Distinguish pending and nonpending requests

[piscisaureus]

As discussed, oio_write, oio_read and oio_connect might complete synchronously. When that happens the request callback will not be made. How do we tell the user that this happened?

options:

• Return 0 on immediate completion, return -1 and set the last error to OIO_PENDING when the request pends.
• Return 0 on immediate completion, -1 on error, and -2 when the request pends.

remarks:

• Maybe It's hard to imagine a situation where a connect completes immediately. However, the windows ConnectEx call I'm making does not guarantee that the overlapped operation always returns WSA_IO_PENDING. Also it is not unexpected that connecting a pipe / fifo could be done synchronously.
• Implementations might choose to always report that a request is pending. For example, windows XP always reports completion asynchronously even if a request could be serviced immediately. (on later windowses this behavior can be specified with SetFileCompletionNotificationModes).

[ry]

also it does not call the callback on immediate completion.

I like option one - as it's more windows-y

[piscisaureus]

"When that happens the request callback will not be made."
I think we agreed on beforehand. :-)

[ry]

How do you get the return value of oio_read - number of bytes read?

[piscisaureus]

Return it? Use int instead of size_t. Also merge the status and nread arguments for oio_read_cb, make that an int too. People are not going to read/write > 2gb of data in one req anyway.

[ry]

Why int? Should be ssize_t

[piscisaureus]

Oh yes that's okay -- I wasn't aware of the existence of ssize_t.

[piscisaureus]

This idea was dropped -- all requests will complete async. Closing.