DependentPolicy


1   /*******************************************************************************
2    * Copyright (c) 2005, 2006 IBM Corporation and others.
3    * All rights reserved. This program and the accompanying materials
4    * are made available under the terms of the Eclipse Public License v1.0
5    * which accompanies this distribution, and is available at
6    * http://www.eclipse.org/legal/epl-v10.html
7    *
8    * Contributors:
9    *     IBM Corporation - initial API and implementation
10   *******************************************************************************/
11  
12  package org.eclipse.osgi.framework.internal.core;
13  
14  import java.io.IOException  ;
15  import java.net.URL  ;
16  import java.util.*;
17  import org.eclipse.osgi.service.resolver.BundleDescription;
18  
19  /**
20   * DependentPolicy is an implementation of a buddy policy. 
21   * It is responsible for looking up a class in the dependents of the bundle
22   * to which this policy is attached to.
23   */
24  public class DependentPolicy implements IBuddyPolicy {
25      BundleLoader buddyRequester;
26      int lastDependentOfAdded = -1; //remember the index of the bundle for which we last added the dependent
27      List allDependents = null; //the list of all dependents known so far
28  
29      public DependentPolicy(BundleLoader requester) {
30          buddyRequester = requester;
31  
32          //Initialize with the first level of dependent the list
33          allDependents = new ArrayList();
34          basicAddImmediateDependents(buddyRequester.getBundle().getBundleDescription());
35          //If there is no dependent, reset to null
36          if (allDependents.size() == 0)
37              allDependents = null;
38      }
39  
40      public Class   loadClass(String   name) {
41          if (allDependents == null)
42              return null;
43  
44          Class   result = null;
45          //size may change, so we must check it every time
46          for (int i = 0; i < allDependents.size() && result == null; i++) {
47              BundleDescription searchedBundle = (BundleDescription) allDependents.get(i);
48              try {
49                  BundleLoaderProxy proxy = buddyRequester.getLoaderProxy(searchedBundle);
50                  if (proxy == null)
51                      continue;
52                  result = proxy.getBundleLoader().findClass(name, true);
53              } catch (ClassNotFoundException   e) {
54                  if (result == null)
55                      addDependent(i, searchedBundle);
56              }
57          }
58          return result;
59      }
60  
61      private synchronized void addDependent(int i, BundleDescription searchedBundle) {
62          if (i > lastDependentOfAdded) {
63              lastDependentOfAdded = i;
64              basicAddImmediateDependents(searchedBundle);
65          }
66      }
67  
68      public URL   loadResource(String   name) {
69          if (allDependents == null)
70              return null;
71  
72          URL   result = null;
73          //size may change, so we must check it every time
74          for (int i = 0; i < allDependents.size() && result == null; i++) {
75              BundleDescription searchedBundle = (BundleDescription) allDependents.get(i);
76              BundleLoaderProxy proxy = buddyRequester.getLoaderProxy(searchedBundle);
77              if (proxy == null)
78                  continue;
79              result = proxy.getBundleLoader().findResource(name, true);
80              if (result == null) {
81                  addDependent(i, searchedBundle);
82              }
83          }
84          return result;
85      }
86  
87      public Enumeration loadResources(String   name) {
88          if (allDependents == null)
89              return null;
90  
91          Enumeration results = null;
92          //size may change, so we must check it every time
93          for (int i = 0; i < allDependents.size(); i++) {
94              BundleDescription searchedBundle = (BundleDescription) allDependents.get(i);
95              try {
96                  BundleLoaderProxy proxy = buddyRequester.getLoaderProxy(searchedBundle);
97                  if (proxy == null)
98                      continue;
99                  results = BundleLoader.compoundEnumerations(results, proxy.getBundleLoader().findResources(name));
100                 addDependent(i, searchedBundle);
101             } catch (IOException   e) {
102                 //Ignore and keep looking
103             }
104         }
105         return results;
106     }
107 
108     private void basicAddImmediateDependents(BundleDescription root) {
109         BundleDescription[] dependents = root.getDependents();
110         for (int i = 0; i < dependents.length; i++) {
111             BundleDescription toAdd = dependents[i];
112             if (toAdd.getHost() == null && !allDependents.contains(toAdd)) {
113                 allDependents.add(toAdd);
114             }
115         }
116     }
117 }
118
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