1 /*
2 * Copyright (c) 2009-2012 Niels Provos and Nick Mathewson
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 * 3. The name of the author may not be used to endorse or promote products
13 * derived from this software without specific prior written permission.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
16 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
17 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
18 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
19 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
20 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
21 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
22 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
23 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
24 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
25 */
26 #ifndef _DEFER_INTERNAL_H_
27 #define _DEFER_INTERNAL_H_
28
29 #ifdef __cplusplus
30 extern "C" {
31 #endif
32
33 #include "event2/event-config.h"
34 #include <sys/queue.h>
35
36 struct deferred_cb;
37
38 typedef void (*deferred_cb_fn)(struct deferred_cb *, void *);
39
40 /** A deferred_cb is a callback that can be scheduled to run as part of
41 * an event_base's event_loop, rather than running immediately. */
42 struct deferred_cb {
43 /** Links to the adjacent active (pending) deferred_cb objects. */
44 TAILQ_ENTRY (deferred_cb) cb_next;
45 /** True iff this deferred_cb is pending in an event_base. */
46 unsigned queued : 1;
47 /** The function to execute when the callback runs. */
48 deferred_cb_fn cb;
49 /** The function's second argument. */
50 void *arg;
51 };
52
53 /** A deferred_cb_queue is a list of deferred_cb that we can add to and run. */
54 struct deferred_cb_queue {
55 /** Lock used to protect the queue. */
56 void *lock;
57
58 /** How many entries are in the queue? */
59 int active_count;
60
61 /** Function called when adding to the queue from another thread. */
62 void (*notify_fn)(struct deferred_cb_queue *, void *);
63 void *notify_arg;
64
65 /** Deferred callback management: a list of deferred callbacks to
66 * run active the active events. */
67 TAILQ_HEAD (deferred_cb_list, deferred_cb) deferred_cb_list;
68 };
69
70 /**
71 Initialize an empty, non-pending deferred_cb.
72
73 @param deferred The deferred_cb structure to initialize.
74 @param cb The function to run when the deferred_cb executes.
75 @param arg The function's second argument.
76 */
77 void event_deferred_cb_init(struct deferred_cb *, deferred_cb_fn, void *);
78 /**
79 Cancel a deferred_cb if it is currently scheduled in an event_base.
80 */
81 void event_deferred_cb_cancel(struct deferred_cb_queue *, struct deferred_cb *);
82 /**
83 Activate a deferred_cb if it is not currently scheduled in an event_base.
84 */
85 void event_deferred_cb_schedule(struct deferred_cb_queue *, struct deferred_cb *);
86
87 #define LOCK_DEFERRED_QUEUE(q) \
88 EVLOCK_LOCK((q)->lock, 0)
89 #define UNLOCK_DEFERRED_QUEUE(q) \
90 EVLOCK_UNLOCK((q)->lock, 0)
91
92 #ifdef __cplusplus
93 }
94 #endif
95
96 void event_deferred_cb_queue_init(struct deferred_cb_queue *);
97 struct deferred_cb_queue *event_base_get_deferred_cb_queue(struct event_base *);
98
99 #endif /* _EVENT_INTERNAL_H_ */
100