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