001    /**
002     * Licensed to the Apache Software Foundation (ASF) under one or more
003     * contributor license agreements.  See the NOTICE file distributed with
004     * this work for additional information regarding copyright ownership.
005     * The ASF licenses this file to You under the Apache License, Version 2.0
006     * (the "License"); you may not use this file except in compliance with
007     * the License.  You may obtain a copy of the License at
008     *
009     *      http://www.apache.org/licenses/LICENSE-2.0
010     *
011     * Unless required by applicable law or agreed to in writing, software
012     * distributed under the License is distributed on an "AS IS" BASIS,
013     * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
014     * See the License for the specific language governing permissions and
015     * limitations under the License.
016     */
017    package org.apache.camel.component.file.strategy;
018    
019    import java.io.File;
020    
021    import org.apache.camel.Exchange;
022    import org.apache.camel.component.file.GenericFile;
023    import org.apache.camel.component.file.GenericFileOperations;
024    
025    /**
026     * Acquires exclusive read lock to the given file. Will wait until the lock is granted.
027     * After granting the read lock it is released, we just want to make sure that when we start
028     * consuming the file its not currently in progress of being written by third party.
029     * <p/>
030     * This implementation is only supported by the File component, that leverages the {@link MarkerFileExclusiveReadLockStrategy}
031     * as well, to ensure only acquiring locks on files, which is not already in progress by another process,
032     * that have marked this using the marker file.
033     */
034    public class FileRenameExclusiveReadLockStrategy extends GenericFileRenameExclusiveReadLockStrategy<File> {
035    
036        private MarkerFileExclusiveReadLockStrategy marker = new MarkerFileExclusiveReadLockStrategy();
037    
038        @Override
039        public boolean acquireExclusiveReadLock(GenericFileOperations<File> operations, GenericFile<File> file, Exchange exchange) throws Exception {
040            // must call marker first
041            if (!marker.acquireExclusiveReadLock(operations, file, exchange)) {
042                return false;
043            }
044    
045            return super.acquireExclusiveReadLock(operations, file, exchange);
046        }
047    
048        @Override
049        public void releaseExclusiveReadLock(GenericFileOperations<File> operations,
050                                             GenericFile<File> file, Exchange exchange) throws Exception {
051            // must call marker first
052            try {
053                marker.releaseExclusiveReadLock(operations, file, exchange);
054            } finally {
055                super.releaseExclusiveReadLock(operations, file, exchange);
056            }
057        }
058    
059    }