-# Copyright (C) 2016 all contributors <meta@public-inbox.org>
+# Copyright (C) 2016-2018 all contributors <meta@public-inbox.org>
# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
+
+# Limits the number of processes spawned
+# This does not depend on Danga::Socket or any other external
+# scheduling mechanism, you just need to call start and finish
+# appropriately
package PublicInbox::Qspawn;
use strict;
use warnings;
use PublicInbox::Spawn qw(popen_rd);
-our $LIMIT = 1;
-my $running = 0;
-my @run_queue;
+require Plack::Util;
+my $def_limiter;
sub new ($$$;) {
my ($class, $cmd, $env, $opt) = @_;
sub _do_spawn {
my ($self, $cb) = @_;
my $err;
+
($self->{rpipe}, $self->{pid}) = popen_rd(@{$self->{args}});
- if ($self->{pid}) {
- $running++;
+ if (defined $self->{pid}) {
+ $self->{limiter}->{running}++;
} else {
$self->{err} = $!;
}
sub finish ($) {
my ($self) = @_;
+ my $limiter = $self->{limiter};
+ my $running;
if (delete $self->{rpipe}) {
my $pid = delete $self->{pid};
$self->{err} = $pid == waitpid($pid, 0) ? $? :
"PID:$pid still running?";
- $running--;
+ $running = --$limiter->{running};
}
- if (my $next = shift @run_queue) {
- _do_spawn(@$next);
+
+ # limiter->{max} may change dynamically
+ if (($running || $limiter->{running}) < $limiter->{max}) {
+ if (my $next = shift @{$limiter->{run_queue}}) {
+ _do_spawn(@$next);
+ }
}
$self->{err};
}
-sub start ($$) {
- my ($self, $cb) = @_;
+sub start {
+ my ($self, $limiter, $cb) = @_;
+ $self->{limiter} = $limiter;
- if ($running < $LIMIT) {
+ if ($limiter->{running} < $limiter->{max}) {
_do_spawn($self, $cb);
} else {
- push @run_queue, [ $self, $cb ];
+ push @{$limiter->{run_queue}}, [ $self, $cb ];
+ }
+}
+
+sub _psgi_finish ($$) {
+ my ($self, $env) = @_;
+ my $err = $self->finish;
+ if ($err && !$env->{'qspawn.quiet'}) {
+ $err = join(' ', @{$self->{args}->[0]}).": $err\n";
+ $env->{'psgi.errors'}->print($err);
}
}
+sub psgi_qx {
+ my ($self, $env, $limiter, $qx_cb) = @_;
+ my $qx = PublicInbox::Qspawn::Qx->new;
+ my $end = sub {
+ _psgi_finish($self, $env);
+ eval { $qx_cb->($qx) };
+ $qx = undef;
+ };
+ my $rpipe;
+ my $async = $env->{'pi-httpd.async'};
+ my $cb = sub {
+ my $r = sysread($rpipe, my $buf, 8192);
+ if ($async) {
+ $async->async_pass($env->{'psgix.io'}, $qx, \$buf);
+ } elsif (defined $r) {
+ $r ? $qx->write($buf) : $end->();
+ } else {
+ return if $!{EAGAIN} || $!{EINTR}; # loop again
+ $end->();
+ }
+ };
+ $limiter ||= $def_limiter ||= PublicInbox::Qspawn::Limiter->new(32);
+ $self->start($limiter, sub { # may run later, much later...
+ ($rpipe) = @_;
+ if ($async) {
+ # PublicInbox::HTTPD::Async->new($rpipe, $cb, $end)
+ $async = $async->($rpipe, $cb, $end);
+ } else { # generic PSGI
+ $cb->() while $qx;
+ }
+ });
+}
+
+# create a filter for "push"-based streaming PSGI writes used by HTTPD::Async
+sub filter_fh ($$) {
+ my ($fh, $filter) = @_;
+ Plack::Util::inline_object(
+ close => sub {
+ $fh->write($filter->(undef));
+ $fh->close;
+ },
+ write => sub {
+ $fh->write($filter->($_[0]));
+ });
+}
+
+sub psgi_return {
+ my ($self, $env, $limiter, $parse_hdr) = @_;
+ my ($fh, $rpipe);
+ my $end = sub {
+ _psgi_finish($self, $env);
+ $fh->close if $fh; # async-only
+ };
+
+ my $buf = '';
+ my $rd_hdr = sub {
+ my $r = sysread($rpipe, $buf, 1024, length($buf));
+ return if !defined($r) && ($!{EINTR} || $!{EAGAIN});
+ $parse_hdr->($r, \$buf);
+ };
+ my $res = delete $env->{'qspawn.response'};
+ my $async = $env->{'pi-httpd.async'};
+ my $cb = sub {
+ my $r = $rd_hdr->() or return;
+ $rd_hdr = undef;
+ my $filter = delete $env->{'qspawn.filter'};
+ if (scalar(@$r) == 3) { # error
+ if ($async) {
+ $async->close; # calls rpipe->close and $end
+ } else {
+ $rpipe->close;
+ $end->();
+ }
+ $res->($r);
+ } elsif ($async) {
+ $fh = $res->($r); # scalar @$r == 2
+ $fh = filter_fh($fh, $filter) if $filter;
+ $async->async_pass($env->{'psgix.io'}, $fh, \$buf);
+ } else { # for synchronous PSGI servers
+ require PublicInbox::GetlineBody;
+ $r->[2] = PublicInbox::GetlineBody->new($rpipe, $end,
+ $buf, $filter);
+ $res->($r);
+ }
+ };
+ $limiter ||= $def_limiter ||= PublicInbox::Qspawn::Limiter->new(32);
+ my $start_cb = sub { # may run later, much later...
+ ($rpipe) = @_;
+ if ($async) {
+ # PublicInbox::HTTPD::Async->new($rpipe, $cb, $end)
+ $async = $async->($rpipe, $cb, $end);
+ } else { # generic PSGI
+ $cb->() while $rd_hdr;
+ }
+ };
+
+ return $self->start($limiter, $start_cb) if $res;
+
+ sub {
+ ($res) = @_;
+ $self->start($limiter, $start_cb);
+ };
+}
+
+package PublicInbox::Qspawn::Limiter;
+use strict;
+use warnings;
+
+sub new {
+ my ($class, $max) = @_;
+ bless {
+ # 32 is same as the git-daemon connection limit
+ max => $max || 32,
+ running => 0,
+ run_queue => [],
+ }, $class;
+}
+
+# captures everything into a buffer and executes a callback when done
+package PublicInbox::Qspawn::Qx;
+use strict;
+use warnings;
+
+sub new {
+ my ($class) = @_;
+ my $buf = '';
+ bless \$buf, $class;
+}
+
+# called by PublicInbox::HTTPD::Async ($fh->write)
+sub write {
+ ${$_[0]} .= $_[1];
+ undef;
+}
+
1;