first commit

Changes

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+Revision history for Net-ZooKeeper-Lock
+
+{{$NEXT}}
+        Initial release.
+

dist.ini

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+name = Net-ZooKeper-Lock
+version = 0.01
+author = Yury Zavarin <yury.zavarin@gmail.com>
+license = Perl_5
+copyright_holder = Yury Zavarin
+
+[@Filter]
+bundle = @Classic
+
+[AutoPrereqs]
+[NextRelease]
+format = %-7v %{eee MMM dd, yyyy}d
+
+[MetaResources]
+homepage = http://github.com/tadam/Net-ZooKeeper-Lock
+repository.url = git://github.com/tadam/Net-ZooKeeper-Lock.git
+repository.web = http://github.com/tadam/Net-ZooKeeper-Lock
+repository.type = git
+
+[PodWeaver]
+
+[@Git]

lib/Net/ZooKeeper/Lock.pm

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+package Net::ZooKeeper::Lock;
+
+use strict;
+use warnings;
+
+use Net::ZooKeeper qw(:events :node_flags :acls);
+use Params::Validate qw(:all);
+
+# ABSTRACT: distributed locks via ZooKeeper
+
+=head1 SYNOPSIS
+
+  use Net::ZooKeeper::Lock;
+
+  # take a lock
+  my $lock = Net::ZooKeeper::Lock->new({
+      zkh => Net::ZooKeeper->new(host => 'localhost:2181'),
+      lock_name   => 'bar',
+  });
+
+  # release a lock
+  $lock->unlock;
+  # or
+  undef $lock;
+
+=head1 DESCRIPTION
+
+=head1 METHODS
+
+=cut
+
+sub new {
+    my $class = shift;
+    my $p = validate(@_, {
+        zkh           => { isa => 'Net::ZooKeeper' },
+        lock_prefix   => { type => SCALAR, regex => qr{^/.+}o, default => '/lock' },
+        lock_name     => { type => SCALAR, regex => qr{^[^/]+$}o },
+        create_prefix => { type => BOOLEAN, default => 1 },
+        watch_timeout => { type => SCALAR, regex => qr/^\d+$/o, default => 86400 * 1000 },
+        nonblocking   => { type => BOOLEAN, default => 0 },
+    });
+    $p->{lock_prefix} =~ s{/$}{};
+
+    my $self = $p;
+    bless $self, $class;
+
+    $self->_lock;
+
+    return $self;
+}
+
+sub unlock {
+    my $self = shift;
+    $self->{zkh}->delete($self->{lock_path}) if ($self->{lock_path});
+}
+
+sub _create_cyclic_path {
+    my ($self, $path) = @_;
+
+    my $current_index = 1;
+    while ($current_index > 0) {
+        $current_index = index($path, "/", $current_index + 1);
+        my $current_path;
+        if ($current_index > 0) {
+            $current_path = substr($path, 0, $current_index);
+        } else {
+            $current_path = $path;
+        }
+
+        if (!$self->{zkh}->exists($path)) {
+            $self->{zkh}->create($path, '0',
+                acl => ZOO_OPEN_ACL_UNSAFE
+            );
+        }
+    }
+}
+sub _lock {
+    my $self = shift;
+
+    my $zkh = $self->{zkh};
+    my $lock_prefix = $self->{lock_prefix};
+    my $lock_name = $self->{lock_name};
+
+    if ($self->{create_prefix}) {
+        $self->_create_cyclic_path($lock_prefix);
+    }
+
+    my $lock_tmpl = $lock_prefix . "/" . $lock_name . "-";
+    my $lock_path = $zkh->create($lock_tmpl, '0',
+        flags => (ZOO_EPHEMERAL | ZOO_SEQUENCE),
+        acl   => ZOO_OPEN_ACL_UNSAFE) or
+    die "unable to create sequence znode $lock_tmpl: " . $zkh->get_error . "\n";
+
+    while (1) {
+        my @child_names = $zkh->get_children($lock_prefix);
+        die "no childs\n" unless (scalar(@child_names));
+
+        my @less_than_me = sort
+                           grep { ($_ =~ m/^${lock_name}-\d+$/) &&
+                                  ($lock_prefix . "/" . $_ lt $lock_path) }
+                           @child_names;
+
+        unless (@less_than_me) {
+            $self->{lock_path} = $lock_path;
+            return;
+        }
+
+        if ($self->{nonblocking}) {
+            die "lock already taken\n";
+        }
+
+        $self->_exists($lock_prefix . "/" . $less_than_me[-1]);
+    }
+}
+
+sub _exists {
+    my ($self, $path) = @_;
+
+    my $zkh = $self->{zkh};
+
+    my $watcher = $zkh->watch(timeout => $self->{watch_timeout});
+    while (1) {
+        my $exists = $zkh->exists(
+            $path,
+            watch => $watcher,
+        );
+
+        if (!$exists) {
+            next;
+        } else {
+            last;
+        }
+    }
+}
+
+sub DESTROY {
+    local $@;
+
+    my $self = shift;
+
+    $self->unlock;
+};
+
+1;

t/main.t

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+#!/usr/bin/perl
+
+use strict;
+use warnings;
+
+use Test::More;
+
+use_ok('Net::ZooKeeper::Lock');
+
+done_testing;