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.

1 files changed, 39 insertions, 0 deletions

diff --git a/kqueue-internal.h b/kqueue-internal.h
new file mode 100644
index 00000000..02c5a360
--- /dev/null
+++ b/kqueue-internal.h
@@ -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