From a5806c1b4be3f74b25ec733328259e7966af6af6 Mon Sep 17 00:00:00 2001 From: "Richard W.M. Jones" Date: Mon, 20 Jun 2016 10:18:22 +0100 Subject: [PATCH] p2v: Poll to make Cancel Conversion button more responsive. Previously cancelling the conversion only set a flag, which was checked when the run dialog displayed new output from virt-v2v. When virt-v2v was showing hundreds of debugging messages, this wasn't a problem, but now that we are hiding those messages, cancelling the conversion might mean a wait of seconds or minutes. By polling (albeit infrequently) we can make the cancel button more responsive. (cherry picked from commit 6da4941db7f8a85997d6281b9b4c5165768e6489) --- p2v/conversion.c | 27 +++++++++++++++++++++++++-- 1 file changed, 25 insertions(+), 2 deletions(-) diff --git a/p2v/conversion.c b/p2v/conversion.c index b54f971..de2a4b2 100644 --- a/p2v/conversion.c +++ b/p2v/conversion.c @@ -25,6 +25,7 @@ #include #include #include +#include #include #include #include @@ -346,13 +347,35 @@ start_conversion (struct config *config, } /* Read output from the virt-v2v process and echo it through the - * notify function, until virt-v2v closes the connection. + * notify function, until virt-v2v closes the connection. We + * actually poll in this loop (albeit it only every 2 seconds) so + * that the user won't have to wait too long between pressing the + * cancel button and having the conversion cancelled. */ while (!is_cancel_requested ()) { + int fd = mexp_get_fd (control_h); + struct pollfd fds[1]; + int rp; char buf[257]; ssize_t r; - r = read (mexp_get_fd (control_h), buf, sizeof buf - 1); + fds[0].fd = fd; + fds[0].events = POLLIN; + fds[0].revents = 0; + rp = poll (fds, 1, 2000 /* ms */); + if (rp == -1) { + /* See comment about this in miniexpect.c. */ + if (errno == EIO) + break; + set_conversion_error ("poll: %m"); + goto out; + } + else if (rp == 0) + /* Timeout. */ + continue; + /* ... else rp == 1, ignore revents and just do the read. */ + + r = read (fd, buf, sizeof buf - 1); if (r == -1) { /* See comment about this in miniexpect.c. */ if (errno == EIO) -- 2.7.4