From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-Status: No, score=-4.0 required=3.0 tests=ALL_TRUSTED,BAYES_00 shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from localhost (dcvr.yhbt.net [127.0.0.1]) by dcvr.yhbt.net (Postfix) with ESMTP id 83D831FA17 for ; Sun, 29 Nov 2020 10:52:30 +0000 (UTC) From: Eric Wong To: meta@public-inbox.org Subject: [PATCH 1/2] git: set non-blocking flag in case of other bugs Date: Sun, 29 Nov 2020 10:52:29 +0000 Message-Id: <20201129105230.12501-2-e@80x24.org> In-Reply-To: <20201129105230.12501-1-e@80x24.org> References: <20201129105230.12501-1-e@80x24.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit List-Id: This makes GitAsyncCat more resilient to bugs in Gcf2 or even git-cat-file itself. I noticed -imapd stuck on read(2) from the Gcf2 pipe, so there may be a bug somewhere in Gcf2 or PublicInbox::Git. This should make us more resilient to them and hopefully help us notice and fix them. --- lib/PublicInbox/Git.pm | 28 +++++++++++++++++++++------- lib/PublicInbox/GitAsyncCat.pm | 6 +----- 2 files changed, 22 insertions(+), 12 deletions(-) diff --git a/lib/PublicInbox/Git.pm b/lib/PublicInbox/Git.pm index 917fa4a1..d53427d7 100644 --- a/lib/PublicInbox/Git.pm +++ b/lib/PublicInbox/Git.pm @@ -12,17 +12,19 @@ use v5.10.1; use parent qw(Exporter); use POSIX (); use IO::Handle; # ->autoflush -use Errno qw(EINTR); +use Errno qw(EINTR EAGAIN); use File::Glob qw(bsd_glob GLOB_NOSORT); use File::Spec (); use Time::HiRes qw(stat); use PublicInbox::Spawn qw(popen_rd); use PublicInbox::Tmpfile; +use IO::Poll qw(POLLIN); use Carp qw(croak); use Digest::SHA (); our @EXPORT_OK = qw(git_unquote git_quote); our $PIPE_BUFSIZ = 65536; # Linux default our $in_cleanup; +our $RDTIMEO = 60_000; # milliseconds use constant MAX_INFLIGHT => (($^O eq 'linux' ? 4096 : POSIX::_POSIX_PIPE_BUF()) * 3) @@ -132,6 +134,8 @@ sub _bidi_pipe { $self->{$in} = $in_r; } +sub poll_in ($) { IO::Poll::_poll($RDTIMEO, fileno($_[0]), my $ev = POLLIN) } + sub my_read ($$$) { my ($fh, $rbuf, $len) = @_; my $left = $len - length($$rbuf); @@ -140,9 +144,12 @@ sub my_read ($$$) { $r = sysread($fh, $$rbuf, $PIPE_BUFSIZ, length($$rbuf)); if ($r) { $left -= $r; + } elsif (defined($r)) { # EOF + return 0; } else { - next if (!defined($r) && $! == EINTR); - return $r; + next if ($! == EAGAIN and poll_in($fh)); + next if $! == EINTR; # may be set by sysread or poll_in + return; # unrecoverable error } } \substr($$rbuf, 0, $len, ''); @@ -154,9 +161,15 @@ sub my_readline ($$) { if ((my $n = index($$rbuf, "\n")) >= 0) { return substr($$rbuf, 0, $n + 1, ''); } - my $r = sysread($fh, $$rbuf, $PIPE_BUFSIZ, length($$rbuf)); - next if $r || (!defined($r) && $! == EINTR); - return defined($r) ? '' : undef; # EOF or error + my $r = sysread($fh, $$rbuf, $PIPE_BUFSIZ, length($$rbuf)) + and next; + + # return whatever's left on EOF + return substr($$rbuf, 0, length($$rbuf)+1, '') if defined($r); + + next if ($! == EAGAIN and poll_in($fh)); + next if $! == EINTR; # may be set by sysread or poll_in + return; # unrecoverable error } } @@ -204,7 +217,8 @@ sub cat_async_step ($$) { $type = 'missing'; $oid = ref($req) ? $$req : $req if $oid eq ''; } else { - $self->fail("Unexpected result from async git cat-file: $head"); + my $err = $! ? " ($!)" : ''; + $self->fail("bad result from async cat-file: $head$err"); } $self->{cat_rbuf} = $rbuf if $$rbuf ne ''; eval { $cb->($bref, $oid, $type, $size, $arg) }; diff --git a/lib/PublicInbox/GitAsyncCat.pm b/lib/PublicInbox/GitAsyncCat.pm index be51f673..dc97af16 100644 --- a/lib/PublicInbox/GitAsyncCat.pm +++ b/lib/PublicInbox/GitAsyncCat.pm @@ -3,11 +3,6 @@ # # internal class used by PublicInbox::Git + PublicInbox::DS # This parses the output pipe of "git cat-file --batch" -# -# Note: this does NOT set the non-blocking flag, we expect `git cat-file' -# to be a local process, and git won't start writing a blob until it's -# fully read. So minimize context switching and read as much as possible -# and avoid holding a buffer in our heap any longer than it has to live. package PublicInbox::GitAsyncCat; use strict; use parent qw(PublicInbox::DS Exporter); @@ -69,6 +64,7 @@ sub git_async_cat ($$$$) { $gitish->{async_cat} //= do { # read-only end of pipe (Gcf2Client is write-only end) my $self = bless { gitish => $gitish }, __PACKAGE__; + $gitish->{in}->blocking(0); $self->SUPER::new($gitish->{in}, EPOLLIN|EPOLLET); \undef; # this is a true ref() };