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 #include <babeltrace/format.h>
  23 #include <babeltrace/context.h>
  24
  25 typedef GQuark bt_event_name;
  26
  27 /* Forward declarations */
  28 struct babeltrace_iter;
  29 struct trace_collection;
  30 struct ctf_stream_event;
  31 struct ctf_stream;
  32 struct babeltrace_saved_pos;
  33 struct bt_dependencies;
  34 struct bt_context;
  35
  36 enum bt_cb_ret {
  37         BT_CB_OK                = 0,
  38         BT_CB_OK_STOP           = 1,
  39         BT_CB_ERROR_STOP        = 2,
  40         BT_CB_ERROR_CONTINUE    = 3,
  41 };
  42
  43 struct trace_collection_pos {
  44         enum {
  45                 BT_SEEK_TIME,           /* uses u.seek_time */
  46                 BT_SEEK_RESTORE,        /* uses u.restore */
  47                 BT_SEEK_CUR,
  48                 BT_SEEK_BEGIN,
  49                 BT_SEEK_END,
  50         } type;
  51         union {
  52                 uint64_t seek_time;
  53                 struct babeltrace_saved_pos *restore;
  54         } u;
  55 };
  56
  57 struct bt_ctf_data {
  58         struct ctf_stream_event *event;
  59         struct ctf_stream *stream;
  60 };
  61
  62 /*
  63  * babeltrace_iter_create - Allocate a trace collection iterator.
  64  *
  65  * begin_pos and end_pos are optional parameters to specify the position
  66  * at which the trace collection should be seeked upon iterator
  67  * creation, and the position at which iteration will start returning
  68  * "EOF".
  69  *
  70  * By default, if begin_pos is NULL, a BT_SEEK_CUR is performed at
  71  * creation. By default, if end_pos is NULL, a BT_SEEK_END (end of
  72  * trace) is the EOF criterion.
  73  */
  74 struct babeltrace_iter *babeltrace_iter_create(struct bt_context *ctx,
  75                 struct trace_collection_pos *begin_pos,
  76                 struct trace_collection_pos *end_pos);
  77
  78 /*
  79  * babeltrace_iter_destroy - Free a trace collection iterator.
  80  */
  81 void babeltrace_iter_destroy(struct babeltrace_iter *iter);
  82
  83 /*
  84  * babeltrace_iter_next: Move trace collection position to the next event.
  85  *
  86  * Returns 0 on success, a negative value on error
  87  */
  88 int babeltrace_iter_next(struct babeltrace_iter *iter);
  89
  90 /*
  91  * babeltrace_iter_save_pos - Save the current trace collection position.
  92  *
  93  * The position returned by this function needs to be freed by
  94  * babeltrace_iter_free_pos after use.
  95  */
  96 struct trace_collection_pos *
  97         babeltrace_iter_save_pos(struct babeltrace_iter *iter);
  98
  99 /*
 100  * babeltrace_iter_free_pos - Free the position.
 101  */
 102 void babeltrace_iter_free_pos(struct trace_collection_pos *pos);
 103
 104 /*
 105  * babeltrace_iter_seek: seek iterator to given position.
 106  *
 107  * Return EOF if position is after the last event of the trace collection.
 108  * Return other negative value for other errors.
 109  * Return 0 for success.
 110  */
 111 int babeltrace_iter_seek(struct babeltrace_iter *iter,
 112                 const struct trace_collection_pos *pos);
 113
 114 /*
 115  * babeltrace_iter_read_event: Read the iterator's current event data.
 116  *
 117  * @iter: trace collection iterator (input)
 118  * @stream: stream containing event at current position (output)
 119  * @event: current event (output)
 120  * Return 0 on success, negative error value on error.
 121  */
 122 int babeltrace_iter_read_event(struct babeltrace_iter *iter,
 123                 struct ctf_stream **stream,
 124                 struct ctf_stream_event **event);
 125
 126 /*
 127  * Receives a variable number of strings as parameter, ended with NULL.
 128  */
 129 struct bt_dependencies *babeltrace_dependencies_create(const char *first, ...);
 130
 131 /*
 132  * struct bt_dependencies must be destroyed explicitly if not passed as
 133  * parameter to a babeltrace_iter_add_callback().
 134  */
 135 void babeltrace_dependencies_destroy(struct bt_dependencies *dep);
 136
 137 /*
 138  * babeltrace_iter_add_callback: Add a callback to iterator.
 139  *
 140  * @iter: trace collection iterator (input)
 141  * @event: event to target. 0 for all events.
 142  * @private_data: private data pointer to pass to the callback
 143  * @flags: specific flags controlling the behavior of this callback
 144  *         (or'd).
 145  *
 146  * @callback: function pointer to call
 147  * @depends: struct bt_dependency detailing the required computation results.
 148  *           Ends with 0.
 149  * @weak_depends: struct bt_dependency detailing the optional computation
 150  *                results that can be optionally consumed by this
 151  *                callback.
 152  * @provides: struct bt_dependency detailing the computation results
 153  *            provided by this callback.
 154  *            Ends with 0.
 155  *
 156  * "depends", "weak_depends" and "provides" memory is handled by the
 157  * babeltrace library after this call succeeds or fails. These objects
 158  * can still be used by the caller until the babeltrace iterator is
 159  * destroyed, but they belong to the babeltrace library.
 160  *
 161  * (note to implementor: we need to keep a gptrarray of struct
 162  * bt_dependencies to "garbage collect" in struct babeltrace_iter, and
 163  * dependencies need to have a refcount to handle the case where they
 164  * would be passed to more than one iterator. Upon iterator detroy, we
 165  * iterate on all the gc ptrarray and decrement the refcounts, freeing
 166  * if we reach 0.)
 167  * (note to implementor: we calculate the dependency graph when
 168  * babeltrace_iter_read_event() is executed after a
 169  * babeltrace_iter_add_callback(). Beware that it is valid to create/add
 170  * callbacks/read/add more callbacks/read some more.)
 171  */
 172 int babeltrace_iter_add_callback(struct babeltrace_iter *iter,
 173                 bt_event_name event, void *private_data, int flags,
 174                 enum bt_cb_ret (*callback)(struct bt_ctf_data *ctf_data,
 175                                            void *caller_data),
 176                 struct bt_dependencies *depends,
 177                 struct bt_dependencies *weak_depends,
 178                 struct bt_dependencies *provides);
 179
 180 /*
 181  * For flags parameter above.
 182  */
 183 enum {
 184         BT_FLAGS_FREE_PRIVATE_DATA      = (1 << 0),
 185 };
 186
 187 #endif /* _BABELTRACE_H */