# Copyright (C) 2020 all contributors
# License: AGPL-3.0+
# base class for remote IPC calls, requires Storable
# TODO: this ought to be usable in SearchIdxShard
package PublicInbox::IPC;
use strict;
use v5.10.1;
use Socket qw(AF_UNIX SOCK_STREAM);
use Carp qw(confess croak);
use PublicInbox::Sigfd;
my ($enc, $dec);
# ->imports at BEGIN turns serial_*_with_object into custom ops on 5.14+
# and eliminate method call overhead
BEGIN {
eval {
require Sereal::Encoder;
require Sereal::Decoder;
Sereal::Encoder->import('sereal_encode_with_object');
Sereal::Decoder->import('sereal_decode_with_object');
($enc, $dec) = (Sereal::Encoder->new, Sereal::Decoder->new);
};
};
if ($enc && $dec) { # should be custom ops
*freeze = sub ($) { sereal_encode_with_object $enc, $_[0] };
*thaw = sub ($) { sereal_decode_with_object $dec, $_[0], my $ret };
} else {
eval { # some distros have Storable as a separate package from Perl
require Storable;
Storable->import(qw(freeze thaw));
$enc = 1;
} // warn("Storable (part of Perl) missing: $@\n");
}
sub _get_rec ($) {
my ($sock) = @_;
local $/ = "\n";
defined(my $len = <$sock>) or return;
chop($len) eq "\n" or croak "no LF byte in $len";
defined(my $r = read($sock, my $buf, $len)) or croak "read error: $!";
$r == $len or croak "short read: $r != $len";
thaw($buf);
}
sub _send_rec ($$) {
my ($sock, $ref) = @_;
my $buf = freeze($ref);
print $sock length($buf), "\n", $buf or croak "print: $!";
}
sub ipc_return ($$$) {
my ($s2, $ret, $exc) = @_;
_send_rec($s2, $exc ? bless(\$exc, 'PublicInbox::IPC::Die') : $ret);
}
sub ipc_worker_loop ($$) {
my ($self, $s2) = @_;
$self->ipc_atfork_child if $self->can('ipc_atfork_child');
$s2->autoflush(1);
while (my $rec = _get_rec($s2)) {
my ($wantarray, $sub, @args) = @$rec;
if (!defined($wantarray)) { # no waiting if client doesn't care
eval { $self->$sub(@args) };
eval { warn "die: $@ (from nowait $sub)\n" } if $@;
} elsif ($wantarray) {
my @ret = eval { $self->$sub(@args) };
ipc_return($s2, \@ret, $@);
} else {
my $ret = eval { $self->$sub(@args) };
ipc_return($s2, \$ret, $@);
}
}
}
sub ipc_worker_spawn ($$$) {
my ($self, $ident, $oldset) = @_;
return unless $enc;
my $pid = $self->{-ipc_worker_pid};
confess "BUG: already spawned PID:$pid" if $pid;
confess "BUG: already have worker socket" if $self->{-ipc_sock};
my ($s1, $s2);
socketpair($s1, $s2, AF_UNIX, SOCK_STREAM, 0) or die "socketpair: $!";
my $sigset = $oldset // PublicInbox::Sigfd::block_signals();
defined($pid = fork) or die "fork: $!";
if ($pid == 0) {
undef $s1;
local $0 = $ident;
$SIG{$_} = 'IGNORE' for (qw(TERM INT QUIT));
PublicInbox::Sigfd::sig_setmask($oldset);
eval { ipc_worker_loop($self, $s2) };
die "worker $ident died: $@\n" if $@;
$self->ipc_at_worker_exit if $self->can('ipc_at_worker_exit');
exit;
}
PublicInbox::Sigfd::sig_setmask($sigset) unless $oldset;
$s1->autoflush(1);
$self->{-ipc_sock} = $s1;
$self->{-ipc_worker_pid} = $pid;
}
sub ipc_reap_worker { # dwaitpid callback
my ($self, $pid) = @_;
warn "PID:$pid died with \$?=$?\n" if $?;
}
sub ipc_worker_stop {
my ($self) = @_;
my $pid;
if (delete $self->{-ipc_sock}) {
$pid = delete $self->{-ipc_worker_pid} or die "no PID?";
} else {
$pid = delete $self->{-ipc_worker_pid} and
die "unexpected PID:$pid";
}
return unless $pid;
eval { PublicInbox::DS::dwaitpid($pid, \&ipc_reap_worker, $self) };
if ($@) {
my $wp = waitpid($pid, 0);
$pid == $wp or die "waitpid($pid) returned $wp: \$?=$?";
ipc_reap_worker($self, $pid);
}
}
# use this if we have multiple readers reading curl or "pigz -dc"
# and writing to the same store
sub ipc_lock_init {
my ($self, $f) = @_;
require PublicInbox::Lock;
$self->{-ipc_lock} //= bless { lock_path => $f }, 'PublicInbox::Lock'
}
sub ipc_do {
my ($self, $sub, @args) = @_;
if (my $s1 = $self->{-ipc_sock}) {
my $ipc_lock = $self->{-ipc_lock};
my $lock = $ipc_lock ? $ipc_lock->lock_for_scope : undef;
_send_rec($s1, [ wantarray, $sub, @args ]);
return unless defined(wantarray);
my $ret = _get_rec($s1) // die "no response on $sub";
die $$ret if ref($ret) eq 'PublicInbox::IPC::Die';
wantarray ? @$ret : $$ret;
} else {
$self->$sub(@args);
}
}
1;