Implemented JavaCountDownLatch

Author: jdantonio

lib/concurrent/atomic/count_down_latch.rb

@@ -57,6 +57,35 @@ def count_down
     def count
       @mutex.synchronize { @count }
     end
+  end
+
+  if RUBY_PLATFORM == 'java'
 
+    class JavaCountDownLatch
+
+      def initialize(count)
+        unless count.is_a?(Fixnum) && count >= 0
+          raise ArgumentError.new('count must be in integer greater than or equal zero')
+        end
+        @latch = java.util.concurrent.CountDownLatch.new(count)
+      end
+
+      def wait(timeout = nil)
+        if timeout.nil?
+          @latch.await
+          true
+        else
+          @latch.await(timeout, java.util.concurrent.TimeUnit::SECONDS)
+        end
+      end
+
+      def count_down
+        @latch.countDown
+      end
+
+      def count
+        @latch.getCount
+      end
+    end
   end
 end

spec/concurrent/atomic/count_down_latch_spec.rb

@@ -81,49 +81,59 @@
       end
     end
   end
+end
 
-  context 'spurious wake ups' do
+module Concurrent
 
-    before(:each) do
-      def latch.simulate_spurious_wake_up
-        @mutex.synchronize do
-          @condition.signal
-          @condition.broadcast
+  describe CountDownLatch do
+
+    it_should_behave_like :count_down_latch
+
+    context 'spurious wake ups' do
+
+      subject { described_class.new(3) }
+
+      before(:each) do
+        def subject.simulate_spurious_wake_up
+          @mutex.synchronize do
+            @condition.signal
+            @condition.broadcast
+          end
         end
       end
-    end
 
-    it 'should resist to spurious wake ups without timeout' do
-      @expected = false
-      Thread.new { latch.wait; @expected = true }
+      it 'should resist to spurious wake ups without timeout' do
+        @expected = false
+        Thread.new { subject.wait; @expected = true }
 
-      sleep(0.1)
-      latch.simulate_spurious_wake_up
+        sleep(0.1)
+        subject.simulate_spurious_wake_up
 
-      sleep(0.1)
-      @expected.should be_false
-    end
+        sleep(0.1)
+        @expected.should be_false
+      end
 
-    it 'should resist to spurious wake ups with timeout' do
-      @expected = false
-      Thread.new { latch.wait(0.5); @expected = true }
+      it 'should resist to spurious wake ups with timeout' do
+        @expected = false
+        Thread.new { subject.wait(0.5); @expected = true }
 
-      sleep(0.1)
-      latch.simulate_spurious_wake_up
+        sleep(0.1)
+        subject.simulate_spurious_wake_up
 
-      sleep(0.1)
-      @expected.should be_false
+        sleep(0.1)
+        @expected.should be_false
 
-      sleep(0.4)
-      @expected.should be_true
+        sleep(0.4)
+        @expected.should be_true
+      end
     end
   end
-end
 
-module Concurrent
+  if jruby?
 
-  describe CountDownLatch do
+    describe JavaCountDownLatch do
 
-    it_should_behave_like :count_down_latch
+      it_should_behave_like :count_down_latch
+    end
   end
 end