Move .userData to the socket driver.

Generally each FD type should have its own .userData property in the respective driver. This is important for drivers that don't have a unified file descriptor space and need to store user data in a type specific way.

source/eventcore/driver.d

@@ -103,8 +103,9 @@ interface EventDriverCore {
 	/// ditto
 	protected void* rawUserData(DatagramSocketFD descriptor, size_t size, DataInitializer initialize, DataInitializer destroy) @system;
 
-	/** Retrieves a reference to a user-defined value associated with a descriptor.
+	/** Deprecated - use `EventDriverSockets.userData` instead.
 	*/
+	deprecated("Use `EventDriverSockets.userData` instead.")
 	@property final ref T userData(T, FD)(FD descriptor)
 	@trusted {
 		import std.conv : emplace;
@@ -277,6 +278,21 @@ interface EventDriverSockets {
 			Returns `false` $(I iff) the last reference was removed by this call.
 	*/
 	bool releaseRef(SocketFD descriptor);
+
+	/// Low-level user data access. Use `getUserData` instead.
+	protected void* rawUserData(StreamSocketFD descriptor, size_t size, DataInitializer initialize, DataInitializer destroy) @system;
+	/// ditto
+	protected void* rawUserData(DatagramSocketFD descriptor, size_t size, DataInitializer initialize, DataInitializer destroy) @system;
+
+	/** Retrieves a reference to a user-defined value associated with a descriptor.
+	*/
+	@property final ref T userData(T, FD)(FD descriptor)
+	@trusted {
+		import std.conv : emplace;
+		static void init(void* ptr) { emplace(cast(T*)ptr); }
+		static void destr(void* ptr) { destroy(*cast(T*)ptr); }
+		return *cast(T*)rawUserData(descriptor, T.sizeof, &init, &destr);
+	}
 }
 
 

source/eventcore/drivers/posix/sockets.d

@@ -728,6 +728,30 @@ final class PosixEventDriverSockets(Loop : PosixEventLoop) : EventDriverSockets
 		return true;
 	}
 
+	final protected override void* rawUserData(StreamSocketFD descriptor, size_t size, DataInitializer initialize, DataInitializer destroy)
+	@system {
+		return rawUserDataImpl(descriptor, size, initialize, destroy);
+	}
+
+	final protected override void* rawUserData(DatagramSocketFD descriptor, size_t size, DataInitializer initialize, DataInitializer destroy)
+	@system {
+		return rawUserDataImpl(descriptor, size, initialize, destroy);
+	}
+
+	private void* rawUserDataImpl(FD descriptor, size_t size, DataInitializer initialize, DataInitializer destroy)
+	@system {
+		auto fds = &m_loop.m_fds[descriptor].common;
+		assert(fds.userDataDestructor is null || fds.userDataDestructor is destroy,
+			"Requesting user data with differing type (destructor).");
+		assert(size <= fds.userData.length, "Requested user data is too large.");
+		if (size > fds.userData.length) assert(false);
+		if (!fds.userDataDestructor) {
+			initialize(fds.userData.ptr);
+			fds.userDataDestructor = destroy;
+		}
+		return m_loop.m_fds[descriptor].common.userData.ptr;
+	}
+
 	private sock_t createSocket(AddressFamily family, int type)
 	{
 		sock_t sock;

source/eventcore/drivers/winapi/sockets.d

@@ -134,4 +134,14 @@ final class WinAPIEventDriverSockets : EventDriverSockets {
 	{
 		assert(false, "TODO!");
 	}
+
+	protected override void* rawUserData(StreamSocketFD descriptor, size_t size, DataInitializer initialize, DataInitializer destroy) @system
+	{
+		assert(false, "TODO!");
+	}
+
+	protected override void* rawUserData(DatagramSocketFD descriptor, size_t size, DataInitializer initialize, DataInitializer destroy) @system
+	{
+		assert(false, "TODO!");
+	}
 }