On Feb 21 18:44, Thomas Wolff wrote: > Am 20.02.2015 um 11:13 schrieb Corinna Vinschen: > >On Feb 20 08:56, Thomas Wolff wrote: > >>By flushing I meant actually waiting until it's been consumed at the > >>other end in this case, if that's technically feasible. > >You mean the actual act of changing the descriptor from non-blocking > >to blocking, as in fcntl(fd, F_SETFL), shall perform the same action > >of waiting as the close call on non-blocking descriptors does? > Yes. > >>I see no strict requirement that the fcntl call removing O_NONBLOCK from > >>a file descriptor should itself still be handled as nonblocking (it can > >>well be argued that the flag is changed first and then the call is > >>allowed to block) - and even if this were not proper it is certainly > >>more acceptable than losing data. > >I'm not sure that works as desired, but it's probably worth a try. An > >fcntl method for pipes has to be added (there is none yet, it's all done > >in fhandler_base::fcntl), then the F_SETFL command would have to be > >augmented to create a thread calling FlushFileBuffers (which is > >*supposed* to work on pipe handles but I never tried it myself), and the > >fcntl call would have to wait for thread completion, allowing > >interruption by signals (calling cygwait, that is). > where the actual code (as I understood you) could be copied from close() > code. Although I looked into the code and didn't find the place where close > would lead to FlushFileBuffers...
close doesn't call FFB. It just calls a waiter thread waiting for all async writes on pipes to be finished. It doesn't handle a single pipe, that's why this has to be implemented differently. > >The question with stuff like this is usually, how long are you willing to > >wait? > Indefinitely... > > You never know what the reader side of a pipe is doing. It > >might just be busy and intends to read from the pipe in a second, a > >minute, or an hour. > ... like it is normal when feeding a pipe in blocking mode (which we just > switched to). I don't see a problem here. You have a point there. Corinna -- Corinna Vinschen Please, send mails regarding Cygwin to Cygwin Maintainer cygwin AT cygwin DOT com Red Hat
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