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RandomWalkWorkerContext xref
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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, software
13   * distributed under the License is distributed on an "AS IS" BASIS,
14   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15   * See the License for the specific language governing permissions and
16   * limitations under the License.
17   */
18  
19  package org.apache.giraph.examples;
20  
21  import java.io.BufferedReader;
22  import java.io.IOException;
23  import java.io.InputStreamReader;
24  import java.nio.charset.Charset;
25  import java.util.Set;
26  
27  import org.apache.giraph.worker.WorkerContext;
28  import org.apache.hadoop.conf.Configuration;
29  import org.apache.hadoop.filecache.DistributedCache;
30  import org.apache.hadoop.fs.FileSystem;
31  import org.apache.hadoop.fs.Path;
32  import org.apache.log4j.Logger;
33  
34  import com.google.common.collect.ImmutableSet;
35  
36  /**
37   * Worker context for random walks.
38   */
39  public class RandomWalkWorkerContext extends WorkerContext {
40    /** Default maximum number of iterations */
41    private static final int DEFAULT_MAX_SUPERSTEPS = 30;
42    /** Default teleportation probability */
43    private static final float DEFAULT_TELEPORTATION_PROBABILITY = 0.15f;
44    /** Maximum number of iterations */
45    private static int MAX_SUPERSTEPS;
46    /** Teleportation probability */
47    private static double TELEPORTATION_PROBABILITY;
48    /** Preference vector */
49    private static Set<Long> SOURCES;
50  
51    /** Configuration parameter for the source vertex */
52    private static final String SOURCE_VERTEX =
53        RandomWalkWithRestartComputation.class.getName() + ".sourceVertex";
54  
55    /** Logger */
56    private static final Logger LOG = Logger
57        .getLogger(RandomWalkWorkerContext.class);
58  
59    /**
60     * @return The maximum number of iterations to perform.
61     */
62    public int getMaxSupersteps() {
63      if (MAX_SUPERSTEPS == 0) {
64        throw new IllegalStateException(
65            RandomWalkWorkerContext.class.getSimpleName() +
66                " was not initialized. Relaunch your job " +
67                "by setting the appropriate WorkerContext");
68      }
69      return MAX_SUPERSTEPS;
70    }
71  
72    /**
73     * @return The teleportation probability.
74     */
75    public double getTeleportationProbability() {
76      if (TELEPORTATION_PROBABILITY == 0) {
77        throw new IllegalStateException(
78            RandomWalkWorkerContext.class.getSimpleName() +
79                " was not initialized. Relaunch your job " +
80                "by setting the appropriate WorkerContext");
81      }
82      return TELEPORTATION_PROBABILITY;
83    }
84  
85    /**
86     * Checks if a vertex is a source.
87     * @param id The vertex ID to check.
88     * @return True if the vertex is a source in the preference vector.
89     */
90    public boolean isSource(long id) {
91      return SOURCES.contains(id);
92    }
93  
94    /**
95     * @return The number of sources in the preference vector.
96     */
97    public int numSources() {
98      return SOURCES.size();
99    }
100 
101   /**
102    * Initialize sources for Random Walk with Restart. First option
103    * (preferential) is single source given from the command line as a parameter.
104    * Second option is a file with a list of vertex IDs, one per line. In this
105    * second case the preference vector is a uniform distribution over these
106    * vertexes.
107    * @param configuration The configuration.
108    * @return a (possibly empty) set of source vertices
109    */
110   private ImmutableSet<Long> initializeSources(Configuration configuration) {
111     ImmutableSet.Builder<Long> builder = ImmutableSet.builder();
112     long sourceVertex = configuration.getLong(SOURCE_VERTEX, Long.MIN_VALUE);
113     if (sourceVertex != Long.MIN_VALUE) {
114       return ImmutableSet.of(sourceVertex);
115     } else {
116       Path sourceFile = null;
117       try {
118 
119         Path[] cacheFiles = DistributedCache.getLocalCacheFiles(configuration);
120         if (cacheFiles == null || cacheFiles.length == 0) {
121           // empty set if no source vertices configured
122           return ImmutableSet.of();
123         }
124 
125         sourceFile = cacheFiles[0];
126         FileSystem fs = FileSystem.getLocal(configuration);
127         BufferedReader in = new BufferedReader(new InputStreamReader(
128             fs.open(sourceFile), Charset.defaultCharset()));
129         String line;
130         while ((line = in.readLine()) != null) {
131           builder.add(Long.parseLong(line));
132         }
133         in.close();
134       } catch (IOException e) {
135         getContext().setStatus(
136             "Could not load local cache files: " + sourceFile);
137         LOG.error("Could not load local cache files: " + sourceFile, e);
138       }
139     }
140     return builder.build();
141   }
142 
143   @Override
144   public void preApplication() throws InstantiationException,
145       IllegalAccessException {
146     setStaticVars(getContext().getConfiguration());
147   }
148 
149   /**
150    * Set static variables from Configuration
151    *
152    * @param configuration the conf
153    */
154   private void setStaticVars(Configuration configuration) {
155     MAX_SUPERSTEPS = configuration.getInt(RandomWalkComputation.MAX_SUPERSTEPS,
156         DEFAULT_MAX_SUPERSTEPS);
157     TELEPORTATION_PROBABILITY = configuration.getFloat(
158         RandomWalkComputation.TELEPORTATION_PROBABILITY,
159         DEFAULT_TELEPORTATION_PROBABILITY);
160     SOURCES = initializeSources(configuration);
161   }
162 
163   @Override
164   public void preSuperstep() {
165   }
166 
167   @Override
168   public void postSuperstep() {
169   }
170 
171   @Override
172   public void postApplication() {
173   }
174 }