HDFS-6497. Make TestAvailableSpaceVolumeChoosingPolicy deterministic (cmccabe)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1601035 13f79535-47bb-0310-9956-ffa450edef68

hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt

@@ -648,6 +648,9 @@ Release 2.5.0 - UNRELEASED
     HDFS-6424. blockReport doesn't need to invalidate blocks on SBN. (Ming Ma
     via jing9)
 
+    HDFS-6497. Make TestAvailableSpaceVolumeChoosingPolicy deterministic
+    (cmccabe)
+
 Release 2.4.1 - UNRELEASED
 
   INCOMPATIBLE CHANGES

hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/AvailableSpaceVolumeChoosingPolicy.java

@@ -45,11 +45,19 @@ public class AvailableSpaceVolumeChoosingPolicy<V extends FsVolumeSpi>
   
   private static final Log LOG = LogFactory.getLog(AvailableSpaceVolumeChoosingPolicy.class);
   
-  private static final Random RAND = new Random();
+  private final Random random;
   
   private long balancedSpaceThreshold = DFS_DATANODE_AVAILABLE_SPACE_VOLUME_CHOOSING_POLICY_BALANCED_SPACE_THRESHOLD_DEFAULT;
   private float balancedPreferencePercent = DFS_DATANODE_AVAILABLE_SPACE_VOLUME_CHOOSING_POLICY_BALANCED_SPACE_PREFERENCE_FRACTION_DEFAULT;
 
+  AvailableSpaceVolumeChoosingPolicy(Random random) {
+    this.random = random;
+  }
+
+  public AvailableSpaceVolumeChoosingPolicy() {
+    this(new Random());
+  }
+
   @Override
   public synchronized void setConf(Configuration conf) {
     balancedSpaceThreshold = conf.getLong(
@@ -128,7 +136,7 @@ public class AvailableSpaceVolumeChoosingPolicy<V extends FsVolumeSpi>
           (highAvailableVolumes.size() * balancedPreferencePercent) /
           preferencePercentScaler;
       if (mostAvailableAmongLowVolumes < replicaSize ||
-          RAND.nextFloat() < scaledPreferencePercent) {
+          random.nextFloat() < scaledPreferencePercent) {
         volume = roundRobinPolicyHighAvailable.chooseVolume(
             highAvailableVolumes,
             replicaSize);

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/datanode/fsdataset/TestAvailableSpaceVolumeChoosingPolicy.java

@@ -22,6 +22,7 @@ import static org.apache.hadoop.hdfs.DFSConfigKeys.DFS_DATANODE_AVAILABLE_SPACE_
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Random;
 
 import org.apache.hadoop.conf.Configurable;
 import org.apache.hadoop.conf.Configuration;
@@ -251,10 +252,10 @@ public class TestAvailableSpaceVolumeChoosingPolicy {
    */
   public void doRandomizedTest(float preferencePercent, int lowSpaceVolumes,
       int highSpaceVolumes) throws Exception {
-    @SuppressWarnings("unchecked")
-    final AvailableSpaceVolumeChoosingPolicy<FsVolumeSpi> policy = 
-        ReflectionUtils.newInstance(AvailableSpaceVolumeChoosingPolicy.class, null);
-    
+    Random random = new Random(123L);
+    final AvailableSpaceVolumeChoosingPolicy<FsVolumeSpi> policy =
+        new AvailableSpaceVolumeChoosingPolicy<FsVolumeSpi>(random);
+
     List<FsVolumeSpi> volumes = new ArrayList<FsVolumeSpi>();
     
     // Volumes with 1MB free space