[PATCH 12/21] mbox_lock: retry on EINTR and use autodie

[Eric Wong]

EINTR needs to be retried in case signalfd and kevent aren't
available.  And autodie makes it easier to focus on more
important stuff.
---
 lib/PublicInbox/MboxLock.pm | 49 +++++++++++++++++--------------------
 1 file changed, 22 insertions(+), 27 deletions(-)

diff --git a/lib/PublicInbox/MboxLock.pm b/lib/PublicInbox/MboxLock.pm
index 856b1e21..95aa9862 100644
--- a/lib/PublicInbox/MboxLock.pm
+++ b/lib/PublicInbox/MboxLock.pm
@@ -1,15 +1,15 @@
-# Copyright (C) 2021 all contributors <meta@public-inbox.org>
+# Copyright (C) all contributors <meta@public-inbox.org>
 # License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
 
 # Various mbox locking methods
 package PublicInbox::MboxLock;
-use strict;
-use v5.10.1;
+use v5.12;
 use PublicInbox::OnDestroy;
 use Fcntl qw(:flock F_SETLK F_SETLKW F_RDLCK F_WRLCK
                        O_CREAT O_EXCL O_WRONLY SEEK_SET);
 use Carp qw(croak);
 use PublicInbox::DS qw(now); # ugh...
+use autodie qw(chdir opendir unlink);
 
 our $TMPL = do {
        if ($^O eq 'linux') { \'s @32' }
@@ -58,16 +58,13 @@ sub acq_dotlock {
                                        rand(0xffffffff), $pid, time);
                if (sysopen(my $fh, $tmp, O_CREAT|O_EXCL|O_WRONLY)) {
                        if (link($tmp, $dot_lock)) {
-                               unlink($tmp) or die "unlink($tmp): $!";
+                               unlink($tmp);
                                $self->{".lock$pid"} = $dot_lock;
-                               if (substr($dot_lock, 0, 1) ne '/') {
-                                       opendir(my $dh, '.') or
-                                                       die "opendir . $!";
-                                       $self->{dh} = $dh;
-                               }
+                               substr($dot_lock, 0, 1) eq '/' or
+                                       opendir($self->{dh}, '.');
                                return;
                        }
-                       unlink($tmp) or die "unlink($tmp): $!";
+                       unlink($tmp);
                        select(undef, undef, undef, $self->{delay});
                } else {
                        croak "open $tmp (for $dot_lock): $!" if !$!{EXIST};
@@ -83,18 +80,20 @@ sub acq_flock {
        my $end = now + $self->{timeout};
        do {
                return if flock($self->{fh}, $op);
-               select(undef, undef, undef, $self->{delay});
+               if ($!{EWOULDBLOCK}) {
+                       select(undef, undef, undef, $self->{delay});
+               } elsif (!$!{EINTR}) {
+                       croak "flock($self->{f} ($self->{fh}): $!";
+               }
        } while (now < $end);
        die "flock timeout $self->{f}: $!\n";
 }
 
 sub acq {
        my ($cls, $f, $rw, $methods) = @_;
-       my $fh;
-       unless (open $fh, $rw ? '+>>' : '<', $f) {
-               croak "open($f): $!" if $rw || !$!{ENOENT};
-       }
-       my $self = bless { f => $f, fh => $fh, rw => $rw }, $cls;
+       my $self = bless { f => $f, rw => $rw }, $cls;
+       my $ok = open $self->{fh}, $rw ? '+>>' : '<', $f;
+       croak "open($f): $!" if !$ok && ($rw || !$!{ENOENT});
        my $m = "@$methods";
        if ($m ne 'none') {
                my @m = map {
@@ -116,20 +115,16 @@ sub acq {
        $self;
 }
 
-sub _fchdir { chdir($_[0]) } # OnDestroy callback
-
 sub DESTROY {
        my ($self) = @_;
-       if (my $f = $self->{".lock$$"}) {
-               my $x;
-               if (my $dh = delete $self->{dh}) {
-                       opendir my $c, '.' or die "opendir . $!";
-                       $x = PublicInbox::OnDestroy->new(\&_fchdir, $c);
-                       chdir($dh) or die "chdir (for $f): $!";
-               }
-               unlink($f) or die "unlink($f): $! (lock stolen?)";
-               undef $x;
+       my $f = $self->{".lock$$"} or return;
+       my $x;
+       if (my $dh = delete $self->{dh}) {
+               opendir my $c, '.';
+               $x = PublicInbox::OnDestroy->new(\&chdir, $c);
+               chdir($dh);
        }
+       CORE::unlink($f) or die "unlink($f): $! (lock stolen?)";
 }
 
 1;