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 */ 017package org.apache.camel.component.file; 018 019import org.apache.camel.Exchange; 020import org.apache.camel.LoggingLevel; 021 022/** 023 * Strategy for acquiring exclusive read locks for files to be consumed. After 024 * granting the read lock it is released, we just want to make sure that when 025 * we start consuming the file its not currently in progress of being written by 026 * third party. 027 * <p/> 028 * Camel supports out of the box the following strategies: 029 * <ul> 030 * <li>FileRenameExclusiveReadLockStrategy waiting until its possible to rename the file.</li> 031 * <li>FileLockExclusiveReadLockStrategy acquiring a RW file lock for the duration of the processing.</li> 032 * <li>MarkerFileExclusiveReadLockStrategy using a marker file for acquiring read lock.</li> 033 * <li>FileChangedExclusiveReadLockStrategy using a file changed detection for acquiring read lock.</li> 034 * <li>FileIdempotentRepositoryReadLockStrategy using a {@link org.apache.camel.spi.IdempotentRepository} to hold the read locks which allows to support clustering.</li> 035 * </ul> 036 */ 037public interface GenericFileExclusiveReadLockStrategy<T> { 038 039 /** 040 * Allows custom logic to be run on startup preparing the strategy, such as removing old lock files etc. 041 * 042 * @param operations generic file operations 043 * @param endpoint the endpoint 044 * @throws Exception can be thrown in case of errors 045 */ 046 void prepareOnStartup(GenericFileOperations<T> operations, GenericFileEndpoint<T> endpoint) throws Exception; 047 048 /** 049 * Acquires exclusive read lock to the file. 050 * 051 * @param operations generic file operations 052 * @param file the file 053 * @param exchange the exchange 054 * @return <tt>true</tt> if read lock was acquired. If <tt>false</tt> Camel 055 * will skip the file and try it on the next poll 056 * @throws Exception can be thrown in case of errors 057 */ 058 boolean acquireExclusiveReadLock(GenericFileOperations<T> operations, GenericFile<T> file, Exchange exchange) throws Exception; 059 060 /** 061 * Releases the exclusive read lock granted by the <tt>acquireExclusiveReadLock</tt> method due an abort operation (acquireExclusiveReadLock returned false). 062 * 063 * @param operations generic file operations 064 * @param file the file 065 * @param exchange the exchange 066 * @throws Exception can be thrown in case of errors 067 */ 068 void releaseExclusiveReadLockOnAbort(GenericFileOperations<T> operations, GenericFile<T> file, Exchange exchange) throws Exception; 069 070 /** 071 * Releases the exclusive read lock granted by the <tt>acquireExclusiveReadLock</tt> method due a rollback operation (Exchange processing failed) 072 * 073 * @param operations generic file operations 074 * @param file the file 075 * @param exchange the exchange 076 * @throws Exception can be thrown in case of errors 077 */ 078 void releaseExclusiveReadLockOnRollback(GenericFileOperations<T> operations, GenericFile<T> file, Exchange exchange) throws Exception; 079 080 /** 081 * Releases the exclusive read lock granted by the <tt>acquireExclusiveReadLock</tt> method due a commit operation (Exchange processing succeeded) 082 * 083 * @param operations generic file operations 084 * @param file the file 085 * @param exchange the exchange 086 * @throws Exception can be thrown in case of errors 087 */ 088 void releaseExclusiveReadLockOnCommit(GenericFileOperations<T> operations, GenericFile<T> file, Exchange exchange) throws Exception; 089 090 /** 091 * Sets an optional timeout period. 092 * <p/> 093 * If the readlock could not be granted within the time period then the wait is stopped and the 094 * <tt>acquireExclusiveReadLock</tt> method returns <tt>false</tt>. 095 * 096 * @param timeout period in millis 097 */ 098 void setTimeout(long timeout); 099 100 /** 101 * Sets the check interval period. 102 * <p/> 103 * The check interval is used for sleeping between attempts to acquire read lock. 104 * Setting a high value allows to cater for <i>slow writes</i> in case the producer 105 * of the file is slow. 106 * <p/> 107 * The default period is 1000 millis. 108 * 109 * @param checkInterval interval in millis 110 */ 111 void setCheckInterval(long checkInterval); 112 113 /** 114 * Sets logging level used when a read lock could not be acquired. 115 * <p/> 116 * Logging level used when a read lock could not be acquired. 117 * <p/> 118 * The default logging level is WARN 119 * @param readLockLoggingLevel LoggingLevel 120 */ 121 void setReadLockLoggingLevel(LoggingLevel readLockLoggingLevel); 122 123 /** 124 * Sets whether marker file should be used or not. 125 * 126 * @param markerFile <tt>true</tt> to use marker files. 127 */ 128 void setMarkerFiler(boolean markerFile); 129 130 /** 131 * Sets whether orphan marker files should be deleted upon startup 132 * 133 * @param deleteOrphanLockFiles <tt>true</tt> to delete files, <tt>false</tt> to skip this check 134 */ 135 void setDeleteOrphanLockFiles(boolean deleteOrphanLockFiles); 136 137}