Graceful and disgraceful disconnect

[piscisaureus]

Thinking about it makes my head hurt. But here's what:

Disgraceful disconnect

Currently, calling oio_close(handle) before the write queue is empty thrashes all data in the write queue. However the kernel will try to do a do a graceful disconnect anyway, so the client thinks he's received all data. This may be undesirable; an incomplete transfer should be recognizable as such by the other end. I think we need to set SO_LINGER with l_onoff=1 and l_linger=0 to achieve this.

Graceful disconnect

A socket can be closed after graceful shutdown when:

• A oio_read call has reported a zero byte read once
• The user has called oio_shutdown once, and
  oio_shutdown_cb has been called to indicate that the write queue was drained and a FIN has been sent.

Questions:

• Should we track which ends of the stream have been closed or should the user do that?
• Should oio_close be called automatically when a socket has been shut down at both ends?
• What if the user isn't reading the socket after shutting it down?

[ry]

• Should we track which ends of the stream have been closed or should the user do that?

I think we should, yes. This is a bit higher level than the systems interfaces - but we get to know more.

• Should oio_close be called automatically when a socket has been shut down at both ends?

Well - close() should be called automatically and the on_close callback fired.

• What if the user isn't reading the socket after shutting it down?

Then it remains open

[piscisaureus]

Landed in 7de6861 and b87f07d.