Merge branch 'master' into bindings/python
[babeltrace.git] / lib / registry.c
1 /*
2 * BabelTrace
3 *
4 * Format Registry
5 *
6 * Copyright 2010-2011 EfficiOS Inc. and Linux Foundation
7 *
8 * Author: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
9 *
10 * Permission is hereby granted, free of charge, to any person obtaining a copy
11 * of this software and associated documentation files (the "Software"), to deal
12 * in the Software without restriction, including without limitation the rights
13 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
14 * copies of the Software, and to permit persons to whom the Software is
15 * furnished to do so, subject to the following conditions:
16 *
17 * The above copyright notice and this permission notice shall be included in
18 * all copies or substantial portions of the Software.
19 *
20 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
21 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
23 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
24 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
25 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
26 * SOFTWARE.
27 */
28
29 #include <babeltrace/format.h>
30 #include <glib.h>
31 #include <errno.h>
32 #include <stdio.h>
33 #include <assert.h>
34
35 struct walk_data {
36 FILE *fp;
37 int iter;
38 };
39
40 /*
41 * Format registry hash table contains the registered formats. Format
42 * registration is typically performed by a format plugin.
43 */
44 static GHashTable *format_registry;
45 static int format_refcount;
46 static int init_done;
47
48 static __attribute__((constructor)) void format_init(void);
49
50 static
51 void format_refcount_inc(void)
52 {
53 format_refcount++;
54 }
55
56 static
57 void format_cleanup(void)
58 {
59 if (format_registry)
60 g_hash_table_destroy(format_registry);
61 }
62
63 static
64 void format_refcount_dec(void)
65 {
66 if (!--format_refcount)
67 format_cleanup();
68 }
69
70 struct format *bt_lookup_format(bt_intern_str name)
71 {
72 if (!init_done)
73 return NULL;
74
75 return g_hash_table_lookup(format_registry,
76 (gconstpointer) (unsigned long) name);
77 }
78
79 static void show_format(gpointer key, gpointer value, gpointer user_data)
80 {
81 struct walk_data *data = user_data;
82
83 fprintf(data->fp, "%s%s", data->iter ? ", " : "",
84 g_quark_to_string((GQuark) (unsigned long) key));
85 data->iter++;
86 }
87
88 void bt_fprintf_format_list(FILE *fp)
89 {
90 struct walk_data data;
91
92 assert(fp);
93
94 data.fp = fp;
95 data.iter = 0;
96
97 fprintf(fp, "Formats available: ");
98 if (!init_done)
99 return;
100 g_hash_table_foreach(format_registry, show_format, &data);
101 if (data.iter == 0)
102 fprintf(fp, "<none>");
103 fprintf(fp, ".\n");
104 }
105
106 int bt_register_format(struct format *format)
107 {
108 if (!format)
109 return -EINVAL;
110
111 if (!init_done)
112 format_init();
113
114 if (bt_lookup_format(format->name))
115 return -EEXIST;
116
117 format_refcount_inc();
118 g_hash_table_insert(format_registry,
119 (gpointer) (unsigned long) format->name,
120 format);
121 return 0;
122 }
123
124 void bt_unregister_format(struct format *format)
125 {
126 assert(bt_lookup_format(format->name));
127 g_hash_table_remove(format_registry,
128 (gpointer) (unsigned long) format->name);
129 format_refcount_dec();
130 }
131
132 /*
133 * We cannot assume that the constructor and destructor order will be
134 * right: another library might be loaded before us, and initialize us
135 * from bt_register_format(). This is why we use a reference count to
136 * handle cleanup of this module. The format_finalize destructor
137 * refcount decrement matches format_init refcount increment.
138 */
139 static __attribute__((constructor))
140 void format_init(void)
141 {
142 if (init_done)
143 return;
144 format_refcount_inc();
145 format_registry = g_hash_table_new(g_direct_hash, g_direct_equal);
146 assert(format_registry);
147 init_done = 1;
148 }
149
150 static __attribute__((destructor))
151 void format_finalize(void)
152 {
153 format_refcount_dec();
154 }
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