1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one 3 * or more contributor license agreements. See the NOTICE file 4 * distributed with this work for additional information 5 * regarding copyright ownership. The ASF licenses this file 6 * to you under the Apache License, Version 2.0 (the 7 * "License"); you may not use this file except in compliance 8 * with the License. You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, 13 * software distributed under the License is distributed on an 14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 15 * KIND, either express or implied. See the License for the 16 * specific language governing permissions and limitations 17 * under the License. 18 * 19 */ 20 package org.apache.directory.mavibot.btree; 21 22 import java.util.concurrent.locks.ReentrantLock; 23 24 import org.apache.directory.mavibot.btree.exception.BadTransactionStateException; 25 26 /** 27 * A data structure used to manage a write transaction 28 * 29 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a> 30 */ 31 /* no qualifier */ class WriteTransaction 32 { 33 /** A lock used to protect the write operation against concurrent access */ 34 protected ReentrantLock writeLock; 35 36 /* no qualifier */WriteTransaction() 37 { 38 //System.out.println( "Creating the transaction oject" ); 39 writeLock = new ReentrantLock(); 40 } 41 42 43 /* no qualifier */ void start() 44 { 45 /* 46 if ( writeLock.isLocked() ) 47 { 48 throw new BadTransactionStateException( "Cannot start a write transaction when it's already started" ); 49 } 50 */ 51 52 //System.out.println( "Start a TXN [" + Thread.currentThread().getName() + "]" ); 53 54 writeLock.lock(); 55 //System.out.println( "WriteTransaction " + Thread.currentThread().getName() ); 56 } 57 58 59 /* no qualifier */ void commit() 60 { 61 if ( !writeLock.isLocked() ) 62 { 63 throw new BadTransactionStateException( "Cannot commit a write transaction when it's not started" ); 64 } 65 66 //System.out.println( "Commit a TXN[" + Thread.currentThread().getName() + "]" ); 67 68 writeLock.unlock(); 69 } 70 71 72 /* no qualifier */ void rollback() 73 { 74 if ( !writeLock.isLocked() ) 75 { 76 throw new BadTransactionStateException( "Cannot commit a write transaction when it's not started" ); 77 } 78 79 //System.out.println( "Rollback a TXN" ); 80 writeLock.unlock(); 81 } 82 83 84 /** 85 * Tells if the transaction has started 86 * @return true if the transaction has started 87 */ 88 /* no qualifier */ boolean isStarted() 89 { 90 return writeLock.isLocked(); 91 } 92 }