Add support for await as in Clojure

Author: pitr-ch

lib/concurrent/agent.rb

@@ -156,6 +156,16 @@ def <<(block)
       self
     end
 
+    # Waits/blocks until all the updates sent before this call are done.
+    #
+    # @param [Numeric] timeout the maximum time in second to wait.
+    # @return [Boolean] false on timeout, true otherwise
+    def await(timeout = nil)
+      done = Event.new
+      post { done.set }
+      done.wait timeout
+    end
+
     private
 
     # @!visibility private
@@ -168,6 +178,7 @@ def try_rescue(ex) # :nodoc:
       end
       rescuer.block.call(ex) if rescuer
     rescue Exception => ex
+      # puts "#{ex} (#{ex.class})\n#{ex.backtrace.join("\n")}"
       # supress
     end
 

spec/concurrent/agent_spec.rb

@@ -167,6 +167,25 @@ def trigger_observable(observable)
         agent.post { |old| old + 1 }
         agent.value.should eq 2
       end
+
+    end
+
+    context '#await' do
+
+      it 'waits until already sent updates are done' do
+        fn = false
+        subject.post { fn = true; sleep 0.1 }
+        subject.await
+        fn.should be_true
+      end
+
+      it 'does not waits until updates sent after are done' do
+        fn = false
+        subject.await
+        subject.post { fn = true; sleep 0.1 }
+        fn.should be_false
+      end
+
     end
 
     context 'fulfillment' do