelTrace API
   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 <glib.h>
  21
  22 typedef GQuark bt_event_name;
  23
  24 /* Forward declarations */
  25 struct babeltrace_iter;
  26 struct trace_collection;
  27 struct ctf_stream_event;
  28 struct ctf_stream;
  29 struct babeltrace_saved_pos;
  30 struct bt_dependencies;
  31
  32 enum bt_cb_ret {
  33         BT_CB_OK                = 0,
  34         BT_CB_OK_STOP           = 1,
  35         BT_CB_ERROR_STOP        = 2,
  36         BT_CB_ERROR_CONTINUE    = 3,
  37 };
  38
  39 struct trace_collection_pos {
  40         enum {
  41                 BT_SEEK_TIME,           /* uses u.seek_time */
  42                 BT_SEEK_RESTORE,        /* uses u.restore */
  43                 BT_SEEK_CUR,
  44                 BT_SEEK_BEGIN,
  45                 BT_SEEK_END,
  46         } type;
  47         union {
  48                 uint64_t seek_time;
  49                 struct babeltrace_saved_pos *restore;
  50         } u;
  51 };
  52
  53 /*
  54  * babeltrace_iter_create - Allocate a trace collection iterator.
  55  *
  56  * begin_pos and end_pos are optional parameters to specify the position
  57  * at which the trace collection should be seeked upon iterator
  58  * creation, and the position at which iteration will start returning
  59  * "EOF".
  60  *
  61  * By default, if begin_pos is NULL, a BT_SEEK_CUR is performed at
  62  * creation. By default, if end_pos is NULL, a BT_SEEK_END (end of
  63  * trace) is the EOF criterion.
  64  */
  65 struct babeltrace_iter *babeltrace_iter_create(struct trace_collection *tc,
  66                 struct trace_collection_pos *begin_pos,
  67                 struct trace_collection_pos *end_pos);
  68
  69 /*
  70  * babeltrace_iter_destroy - Free a trace collection iterator.
  71  */
  72 void babeltrace_iter_destroy(struct babeltrace_iter *iter);
  73
  74 /*
  75  * babeltrace_iter_next: Move trace collection position to the next event.
  76  *
  77  * Returns 0 on success, a negative value on error
  78  */
  79 int babeltrace_iter_next(struct babeltrace_iter *iter);
  80
  81 /*
  82  * babeltrace_iter_save_pos - Save the current trace collection position.
  83  *
  84  * The position returned by this function needs to be freed by
  85  * babeltrace_iter_free_pos after use.
  86  */
  87 struct trace_collection_pos *
  88         babeltrace_iter_save_pos(struct babeltrace_iter *iter);
  89
  90 /*
  91  * babeltrace_iter_free_pos - Free the position.
  92  */
  93 void babeltrace_iter_free_pos(struct trace_collection_pos *pos);
  94
  95 /*
  96  * babeltrace_iter_seek: seek iterator to given position.
  97  *
  98  * Return EOF if position is after the last event of the trace collection.
  99  * Return other negative value for other errors.
 100  * Return 0 for success.
 101  */
 102 int babeltrace_iter_seek(struct babeltrace_iter *iter,
 103                 const struct trace_collection_pos *pos);
 104
 105 /*
 106  * babeltrace_iter_read_event: Read the iterator's current event data.
 107  *
 108  * @iter: trace collection iterator (input)
 109  * @stream: stream containing event at current position (output)
 110  * @event: current event (output)
 111  * Return 0 on success, negative error value on error.
 112  */
 113 int babeltrace_iter_read_event(struct babeltrace_iter *iter,
 114                 struct ctf_stream **stream,
 115                 struct ctf_stream_event **event);
 116
 117 /*
 118  * Receives a variable number of strings as parameter, ended with NULL.
 119  */
 120 struct bt_dependencies *babeltrace_dependencies_create(const char *first, ...);
 121
 122 /*
 123  * struct bt_dependencies must be destroyed explicitly if not passed as
 124  * parameter to a babeltrace_iter_add_callback().
 125  */
 126 void babeltrace_dependencies_destroy(struct bt_dependencies *dep);
 127
 128 /*
 129  * babeltrace_iter_add_callback: Add a callback to iterator.
 130  *
 131  * @iter: trace collection iterator (input)
 132  * @event: event to target. 0 for all events.
 133  * @private_data: private data pointer to pass to the callback
 134  * @flags: specific flags controlling the behavior of this callback
 135  *         (or'd).
 136  *
 137  * @callback: function pointer to call
 138  * @depends: struct bt_dependency detailing the required computation results.
 139  *           Ends with 0.
 140  * @weak_depends: struct bt_dependency detailing the optional computation
 141  *                results that can be optionally consumed by this
 142  *                callback.
 143  * @provides: struct bt_dependency detailing the computation results
 144  *            provided by this callback.
 145  *            Ends with 0.
 146  *
 147  * "depends", "weak_depends" and "provides" memory is handled by the
 148  * babeltrace library after this call succeeds or fails. These objects
 149  * can still be used by the caller until the babeltrace iterator is
 150  * destroyed, but they belong to the babeltrace library.
 151  *
 152  * (note to implementor: we need to keep a gptrarray of struct
 153  * bt_dependencies to "garbage collect" in struct babeltrace_iter, and
 154  * dependencies need to have a refcount to handle the case where they
 155  * would be passed to more than one iterator. Upon iterator detroy, we
 156  * iterate on all the gc ptrarray and decrement the refcounts, freeing
 157  * if we reach 0.)
 158  * (note to implementor: we calculate the dependency graph when
 159  * babeltrace_iter_read_event() is executed after a
 160  * babeltrace_iter_add_callback(). Beware that it is valid to create/add
 161  * callbacks/read/add more callbacks/read some more.)
 162  */
 163 int babeltrace_iter_add_callback(struct babeltrace_iter *iter,
 164                 bt_event_name event, void *private_data, int flags,
 165                 enum bt_cb_ret (*callback)(void *private_data,
 166                                         void *caller_data),
 167                 struct bt_dependencies *depends,
 168                 struct bt_dependencies *weak_depends,
 169                 struct bt_dependencies *provides);
 170
 171 /*
 172  * For flags parameter above.
 173  */
 174 enum {
 175         BT_FLAGS_FREE_PRIVATE_DATA      = (1 << 0),
 176 };
 177
 178 #endif /* _BABELTRACE_H */