DisplayDriverServer : Create IPv6 endpoint

This avoids delays on Windows, where the ClientDisplayDriver was first trying a V6 connection and then only making a V4 connection if that failed (after a timeout).

Changes

@@ -1,6 +1,12 @@
 10.5.x.x (relative to 10.5.6.0)
 ========
 
+
+Improvements
+------------
+
+- DisplayDriverServer : Fixed delays connecting to the server on Windows.
+
 10.5.6.0 (relative to 10.5.5.0)
 ========
 
@@ -11,7 +17,6 @@ Improvements
 - `IECoreGL::ColorTexture`: Added new constructor that accepts an argument specifying the internal storage format to use.
 
 
-
 10.5.5.0 (relative to 10.5.4.2)
 ========
 

src/IECoreImage/DisplayDriverServer.cpp

@@ -175,7 +175,7 @@ class DisplayDriverServer::PrivateData : public RefCounted
 
 		void openPort( DisplayDriverServer::Port portNumber )
 		{
-			m_endpoint = boost::asio::ip::tcp::endpoint( tcp::v4(), portNumber );
+			m_endpoint = boost::asio::ip::tcp::endpoint( tcp::v6(), portNumber );
 			m_acceptor.open(  m_endpoint.protocol() );
 #ifdef _MSC_VER
 			m_acceptor.set_option( boost::asio::ip::tcp::acceptor::reuse_address( false ) );
@@ -184,6 +184,7 @@ class DisplayDriverServer::PrivateData : public RefCounted
 #else
 			m_acceptor.set_option( boost::asio::ip::tcp::acceptor::reuse_address( true ) );
 #endif
+			m_acceptor.set_option( boost::asio::ip::v6_only( false ) );
 			m_acceptor.bind( m_endpoint );
 			m_acceptor.listen();
 		}