2009-04-10 14:22:33 +00:00
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/*
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2012-02-10 17:29:53 -05:00
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* Copyright (c) 2009-2012 Niels Provos and Nick Mathewson
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2009-04-10 14:22:33 +00:00
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote products
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* derived from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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2012-02-29 15:07:31 -05:00
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#ifndef DEFER_INTERNAL_H_INCLUDED_
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#define DEFER_INTERNAL_H_INCLUDED_
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2009-04-10 14:22:33 +00:00
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#ifdef __cplusplus
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extern "C" {
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#endif
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2010-07-07 16:45:03 -04:00
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#include "event2/event-config.h"
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2011-01-02 08:43:45 -07:00
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#include "evconfig-private.h"
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2009-04-10 14:22:33 +00:00
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#include <sys/queue.h>
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2012-04-06 04:33:19 -04:00
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struct event_callback;
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typedef void (*deferred_cb_fn)(struct event_callback *, void *);
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2009-07-26 01:29:39 +00:00
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2009-04-17 06:55:08 +00:00
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/**
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2012-04-06 11:05:35 -04:00
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Initialize an empty, non-pending event_callback.
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2009-04-17 06:55:08 +00:00
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2012-04-06 11:05:35 -04:00
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@param deferred The struct event_callback structure to initialize.
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Restore our priority-inversion-prevention code with deferreds
Back when deferred_cb stuff had its own queue, the queue was always
executed, but we never ran more than 16 callbacks per iteration.
That made for two problems:
1: Because deferred_cb stuff would always run, and had no priority,
it could cause priority inversion.
2: It doesn't respect the max_dispatch_interval code.
Then, when I refactored deferred_cb to be a special case of
event_callback, that solved the above issues, but made for two more
issues:
3: Because deferred_cb stuff would always get the default priority,
it could could low-priority bufferevents to get too much priority.
4: With code like bufferevent_pair, it's easy to get into a
situation where two deferreds keep adding one another, preventing
the event loop from ever actually scanning for more events.
This commit fixes the above by giving deferreds a better notion of
priorities, and by limiting the number of deferreds that can be
added to the _current_ loop iteration's active queues. (Extra
deferreds are put into the active_later state.)
That isn't an all-purpose priority inversion solution, of course: for
that, you may need to mess around with max_dispatch_interval.
2012-05-09 11:06:06 -04:00
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@param priority The priority that the callback should run at.
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2012-04-06 11:05:35 -04:00
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@param cb The function to run when the struct event_callback executes.
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2009-04-17 06:55:08 +00:00
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@param arg The function's second argument.
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*/
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2017-03-12 20:50:35 +03:00
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EVENT2_EXPORT_SYMBOL
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Restore our priority-inversion-prevention code with deferreds
Back when deferred_cb stuff had its own queue, the queue was always
executed, but we never ran more than 16 callbacks per iteration.
That made for two problems:
1: Because deferred_cb stuff would always run, and had no priority,
it could cause priority inversion.
2: It doesn't respect the max_dispatch_interval code.
Then, when I refactored deferred_cb to be a special case of
event_callback, that solved the above issues, but made for two more
issues:
3: Because deferred_cb stuff would always get the default priority,
it could could low-priority bufferevents to get too much priority.
4: With code like bufferevent_pair, it's easy to get into a
situation where two deferreds keep adding one another, preventing
the event loop from ever actually scanning for more events.
This commit fixes the above by giving deferreds a better notion of
priorities, and by limiting the number of deferreds that can be
added to the _current_ loop iteration's active queues. (Extra
deferreds are put into the active_later state.)
That isn't an all-purpose priority inversion solution, of course: for
that, you may need to mess around with max_dispatch_interval.
2012-05-09 11:06:06 -04:00
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void event_deferred_cb_init_(struct event_callback *, ev_uint8_t, deferred_cb_fn, void *);
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/**
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Change the priority of a non-pending event_callback.
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*/
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void event_deferred_cb_set_priority_(struct event_callback *, ev_uint8_t);
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2009-04-17 06:55:08 +00:00
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/**
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2012-04-06 11:05:35 -04:00
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Cancel a struct event_callback if it is currently scheduled in an event_base.
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2009-04-17 06:55:08 +00:00
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*/
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2017-03-12 20:50:35 +03:00
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EVENT2_EXPORT_SYMBOL
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2012-04-06 04:33:19 -04:00
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void event_deferred_cb_cancel_(struct event_base *, struct event_callback *);
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2009-04-17 06:55:08 +00:00
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/**
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2012-04-06 11:05:35 -04:00
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Activate a struct event_callback if it is not currently scheduled in an event_base.
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2009-07-26 01:29:39 +00:00
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2015-03-24 17:29:40 -07:00
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Return true if it was not previously scheduled.
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2012-04-06 04:33:19 -04:00
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*/
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2017-03-12 20:50:35 +03:00
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EVENT2_EXPORT_SYMBOL
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2012-04-06 04:33:19 -04:00
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int event_deferred_cb_schedule_(struct event_base *, struct event_callback *);
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2009-04-10 14:22:33 +00:00
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#ifdef __cplusplus
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}
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#endif
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2012-02-29 15:07:31 -05:00
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#endif /* EVENT_INTERNAL_H_INCLUDED_ */
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2009-04-10 14:22:33 +00:00
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