Merge pull request resque#575 from tenderlove/resque

---

MultiQueue#poll will allow us to use a blocking pop in our runloop, but timeout and check for process shutdown.

lib/resque/multi_queue.rb

@@ -54,5 +54,20 @@ def pop(non_block = false)
         end
       end
     end
+
+    # Retrieves data from the queue head, and removes it.
+    #
+    # Blocks for +timeout+ seconds if the queue is empty, and returns nil if
+    # the timeout expires.
+    def poll(timeout)
+      queue_names = @queues.map {|queue| queue.redis_name }
+      queue_name, payload = @redis.blpop(*(queue_names + [timeout]))
+      return unless payload
+
+      synchronize do
+        queue = @queue_hash[queue_name]
+        [queue, queue.decode(payload)]
+      end
+    end
   end
 end

test/multi_queue_test.rb

@@ -8,6 +8,13 @@
     redis.flushall
   end
 
+  it "poll times out and returns nil" do
+    foo   = Resque::Queue.new 'foo', redis
+    bar   = Resque::Queue.new 'bar', redis
+    queue = Resque::MultiQueue.new([foo, bar], redis)
+    assert_nil queue.poll(1)
+  end
+
   it "blocks on pop" do
     foo   = Resque::Queue.new 'foo', redis, coder
     bar   = Resque::Queue.new 'bar', redis, coder