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.server.core.invocation; 21 22 23 import java.util.ArrayList; 24 import java.util.Collections; 25 import java.util.IdentityHashMap; 26 import java.util.List; 27 import java.util.Map; 28 29 import org.apache.directory.server.core.interceptor.context.OperationContext; 30 31 32 /** 33 * Keeps track of recursive {@link Invocation}s. This stack assumes an invocation 34 * occurs in the same thread since it is called first, so we manages stacks 35 * for each invocation in {@link ThreadLocal}-like manner. You can just use 36 * {@link #getInstance()} to get current invocation stack. 37 * 38 * @author <a href="mailto:dev@directory.apache.org">Apache Directory Project</a> 39 * @version $Rev: 662440 $, $Date: 2008-06-02 16:00:23 +0200 (Mo, 02 Jun 2008) $ 40 */ 41 public final class InvocationStack 42 { 43 // I didn't use ThreadLocal to release contexts explicitly. 44 // It seems like JDK 1.5 supports explicit release by introducing 45 // <tt>ThreadLocal.remove()</tt>, but we're still targetting 1.4. 46 private static final Map<Thread, InvocationStack> stacks = 47 Collections.synchronizedMap( new IdentityHashMap<Thread, InvocationStack>() ); 48 49 private final Thread thread; 50 private final List<OperationContext> stack = new ArrayList<OperationContext>(); 51 52 53 /** 54 * Returns the invocation stack of current thread. 55 */ 56 public static InvocationStack getInstance() 57 { 58 Thread currentThread = Thread.currentThread(); 59 InvocationStack ctx; 60 ctx = stacks.get( currentThread ); 61 62 if ( ctx == null ) 63 { 64 ctx = new InvocationStack( currentThread ); 65 } 66 67 return ctx; 68 } 69 70 71 private InvocationStack( Thread currentThread ) 72 { 73 thread = currentThread; 74 stacks.put( currentThread, this ); 75 } 76 77 78 /** 79 * Returns an array of {@link Invocation}s. 0th element is the 80 * latest invocation. 81 */ 82 public OperationContext[] toArray() 83 { 84 OperationContext[] result = new OperationContext[stack.size()]; 85 result = stack.toArray( result ); 86 return result; 87 } 88 89 90 /** 91 * Returns the latest invocation. 92 */ 93 public OperationContext peek() 94 { 95 return stack.get( 0 ); 96 } 97 98 99 /** 100 * Returns true if the stack is empty false otherwise. 101 */ 102 public boolean isEmpty() 103 { 104 return stack.isEmpty(); 105 } 106 107 108 /** 109 * Pushes the specified invocation to this stack. 110 */ 111 public void push( OperationContext opContext ) 112 { 113 stack.add( 0, opContext ); 114 } 115 116 117 /** 118 * Pops the latest invocation from this stack. This stack is released 119 * automatically if you pop all items from this stack. 120 */ 121 public OperationContext pop() 122 { 123 OperationContext invocation = stack.remove( 0 ); 124 125 if ( stack.size() == 0 ) 126 { 127 stacks.remove( thread ); 128 } 129 130 return invocation; 131 } 132 }