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 struct bt_ctf_data {
  54         struct ctf_stream_event *event;
  55 };
  56
  57 /*
  58  * babeltrace_iter_create - Allocate a trace collection iterator.
  59  *
  60  * begin_pos and end_pos are optional parameters to specify the position
  61  * at which the trace collection should be seeked upon iterator
  62  * creation, and the position at which iteration will start returning
  63  * "EOF".
  64  *
  65  * By default, if begin_pos is NULL, a BT_SEEK_CUR is performed at
  66  * creation. By default, if end_pos is NULL, a BT_SEEK_END (end of
  67  * trace) is the EOF criterion.
  68  */
  69 struct babeltrace_iter *babeltrace_iter_create(struct trace_collection *tc,
  70                 struct trace_collection_pos *begin_pos,
  71                 struct trace_collection_pos *end_pos);
  72
  73 /*
  74  * babeltrace_iter_destroy - Free a trace collection iterator.
  75  */
  76 void babeltrace_iter_destroy(struct babeltrace_iter *iter);
  77
  78 /*
  79  * babeltrace_iter_next: Move trace collection position to the next event.
  80  *
  81  * Returns 0 on success, a negative value on error
  82  */
  83 int babeltrace_iter_next(struct babeltrace_iter *iter);
  84
  85 /*
  86  * babeltrace_iter_save_pos - Save the current trace collection position.
  87  *
  88  * The position returned by this function needs to be freed by
  89  * babeltrace_iter_free_pos after use.
  90  */
  91 struct trace_collection_pos *
  92         babeltrace_iter_save_pos(struct babeltrace_iter *iter);
  93
  94 /*
  95  * babeltrace_iter_free_pos - Free the position.
  96  */
  97 void babeltrace_iter_free_pos(struct trace_collection_pos *pos);
  98
  99 /*
 100  * babeltrace_iter_seek: seek iterator to given position.
 101  *
 102  * Return EOF if position is after the last event of the trace collection.
 103  * Return other negative value for other errors.
 104  * Return 0 for success.
 105  */
 106 int babeltrace_iter_seek(struct babeltrace_iter *iter,
 107                 const struct trace_collection_pos *pos);
 108
 109 /*
 110  * babeltrace_iter_read_event: Read the iterator's current event data.
 111  *
 112  * @iter: trace collection iterator (input)
 113  * @stream: stream containing event at current position (output)
 114  * @event: current event (output)
 115  * Return 0 on success, negative error value on error.
 116  */
 117 int babeltrace_iter_read_event(struct babeltrace_iter *iter,
 118                 struct ctf_stream **stream,
 119                 struct ctf_stream_event **event);
 120
 121 /*
 122  * Receives a variable number of strings as parameter, ended with NULL.
 123  */
 124 struct bt_dependencies *babeltrace_dependencies_create(const char *first, ...);
 125
 126 /*
 127  * struct bt_dependencies must be destroyed explicitly if not passed as
 128  * parameter to a babeltrace_iter_add_callback().
 129  */
 130 void babeltrace_dependencies_destroy(struct bt_dependencies *dep);
 131
 132 /*
 133  * babeltrace_iter_add_callback: Add a callback to iterator.
 134  *
 135  * @iter: trace collection iterator (input)
 136  * @event: event to target. 0 for all events.
 137  * @private_data: private data pointer to pass to the callback
 138  * @flags: specific flags controlling the behavior of this callback
 139  *         (or'd).
 140  *
 141  * @callback: function pointer to call
 142  * @depends: struct bt_dependency detailing the required computation results.
 143  *           Ends with 0.
 144  * @weak_depends: struct bt_dependency detailing the optional computation
 145  *                results that can be optionally consumed by this
 146  *                callback.
 147  * @provides: struct bt_dependency detailing the computation results
 148  *            provided by this callback.
 149  *            Ends with 0.
 150  *
 151  * "depends", "weak_depends" and "provides" memory is handled by the
 152  * babeltrace library after this call succeeds or fails. These objects
 153  * can still be used by the caller until the babeltrace iterator is
 154  * destroyed, but they belong to the babeltrace library.
 155  *
 156  * (note to implementor: we need to keep a gptrarray of struct
 157  * bt_dependencies to "garbage collect" in struct babeltrace_iter, and
 158  * dependencies need to have a refcount to handle the case where they
 159  * would be passed to more than one iterator. Upon iterator detroy, we
 160  * iterate on all the gc ptrarray and decrement the refcounts, freeing
 161  * if we reach 0.)
 162  * (note to implementor: we calculate the dependency graph when
 163  * babeltrace_iter_read_event() is executed after a
 164  * babeltrace_iter_add_callback(). Beware that it is valid to create/add
 165  * callbacks/read/add more callbacks/read some more.)
 166  */
 167 int babeltrace_iter_add_callback(struct babeltrace_iter *iter,
 168                 bt_event_name event, void *private_data, int flags,
 169                 enum bt_cb_ret (*callback)(struct bt_ctf_data *ctf_data,
 170                                            void *caller_data),
 171                 struct bt_dependencies *depends,
 172                 struct bt_dependencies *weak_depends,
 173                 struct bt_dependencies *provides);
 174
 175 /*
 176  * For flags parameter above.
 177  */
 178 enum {
 179         BT_FLAGS_FREE_PRIVATE_DATA      = (1 << 0),
 180 };
 181
 182 #endif /* _BABELTRACE_H */