emergency: implement new emergency Maildir delivery

[public-inbox.git] / lib / PublicInbox / Emergency.pm

diff --git a/lib/PublicInbox/Emergency.pm b/lib/PublicInbox/Emergency.pm
new file mode 100644 (file)
index 0000000..e402d30
--- /dev/null
+++ b/lib/PublicInbox/Emergency.pm
@@ -0,0 +1,96 @@
+# Copyright (C) 2016 all contributors <meta@public-inbox.org>
+# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
+#
+# Emergency Maildir delivery for MDA
+package PublicInbox::Emergency;
+use strict;
+use warnings;
+use Fcntl qw(:DEFAULT SEEK_SET);
+use Sys::Hostname qw(hostname);
+use IO::Handle;
+
+sub new {
+       my ($class, $dir) = @_;
+
+       foreach (qw(new tmp cur)) {
+               my $d = "$dir/$_";
+               next if -d $d;
+               require File::Path;
+               File::Path::mkpath($d); # croaks on fatal errors
+       }
+       bless { dir => $dir, files => {}, t => 0, cnt => 0 }, $class;
+}
+
+sub _fn_in {
+       my ($self, $dir) = @_;
+       my @host = split(/\./, hostname);
+       my $now = time;
+       if ($self->{t} != $now) {
+               $self->{t} = $now;
+               $self->{cnt} = 0;
+       } else {
+               $self->{cnt}++;
+       }
+
+       my $f;
+       do {
+               $f = "$self->{dir}/$dir/$self->{t}.$$"."_$self->{cnt}.$host[0]";
+               $self->{cnt}++;
+       } while (-e $f);
+       $f;
+}
+
+sub prepare {
+       my ($self, $strref) = @_;
+
+       die "already in transaction: $self->{tmp}" if $self->{tmp};
+       my ($tmp, $fh);
+       do {
+               $tmp = _fn_in($self, 'tmp');
+               $! = undef;
+       } while (!sysopen($fh, $tmp, O_CREAT|O_EXCL|O_RDWR) && $!{EEXIST});
+       print $fh $$strref or die "write failed: $!";
+       $fh->flush or die "flush failed: $!";
+       $fh->autoflush(1);
+       $self->{fh} = $fh;
+       $self->{tmp} = $tmp;
+}
+
+sub abort {
+       my ($self) = @_;
+       delete $self->{fh};
+       my $tmp = delete $self->{tmp} or return;
+
+       unlink($tmp) or warn "Failed to unlink $tmp: $!";
+       undef;
+}
+
+sub fh {
+       my ($self) = @_;
+       my $fh = $self->{fh} or die "{fh} not open!\n";
+       seek($fh, 0, SEEK_SET) or die "seek(fh) failed: $!";
+       sysseek($fh, 0, SEEK_SET) or die "sysseek(fh) failed: $!";
+       $fh;
+}
+
+sub commit {
+       my ($self) = @_;
+
+       delete $self->{fh};
+       my $tmp = delete $self->{tmp} or return;
+       my $new;
+       do {
+               $new = _fn_in($self, 'new');
+       } while (!link($tmp, $new) && $!{EEXIST});
+       my @sn = stat($new) or die "stat $new failed: $!";
+       my @st = stat($tmp) or die "stat $tmp failed: $!";
+       if ($st[0] == $sn[0] && $st[1] == $sn[1]) {
+               unlink($tmp) or warn "Failed to unlink $tmp: $!";
+       } else {
+               warn "stat($new) and stat($tmp) differ";
+       }
+}
+
+sub DESTROY { commit($_[0]) }
+
+1;