Fix comment in context.h
[babeltrace.git] / 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 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 stream_pos *pos,
86 size_t index, int whence),
87 struct 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 */
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