From 9f0f3d6da29f5e323c025f2955a9d21a0efa4af0 Mon Sep 17 00:00:00 2001
From: Nick Mathewson <nickm@torproject.org>
Date: Sat, 10 Nov 2007 05:18:11 +0000
Subject: [PATCH]  r16584@catbus:  nickm | 2007-11-10 00:00:59 -0500  Patch
 from Christopher Lane: reduce branch count in epoll_dispatch.c and generally
 improve clarity.

svn:r505
---
 ChangeLog |  2 +-
 epoll.c   | 37 ++++++++++++-------------------------
 2 files changed, 13 insertions(+), 26 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index aea092a3..f2b34b54 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -35,7 +35,7 @@ Changes in current version:
  o added two additional libraries: libevent_core and libevent_extra in addition to the regular libevent.  libevent_core contains only the event core whereas libevent_extra contains dns, http and rpc support
  o Begin using libtool's library versioning support correctly.  If we don't mess up, this will more or less guarantee binaries linked against old versions of libevent continue working when we make changes to libevent that do not break backward compatibility.
  o Fix evhttp.h compilation when TAILQ_ENTRY is not defined.
- o Small code cleanups in epoll_dispatch().
+ o Clean up code in epoll_dispatch() to reduce branch count and generally run better.  Patch from Christopher Layne.
  o Increase the maximum number of addresses read from a packet in evdns to 32.
  o Remove support for the rtsig method: it hasn't compiled for a while, and nobody seems to miss it very much.  Let us know if there's a good reason to put it back in.
  o Rename the "class" field in evdns_server_request to dns_question_class, so that it won't break compilation under C++.  Use a macro so that old code won't break.  Mark the macro as deprecated.
diff --git a/epoll.c b/epoll.c
index 5afc8307..86a97a4c 100644
--- a/epoll.c
+++ b/epoll.c
@@ -209,36 +209,23 @@ epoll_dispatch(struct event_base *base, void *arg, struct timeval *tv)
 
 	for (i = 0; i < res; i++) {
 		int what = events[i].events;
-		struct event *evread = NULL, *evwrite = NULL;
+		struct event *evread, *evwrite;
 
 		evep = (struct evepoll *)events[i].data.ptr;
+		evread = evep->evread;
+		evwrite = evep->evwrite;
 
-		if (what & (EPOLLHUP|EPOLLERR)) {
-			evread = evep->evread;
-			evwrite = evep->evwrite;
-		} else {
-			if (what & EPOLLIN) {
-				evread = evep->evread;
-			}
-
-			if (what & EPOLLOUT) {
-				evwrite = evep->evwrite;
-			}
-		}
-
-		if (!(evread||evwrite))
-			continue;
-
-		if (evread != NULL && !(evread->ev_events & EV_PERSIST))
-			event_del(evread);
-		if (evwrite != NULL && evwrite != evread &&
-			!(evwrite->ev_events & EV_PERSIST))
-			event_del(evwrite);
-
-		if (evread != NULL)
+		if (evread && what & (EPOLLIN|EPOLLHUP|EPOLLERR)) {
+			if (~evread->ev_events & EV_PERSIST)
+				event_del(evread);
 			event_active(evread, EV_READ, 1);
-		if (evwrite != NULL)
+		}
+		if (evwrite && what & (EPOLLOUT|EPOLLHUP|EPOLLERR)) {
+			if (~evwrite->ev_events & EV_PERSIST
+				&& evwrite != evread)
+				event_del(evwrite);
 			event_active(evwrite, EV_WRITE, 1);
+		}
 	}
 
 	return (0);