Nonblocking connect using poll

[ericonr]

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Replacing #210

[AppVeyorBot]

:x: Build asyn 1.0.283 failed (commit https://github.com/epics-modules/asyn/commit/ae16b99eb5 by @ericonr)

[ericonr]

The failure seems unrelated: https://ci.appveyor.com/project/MarkRivers/asyn/builds/51101760/job/iyv53p19fkkop0vd

[AppVeyorBot]

:x: Build asyn 1.0.284 failed (commit https://github.com/epics-modules/asyn/commit/b8bbe39652 by @ericonr)

[MarkRivers]

@ericonr I would like to merge this soon. Can you create a Github issue that describes the problem this PR is designed to fix, and some simple observations that will confirm that it is working? I think it fixes a problem like this:

drvAsynIPPortConfigure("MyPort", "ip_address", 0, 0, 0)
asynOctetSetInputEos("MyPort",0,"\r")
asynOctetSetOutputEos("MyPort",0,"\r")

If ip_address is not reachable then the asynOcterSetInputEos() asynOcterSetOutputEos() commands will each hang for a long time because the port is locked waiting for the connect() to time out. Is this correct?

[ericonr]

Hi @MarkRivers

I have updated the commit message to include a better description of the problem being solved, as well as what was used to confirm it's working. Should I still open an issue, or is the commit description enough?

If ip_address is not reachable then the asynOcterSetInputEos() asynOcterSetOutputEos() commands will each hang for a long time because the port is locked waiting for the connect() to time out. Is this correct?

That is correct!

[AppVeyorBot]

:x: Build asyn 1.0.296 failed (commit https://github.com/epics-modules/asyn/commit/7ab23bcecf by @ericonr)

[chrschroeder]

@MarkRivers @ericonr There is already an open issue for this (https://github.com/epics-modules/asyn/issues/103). I have backported the patches to our local branch and rolled it out to some of our IOCs. Works fine and no problems so far. Thanks for your work to fix this!