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 #include <stdint.h>
  22
  23 typedef GQuark bt_event_name;
  24
  25 /* Forward declarations */
  26 struct babeltrace_iter;
  27 struct trace_collection;
  28 struct ctf_stream_event;
  29 struct ctf_stream;
  30 struct babeltrace_saved_pos;
  31 struct bt_dependencies;
  32
  33 enum bt_cb_ret {
  34         BT_CB_OK                = 0,
  35         BT_CB_OK_STOP           = 1,
  36         BT_CB_ERROR_STOP        = 2,
  37         BT_CB_ERROR_CONTINUE    = 3,
  38 };
  39
  40 struct trace_collection_pos {
  41         enum {
  42                 BT_SEEK_TIME,           /* uses u.seek_time */
  43                 BT_SEEK_RESTORE,        /* uses u.restore */
  44                 BT_SEEK_CUR,
  45                 BT_SEEK_BEGIN,
  46                 BT_SEEK_END,
  47         } type;
  48         union {
  49                 uint64_t seek_time;
  50                 struct babeltrace_saved_pos *restore;
  51         } u;
  52 };
  53
  54 struct bt_ctf_data {
  55         struct ctf_stream_event *event;
  56 };
  57
  58 /*
  59  * babeltrace_iter_create - Allocate a trace collection iterator.
  60  *
  61  * begin_pos and end_pos are optional parameters to specify the position
  62  * at which the trace collection should be seeked upon iterator
  63  * creation, and the position at which iteration will start returning
  64  * "EOF".
  65  *
  66  * By default, if begin_pos is NULL, a BT_SEEK_CUR is performed at
  67  * creation. By default, if end_pos is NULL, a BT_SEEK_END (end of
  68  * trace) is the EOF criterion.
  69  */
  70 struct babeltrace_iter *babeltrace_iter_create(struct trace_collection *tc,
  71                 struct trace_collection_pos *begin_pos,
  72                 struct trace_collection_pos *end_pos);
  73
  74 /*
  75  * babeltrace_iter_destroy - Free a trace collection iterator.
  76  */
  77 void babeltrace_iter_destroy(struct babeltrace_iter *iter);
  78
  79 /*
  80  * babeltrace_iter_next: Move trace collection position to the next event.
  81  *
  82  * Returns 0 on success, a negative value on error
  83  */
  84 int babeltrace_iter_next(struct babeltrace_iter *iter);
  85
  86 /*
  87  * babeltrace_iter_save_pos - Save the current trace collection position.
  88  *
  89  * The position returned by this function needs to be freed by
  90  * babeltrace_iter_free_pos after use.
  91  */
  92 struct trace_collection_pos *
  93         babeltrace_iter_save_pos(struct babeltrace_iter *iter);
  94
  95 /*
  96  * babeltrace_iter_free_pos - Free the position.
  97  */
  98 void babeltrace_iter_free_pos(struct trace_collection_pos *pos);
  99
 100 /*
 101  * babeltrace_iter_seek: seek iterator to given position.
 102  *
 103  * Return EOF if position is after the last event of the trace collection.
 104  * Return other negative value for other errors.
 105  * Return 0 for success.
 106  */
 107 int babeltrace_iter_seek(struct babeltrace_iter *iter,
 108                 const struct trace_collection_pos *pos);
 109
 110 /*
 111  * babeltrace_iter_read_event: Read the iterator's current event data.
 112  *
 113  * @iter: trace collection iterator (input)
 114  * @stream: stream containing event at current position (output)
 115  * @event: current event (output)
 116  * Return 0 on success, negative error value on error.
 117  */
 118 int babeltrace_iter_read_event(struct babeltrace_iter *iter,
 119                 struct ctf_stream **stream,
 120                 struct ctf_stream_event **event);
 121
 122 /*
 123  * Receives a variable number of strings as parameter, ended with NULL.
 124  */
 125 struct bt_dependencies *babeltrace_dependencies_create(const char *first, ...);
 126
 127 /*
 128  * struct bt_dependencies must be destroyed explicitly if not passed as
 129  * parameter to a babeltrace_iter_add_callback().
 130  */
 131 void babeltrace_dependencies_destroy(struct bt_dependencies *dep);
 132
 133 /*
 134  * babeltrace_iter_add_callback: Add a callback to iterator.
 135  *
 136  * @iter: trace collection iterator (input)
 137  * @event: event to target. 0 for all events.
 138  * @private_data: private data pointer to pass to the callback
 139  * @flags: specific flags controlling the behavior of this callback
 140  *         (or'd).
 141  *
 142  * @callback: function pointer to call
 143  * @depends: struct bt_dependency detailing the required computation results.
 144  *           Ends with 0.
 145  * @weak_depends: struct bt_dependency detailing the optional computation
 146  *                results that can be optionally consumed by this
 147  *                callback.
 148  * @provides: struct bt_dependency detailing the computation results
 149  *            provided by this callback.
 150  *            Ends with 0.
 151  *
 152  * "depends", "weak_depends" and "provides" memory is handled by the
 153  * babeltrace library after this call succeeds or fails. These objects
 154  * can still be used by the caller until the babeltrace iterator is
 155  * destroyed, but they belong to the babeltrace library.
 156  *
 157  * (note to implementor: we need to keep a gptrarray of struct
 158  * bt_dependencies to "garbage collect" in struct babeltrace_iter, and
 159  * dependencies need to have a refcount to handle the case where they
 160  * would be passed to more than one iterator. Upon iterator detroy, we
 161  * iterate on all the gc ptrarray and decrement the refcounts, freeing
 162  * if we reach 0.)
 163  * (note to implementor: we calculate the dependency graph when
 164  * babeltrace_iter_read_event() is executed after a
 165  * babeltrace_iter_add_callback(). Beware that it is valid to create/add
 166  * callbacks/read/add more callbacks/read some more.)
 167  */
 168 int babeltrace_iter_add_callback(struct babeltrace_iter *iter,
 169                 bt_event_name event, void *private_data, int flags,
 170                 enum bt_cb_ret (*callback)(struct bt_ctf_data *ctf_data,
 171                                            void *caller_data),
 172                 struct bt_dependencies *depends,
 173                 struct bt_dependencies *weak_depends,
 174                 struct bt_dependencies *provides);
 175
 176 /*
 177  * For flags parameter above.
 178  */
 179 enum {
 180         BT_FLAGS_FREE_PRIVATE_DATA      = (1 << 0),
 181 };
 182
 183 #endif /* _BABELTRACE_H */