ruby-changes:39224
From: normal <ko1@a...>
Date: Tue, 21 Jul 2015 05:34:13 +0900 (JST)
Subject: [ruby-changes:39224] normal:r51305 (trunk): io.c: IO.copy_stream uses poll on Linux
normal 2015-07-21 05:33:50 +0900 (Tue, 21 Jul 2015) New Revision: 51305 http://svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=51305 Log: io.c: IO.copy_stream uses poll on Linux poll and ppoll have a superior API which doesn't require the kernel to scan a potentially large bitmap to find a high-numbered FD [ruby-core:35572]. So favor using poll in case IO.copy_stream encounters a non-blocking FD. We cannot reliably use poll on most OSes, because file types (e.g. FIFOs) which work with select may not work with poll. Fortunately, Linux uses a common notification mechanism between all select/poll/epoll variants, so all file types are equally supported between the notification mechanisms. Verified by watching strace on the following scripts: *** maygvl_copy_stream_wait_read *** require 'io/nonblock' r, w = IO.pipe r.nonblock = true IO.copy_stream(r, "/dev/null") *** nogvl_copy_stream_wait_write *** require 'io/nonblock' r, w = IO.pipe w.nonblock = true IO.copy_stream("/dev/zero", w) * io.c (nogvl_wait_for_single_fd): new function for Linux (maygvl_copy_stream_wait_read): Linux-specific version (nogvl_copy_stream_wait_write): use nogvl_wait_for_single_fd [ruby-core:70051] [Feature #11377] Modified files: trunk/ChangeLog trunk/io.c Index: ChangeLog =================================================================== --- ChangeLog (revision 51304) +++ ChangeLog (revision 51305) @@ -1,3 +1,10 @@ https://github.com/ruby/ruby/blob/trunk/ChangeLog#L1 +Tue Jul 21 05:20:21 2015 Eric Wong <e@8...> + + * io.c (nogvl_wait_for_single_fd): new function for Linux + (maygvl_copy_stream_wait_read): Linux-specific version + (nogvl_copy_stream_wait_write): use nogvl_wait_for_single_fd + [ruby-core:70051] [Feature #11377] + Mon Jul 20 15:04:30 2015 Eric Wong <e@8...> * parse.y (parser_initialize): avoid redundant zero-ing Index: io.c =================================================================== --- io.c (revision 51304) +++ io.c (revision 51305) @@ -10087,6 +10087,49 @@ maygvl_copy_stream_continue_p(int has_gv https://github.com/ruby/ruby/blob/trunk/io.c#L10087 return FALSE; } +/* non-Linux poll may not work on all FDs */ +#if defined(HAVE_POLL) && defined(__linux__) +# define USE_POLL 1 +# define IOWAIT_SYSCALL "poll" +#else +# define IOWAIT_SYSCALL "select" +# define USE_POLL 0 +#endif + +#if USE_POLL +static int +nogvl_wait_for_single_fd(int fd, short events) +{ + struct pollfd fds; + + fds.fd = fd; + fds.events = events; + + return poll(&fds, 1, 0); +} + +static int +maygvl_copy_stream_wait_read(int has_gvl, struct copy_stream_struct *stp) +{ + int ret; + + do { + if (has_gvl) { + ret = rb_wait_for_single_fd(stp->src_fd, RB_WAITFD_IN, NULL); + } + else { + ret = nogvl_wait_for_single_fd(stp->src_fd, POLLIN); + } + } while (ret == -1 && maygvl_copy_stream_continue_p(has_gvl, stp)); + + if (ret == -1) { + stp->syserr = "poll"; + stp->error_no = errno; + return -1; + } + return 0; +} +#else /* !USE_POLL */ static int maygvl_select(int has_gvl, int n, rb_fdset_t *rfds, rb_fdset_t *wfds, rb_fdset_t *efds, struct timeval *timeout) { @@ -10114,6 +10157,7 @@ maygvl_copy_stream_wait_read(int has_gvl https://github.com/ruby/ruby/blob/trunk/io.c#L10157 } return 0; } +#endif /* !USE_POLL */ static int nogvl_copy_stream_wait_write(struct copy_stream_struct *stp) @@ -10121,13 +10165,17 @@ nogvl_copy_stream_wait_write(struct copy https://github.com/ruby/ruby/blob/trunk/io.c#L10165 int ret; do { +#if USE_POLL + ret = nogvl_wait_for_single_fd(stp->dst_fd, POLLOUT); +#else rb_fd_zero(&stp->fds); rb_fd_set(stp->dst_fd, &stp->fds); ret = rb_fd_select(rb_fd_max(&stp->fds), NULL, &stp->fds, NULL, NULL); +#endif } while (ret == -1 && maygvl_copy_stream_continue_p(0, stp)); if (ret == -1) { - stp->syserr = "select"; + stp->syserr = IOWAIT_SYSCALL; stp->error_no = errno; return -1; } -- ML: ruby-changes@q... Info: http://www.atdot.net/~ko1/quickml/