diff options
Diffstat (limited to 'lib/PublicInbox/Qspawn.pm')
-rw-r--r-- | lib/PublicInbox/Qspawn.pm | 52 |
1 files changed, 52 insertions, 0 deletions
diff --git a/lib/PublicInbox/Qspawn.pm b/lib/PublicInbox/Qspawn.pm new file mode 100644 index 00000000..9e4c8e08 --- /dev/null +++ b/lib/PublicInbox/Qspawn.pm @@ -0,0 +1,52 @@ +# Copyright (C) 2016 all contributors <meta@public-inbox.org> +# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt> +package PublicInbox::Qspawn; +use strict; +use warnings; +use PublicInbox::Spawn qw(popen_rd); +our $LIMIT = 1; +my $running = 0; +my @run_queue; + +sub new ($$$;) { + my ($class, $cmd, $env, $opt) = @_; + bless { args => [ $cmd, $env, $opt ] }, $class; +} + +sub _do_spawn { + my ($self, $cb) = @_; + my $err; + ($self->{rpipe}, $self->{pid}) = popen_rd(@{$self->{args}}); + if ($self->{pid}) { + $running++; + } else { + $self->{err} = $!; + } + $cb->($self->{rpipe}); +} + +sub finish ($) { + my ($self) = @_; + if (delete $self->{rpipe}) { + my $pid = delete $self->{pid}; + $self->{err} = $pid == waitpid($pid, 0) ? $? : + "PID:$pid still running?"; + $running--; + } + if (my $next = shift @run_queue) { + _do_spawn(@$next); + } + $self->{err}; +} + +sub start ($$) { + my ($self, $cb) = @_; + + if ($running < $LIMIT) { + _do_spawn($self, $cb); + } else { + push @run_queue, [ $self, $cb ]; + } +} + +1; |