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745a63dba3
An event or event callback can now be in an additional state: "active later". When an event is in this state, it will become active the next time we run through the event loop. This lets us do what we wanted to with deferred callbacks: make a type of active thing that avoids infinite circular regress in a way that starves other events or exhausts the stack. It improves on deferred callbacks by respecting priorities, and by having a non-kludgy way to avoid event starvation.
163 lines
4.5 KiB
C
163 lines
4.5 KiB
C
/*
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* Copyright (c) 2000-2007 Niels Provos <provos@citi.umich.edu>
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* Copyright (c) 2007-2012 Niels Provos and Nick Mathewson
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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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#ifndef EVENT2_EVENT_STRUCT_H_INCLUDED_
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#define EVENT2_EVENT_STRUCT_H_INCLUDED_
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/** @file event2/event_struct.h
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Structures used by event.h. Using these structures directly WILL harm
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forward compatibility: be careful.
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No field declared in this file should be used directly in user code. Except
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for historical reasons, these fields would not be exposed at all.
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*/
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include <event2/event-config.h>
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#ifdef EVENT__HAVE_SYS_TYPES_H
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#include <sys/types.h>
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#endif
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#ifdef EVENT__HAVE_SYS_TIME_H
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#include <sys/time.h>
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#endif
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/* For int types. */
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#include <event2/util.h>
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/* For evkeyvalq */
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#include <event2/keyvalq_struct.h>
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#define EVLIST_TIMEOUT 0x01
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#define EVLIST_INSERTED 0x02
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#define EVLIST_SIGNAL 0x04
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#define EVLIST_ACTIVE 0x08
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#define EVLIST_INTERNAL 0x10
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#define EVLIST_ACTIVE_LATER 0x20
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#define EVLIST_INIT 0x80
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#define EVLIST_ALL 0xbf
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/* Fix so that people don't have to run with <sys/queue.h> */
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#ifndef TAILQ_ENTRY
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#define EVENT_DEFINED_TQENTRY_
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#define TAILQ_ENTRY(type) \
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struct { \
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struct type *tqe_next; /* next element */ \
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struct type **tqe_prev; /* address of previous next element */ \
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}
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#endif /* !TAILQ_ENTRY */
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#ifndef TAILQ_HEAD
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#define EVENT_DEFINED_TQHEAD_
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#define TAILQ_HEAD(name, type) \
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struct name { \
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struct type *tqh_first; \
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struct type **tqh_last; \
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}
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#endif
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/* Fix so that people don't have to run with <sys/queue.h> */
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#ifndef LIST_ENTRY
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#define EVENT_DEFINED_LISTENTRY_
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#define LIST_ENTRY(type) \
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struct { \
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struct type *le_next; /* next element */ \
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struct type **le_prev; /* address of previous next element */ \
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}
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#endif /* !TAILQ_ENTRY */
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struct event_callback {
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TAILQ_ENTRY(event_callback) evcb_active_next;
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short evcb_flags;
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ev_uint8_t evcb_pri; /* smaller numbers are higher priority */
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ev_uint8_t evcb_closure;
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/* allows us to adopt for different types of events */
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void (*evcb_callback)(evutil_socket_t, short, void *arg);
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void *evcb_arg;
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};
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struct event_base;
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struct event {
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struct event_callback ev_evcallback;
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/* for managing timeouts */
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union {
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TAILQ_ENTRY(event) ev_next_with_common_timeout;
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int min_heap_idx;
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} ev_timeout_pos;
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evutil_socket_t ev_fd;
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struct event_base *ev_base;
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union {
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/* used for io events */
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struct {
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LIST_ENTRY (event) ev_io_next;
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struct timeval ev_timeout;
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} ev_io;
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/* used by signal events */
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struct {
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LIST_ENTRY (event) ev_signal_next;
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short ev_ncalls;
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/* Allows deletes in callback */
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short *ev_pncalls;
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} ev_signal;
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} ev_;
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short ev_events;
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short ev_res; /* result passed to event callback */
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struct timeval ev_timeout;
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};
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TAILQ_HEAD (event_list, event);
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#ifdef EVENT_DEFINED_TQENTRY_
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#undef TAILQ_ENTRY
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#endif
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#ifdef EVENT_DEFINED_TQHEAD_
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#undef TAILQ_HEAD
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#endif
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#ifdef EVENT_DEFINED_LISTENTRY_
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#undef LIST_ENTRY
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struct event_dlist;
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#undef EVENT_DEFINED_LISTENTRY_
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#else
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LIST_HEAD (event_dlist, event);
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#endif /* EVENT_DEFINED_LISTENTRY_ */
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#ifdef __cplusplus
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}
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#endif
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#endif /* EVENT2_EVENT_STRUCT_H_INCLUDED_ */
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