X-Git-Url: http://www.git.stargrave.org/?a=blobdiff_plain;f=lib%2FPublicInbox%2FQspawn.pm;h=3500f8a4a86fcd35fe21e6b0fcded3ceeea7f87d;hb=3d41aa23f35501ca92aab8aa42980fa73f7fa74f;hp=9e4c8e081903ff183aec7a2a8ad4a2cd35289d2b;hpb=3f779258173530ca88f31e1dc5332f951d2c44cd;p=public-inbox.git

diff --git a/lib/PublicInbox/Qspawn.pm b/lib/PublicInbox/Qspawn.pm
index 9e4c8e08..3500f8a4 100644
--- 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 ($self->{pid}) {
-		$running++;
+	if (defined $self->{pid}) {
+		$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;