4ad1797134e890e82b66e531e165f696f61286b6
[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
26 #include <unistd.h>
27 #include <babeltrace/format.h>
28
29 /* struct bt_context is opaque to the user */
30 struct bt_context;
31 struct stream_pos;
32
33 /*
34 * bt_context_create : create a Babeltrace context
35 *
36 * Allocate a new context. The creation of the context sets the refcount
37 * to 1.
38 *
39 * Returns an allocated context on success and NULL on error
40 */
41 struct bt_context *bt_context_create(void);
42
43 /*
44 * bt_context_add_trace : Add a trace by path to the context
45 *
46 * Open a trace.
47 *
48 * packet_seek can be NULL to use the default packet_seek handler
49 * provided by the trace format. If non-NULL, it is used as an override
50 * of the handler for seeks across packets. It takes as parameter a
51 * stream position, the packet index it needs to seek to (for SEEK_SET),
52 * and a "whence" parameter (either SEEK_CUR: seek to next packet, or
53 * SEEK_SET: seek to packet at packet index).
54 *
55 * If "path" is NULL, stream_list is used instread as a list of streams
56 * to open for the trace.
57
58 * The metadata parameter acts as a metadata override when not NULL.
59 *
60 * Return: the trace handle id (>= 0) on success, a negative
61 * value on error.
62 */
63 int bt_context_add_trace(struct bt_context *ctx, const char *path,
64 const char *format,
65 void (*packet_seek)(struct stream_pos *pos,
66 size_t index, int whence),
67 struct mmap_stream_list *stream_list,
68 FILE *metadata);
69
70 /*
71 * bt_context_remove_trace: Remove a trace from the context.
72 *
73 * Effectively closing the trace.
74 */
75 void bt_context_remove_trace(struct bt_context *ctx, int trace_id);
76
77 /*
78 * bt_context_get and bt_context_put : increments and decrement the
79 * refcount of the context
80 *
81 * These functions ensures that the context won't be destroyed when it
82 * is in use. The same number of get and put (plus one extra put to
83 * release the initial reference done at creation) has to be done to
84 * destroy a context.
85 *
86 * When the context refcount is decremented to 0 by a bt_context_put,
87 * the context is freed.
88 */
89 void bt_context_get(struct bt_context *ctx);
90 void bt_context_put(struct bt_context *ctx);
91
92 #endif /* _BABELTRACE_CONTEXT_H */
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