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Replace pipe-based notification with EVFILT_USER where possible

Sufficiently recent kqueue implementations have an EVFILT_USER filter
that we can use to wake up an event base from another thread.  When
it's supported, we now use this mechanism rather than our old
(pipe-based) mechanism.  This should save some time and complications
on newer OSX and freebsds.
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Nick Mathewson
Nick Mathewson committed Sep 17, 2010
1 parent 9bf866f commit 53a07fe2f95c360d060b9fd58dfcd929c2c1aac2
Showing with 133 additions and 2 deletions.
  1. +2 −0 Makefile.am
  2. +19 −2 event.c
  3. +39 −0 kqueue-internal.h
  4. +73 −0 kqueue.c
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@@ -234,6 +234,8 @@ noinst_HEADERS = util-internal.h mm-internal.h ipv6-internal.h \
changelist-internal.h iocp-internal.h \
ratelim-internal.h \
evconfig-private.h \
+ ratelim-internal.h \
+ kqueue-internal.h \
WIN32-Code/event2/event-config.h \
WIN32-Code/evconfig-private.h \
WIN32-Code/tree.h \
View
21 event.c
@@ -72,6 +72,11 @@
#include "ht-internal.h"
#include "util-internal.h"
+
+#ifdef EVENT__HAVE_WORKING_KQUEUE
+#include "kqueue-internal.h"
+#endif
+
#ifdef EVENT__HAVE_EVENT_PORTS
extern const struct eventop evportops;
#endif
@@ -927,16 +932,18 @@ event_reinit(struct event_base *base)
had_signal_added = 1;
base->sig.ev_signal_added = 0;
}
- if (base->th_notify_fd[0] != -1) {
+ if (base->th_notify_fn != NULL) {
was_notifiable = 1;
+ base->th_notify_fn = NULL;
+ }
+ if (base->th_notify_fd[0] != -1) {
event_del(&base->th_notify);
EVUTIL_CLOSESOCKET(base->th_notify_fd[0]);
if (base->th_notify_fd[1] != -1)
EVUTIL_CLOSESOCKET(base->th_notify_fd[1]);
base->th_notify_fd[0] = -1;
base->th_notify_fd[1] = -1;
event_debug_unassign(&base->th_notify);
- base->th_notify_fn = NULL;
}
/* Replace the original evsel. */
@@ -3056,6 +3063,16 @@ evthread_make_base_notifiable(struct event_base *base)
return 0;
}
+
+#if defined(EVENT__HAVE_WORKING_KQUEUE)
+ if (base->evsel == &kqops && event_kq_add_notify_event_(base) == 0) {
+ base->th_notify_fn = event_kq_notify_base_;
+ /* No need to add an event here; the backend can wake
+ * itself up just fine. */
+ return 0;
+ }
+#endif
+
#ifdef EVENT__HAVE_EVENTFD
base->th_notify_fd[0] = evutil_eventfd_(0,
EVUTIL_EFD_CLOEXEC|EVUTIL_EFD_NONBLOCK);
View
@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2012 Niels Provos and Nick Mathewson
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ * derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+#ifndef KQUEUE_INTERNAL_H_INCLUDED_
+#define KQUEUE_INTERNAL_H_INCLUDED_
+
+/** Notification function, used to tell an event base to wake up from another
+ * thread. Only works when event_kq_add_notify_event_() has previously been
+ * called successfully on that base. */
+int event_kq_notify_base_(struct event_base *base);
+
+/** Prepare a kqueue-using event base to receive notifications via an internal
+ * EVFILT_USER event. Return 0 on sucess, -1 on failure.
+ */
+int event_kq_add_notify_event_(struct event_base *base);
+
+#endif
View
@@ -65,6 +65,8 @@
#include "evthread-internal.h"
#include "changelist-internal.h"
+#include "kqueue-internal.h"
+
#define NEVENT 64
struct kqop {
@@ -74,6 +76,7 @@ struct kqop {
struct kevent *events;
int events_size;
int kq;
+ int notify_event_added;
pid_t pid;
};
@@ -369,6 +372,10 @@ kq_dispatch(struct event_base *base, struct timeval *tv)
which |= EV_WRITE;
} else if (events[i].filter == EVFILT_SIGNAL) {
which |= EV_SIGNAL;
+#ifdef EVFILT_USER
+ } else if (events[i].filter == EVFILT_USER) {
+ base->is_notify_pending = 0;
+#endif
}
if (!which)
@@ -473,4 +480,70 @@ kq_sig_del(struct event_base *base, int nsignal, short old, short events, void *
return (0);
}
+
+/* OSX 10.6 and FreeBSD 8.1 add support for EVFILT_USER, which we can use
+ * to wake up the event loop from another thread. */
+
+/* Magic number we use for our filter ID. */
+#define NOTIFY_IDENT 42
+
+int
+event_kq_add_notify_event_(struct event_base *base)
+{
+ struct kqop *kqop = base->evbase;
+#if defined(EVFILT_USER) && defined(NOTE_TRIGGER)
+ struct kevent kev;
+ struct timespec timeout = { 0, 0 };
+#endif
+
+ if (kqop->notify_event_added)
+ return 0;
+
+#if defined(EVFILT_USER) && defined(NOTE_TRIGGER)
+ memset(&kev, 0, sizeof(kev));
+ kev.ident = NOTIFY_IDENT;
+ kev.filter = EVFILT_USER;
+ kev.flags = EV_ADD | EV_CLEAR;
+
+ if (kevent(kqop->kq, &kev, 1, NULL, 0, &timeout) == -1) {
+ event_warn("kevent: adding EVFILT_USER event");
+ return -1;
+ }
+
+ kqop->notify_event_added = 1;
+
+ return 0;
+#else
+ return -1;
+#endif
+}
+
+int
+event_kq_notify_base_(struct event_base *base)
+{
+ struct kqop *kqop = base->evbase;
+#if defined(EVFILT_USER) && defined(NOTE_TRIGGER)
+ struct kevent kev;
+ struct timespec timeout = { 0, 0 };
+#endif
+ if (! kqop->notify_event_added)
+ return -1;
+
+#if defined(EVFILT_USER) && defined(NOTE_TRIGGER)
+ memset(&kev, 0, sizeof(kev));
+ kev.ident = NOTIFY_IDENT;
+ kev.filter = EVFILT_USER;
+ kev.fflags = NOTE_TRIGGER;
+
+ if (kevent(kqop->kq, &kev, 1, NULL, 0, &timeout) == -1) {
+ event_warn("kevent: triggering EVFILT_USER event");
+ return -1;
+ }
+
+ return 0;
+#else
+ return -1;
+#endif
+}
+
#endif /* EVENT__HAVE_KQUEUE */

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