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