001    /*
002     * Copyright (c) 2007-2015 Concurrent, Inc. All Rights Reserved.
003     *
004     * Project and contact information: http://www.cascading.org/
005     *
006     * This file is part of the Cascading project.
007     *
008     * Licensed under the Apache License, Version 2.0 (the "License");
009     * you may not use this file except in compliance with the License.
010     * You may obtain a copy of the License at
011     *
012     *     http://www.apache.org/licenses/LICENSE-2.0
013     *
014     * Unless required by applicable law or agreed to in writing, software
015     * distributed under the License is distributed on an "AS IS" BASIS,
016     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
017     * See the License for the specific language governing permissions and
018     * limitations under the License.
019     */
020    
021    package cascading.flow;
022    
023    import java.io.IOException;
024    
025    /**
026     * Class FlowSkipIfSinkNotStale is a {@link cascading.flow.FlowSkipStrategy} implementation that returns
027     * {@code true} if the Flow sink exists and is not stale in relation to the Flow sources.
028     * <p/>
029     * This is the default Cascading strategy.
030     *
031     * @see cascading.flow.FlowSkipIfSinkExists
032     */
033    public class FlowSkipIfSinkNotStale implements FlowSkipStrategy
034      {
035      public boolean skipFlow( Flow flow ) throws IOException
036        {
037        long sinkModified = flow.getSinkModified();
038    
039        return sinkModified > 0 && !flow.areSourcesNewer( sinkModified );
040        }
041      }