update copyrights for 2018

[public-inbox.git] / lib / PublicInbox / Qspawn.pm

diff --git a/lib/PublicInbox/Qspawn.pm b/lib/PublicInbox/Qspawn.pm
index 9299096a40d9d36b07e488b626ed0e1ecf3e1fed..3500f8a4a86fcd35fe21e6b0fcded3ceeea7f87d 100644 (file)
--- a/lib/PublicInbox/Qspawn.pm
+++ b/lib/PublicInbox/Qspawn.pm
@@ -1,12 +1,14 @@
-# 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;
 
 sub new ($$$;) {
        my ($class, $cmd, $env, $opt) = @_;
@@ -16,9 +18,10 @@ sub new ($$$;) {
 sub _do_spawn {
        my ($self, $cb) = @_;
        my $err;
+
        ($self->{rpipe}, $self->{pid}) = popen_rd(@{$self->{args}});
        if (defined $self->{pid}) {
-               $running++;
+               $self->{limiter}->{running}++;
        } else {
                $self->{err} = $!;
        }
@@ -27,26 +30,47 @@ sub _do_spawn {
 
 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 ];
        }
 }
 
+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;