bc7de3a0e84c5de89967cae08cc020d7e18145ac
[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 #ifdef __cplusplus
30 extern "C" {
31 #endif
32
33 /* struct bt_context is opaque to the user */
34 struct bt_context;
35 struct stream_pos;
36 struct bt_ctf_event;
37
38 /*
39 * bt_context_create : create a Babeltrace context
40 *
41 * Allocate a new context. The creation of the context sets the refcount
42 * to 1.
43 *
44 * Returns an allocated context on success and NULL on error
45 */
46 struct bt_context *bt_context_create(void);
47
48 /*
49 * bt_context_add_trace : Add a trace by path to the context
50 *
51 * Open a trace.
52 *
53 * path is the path to the trace, it is not recursive. If "path" is NULL,
54 * stream_list is used instead as a list of mmap streams to open for the trace.
55 *
56 * format is a string containing the format name in which the trace was
57 * produced.
58 *
59 * packet_seek can be NULL to use the default packet_seek handler provided by
60 * the trace format. If non-NULL, it is used as an override of the handler for
61 * seeks across packets. It takes as parameter a stream position, the packet
62 * index it needs to seek to (for SEEK_SET), and a "whence" parameter (either
63 * SEEK_CUR: seek to next packet, or SEEK_SET: seek to packet at packet index).
64 *
65 * stream_list is a linked list of streams, it is used to open a trace where
66 * the trace data is located in memory mapped areas instead of trace files,
67 * this argument should be set to NULL when path is NULL.
68 *
69 * The metadata parameter acts as a metadata override when not NULL, otherwise
70 * the format handles the metadata opening.
71 *
72 * Return: the trace handle id (>= 0) on success, a negative
73 * value on error.
74 */
75 int bt_context_add_trace(struct bt_context *ctx, const char *path,
76 const char *format,
77 void (*packet_seek)(struct stream_pos *pos,
78 size_t index, int whence),
79 struct mmap_stream_list *stream_list,
80 FILE *metadata);
81
82 /*
83 * bt_context_remove_trace: Remove a trace from the context.
84 *
85 * Effectively closing the trace. Return negative error value if trace
86 * is not in context.
87 */
88 int bt_context_remove_trace(struct bt_context *ctx, int trace_id);
89
90 /*
91 * bt_context_get and bt_context_put : increments and decrement the
92 * refcount of the context
93 *
94 * These functions ensures that the context won't be destroyed when it
95 * is in use. The same number of get and put (plus one extra put to
96 * release the initial reference done at creation) has to be done to
97 * destroy a context.
98 *
99 * When the context refcount is decremented to 0 by a bt_context_put,
100 * the context is freed.
101 */
102 void bt_context_get(struct bt_context *ctx);
103 void bt_context_put(struct bt_context *ctx);
104
105 /*
106 * bt_ctf_get_context : get the context associated with an event
107 *
108 * Returns NULL on error
109 */
110 struct bt_context *bt_ctf_event_get_context(const struct bt_ctf_event *event);
111
112 #ifdef __cplusplus
113 }
114 #endif
115
116 #endif /* _BABELTRACE_CONTEXT_H */
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