Add StreamListenOptions.

Can be used to set the SO_REUSEPORT option for multi-thread/multi-process incoming TCP connection distribution.

source/eventcore/driver.d

@@ -144,7 +144,11 @@ interface EventDriverSockets {
 	StreamSocketFD adoptStream(int socket);
 
 	/// Creates a socket listening for incoming stream connections.
-	StreamListenSocketFD listenStream(scope Address bind_address, AcceptCallback on_accept);
+	StreamListenSocketFD listenStream(scope Address bind_address, StreamListenOptions options, AcceptCallback on_accept);
+
+	final StreamListenSocketFD listenStream(scope Address bind_address, AcceptCallback on_accept) {
+		return listenStream(bind_address, StreamListenOptions.defaults, on_accept);
+	}
 
 	/// Starts to wait for incoming connections on a listening socket.
 	void waitForConnections(StreamListenSocketFD sock, AcceptCallback on_accept);
@@ -504,6 +508,11 @@ enum ConnectionState {
 	closed
 }
 
+enum StreamListenOptions {
+	defaults = 0,
+	reusePort = 1<<0,
+}
+
 /**
 	Specifies how a file is manipulated on disk.
 */

source/eventcore/drivers/libasync.d

@@ -94,7 +94,8 @@ final class LibasyncEventDriverSockets : EventDriverSockets {
 		assert(false, "TODO!");
 	}
 
-	override StreamListenSocketFD listenStream(scope Address bind_address, AcceptCallback on_accept)
+	alias listenStream = EventDriverSockets.listenStream;
+	override StreamListenSocketFD listenStream(scope Address bind_address, ListenStreamOptions options, AcceptCallback on_accept)
 	{
 		assert(false, "TODO!");
 	}

source/eventcore/drivers/posix/sockets.d

@@ -17,6 +17,9 @@ version (Posix) {
 	import core.sys.posix.unistd : close, read, write;
 	import core.stdc.errno : errno, EAGAIN, EINPROGRESS;
 	import core.sys.posix.fcntl;
+
+	version (linux) enum SO_REUSEPORT = 15;
+	else enum SO_REUSEPORT = 0x200;
 }
 version (Windows) {
 	import core.sys.windows.windows;
@@ -117,7 +120,8 @@ final class PosixEventDriverSockets(Loop : PosixEventLoop) : EventDriverSockets
 		}
 	}
 
-	final override StreamListenSocketFD listenStream(scope Address address, AcceptCallback on_accept)
+	alias listenStream = EventDriverSockets.listenStream;
+	final override StreamListenSocketFD listenStream(scope Address address, StreamListenOptions options, AcceptCallback on_accept)
 	{
 		log("Listen stream");
 		auto sockfd = createSocket(address.addressFamily, SOCK_STREAM);
@@ -131,15 +135,28 @@ final class PosixEventDriverSockets(Loop : PosixEventLoop) : EventDriverSockets
 			int tmp_reuse = 1;
 			// FIXME: error handling!
 			if (setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &tmp_reuse, tmp_reuse.sizeof) != 0) {
-				log("setsockopt failed.");
+				log("setsockopt SO_REUSEADDR failed.");
 				invalidateSocket();
-			} else if (bind(sockfd, address.name, address.nameLen) != 0) {
+				return;
+			}
+			version (Windows) {} else {
+				if ((options & StreamListenOptions.reusePort) && setsockopt(sockfd, SOL_SOCKET, SO_REUSEPORT, &tmp_reuse, tmp_reuse.sizeof) != 0) {
+					log("setsockopt SO_REUSEPORT failed.");
+					invalidateSocket();
+					return;
+				}
+			}
+			if (bind(sockfd, address.name, address.nameLen) != 0) {
 				log("bind failed.");
 				invalidateSocket();
-			} else if (listen(sockfd, 128) != 0) {
+				return;
+			}
+			if (listen(sockfd, 128) != 0) {
 				log("listen failed.");
 				invalidateSocket();
-			} else log("Success!");
+				return;
+			}
+			log("Success!");
 		} ();
 
 		if (sock == StreamListenSocketFD.invalid)

source/eventcore/drivers/winapi/sockets.d

@@ -19,7 +19,8 @@ final class WinAPIEventDriverSockets : EventDriverSockets {
 		assert(false, "TODO!");
 	}
 
-	override StreamListenSocketFD listenStream(scope Address bind_address, AcceptCallback on_accept)
+	alias listenStream = EventDriverSockets.listenStream;
+	override StreamListenSocketFD listenStream(scope Address bind_address, StreamListenOptions options, AcceptCallback on_accept)
 	{
 		assert(false, "TODO!");
 	}