From a64e860b2690ffef19e62396e0a76056a56a7766 Mon Sep 17 00:00:00 2001
From: psychon <psychon@e03df62e-2008-0410-955e-edbf42e46eb7>
Date: Fri, 6 Feb 2009 16:29:29 +0000
Subject: Some fixes to the kqueue socket engine

The old code choked badly if a socket which was !eh->Readable() was added
(it went into an endless loop where kqueue would keep reporting that socket
for writeability).
This also fixes a bug where DelFd() failed to clean up properly which caused
the next AddFd() for an identical fd number to fail.
Oh and this also adds some error messages and does some minor cleanup...


git-svn-id: http://svn.inspircd.org/repository/trunk/inspircd@11033 e03df62e-2008-0410-955e-edbf42e46eb7
---
 src/socketengines/socketengine_kqueue.cpp | 53 +++++++++++++++++++------------
 1 file changed, 33 insertions(+), 20 deletions(-)

(limited to 'src')

diff --git a/src/socketengines/socketengine_kqueue.cpp b/src/socketengines/socketengine_kqueue.cpp
index 81ef4be1d..80d73581e 100644
--- a/src/socketengines/socketengine_kqueue.cpp
+++ b/src/socketengines/socketengine_kqueue.cpp
@@ -67,15 +67,23 @@ bool KQueueEngine::AddFd(EventHandler* eh)
 	if (ref[fd])
 		return false;
 
+	// We always want to read from the socket...
 	struct kevent ke;
-	EV_SET(&ke, fd, eh->Readable() ? EVFILT_READ : EVFILT_WRITE, EV_ADD, 0, 0, NULL);
+	EV_SET(&ke, fd, EVFILT_READ, EV_ADD, 0, 0, NULL);
 
 	int i = kevent(EngineHandle, &ke, 1, 0, 0, NULL);
 	if (i == -1)
 	{
+		ServerInstance->Logs->Log("SOCKET",DEFAULT,"Failed to add fd: %d %s",
+					  fd, strerror(errno));
 		return false;
 	}
 
+	if (!eh->Readable()) {
+		// ...and sometimes want to write
+		WantWrite(eh);
+	}
+
 	ref[fd] = eh;
 	CurrentSetSize++;
 
@@ -88,37 +96,46 @@ bool KQueueEngine::DelFd(EventHandler* eh, bool force)
 	int fd = eh->GetFd();
 
 	if ((fd < 0) || (fd > GetMaxFds() - 1))
+	{
+		ServerInstance->Logs->Log("SOCKET",DEFAULT,"DelFd() on invalid fd: %d", fd);
 		return false;
+	}
 
 	struct kevent ke;
-	EV_SET(&ke, eh->GetFd(), EVFILT_READ, EV_DELETE, 0, 0, NULL);
-
-	int i = kevent(EngineHandle, &ke, 1, 0, 0, NULL);
 
+	// First remove the write filter ignoring errors, since we can't be
+	// sure if there are actually any write filters registered.
 	EV_SET(&ke, eh->GetFd(), EVFILT_WRITE, EV_DELETE, 0, 0, NULL);
+	kevent(EngineHandle, &ke, 1, 0, 0, NULL);
 
+	// Then remove the read filter.
+	EV_SET(&ke, eh->GetFd(), EVFILT_READ, EV_DELETE, 0, 0, NULL);
 	int j = kevent(EngineHandle, &ke, 1, 0, 0, NULL);
 
-	if ((j < 0) && (i < 0) && !force)
+	if ((j < 0) && !force)
+	{
+		ServerInstance->Logs->Log("SOCKET",DEFAULT,"Failed to remove fd: %d %s",
+					  fd, strerror(errno));
 		return false;
+	}
 
 	CurrentSetSize--;
 	ref[fd] = NULL;
 
-	//ServerInstance->Logs->Log("SOCKET",DEBUG,"Remove file descriptor: %d", fd);
+	ServerInstance->Logs->Log("SOCKET",DEBUG,"Remove file descriptor: %d", fd);
 	return true;
 }
 
 void KQueueEngine::WantWrite(EventHandler* eh)
 {
-	/** When changing an item in a kqueue, there is no 'modify' call
-	 * as in epoll. Instead, we add the item again, and this overwrites
-	 * the original setting rather than adding it twice. See man kqueue.
-	 */
 	struct kevent ke;
-	EV_SET(&ke, eh->GetFd(), EVFILT_READ, EV_ADD | EV_ONESHOT, 0, 0, NULL);
+	// EV_ONESHOT since we only ever want one write event
 	EV_SET(&ke, eh->GetFd(), EVFILT_WRITE, EV_ADD | EV_ONESHOT, 0, 0, NULL);
-	kevent(EngineHandle, &ke, 1, 0, 0, NULL);
+	int i = kevent(EngineHandle, &ke, 1, 0, 0, NULL);
+	if (i < 0) {
+		ServerInstance->Logs->Log("SOCKET",DEFAULT,"Failed to mark for writing: %d %s",
+					  eh->GetFd(), strerror(errno));
+	}
 }
 
 int KQueueEngine::GetMaxFds()
@@ -168,15 +185,11 @@ int KQueueEngine::DispatchEvents()
 		}
 		if (ke_list[j].filter == EVFILT_WRITE)
 		{
-			/* This looks wrong but its right. As above, theres no modify
-			 * call in kqueue. See the manpage.
+			/* We only ever add write events with EV_ONESHOT, which
+			 * means they are automatically removed once such a
+			 * event fires, so nothing to do here.
 			 */
-			if (ref[ke_list[j].ident]->Readable())
-			{
-				struct kevent ke;
-				EV_SET(&ke, ke_list[j].ident, EVFILT_READ, EV_ADD, 0, 0, NULL);
-				kevent(EngineHandle, &ke, 1, 0, 0, NULL);
-			}
+
 			WriteEvents++;
 			if (ref[ke_list[j].ident])
 				ref[ke_list[j].ident]->HandleEvent(EVENT_WRITE);
-- 
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