Add FD_WANT_SINGLE_WRITE to efficiently replace FD_WANT_POLL_WRITE

git-svn-id: http://svn.inspircd.org/repository/trunk/inspircd@11762 e03df62e-2008-0410-955e-edbf42e46eb7

10 files changed, 61 insertions, 39 deletions

diff --git a/include/socketengine.h b/include/socketengine.h
index 9c45bcf21..1a0a61670 100644
--- a/include/socketengine.h
+++ b/include/socketengine.h
@@ -71,8 +71,10 @@ enum EventMask
 	FD_WANT_NO_WRITE = 0x10,
 	/** Give a write event at all times when writes will not block.
 	 *
-	 * You probably don't need to use this state; try your write first, and
-	 * then use FD_WANT_FAST_WRITE.
+	 * You probably shouldn't use this state; if it's likely that the write
+	 * will not block, try it first, then use FD_WANT_FAST_WRITE if it
+	 * fails. If it's likely to block (or you are using polling-style reads)
+	 * then use FD_WANT_SINGLE_WRITE.
 	 */
 	FD_WANT_POLL_WRITE = 0x20,
 	/** Give a write event when writes don't block any more
@@ -95,19 +97,23 @@ enum EventMask
 	 * FD_WANT_FAST_WRITE when writing data to a mostly-unblocked socket.
 	 */
 	FD_WANT_EDGE_WRITE = 0x80,
+	/** Request a one-shot poll-style write notification. The socket will
+	 * return to the FD_WANT_NO_WRITE state before HandleEvent is called.
+	 */
+	FD_WANT_SINGLE_WRITE = 0x100,
 
 	/** Mask for all write events */
-	FD_WANT_WRITE_MASK = 0xF0,
+	FD_WANT_WRITE_MASK = 0x1F0,
 
 	/** Add a trial read. During the next DispatchEvents invocation, this
 	 * will call HandleEvent with EVENT_READ unless reads are known to be
-	 * blocking. Useful for edge-triggered reads; does nothing if
-	 * FD_READ_WILL_BLOCK has been set on this EventHandler.
+	 * blocking.
 	 */
-	FD_ADD_TRIAL_READ  = 0x100,
+	FD_ADD_TRIAL_READ  = 0x1000,
 	/** Assert that reads are known to block. This cancels FD_ADD_TRIAL_READ.
+	 * Reset by SE before running EVENT_READ
 	 */
-	FD_READ_WILL_BLOCK = 0x200,
+	FD_READ_WILL_BLOCK = 0x2000,
 
 	/** Add a trial write. During the next DispatchEvents invocation, this
 	 * will call HandleEvent with EVENT_WRITE unless writes are known to be
@@ -117,15 +123,14 @@ enum EventMask
 	 * send() syscall, or to ensure that writes are blocking when attempting
 	 * to use FD_WANT_FAST_WRITE.
 	 */
-	FD_ADD_TRIAL_WRITE = 0x1000,
+	FD_ADD_TRIAL_WRITE = 0x4000,
 	/** Assert that writes are known to block. This cancels FD_ADD_TRIAL_WRITE.
+	 * Reset by SE before running EVENT_WRITE
 	 */
-	FD_WRITE_WILL_BLOCK = 0x2000, 
+	FD_WRITE_WILL_BLOCK = 0x8000, 
 
-	/** Mask for trial read/write items */
-	FD_TRIAL_NOTE_MASK = 0x1100,
-	/** Mask for read/write blocking notifications */
-	FD_BLOCK_NOTE_MASK = 0x2200
+	/** Mask for trial read/trial write */
+	FD_TRIAL_NOTE_MASK = 0x5000
 };
 
 class InspIRCd;
diff --git a/src/inspsocket.cpp b/src/inspsocket.cpp
index 6348d7982..004d679ed 100644
--- a/src/inspsocket.cpp
+++ b/src/inspsocket.cpp
@@ -97,7 +97,7 @@ BufferedSocketError BufferedSocket::BeginConnect(const irc::sockets::sockaddrs&
 
 	this->state = I_CONNECTING;
 
-	if (!ServerInstance->SE->AddFd(this, FD_WANT_NO_READ | FD_WANT_POLL_WRITE))
+	if (!ServerInstance->SE->AddFd(this, FD_WANT_NO_READ | FD_WANT_SINGLE_WRITE))
 		return I_ERR_NOMOREFDS;
 
 	this->Timeout = new SocketTimeout(this->GetFd(), this, timeout, ServerInstance->Time());
@@ -414,6 +414,8 @@ void BufferedSocket::DoWrite()
 		this->OnConnected();
 		if (GetIOHook())
 			GetIOHook()->OnStreamSocketConnect(this);
+		else
+			ServerInstance->SE->ChangeEventMask(this, FD_WANT_FAST_READ | FD_WANT_EDGE_WRITE);
 	}
 	this->StreamSocket::DoWrite();
 }
diff --git a/src/modules/extra/m_ssl_gnutls.cpp b/src/modules/extra/m_ssl_gnutls.cpp
index c65b8528a..3362e9378 100644
--- a/src/modules/extra/m_ssl_gnutls.cpp
+++ b/src/modules/extra/m_ssl_gnutls.cpp
@@ -540,12 +540,12 @@ class ModuleSSLGnuTLS : public Module
 			else if (ret > 0)
 			{
 				sendq = sendq.substr(ret);
-				ServerInstance->SE->ChangeEventMask(user, FD_WANT_POLL_WRITE);
+				ServerInstance->SE->ChangeEventMask(user, FD_WANT_SINGLE_WRITE);
 				return 0;
 			}
 			else if (ret == GNUTLS_E_AGAIN || ret == GNUTLS_E_INTERRUPTED)
 			{
-				ServerInstance->SE->ChangeEventMask(user, FD_WANT_POLL_WRITE);
+				ServerInstance->SE->ChangeEventMask(user, FD_WANT_SINGLE_WRITE);
 				return 0;
 			}
 			else if (ret == 0)
@@ -585,7 +585,7 @@ class ModuleSSLGnuTLS : public Module
 				{
 					// gnutls_handshake() wants to write() again.
 					session->status = ISSL_HANDSHAKING_WRITE;
-					ServerInstance->SE->ChangeEventMask(user, FD_WANT_NO_READ | FD_WANT_POLL_WRITE);
+					ServerInstance->SE->ChangeEventMask(user, FD_WANT_NO_READ | FD_WANT_SINGLE_WRITE);
 				}
 			}
 			else
diff --git a/src/modules/extra/m_ssl_openssl.cpp b/src/modules/extra/m_ssl_openssl.cpp
index e72bdc816..645add4c2 100644
--- a/src/modules/extra/m_ssl_openssl.cpp
+++ b/src/modules/extra/m_ssl_openssl.cpp
@@ -450,7 +450,7 @@ class ModuleSSLOpenSSL : public Module
 				}
 				else if (err == SSL_ERROR_WANT_WRITE)
 				{
-					ServerInstance->SE->ChangeEventMask(user, FD_WANT_NO_READ | FD_WANT_POLL_WRITE);
+					ServerInstance->SE->ChangeEventMask(user, FD_WANT_NO_READ | FD_WANT_SINGLE_WRITE);
 					return 0;
 				}
 				else
@@ -501,7 +501,7 @@ class ModuleSSLOpenSSL : public Module
 			else if (ret > 0)
 			{
 				buffer = buffer.substr(ret);
-				ServerInstance->SE->ChangeEventMask(user, FD_WANT_POLL_WRITE);
+				ServerInstance->SE->ChangeEventMask(user, FD_WANT_SINGLE_WRITE);
 				return 0;
 			}
 			else if (ret == 0)
@@ -515,7 +515,7 @@ class ModuleSSLOpenSSL : public Module
 
 				if (err == SSL_ERROR_WANT_WRITE)
 				{
-					ServerInstance->SE->ChangeEventMask(user, FD_WANT_POLL_WRITE);
+					ServerInstance->SE->ChangeEventMask(user, FD_WANT_SINGLE_WRITE);
 					return 0;
 				}
 				else if (err == SSL_ERROR_WANT_READ)
@@ -554,7 +554,7 @@ class ModuleSSLOpenSSL : public Module
 			}
 			else if (err == SSL_ERROR_WANT_WRITE)
 			{
-				ServerInstance->SE->ChangeEventMask(user, FD_WANT_NO_READ | FD_WANT_POLL_WRITE);
+				ServerInstance->SE->ChangeEventMask(user, FD_WANT_NO_READ | FD_WANT_SINGLE_WRITE);
 				session->status = ISSL_HANDSHAKING;
 				return true;
 			}
diff --git a/src/socketengines/socketengine_epoll.cpp b/src/socketengines/socketengine_epoll.cpp
index 672ff4a7b..059798d25 100644
--- a/src/socketengines/socketengine_epoll.cpp
+++ b/src/socketengines/socketengine_epoll.cpp
@@ -58,12 +58,12 @@ EPollEngine::~EPollEngine()
 static int mask_to_epoll(int event_mask)
 {
 	int rv = 0;
-	if (event_mask & (FD_WANT_POLL_READ | FD_WANT_POLL_WRITE))
+	if (event_mask & (FD_WANT_POLL_READ | FD_WANT_POLL_WRITE | FD_WANT_SINGLE_WRITE))
 	{
 		// we need to use standard polling on this FD
 		if (event_mask & (FD_WANT_POLL_READ | FD_WANT_FAST_READ))
 			rv |= EPOLLIN;
-		if (event_mask & (FD_WANT_POLL_WRITE | FD_WANT_FAST_WRITE))
+		if (event_mask & (FD_WANT_POLL_WRITE | FD_WANT_FAST_WRITE | FD_WANT_SINGLE_WRITE))
 			rv |= EPOLLOUT;
 	}
 	else
@@ -182,16 +182,28 @@ int EPollEngine::DispatchEvents()
 			eh->HandleEvent(EVENT_ERROR, errcode);
 			continue;
 		}
+		int mask = eh->GetEventMask();
+		if (events[j].events & EPOLLIN)
+			mask &= ~FD_READ_WILL_BLOCK;
+		if (events[j].events & EPOLLOUT)
+		{
+			mask &= ~FD_WRITE_WILL_BLOCK;
+			if (mask & FD_WANT_SINGLE_WRITE)
+			{
+				int nm = mask & ~FD_WANT_SINGLE_WRITE;
+				OnSetEvent(eh, mask, nm);
+				mask = nm;
+			}
+		}
+		SetEventMask(eh, mask);
 		if (events[j].events & EPOLLIN)
 		{
 			ReadEvents++;
-			SetEventMask(eh, eh->GetEventMask() & ~FD_READ_WILL_BLOCK);
 			eh->HandleEvent(EVENT_READ);
 		}
 		if (events[j].events & EPOLLOUT)
 		{
 			WriteEvents++;
-			SetEventMask(eh, eh->GetEventMask() & ~FD_WRITE_WILL_BLOCK);
 			eh->HandleEvent(EVENT_WRITE);
 		}
 	}
diff --git a/src/socketengines/socketengine_iocp.cpp b/src/socketengines/socketengine_iocp.cpp
index e09fb4d0a..c253bf0a6 100644
--- a/src/socketengines/socketengine_iocp.cpp
+++ b/src/socketengines/socketengine_iocp.cpp
@@ -91,7 +91,7 @@ bool IOCPEngine::AddFd(EventHandler* eh, int event_mask)
 	ServerInstance->Logs->Log("SOCKET",DEBUG, "New fake fd: %u, real fd: %u, address 0x%p", *fake_fd, eh->GetFd(), eh);
 
 	/* post a write event if there is data to be written */
-	if (event_mask & (FD_WANT_POLL_WRITE | FD_WANT_FAST_WRITE))
+	if (event_mask & (FD_WANT_POLL_WRITE | FD_WANT_FAST_WRITE | FD_WANT_SINGLE_WRITE))
 		WantWrite(eh);
 
 	/* we're all good =) */
@@ -183,7 +183,7 @@ void IOCPEngine::OnSetEvent(EventHandler* eh, int old_mask, int new_mask)
 		return;
 
 	/* Post event - write begin */
-	if((new_mask & (FD_WANT_POLL_WRITE | FD_WANT_FAST_WRITE)) && !eh->GetExt("windows_writeevent", m_writeEvent))
+	if((new_mask & (FD_WANT_POLL_WRITE | FD_WANT_FAST_WRITE | FD_WANT_SINGLE_WRITE)) && !eh->GetExt("windows_writeevent", m_writeEvent))
 	{
 		ULONG_PTR completion_key = (ULONG_PTR)*fake_fd;
 		Overlapped * ov = new Overlapped(SOCKET_IO_EVENT_WRITE_READY, 0);
diff --git a/src/socketengines/socketengine_kqueue.cpp b/src/socketengines/socketengine_kqueue.cpp
index c9734e85d..1a783153e 100644
--- a/src/socketengines/socketengine_kqueue.cpp
+++ b/src/socketengines/socketengine_kqueue.cpp
@@ -76,7 +76,7 @@ bool KQueueEngine::AddFd(EventHandler* eh, int event_mask)
 		return false;
 	}
 
-	if (event_mask & (FD_WANT_POLL_WRITE | FD_WANT_FAST_WRITE)) {
+	if (event_mask & (FD_WANT_POLL_WRITE | FD_WANT_FAST_WRITE | FD_WANT_SINGLE_WRITE)) {
 		// ...and sometimes want to write
 		WantWrite(eh);
 	}
@@ -148,7 +148,7 @@ void KQueueEngine::OnSetEvent(EventHandler* eh, int old_mask, int new_mask)
 						  eh->GetFd(), strerror(errno));
 		}
 	}
-	if ((new_mask & FD_WANT_EDGE_WRITE) && !(old_mask & FD_WANT_EDGE_WRITE))
+	if ((new_mask & (FD_WANT_FAST_WRITE | FD_WANT_SINGLE_WRITE)) && !(old_mask & (FD_WANT_FAST_WRITE | FD_WANT_SINGLE_WRITE)))
 	{
 		// new one-shot write
 		struct kevent ke;
@@ -184,11 +184,11 @@ int KQueueEngine::DispatchEvents()
 		if (ke_list[j].filter == EVFILT_WRITE)
 		{
 			WriteEvents++;
-			/* When mask is FD_WANT_FAST_WRITE, we set a one-shot
-			 * write, so we need to clear that bit to detect when it
-			 * set again.
+			/* When mask is FD_WANT_FAST_WRITE or FD_WANT_SINGLE_WRITE,
+			 * we set a one-shot write, so we need to clear that bit
+			 * to detect when it set again.
 			 */
-			const int bits_to_clr = FD_WANT_FAST_WRITE | FD_WRITE_WILL_BLOCK;
+			const int bits_to_clr = FD_WANT_SINGLE_WRITE | FD_WANT_FAST_WRITE | FD_WRITE_WILL_BLOCK;
 			SetEventMask(eh, eh->GetEventMask() & ~bits_to_clr);
 			eh->HandleEvent(EVENT_WRITE);
 		}
diff --git a/src/socketengines/socketengine_poll.cpp b/src/socketengines/socketengine_poll.cpp
index 6f50e2798..a72d21d1f 100644
--- a/src/socketengines/socketengine_poll.cpp
+++ b/src/socketengines/socketengine_poll.cpp
@@ -63,7 +63,7 @@ static int mask_to_poll(int event_mask)
 	int rv = 0;
 	if (event_mask & (FD_WANT_POLL_READ | FD_WANT_FAST_READ))
 		rv |= POLLIN;
-	if (event_mask & (FD_WANT_POLL_WRITE | FD_WANT_FAST_WRITE))
+	if (event_mask & (FD_WANT_POLL_WRITE | FD_WANT_FAST_WRITE | FD_WANT_SINGLE_WRITE))
 		rv |= POLLOUT;
 	return rv;
 }
@@ -208,7 +208,10 @@ int PollEngine::DispatchEvents()
 			
 			if (events[index].revents & POLLOUT)
 			{
-				SetEventMask(eh, eh->GetEventMask() & ~FD_WRITE_WILL_BLOCK);
+				int mask = eh->GetEventMask();
+				mask &= ~(FD_WRITE_WILL_BLOCK | FD_WANT_SINGLE_WRITE);
+				SetEventMask(eh, mask);
+				events[index].events = mask_to_poll(mask);
 				eh->HandleEvent(EVENT_WRITE);
 			}
 		}
diff --git a/src/socketengines/socketengine_ports.cpp b/src/socketengines/socketengine_ports.cpp
index a99806fc4..d23857f50 100644
--- a/src/socketengines/socketengine_ports.cpp
+++ b/src/socketengines/socketengine_ports.cpp
@@ -60,7 +60,7 @@ static int mask_to_events(int event_mask)
 	int rv = 0;
 	if (event_mask & (FD_WANT_POLL_READ | FD_WANT_FAST_READ))
 		rv |= POLLRDNORM;
-	if (event_mask & (FD_WANT_POLL_WRITE | FD_WANT_FAST_WRITE))
+	if (event_mask & (FD_WANT_POLL_WRITE | FD_WANT_FAST_WRITE | FD_WANT_SINGLE_WRITE))
 		rv |= POLLWRNORM;
 	return rv;
 }
@@ -132,7 +132,7 @@ int PortsEngine::DispatchEvents()
 				{
 					int mask = eh->GetEventMask();
 					if (events[i].portev_events & POLLWRNORM)
-						mask &= ~(FD_WRITE_WILL_BLOCK | FD_WANT_FAST_WRITE);
+						mask &= ~(FD_WRITE_WILL_BLOCK | FD_WANT_FAST_WRITE | FD_WANT_SINGLE_WRITE);
 					if (events[i].portev_events & POLLRDNORM)
 						mask &= ~FD_READ_WILL_BLOCK;
 					// reinsert port for next time around, pretending to be one-shot for writes
diff --git a/src/socketengines/socketengine_select.cpp b/src/socketengines/socketengine_select.cpp
index f089fd698..eacfc0fbf 100644
--- a/src/socketengines/socketengine_select.cpp
+++ b/src/socketengines/socketengine_select.cpp
@@ -89,7 +89,7 @@ int SelectEngine::DispatchEvents()
 		int state = eh->GetEventMask();
 		if (state & (FD_WANT_POLL_READ | FD_WANT_FAST_READ))
 			FD_SET (i, &rfdset);
-		if (state & (FD_WANT_POLL_WRITE | FD_WANT_FAST_WRITE))
+		if (state & (FD_WANT_POLL_WRITE | FD_WANT_FAST_WRITE | FD_WANT_SINGLE_WRITE))
 			FD_SET (i, &wfdset);
 		FD_SET (i, &errfdset);
 	}
@@ -134,7 +134,7 @@ int SelectEngine::DispatchEvents()
 				if (FD_ISSET (i, &wfdset))
 				{
 					WriteEvents++;
-					SetEventMask(eh, eh->GetEventMask() & ~FD_WRITE_WILL_BLOCK);
+					SetEventMask(eh, eh->GetEventMask() & ~(FD_WRITE_WILL_BLOCK | FD_WANT_SINGLE_WRITE));
 					ev->HandleEvent(EVENT_WRITE);
 				}
 			}