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| | # 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);
sub new ($$$;) {
my ($class, $cmd, $env, $opt) = @_;
bless { args => [ $cmd, $env, $opt ] }, $class;
}
sub _do_spawn {
my ($self, $cb) = @_;
my $err;
($self->{rpipe}, $self->{pid}) = popen_rd(@{$self->{args}});
if (defined $self->{pid}) {
$self->{limiter}->{running}++;
} else {
$self->{err} = $!;
}
$cb->($self->{rpipe});
}
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?";
$running = --$limiter->{running};
}
# 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, $limiter, $cb) = @_;
$self->{limiter} = $limiter;
if ($limiter->{running} < $limiter->{max}) {
_do_spawn($self, $cb);
} else {
push @{$limiter->{run_queue}}, [ $self, $cb ];
}
}
package PublicInbox::Qspawn::Limiter;
use strict;
use warnings;
sub new {
my ($class, $max) = @_;
bless {
# 32 is same as the git-daemon connection limit
max => $max || 32,
running => 0,
run_queue => [],
}, $class;
}
1;
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