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.api.ldap.model.cursor; 21 22 23 /** 24 * A basic ClosureMonitor that simply uses a boolean for state and a cause 25 * exception. 26 * 27 * Note that we consciously chose not to synchronize close() operations with 28 * checks to see if the monitor state is closed because it costs to 29 * synchronize and it's OK for the Cursor not to stop immediately when close() 30 * is called. 31 * 32 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a> 33 */ 34 public class DefaultClosureMonitor implements ClosureMonitor 35 { 36 /** Tells if the monitor is closed or not */ 37 private boolean closed; 38 39 /** If we get an exception, the cause is stored in this variable */ 40 private Exception cause; 41 42 43 /** 44 * {@inheritDoc} 45 */ 46 @Override 47 public final void close() 48 { 49 // state check needed to "try" not to overwrite exception (lack of 50 // synchronization may still allow overwriting but who cares that much 51 if ( !closed ) 52 { 53 // not going to sync because who cares if it takes a little longer 54 // to stop but we need to set cause before toggling closed state 55 // or else check for closure can throw null cause 56 cause = CursorClosedException.INSTANCE; 57 closed = true; 58 } 59 } 60 61 62 /** 63 * {@inheritDoc} 64 */ 65 @Override 66 public final void close( final String cause ) 67 { 68 // state check needed to "try" not to overwrite exception (lack of 69 // synchronization may still allow overwriting but who cares that much 70 if ( !closed ) 71 { 72 // not going to sync because who cares if it takes a little longer 73 // to stop but we need to set cause before toggling closed state 74 // or else check for closure can throw null cause 75 this.cause = new CursorClosedException( cause ); 76 closed = true; 77 } 78 } 79 80 81 /** 82 * {@inheritDoc} 83 */ 84 @Override 85 public final void close( final Exception cause ) 86 { 87 // state check needed to "try" not to overwrite exception (lack of 88 // synchronization may still allow overwriting but who cares that much 89 if ( !closed ) 90 { 91 // not going to sync because who cares if it takes a little longer 92 // to stop but we need to set cause before toggling closed state 93 // or else check for closure can throw null cause 94 this.cause = cause; 95 closed = true; 96 } 97 } 98 99 100 /** 101 * {@inheritDoc} 102 */ 103 @Override 104 public final Exception getCause() 105 { 106 return cause; 107 } 108 109 110 /** 111 * {@inheritDoc} 112 */ 113 @Override 114 public final boolean isClosed() 115 { 116 return closed; 117 } 118 119 120 /** 121 * {@inheritDoc} 122 */ 123 @Override 124 public void checkNotClosed() throws CursorClosedException 125 { 126 // lack of synchronization may cause pass but eventually it will work 127 if ( closed ) 128 { 129 throw new CursorClosedException( cause.getMessage() ); 130 } 131 } 132 }