Re: [OT] Two sockets questions

[tmoran@acm.org]

> Tom> It's intended for blocking sockets, so it sits around and polls
> Tom> till the select says its writable, or some other error is
> Tom> returned.  It actually opens as non-blocking so it can get
> Tom> control back from the OS to do this polling, and timeout
> Tom> checking, etc.
>
> Why not make the socket blocking in this case (around connect()) since
> your code sits and waits for select() to return?
  Three reasons:  The Open procedure has a timeout parameter, so it needs
to be able to terminate the "connect" early.  The package also has a
"Request_Quit" mechanism whereby some task can ask another to abort a wait
on socket activity.  It's simpler and clearer to check with a direct poll
loop (with "delay") than with Windows' message loop polling.  Also, one of
the targeted compilers does its own tasking within a single Windows
thread, so a true block of the thread would block all tasks.  (That
compiler's Ada task switch time, not going through the OS, is quite a bit
faster.  It also can target Windows 3.1, though I grant that may no longer
be very important.)