From c731d1f93c88d537698700652e13e4957a662425 Mon Sep 17 00:00:00 2001
From: Tatsuhiko Miyagawa <miyagawa@bulknews.net>
Date: Wed, 9 Jan 2013 16:34:14 -0800
Subject: [PATCH 1/5] relax resque dependency

---
 resque-lonely_job.gemspec | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/resque-lonely_job.gemspec b/resque-lonely_job.gemspec
index 54a7d61..933237a 100644
--- a/resque-lonely_job.gemspec
+++ b/resque-lonely_job.gemspec
@@ -14,7 +14,7 @@ Gem::Specification.new do |gem|
   gem.require_paths = ["lib"]
   gem.version       = Resque::Plugins::LonelyJob::VERSION
 
-  gem.add_dependency 'resque', '~> 1.20.0'
+  gem.add_dependency 'resque', '>= 1.20.0'
   gem.add_development_dependency 'mock_redis', '~> 0.4.1'
   gem.add_development_dependency 'rake'
   gem.add_development_dependency 'rspec'

From b7ce63e13d851b02dbaf4fdb0e94dc737f6e2fbf Mon Sep 17 00:00:00 2001
From: Tatsuhiko Miyagawa <miyagawa@bulknews.net>
Date: Sun, 20 Jan 2013 16:53:11 -0800
Subject: [PATCH 2/5] save integer value of the lock

---
 lib/resque-lonely_job.rb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/resque-lonely_job.rb b/lib/resque-lonely_job.rb
index ce29cad..e7d8400 100644
--- a/lib/resque-lonely_job.rb
+++ b/lib/resque-lonely_job.rb
@@ -6,7 +6,7 @@ module LonelyJob
       LOCK_TIMEOUT = 60 * 60 * 24 * 5 # 5 days
 
       def lock_timeout
-        Time.now.utc + LOCK_TIMEOUT + 1
+        Time.now.to_i + LOCK_TIMEOUT + 1
       end
 
       # Overwrite this method to uniquely identify which mutex should be used

From 8ab67f6aaff3fd7c725f30d146ea3ddc791bb852 Mon Sep 17 00:00:00 2001
From: Tatsuhiko Miyagawa <miyagawa@bulknews.net>
Date: Sun, 20 Jan 2013 17:17:13 -0800
Subject: [PATCH 3/5] Implement locking timeout per SETNX design pattern at
 http://redis.io/commands/setnx

---
 lib/resque-lonely_job.rb | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/lib/resque-lonely_job.rb b/lib/resque-lonely_job.rb
index e7d8400..04742f6 100644
--- a/lib/resque-lonely_job.rb
+++ b/lib/resque-lonely_job.rb
@@ -16,7 +16,15 @@ def redis_key(*args)
       end
 
       def can_lock_queue?(*args)
-        Resque.redis.setnx(redis_key(*args), lock_timeout)
+        now = Time.now.to_i
+        key = redis_key(*args)
+        timeout = lock_timeout
+
+        # Per http://redis.io/commands/getset
+        return true  if Resque.redis.setnx(key, timeout)
+        return false if Resque.redis.get(key).to_i > now
+        return true  if Resque.redis.getset(key, timeout).to_i <= now
+        return false
       end
 
       def unlock_queue(*args)

From f8791b12746fe1e62bfbf672d3db8e5a34789227 Mon Sep 17 00:00:00 2001
From: Tatsuhiko Miyagawa <miyagawa@bulknews.net>
Date: Mon, 21 Jan 2013 17:38:47 -0800
Subject: [PATCH 4/5] fix link in the comment

---
 lib/resque-lonely_job.rb | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/resque-lonely_job.rb b/lib/resque-lonely_job.rb
index 04742f6..11ee9bd 100644
--- a/lib/resque-lonely_job.rb
+++ b/lib/resque-lonely_job.rb
@@ -20,7 +20,7 @@ def can_lock_queue?(*args)
         key = redis_key(*args)
         timeout = lock_timeout
 
-        # Per http://redis.io/commands/getset
+        # Per http://redis.io/commands/setnx
         return true  if Resque.redis.setnx(key, timeout)
         return false if Resque.redis.get(key).to_i > now
         return true  if Resque.redis.getset(key, timeout).to_i <= now

From 6bfac4294ab975a91a2a95c5ce669fbd627a5365 Mon Sep 17 00:00:00 2001
From: Tatsuhiko Miyagawa <miyagawa@bulknews.net>
Date: Wed, 23 Jan 2013 10:14:35 -0800
Subject: [PATCH 5/5] Added spec to test setnx/getset unlock expired lock
 behavior

---
 resque-lonely_job.gemspec   |  1 +
 spec/lib/lonely_job_spec.rb | 31 +++++++++++++++++++++++++++++++
 spec/spec_helper.rb         |  1 +
 3 files changed, 33 insertions(+)

diff --git a/resque-lonely_job.gemspec b/resque-lonely_job.gemspec
index 933237a..9d78dae 100644
--- a/resque-lonely_job.gemspec
+++ b/resque-lonely_job.gemspec
@@ -19,6 +19,7 @@ Gem::Specification.new do |gem|
   gem.add_development_dependency 'rake'
   gem.add_development_dependency 'rspec'
   gem.add_development_dependency 'debugger'
+  gem.add_development_dependency 'timecop'
 
   gem.description   = <<desc
 Ensures that for a given queue, only one worker is working on a job at any given time.
diff --git a/spec/lib/lonely_job_spec.rb b/spec/lib/lonely_job_spec.rb
index 675b1fe..c6cca4f 100644
--- a/spec/lib/lonely_job_spec.rb
+++ b/spec/lib/lonely_job_spec.rb
@@ -32,6 +32,37 @@ def self.perform(account_id, *args); end
       SerialJob.can_lock_queue?(:serial_work).should be_true
       SerialJob.can_lock_queue?(:serial_work).should be_false
     end
+
+    it 'cannot lock a queue with active lock' do
+      SerialJob.can_lock_queue?(:serial_work).should be_true
+      Timecop.travel(Date.today + 1) do
+        SerialJob.can_lock_queue?(:serial_work).should be_false
+      end
+    end
+
+    it 'can relock a queue with expired lock' do
+      SerialJob.can_lock_queue?(:serial_work).should be_true
+
+      Timecop.travel(Date.today + 10) do
+        SerialJob.can_lock_queue?(:serial_work).should be_true
+      end
+    end
+
+    it 'solves race condition with getset' do
+      SerialJob.can_lock_queue?(:serial_work).should be_true
+
+      Timecop.travel(Date.today + 10) do
+        threads = (1..10).to_a.map {
+          Thread.new {
+            Thread.current[:locked] = SerialJob.can_lock_queue?(:serial_work)
+          }
+        }
+
+        # Only one worker should acquire lock
+        locks = threads.map {|t| t.join; t[:locked] }
+        locks.count(true).should == 1
+      end
+    end
   end
 
   describe ".perform" do
diff --git a/spec/spec_helper.rb b/spec/spec_helper.rb
index f7b36fc..9c424f7 100644
--- a/spec/spec_helper.rb
+++ b/spec/spec_helper.rb
@@ -5,6 +5,7 @@
 require 'mock_redis'
 require 'resque'
 require 'resque-lonely_job'
+require 'timecop'
 
 RSpec.configure do |config|
   config.before(:suite) do