include/babeltrace/context.h

   1 #ifndef _BABELTRACE_CONTEXT_H
   2 #define _BABELTRACE_CONTEXT_H
   3
   4 /*
   5  * BabelTrace
   6  *
   7  * context header
   8  *
   9  * Copyright 2012 EfficiOS Inc. and Linux Foundation
  10  *
  11  * Author: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
  12  *         Julien Desfossez <julien.desfossez@efficios.com>
  13  *
  14  * Permission is hereby granted, free of charge, to any person obtaining
  15  * a copy of this software and associated documentation files (the
  16  * "Software"), to deal in the Software without restriction, including
  17  * without limitation the rights to use, copy, modify, merge, publish,
  18  * distribute, sublicense, and/or sell copies of the Software, and to
  19  * permit persons to whom the Software is furnished to do so, subject to
  20  * the following conditions:
  21  *
  22  * The above copyright notice and this permission notice shall be
  23  * included in all copies or substantial portions of the Software.
  24  *
  25  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  26  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  27  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  28  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  29  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  30  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  31  * SOFTWARE.
  32  */
  33
  34 #include <unistd.h>
  35 #include <babeltrace/format.h>
  36
  37 #ifdef __cplusplus
  38 extern "C" {
  39 #endif
  40
  41 /* struct bt_context is opaque to the user */
  42 struct bt_context;
  43 struct bt_stream_pos;
  44 struct bt_ctf_event;
  45
  46 /*
  47  * bt_context_create : create a Babeltrace context
  48  *
  49  * Allocate a new context. The creation of the context sets the refcount
  50  * to 1.
  51  *
  52  * Returns an allocated context on success and NULL on error
  53  */
  54 struct bt_context *bt_context_create(void);
  55
  56 /*
  57  * bt_context_add_trace : Add a trace by path to the context
  58  *
  59  * Open a trace.
  60  *
  61  * path is the path to the trace, it is not recursive. If "path" is NULL,
  62  * stream_list is used instead as a list of mmap streams to open for the trace.
  63  *
  64  * format is a string containing the format name in which the trace was
  65  * produced.
  66  *
  67  * packet_seek can be NULL to use the default packet_seek handler provided by
  68  * the trace format. If non-NULL, it is used as an override of the handler for
  69  * seeks across packets. It takes as parameter a stream position, the packet
  70  * index it needs to seek to (for SEEK_SET), and a "whence" parameter (either
  71  * SEEK_CUR: seek to next packet, or SEEK_SET: seek to packet at packet index).
  72  *
  73  * stream_list is a linked list of streams, it is used to open a trace where
  74  * the trace data is located in memory mapped areas instead of trace files,
  75  * this argument should be non-NULL when path is NULL.
  76  *
  77  * The metadata parameter acts as a metadata override when not NULL, otherwise
  78  * the format handles the metadata opening.
  79  *
  80  * Return: the trace handle id (>= 0) on success, a negative
  81  * value on error.
  82  */
  83 int bt_context_add_trace(struct bt_context *ctx, const char *path,
  84                 const char *format,
  85                 void (*packet_seek)(struct bt_stream_pos *pos,
  86                         size_t index, int whence),
  87                 struct bt_mmap_stream_list *stream_list,
  88                 FILE *metadata);
  89
  90 /*
  91  * bt_context_remove_trace: Remove a trace from the context.
  92  *
  93  * Effectively closing the trace. Return negative error value if trace
  94  * is not in context.
  95  */
  96 int bt_context_remove_trace(struct bt_context *ctx, int trace_id);
  97
  98 /*
  99  * bt_context_get and bt_context_put : increments and decrement the
 100  * refcount of the context
 101  *
 102  * These functions ensures that the context won't be destroyed when it
 103  * is in use. The same number of get and put (plus one extra put to
 104  * release the initial reference done at creation) has to be done to
 105  * destroy a context.
 106  *
 107  * When the context refcount is decremented to 0 by a bt_context_put,
 108  * the context is freed.
 109  */
 110 void bt_context_get(struct bt_context *ctx);
 111 void bt_context_put(struct bt_context *ctx);
 112
 113 /*
 114  * bt_ctf_get_context : get the context associated with an event
 115  *
 116  * Returns NULL on error
 117  */
 118 struct bt_context *bt_ctf_event_get_context(const struct bt_ctf_event *event);
 119
 120 #ifdef __cplusplus
 121 }
 122 #endif
 123
 124 #endif /* _BABELTRACE_CONTEXT_H */