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1   package org.apache.maven.repository.metadata;
2   
3   /*
4    * Licensed to the Apache Software Foundation (ASF) under one
5    * or more contributor license agreements.  See the NOTICE file
6    * distributed with this work for additional information
7    * regarding copyright ownership.  The ASF licenses this file
8    * to you under the Apache License, Version 2.0 (the
9    * "License"); you may not use this file except in compliance
10   * with the License.  You may obtain a copy of the License at
11   *
12   *  http://www.apache.org/licenses/LICENSE-2.0
13   *
14   * Unless required by applicable law or agreed to in writing,
15   * software distributed under the License is distributed on an
16   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
17   * KIND, either express or implied.  See the License for the
18   * specific language governing permissions and limitations
19   * under the License.
20   */
21  
22  import java.util.ArrayList;
23  import java.util.List;
24  import java.util.TreeSet;
25  
26  import org.apache.maven.artifact.ArtifactScopeEnum;
27  import org.codehaus.plexus.component.annotations.Component;
28  import org.codehaus.plexus.component.annotations.Requirement;
29  
30  /**
31   * Default conflict resolver.Implements closer newer first policy by default, but could be configured via plexus
32   *
33   * @author <a href="mailto:oleg@codehaus.org">Oleg Gusakov</a>
34   */
35  @Component( role = GraphConflictResolver.class )
36  public class DefaultGraphConflictResolver
37      implements GraphConflictResolver
38  {
39      /**
40       * artifact, closer to the entry point, is selected
41       */
42      @Requirement( role = GraphConflictResolutionPolicy.class )
43      protected GraphConflictResolutionPolicy policy;
44  
45      // -------------------------------------------------------------------------------------
46      // -------------------------------------------------------------------------------------
47      public MetadataGraph resolveConflicts( MetadataGraph graph, ArtifactScopeEnum scope )
48          throws GraphConflictResolutionException
49      {
50          if ( policy == null )
51          {
52              throw new GraphConflictResolutionException( "no GraphConflictResolutionPolicy injected" );
53          }
54  
55          if ( graph == null )
56          {
57              return null;
58          }
59  
60          final MetadataGraphVertex entry = graph.getEntry();
61          if ( entry == null )
62          {
63              return null;
64          }
65  
66          if ( graph.isEmpty() )
67          {
68              throw new GraphConflictResolutionException( "graph with an entry, but not vertices do not exist" );
69          }
70  
71          if ( graph.isEmptyEdges() )
72          {
73              return null; // no edges - nothing to worry about
74          }
75  
76          final TreeSet<MetadataGraphVertex> vertices = graph.getVertices();
77  
78          try
79          {
80              // edge case - single vertex graph
81              if ( vertices.size() == 1 )
82              {
83                  return new MetadataGraph( entry );
84              }
85  
86              final ArtifactScopeEnum requestedScope = ArtifactScopeEnum.checkScope( scope );
87  
88              MetadataGraph res = new MetadataGraph( vertices.size() );
89              res.setVersionedVertices( false );
90              res.setScopedVertices( false );
91  
92              MetadataGraphVertex resEntry = res.addVertex( entry.getMd() );
93              res.setEntry( resEntry );
94  
95              res.setScope( requestedScope );
96  
97              for ( MetadataGraphVertex v : vertices )
98              {
99                  final List<MetadataGraphEdge> ins = graph.getIncidentEdges( v );
100                 final MetadataGraphEdge edge = cleanEdges( v, ins, requestedScope );
101 
102                 if ( edge == null )
103                 { // no edges - don't need this vertex any more
104                     if ( entry.equals( v ) )
105                     { // unless it's an entry point.
106                         // currently processing the entry point - it should not have any entry incident edges
107                         res.getEntry().getMd().setWhy( "This is a graph entry point. No links." );
108                     }
109                     else
110                     {
111                         // System.out.println("--->"+v.getMd().toDomainString()
112                         // +" has been terminated on this entry set\n-------------------\n"
113                         // +ins
114                         // +"\n-------------------\n"
115                         // );
116                     }
117                 }
118                 else
119                 {
120                     // System.out.println("+++>"+v.getMd().toDomainString()+" still has "+edge.toString() );
121                     // fill in domain md with actual version data
122                     ArtifactMetadata md = v.getMd();
123                     ArtifactMetadata newMd =
124                         new ArtifactMetadata( md.getGroupId(), md.getArtifactId(), edge.getVersion(), md.getType(),
125                                               md.getScopeAsEnum(), md.getClassifier(), edge.getArtifactUri(),
126                                               edge.getSource() == null ? "" : edge.getSource().getMd().toString(),
127                                               edge.isResolved(), edge.getTarget() == null ? null
128                                                               : edge.getTarget().getMd().getError() );
129                     MetadataGraphVertex newV = res.addVertex( newMd );
130                     MetadataGraphVertex sourceV = res.addVertex( edge.getSource().getMd() );
131 
132                     res.addEdge( sourceV, newV, edge );
133                 }
134             }
135             MetadataGraph linkedRes = findLinkedSubgraph( res );
136             // System.err.println("Original graph("+graph.getVertices().size()+"):\n"+graph.toString());
137             // System.err.println("Cleaned("+requestedScope+") graph("+res.getVertices().size()+"):\n"+res.toString());
138             // System.err.println("Linked("+requestedScope+")
139             // subgraph("+linkedRes.getVertices().size()+"):\n"+linkedRes.toString());
140             return linkedRes;
141         }
142         catch ( MetadataResolutionException e )
143         {
144             throw new GraphConflictResolutionException( e );
145         }
146     }
147 
148     // -------------------------------------------------------------------------------------
149     private MetadataGraph findLinkedSubgraph( MetadataGraph g )
150     {
151         if ( g.getVertices().size() == 1 )
152         {
153             return g;
154         }
155 
156         List<MetadataGraphVertex> visited = new ArrayList<>( g.getVertices().size() );
157         visit( g.getEntry(), visited, g );
158 
159         List<MetadataGraphVertex> dropList = new ArrayList<>( g.getVertices().size() );
160 
161         // collect drop list
162         for ( MetadataGraphVertex v : g.getVertices() )
163         {
164             if ( !visited.contains( v ) )
165             {
166                 dropList.add( v );
167             }
168         }
169 
170         if ( dropList.size() < 1 )
171         {
172             return g;
173         }
174 
175         // now - drop vertices
176         TreeSet<MetadataGraphVertex> vertices = g.getVertices();
177         for ( MetadataGraphVertex v : dropList )
178         {
179             vertices.remove( v );
180         }
181 
182         return g;
183     }
184 
185     // -------------------------------------------------------------------------------------
186     private void visit( MetadataGraphVertex from, List<MetadataGraphVertex> visited, MetadataGraph graph )
187     {
188         if ( visited.contains( from ) )
189         {
190             return;
191         }
192 
193         visited.add( from );
194 
195         List<MetadataGraphEdge> exitList = graph.getExcidentEdges( from );
196         // String s = "|---> "+from.getMd().toString()+" - "+(exitList == null ? -1 : exitList.size()) + " exit links";
197         if ( exitList != null && exitList.size() > 0 )
198         {
199             for ( MetadataGraphEdge e : graph.getExcidentEdges( from ) )
200             {
201                 visit( e.getTarget(), visited, graph );
202             }
203         }
204     }
205 
206     // -------------------------------------------------------------------------------------
207     private MetadataGraphEdge cleanEdges( MetadataGraphVertex v, List<MetadataGraphEdge> edges,
208                                           ArtifactScopeEnum scope )
209     {
210         if ( edges == null || edges.isEmpty() )
211         {
212             return null;
213         }
214 
215         if ( edges.size() == 1 )
216         {
217             MetadataGraphEdge e = edges.get( 0 );
218             if ( scope.encloses( e.getScope() ) )
219             {
220                 return e;
221             }
222 
223             return null;
224         }
225 
226         MetadataGraphEdge res = null;
227 
228         for ( MetadataGraphEdge e : edges )
229         {
230             if ( !scope.encloses( e.getScope() ) )
231             {
232                 continue;
233             }
234 
235             if ( res == null )
236             {
237                 res = e;
238             }
239             else
240             {
241                 res = policy.apply( e, res );
242             }
243         }
244 
245         return res;
246     }
247     // -------------------------------------------------------------------------------------
248     // -------------------------------------------------------------------------------------
249 }