external/bsd/libevent/dist/defer-internal.h

   1 /*      $NetBSD: defer-internal.h,v 1.1.1.1 2013/04/11 16:43:21 christos Exp $  */
   2 /*
   3  * Copyright (c) 2009-2012 Niels Provos and Nick Mathewson
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. The name of the author may not be used to endorse or promote products
  14  *    derived from this software without specific prior written permission.
  15  *
  16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  26  */
  27 #ifndef _DEFER_INTERNAL_H_
  28 #define _DEFER_INTERNAL_H_
  29
  30 #ifdef __cplusplus
  31 extern "C" {
  32 #endif
  33
  34 #include "event2/event-config.h"
  35 #include <sys/queue.h>
  36
  37 struct deferred_cb;
  38
  39 typedef void (*deferred_cb_fn)(struct deferred_cb *, void *);
  40
  41 /** A deferred_cb is a callback that can be scheduled to run as part of
  42  * an event_base's event_loop, rather than running immediately. */
  43 struct deferred_cb {
  44         /** Links to the adjacent active (pending) deferred_cb objects. */
  45         TAILQ_ENTRY (deferred_cb) cb_next;
  46         /** True iff this deferred_cb is pending in an event_base. */
  47         unsigned queued : 1;
  48         /** The function to execute when the callback runs. */
  49         deferred_cb_fn cb;
  50         /** The function's second argument. */
  51         void *arg;
  52 };
  53
  54 /** A deferred_cb_queue is a list of deferred_cb that we can add to and run. */
  55 struct deferred_cb_queue {
  56         /** Lock used to protect the queue. */
  57         void *lock;
  58
  59         /** How many entries are in the queue? */
  60         int active_count;
  61
  62         /** Function called when adding to the queue from another thread. */
  63         void (*notify_fn)(struct deferred_cb_queue *, void *);
  64         void *notify_arg;
  65
  66         /** Deferred callback management: a list of deferred callbacks to
  67          * run active the active events. */
  68         TAILQ_HEAD (deferred_cb_list, deferred_cb) deferred_cb_list;
  69 };
  70
  71 /**
  72    Initialize an empty, non-pending deferred_cb.
  73
  74    @param deferred The deferred_cb structure to initialize.
  75    @param cb The function to run when the deferred_cb executes.
  76    @param arg The function's second argument.
  77  */
  78 void event_deferred_cb_init(struct deferred_cb *, deferred_cb_fn, void *);
  79 /**
  80    Cancel a deferred_cb if it is currently scheduled in an event_base.
  81  */
  82 void event_deferred_cb_cancel(struct deferred_cb_queue *, struct deferred_cb *);
  83 /**
  84    Activate a deferred_cb if it is not currently scheduled in an event_base.
  85  */
  86 void event_deferred_cb_schedule(struct deferred_cb_queue *, struct deferred_cb *);
  87
  88 #define LOCK_DEFERRED_QUEUE(q)                                          \
  89         EVLOCK_LOCK((q)->lock, 0)
  90 #define UNLOCK_DEFERRED_QUEUE(q)                                        \
  91         EVLOCK_UNLOCK((q)->lock, 0)
  92
  93 #ifdef __cplusplus
  94 }
  95 #endif
  96
  97 void event_deferred_cb_queue_init(struct deferred_cb_queue *);
  98 struct deferred_cb_queue *event_base_get_deferred_cb_queue(struct event_base *);
  99
 100 #endif /* _EVENT_INTERNAL_H_ */
 101