From f89bd1444a595b569606679293d2d01b0b7a049e Mon Sep 17 00:00:00 2001
From: Eric Wong <e@80x24.org>
Date: Sat, 9 Jul 2016 03:18:34 +0000
Subject: qspawn: allow configurable limiters

And bump the default limit to 32 so we match git-daemon
behavior.  This shall allow us to configure different levels
of concurrency for different repositories and prevent clones
of giant repos from stalling service to small repos.
---
 lib/PublicInbox/Qspawn.pm | 38 ++++++++++++++++++++++++++++----------
 1 file changed, 28 insertions(+), 10 deletions(-)

(limited to 'lib/PublicInbox/Qspawn.pm')

diff --git a/lib/PublicInbox/Qspawn.pm b/lib/PublicInbox/Qspawn.pm
index 9299096a..cc9c340d 100644
--- a/lib/PublicInbox/Qspawn.pm
+++ b/lib/PublicInbox/Qspawn.pm
@@ -1,12 +1,14 @@
 # Copyright (C) 2016 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 +30,41 @@ sub _do_spawn {
 
 sub finish ($) {
 	my ($self) = @_;
+	my $limiter = $self->{limiter};
 	if (delete $self->{rpipe}) {
 		my $pid = delete $self->{pid};
 		$self->{err} = $pid == waitpid($pid, 0) ? $? :
 				"PID:$pid still running?";
-		$running--;
+		$limiter->{running}--;
 	}
-	if (my $next = shift @run_queue) {
+	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} < $limiter->{limit}) {
 		_do_spawn($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, $limit) = @_;
+	bless {
+		limit => $limit || 1,
+		running => 0,
+		run_queue => [],
+	}, $class;
+}
+
 1;
-- 
cgit v1.2.3-24-ge0c7