1 # Copyright (C) 2016-2018 all contributors <meta@public-inbox.org>
2 # License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
4 # Limits the number of processes spawned
5 # This does not depend on Danga::Socket or any other external
6 # scheduling mechanism, you just need to call start and finish
8 package PublicInbox::Qspawn;
11 use PublicInbox::Spawn qw(popen_rd);
16 my ($class, $cmd, $env, $opt) = @_;
17 bless { args => [ $cmd, $env, $opt ] }, $class;
24 ($self->{rpipe}, $self->{pid}) = popen_rd(@{$self->{args}});
25 if (defined $self->{pid}) {
26 $self->{limiter}->{running}++;
30 $cb->($self->{rpipe});
35 my $limiter = $self->{limiter};
37 if (delete $self->{rpipe}) {
38 my $pid = delete $self->{pid};
39 $self->{err} = $pid == waitpid($pid, 0) ? $? :
40 "PID:$pid still running?";
41 $running = --$limiter->{running};
44 # limiter->{max} may change dynamically
45 if (($running || $limiter->{running}) < $limiter->{max}) {
46 if (my $next = shift @{$limiter->{run_queue}}) {
54 my ($self, $limiter, $cb) = @_;
55 $self->{limiter} = $limiter;
57 if ($limiter->{running} < $limiter->{max}) {
58 _do_spawn($self, $cb);
60 push @{$limiter->{run_queue}}, [ $self, $cb ];
64 # create a filter for "push"-based streaming PSGI writes used by HTTPD::Async
66 my ($fh, $filter) = @_;
67 Plack::Util::inline_object(
69 $fh->write($filter->(undef));
73 $fh->write($filter->($_[0]));
78 my ($self, $env, $limiter, $parse_hdr) = @_;
81 my $err = $self->finish;
82 if ($err && !$env->{'qspawn.quiet'}) {
83 $err = join(' ', @{$self->{args}->[0]}).": $err\n";
84 $env->{'psgi.errors'}->print($err);
86 $fh->close if $fh; # async-only
89 # Danga::Socket users, we queue up the read_enable callback to
90 # fire after pending writes are complete:
93 my $r = sysread($rpipe, $buf, 1024, length($buf));
94 return if !defined($r) && ($!{EINTR} || $!{EAGAIN});
95 $parse_hdr->($r, \$buf);
98 my $async = $env->{'pi-httpd.async'};
100 my $r = $rd_hdr->() or return;
102 my $filter = delete $env->{'qspawn.filter'};
103 if (scalar(@$r) == 3) { # error
105 $async->close; # calls rpipe->close
112 $fh = $res->($r); # scalar @$r == 2
113 $fh = filter_fh($fh, $filter) if $filter;
114 $async->async_pass($env->{'psgix.io'}, $fh, \$buf);
115 } else { # for synchronous PSGI servers
116 require PublicInbox::GetlineBody;
117 $r->[2] = PublicInbox::GetlineBody->new($rpipe, $end,
122 $limiter ||= $def_limiter ||= PublicInbox::Qspawn::Limiter->new(32);
125 $self->start($limiter, sub { # may run later, much later...
128 # PublicInbox::HTTPD::Async->new($rpipe, $cb, $end)
129 $async = $async->($rpipe, $cb, $end);
130 } else { # generic PSGI
131 $cb->() while $rd_hdr;
137 package PublicInbox::Qspawn::Limiter;
142 my ($class, $max) = @_;
144 # 32 is same as the git-daemon connection limit