www: add configurable limiters

Currently only for git-http-backend use, this allows limiting
the number of spawned processes per-inbox or by group, if there
are multiple large inboxes amidst a sea of small ones.

For example, a "big" repo limiter could be used for big inboxes:
which would be shared between multiple repos:

[limiter "big"]
	max = 4
[publicinbox "git"]
	address = git@vger.kernel.org
	mainrepo = /path/to/git.git
	; shared limiter with giant:
	httpbackendmax = big
[publicinbox "giant"]
	address = giant@project.org
	mainrepo = /path/to/giant.git
	; shared limiter with git:
	httpbackendmax = big

; This is a tiny inbox, use the default limiter with 32 slots:
[publicinbox "meta"]
	address = meta@public-inbox.org
	mainrepo = /path/to/meta.git

2 files changed, 52 insertions, 0 deletions

diff --git a/t/config.t b/t/config.t
index dc448cdf..77e8f4ac 100644
--- a/t/config.t
+++ b/t/config.t
@@ -30,6 +30,7 @@ my $tmpdir = tempdir('pi-config-XXXXXX', TMPDIR => 1, CLEANUP => 1);
                 'url' => 'http://example.com/meta',
                 -primary_address => 'meta@public-inbox.org',
                 'name' => 'meta',
+                -pi_config => $cfg,
         }, "lookup matches expected output");
 
         is($cfg->lookup('blah@example.com'), undef,
@@ -45,6 +46,7 @@ my $tmpdir = tempdir('pi-config-XXXXXX', TMPDIR => 1, CLEANUP => 1);
                 'domain' => 'public-inbox.org',
                 'name' => 'test',
                 'url' => 'http://example.com/test',
+                -pi_config => $cfg,
         }, "lookup matches expected output for test");
 }
 
diff --git a/t/config_limiter.t b/t/config_limiter.t
new file mode 100644
index 00000000..bfea1510
--- /dev/null
+++ b/t/config_limiter.t
@@ -0,0 +1,50 @@
+# Copyright (C) 2016 all contributors <meta@public-inbox.org>
+# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
+use strict;
+use warnings;
+use Test::More;
+use PublicInbox::Config;
+my $cfgpfx = "publicinbox.test";
+{
+        my $config = PublicInbox::Config->new({
+                "$cfgpfx.address" => 'test@example.com',
+                "$cfgpfx.mainrepo" => '/path/to/non/existent',
+                "$cfgpfx.httpbackendmax" => 12,
+        });
+        my $ibx = $config->lookup_name('test');
+        my $git = $ibx->git;
+        my $old = "$git";
+        my $lim = $git->{-httpbackend_limiter};
+        ok($lim, 'Limiter exists');
+        is($lim->{max}, 12, 'limiter has expected slots');
+        $git = undef;
+        $ibx->{git} = undef;
+        $git = $ibx->git;
+        isnt($old, "$git", 'got new Git object');
+        is("$git->{-httpbackend_limiter}", "$lim", 'same limiter');
+}
+
+{
+        my $config = PublicInbox::Config->new({
+                'limiter.named.max' => 3,
+                "$cfgpfx.address" => 'test@example.com',
+                "$cfgpfx.mainrepo" => '/path/to/non/existent',
+                "$cfgpfx.httpbackendmax" => 'named',
+        });
+        my $ibx = $config->lookup_name('test');
+        my $git = $ibx->git;
+        ok($git, 'got git object');
+        my $old = "$git";
+        my $lim = $git->{-httpbackend_limiter};
+        ok($lim, 'Limiter exists');
+        is($lim->{max}, 3, 'limiter has expected slots');
+        $git = undef;
+        $ibx->{git} = undef;
+        PublicInbox::Inbox::weaken_task;
+        $git = $ibx->git;
+        isnt($old, "$git", 'got new Git object');
+        is("$git->{-httpbackend_limiter}", "$lim", 'same limiter');
+        is($lim->{max}, 3, 'limiter has expected slots');
+}
+
+done_testing;