HaO 2014-06-04 I created this page to document issues and design points I had with this command within the rewrite of the Windows socket driver. Thanks to DGP for discussions on this on the chat.
socket -async connect failed which should be reported to a readable and writable eventHaO 2014-06-04: Within the socket driver, an async connect socket -async failed. This may happen: and socket -async
- Within the event queue
- As a side effect of other commands touching the driver like fconfigure
1.Directly at the position where the fail arises.
This has the following issues:- The man page [1] does not recomment this to give other notifications a fair chance
- One call is not enough: If there is a pending flush, a writable notification may be eaten by the Tcl framework and there is no call to the user function.
- If the issue is not fixed (and a failed async connect is not fixable), the call must be repeated until the socket is closed.
2.By the event queue.
The upper issues are solved if Tcl_NotifyChannel is called within the event queue. The registered event source procedures (Tcl_CreateEventSource(SocketSetupProc, SocketCheckProc, NULL)) should do this:- The need to call Tcl_NotifyChannel should be saved in a driver internal flag variable
- SocketSetupProc should stop blocking if flag set
- SocketCheckProc should queue an event if flag set
- SocketEventProc should finally call Tcl_NotifyChannel
and socket -async
