001    // Copyright 2006, 2007, 2010 The Apache Software Foundation
002    //
003    // Licensed under the Apache License, Version 2.0 (the "License");
004    // you may not use this file except in compliance with the License.
005    // You may obtain a copy of the License at
006    //
007    //     http://www.apache.org/licenses/LICENSE-2.0
008    //
009    // Unless required by applicable law or agreed to in writing, software
010    // distributed under the License is distributed on an "AS IS" BASIS,
011    // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
012    // See the License for the specific language governing permissions and
013    // limitations under the License.
014    
015    package org.apache.tapestry5.internal.services;
016    
017    import static org.apache.tapestry5.ioc.internal.util.CollectionFactory.newStack;
018    
019    import java.util.List;
020    
021    import org.apache.tapestry5.ioc.internal.util.CollectionFactory;
022    import org.apache.tapestry5.ioc.util.Stack;
023    import org.apache.tapestry5.services.Heartbeat;
024    
025    public class HeartbeatImpl implements Heartbeat
026    {
027        private final Stack<List<Runnable>> stack = newStack();
028    
029        public void begin()
030        {
031            List<Runnable> beat = CollectionFactory.newList();
032    
033            stack.push(beat);
034        }
035    
036        public void defer(Runnable command)
037        {
038            assert command != null;
039    
040            stack.peek().add(command);
041    
042        }
043    
044        public void end()
045        {
046            List<Runnable> beat = stack.pop();
047    
048            for (Runnable r : beat)
049                r.run();
050        }
051    
052    }