RFC: How should ReadFile() on sockets behave ??

[Martin Wilck]

Hi Mike,

> Hmmm. MSDN says that FD_READ is only re-enabled on recv, recvfrom,
> WSARecv and WSARecvFrom. Maybe you should verify that ReadFile doesn't
> re-enable FD_READ on a windows platform or two?

You're absolutely right. Unfortunately this will take some time.
The problem is that FD_READ has some really awkward connection
with FD_CLOSE events, pretty hard to explain shortly.
The discussion I had with Ove lately ("Urgent need for advice...")
may give you some insight.

> ReadFile in asynchronous mode already reports completion of reads to the
> wineserver...

Are you talking about finish_async() ?

> why not make it always work like FILE_TimeoutRead in
> files/file.c for sockets?

I have been thinking about that, but it means adding some overhead
for non-overlapped operations (doing an overlapped request this way
requires more than just one server call).

This hardly matters for slow comm ports, but it may matter if you
communicate over a Gbit ethernet network socket.

I like the idea, though, of getting rid of the distinction between
overlapped and non-overlapped IO by just making everything overlapped
and immediately waiting for the results in the synchronous case.
(Basically the same code we're already using now in order to check
if an overlapped operation can be completed immediately, just with
bWait=TRUE).

It would also have the benefit that you could mix asynchronous
and synchronous calls to an overlapped fd without corrupting your data
(I don't know if there are apps out there which do that, nor what Windows
would do - the ReadFile() docs forbid it, but the WSARecv() docs don't).

Of course this would also mean that all server objects that can be
addressed with ReadFile() and WriteFile() must support asynchronous IO
(wine-internally).

I'll wait for other people's opinions.

Martin

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