[TUHS] non-blocking IO

Paul Ruizendaal pnr at planet.nl
Tue Jun 2 18:22:12 AEST 2020

>     > when you're working below the reliable stream level, you can't just do a > blocking 'read' for a packet; it pretty much has to be asynchronous
> Oh, you should look at the early BBN TCP for V6 Unix - they would have faced the same issue, with their TCP process. They did have the capac() call (which kind of alleviates the need for non-blocking I/O), but that may have only been available for ports/pipes; I'm not sure if the ARPANET device supported it.

I did. There is capac() support also for the IMP interface:
(see bottom two functions)

BBN took the same approach as Research: with capac() or select() one can prevent blocking on read() and write().

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