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
015package org.apache.tapestry5.internal.services;
016
017import static org.apache.tapestry5.commons.util.CollectionFactory.newStack;
018
019import java.util.List;
020
021import org.apache.tapestry5.commons.util.CollectionFactory;
022import org.apache.tapestry5.commons.util.Stack;
023import org.apache.tapestry5.services.Heartbeat;
024
025public 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}