MAPREDUCE-6535. TaskID default constructor results in NPE on toString(). Contributed by Daniel Templeton

(cherry picked from commit 3f622a143c)

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/main/java/org/apache/hadoop/mapreduce/TaskID.java

@@ -63,6 +63,7 @@ public class TaskID extends org.apache.hadoop.mapred.ID {
   public static final String TASK_ID_REGEX = TASK + "_(\\d+)_(\\d+)_" +
       CharTaskTypeMaps.allTaskTypes + "_(\\d+)";
   public static final Pattern taskIdPattern = Pattern.compile(TASK_ID_REGEX);
+
   static {
     idFormat.setGroupingUsed(false);
     idFormat.setMinimumIntegerDigits(6);
@@ -73,6 +74,7 @@ public class TaskID extends org.apache.hadoop.mapred.ID {
   
   /**
    * Constructs a TaskID object from given {@link JobID}.
+   *
    * @param jobId JobID that this tip belongs to 
    * @param type the {@link TaskType} of the task 
    * @param id the tip number
@@ -88,6 +90,7 @@ public class TaskID extends org.apache.hadoop.mapred.ID {
   
   /**
    * Constructs a TaskInProgressId object from given parts.
+   *
    * @param jtIdentifier jobTracker identifier
    * @param jobId job number 
    * @param type the TaskType 
@@ -99,6 +102,7 @@ public class TaskID extends org.apache.hadoop.mapred.ID {
 
   /**
    * Constructs a TaskID object from given {@link JobID}.
+   *
    * @param jobId JobID that this tip belongs to
    * @param isMap whether the tip is a map
    * @param id the tip number
@@ -110,6 +114,7 @@ public class TaskID extends org.apache.hadoop.mapred.ID {
 
   /**
    * Constructs a TaskInProgressId object from given parts.
+   *
    * @param jtIdentifier jobTracker identifier
    * @param jobId job number
    * @param isMap whether the tip is a map
@@ -120,23 +125,37 @@ public class TaskID extends org.apache.hadoop.mapred.ID {
     this(new JobID(jtIdentifier, jobId), isMap, id);
   }
   
+  /**
+   * Default constructor for Writable. Sets the task type to
+   * {@link TaskType#REDUCE}, the ID to 0, and the job ID to an empty job ID.
+   */
   public TaskID() { 
-    jobId = new JobID();
+    this(new JobID(), TaskType.REDUCE, 0);
   }
   
-  /** Returns the {@link JobID} object that this tip belongs to */
+  /**
+   * Returns the {@link JobID} object that this tip belongs to.
+   *
+   * @return the JobID object
+   */
   public JobID getJobID() {
     return jobId;
   }
   
-  /**Returns whether this TaskID is a map ID */
+  /**
+   * Returns whether this TaskID is a map ID.
+   *
+   * @return whether this TaskID is a map ID
+   */
   @Deprecated
   public boolean isMap() {
     return type == TaskType.MAP;
   }
     
   /**
-   * Get the type of the task
+   * Get the type of the task.
+   *
+   * @return the type of the task
    */
   public TaskType getTaskType() {
     return type;
@@ -151,8 +170,14 @@ public class TaskID extends org.apache.hadoop.mapred.ID {
     return this.type == that.type && this.jobId.equals(that.jobId);
   }
 
-  /**Compare TaskInProgressIds by first jobIds, then by tip numbers. Reduces are 
+  /**
-   * defined as greater then maps.*/
+   * Compare TaskInProgressIds by first jobIds, then by tip numbers.
+   * Reducers are defined as greater than mappers.
+   *
+   * @param o the TaskID against which to compare
+   * @return 0 if equal, positive if this TaskID is greater, and negative if
+   * this TaskID is less
+   */
   @Override
   public int compareTo(ID o) {
     TaskID that = (TaskID)o;
@@ -174,6 +199,7 @@ public class TaskID extends org.apache.hadoop.mapred.ID {
 
   /**
    * Add the unique string to the given builder.
+   *
    * @param builder the builder to append to
    * @return the builder that was passed in
    */
@@ -204,7 +230,10 @@ public class TaskID extends org.apache.hadoop.mapred.ID {
     WritableUtils.writeEnum(out, type);
   }
   
-  /** Construct a TaskID object from given string 
+  /**
+   * Construct a TaskID object from given string.
+   *
+   * @param str the target string
    * @return constructed TaskID object or null if the given String is null
    * @throws IllegalArgumentException if the given string is malformed
    */
@@ -224,7 +253,8 @@ public class TaskID extends org.apache.hadoop.mapred.ID {
     throw new IllegalArgumentException(exceptionMsg);
   }
   /**
-   * Gets the character representing the {@link TaskType}
+   * Gets the character representing the {@link TaskType}.
+   *
    * @param type the TaskType
    * @return the character
    */
@@ -232,7 +262,8 @@ public class TaskID extends org.apache.hadoop.mapred.ID {
     return CharTaskTypeMaps.getRepresentingCharacter(type);
   }
   /**
-   * Gets the {@link TaskType} corresponding to the character
+   * Gets the {@link TaskType} corresponding to the character.
+   *
    * @param c the character
    * @return the TaskType
    */
@@ -240,6 +271,12 @@ public class TaskID extends org.apache.hadoop.mapred.ID {
     return CharTaskTypeMaps.getTaskType(c);
   }
   
+  /**
+   * Returns a string of characters describing all possible {@link TaskType}
+   * values
+   *
+   * @return a string of all task type characters
+   */
   public static String getAllTaskTypes() {
     return CharTaskTypeMaps.allTaskTypes;
   }

hadoop-mapreduce-project/hadoop-mapreduce-client/hadoop-mapreduce-client-core/src/test/java/org/apache/hadoop/mapreduce/TestTaskID.java

@@ -0,0 +1,461 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.apache.hadoop.mapreduce;
+
+import org.apache.hadoop.io.DataInputByteBuffer;
+import org.apache.hadoop.io.DataOutputByteBuffer;
+import org.apache.hadoop.io.WritableUtils;
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+/**
+ * Test the {@link TaskID} class.
+ */
+public class TestTaskID {
+  /**
+   * Test of getJobID method, of class TaskID.
+   */
+  @Test
+  public void testGetJobID() {
+    JobID jobId = new JobID("1234", 0);
+    TaskID taskId = new TaskID(jobId, TaskType.MAP, 0);
+
+    assertSame("TaskID did not store the JobID correctly",
+        jobId, taskId.getJobID());
+
+    taskId = new TaskID();
+
+    assertEquals("Job ID was set unexpectedly in default contsructor",
+        "", taskId.getJobID().getJtIdentifier());
+  }
+
+  /**
+   * Test of isMap method, of class TaskID.
+   */
+  @Test
+  public void testIsMap() {
+    JobID jobId = new JobID("1234", 0);
+
+    for (TaskType type : TaskType.values()) {
+      TaskID taskId = new TaskID(jobId, type, 0);
+
+      if (type == TaskType.MAP) {
+        assertTrue("TaskID for map task did not correctly identify itself "
+            + "as a map task", taskId.isMap());
+      } else {
+        assertFalse("TaskID for " + type + " task incorrectly identified "
+            + "itself as a map task", taskId.isMap());
+      }
+    }
+
+    TaskID taskId = new TaskID();
+
+    assertFalse("TaskID of default type incorrectly identified itself as a "
+        + "map task", taskId.isMap());
+  }
+
+  /**
+   * Test of getTaskType method, of class TaskID.
+   */
+  @Test
+  public void testGetTaskType_0args() {
+    JobID jobId = new JobID("1234", 0);
+
+    for (TaskType type : TaskType.values()) {
+      TaskID taskId = new TaskID(jobId, type, 0);
+
+      assertEquals("TaskID incorrectly reported its type",
+          type, taskId.getTaskType());
+    }
+
+    TaskID taskId = new TaskID();
+
+    assertEquals("TaskID of default type incorrectly reported its type",
+        TaskType.REDUCE, taskId.getTaskType());
+  }
+
+  /**
+   * Test of equals method, of class TaskID.
+   */
+  @Test
+  public void testEquals() {
+    JobID jobId1 = new JobID("1234", 1);
+    JobID jobId2 = new JobID("2345", 2);
+    TaskID taskId1 = new TaskID(jobId1, TaskType.MAP, 0);
+    TaskID taskId2 = new TaskID(jobId1, TaskType.MAP, 0);
+
+    assertTrue("The equals() method reported two equal task IDs were not equal",
+        taskId1.equals(taskId2));
+
+    taskId2 = new TaskID(jobId2, TaskType.MAP, 0);
+
+    assertFalse("The equals() method reported two task IDs with different "
+        + "job IDs were equal", taskId1.equals(taskId2));
+
+    taskId2 = new TaskID(jobId1, TaskType.MAP, 1);
+
+    assertFalse("The equals() method reported two task IDs with different IDs "
+        + "were equal", taskId1.equals(taskId2));
+
+    TaskType[] types = TaskType.values();
+
+    for (int i = 0; i < types.length; i++) {
+      for (int j = 0; j < types.length; j++) {
+        taskId1 = new TaskID(jobId1, types[i], 0);
+        taskId2 = new TaskID(jobId1, types[j], 0);
+
+        if (i == j) {
+          assertTrue("The equals() method reported two equal task IDs were not "
+              + "equal", taskId1.equals(taskId2));
+        } else {
+          assertFalse("The equals() method reported two task IDs with "
+              + "different types were equal", taskId1.equals(taskId2));
+        }
+      }
+    }
+
+    assertFalse("The equals() method matched against a JobID object",
+        taskId1.equals(jobId1));
+
+    assertFalse("The equals() method matched against a null object",
+        taskId1.equals(null));
+  }
+
+  /**
+   * Test of compareTo method, of class TaskID.
+   */
+  @Test
+  public void testCompareTo() {
+    JobID jobId = new JobID("1234", 1);
+    TaskID taskId1 = new TaskID(jobId, TaskType.REDUCE, 0);
+    TaskID taskId2 = new TaskID(jobId, TaskType.REDUCE, 0);
+
+    assertEquals("The compareTo() method returned non-zero for two equal "
+        + "task IDs", 0, taskId1.compareTo(taskId2));
+
+    taskId2 = new TaskID(jobId, TaskType.MAP, 1);
+
+    assertTrue("The compareTo() method did not weigh task type more than task "
+        + "ID", taskId1.compareTo(taskId2) > 0);
+
+    TaskType[] types = TaskType.values();
+
+    for (int i = 0; i < types.length; i++) {
+      for (int j = 0; j < types.length; j++) {
+        taskId1 = new TaskID(jobId, types[i], 0);
+        taskId2 = new TaskID(jobId, types[j], 0);
+
+        if (i == j) {
+          assertEquals("The compareTo() method returned non-zero for two equal "
+              + "task IDs", 0, taskId1.compareTo(taskId2));
+        } else if (i < j) {
+          assertTrue("The compareTo() method did not order " + types[i]
+              + " before " + types[j], taskId1.compareTo(taskId2) < 0);
+        } else {
+          assertTrue("The compareTo() method did not order " + types[i]
+              + " after " + types[j], taskId1.compareTo(taskId2) > 0);
+        }
+      }
+    }
+
+    try {
+      taskId1.compareTo(jobId);
+      fail("The compareTo() method allowed comparison to a JobID object");
+    } catch (ClassCastException ex) {
+      // Expected
+    }
+
+    try {
+      taskId1.compareTo(null);
+      fail("The compareTo() method allowed comparison to a null object");
+    } catch (NullPointerException ex) {
+      // Expected
+    }
+  }
+
+  /**
+   * Test of toString method, of class TaskID.
+   */
+  @Test
+  public void testToString() {
+    JobID jobId = new JobID("1234", 1);
+
+    for (TaskType type : TaskType.values()) {
+      TaskID taskId = new TaskID(jobId, type, 0);
+      String str = String.format("task_1234_0001_%c_000000",
+          TaskID.getRepresentingCharacter(type));
+
+      assertEquals("The toString() method returned the wrong value",
+          str, taskId.toString());
+    }
+  }
+
+  /**
+   * Test of appendTo method, of class TaskID.
+   */
+  @Test
+  public void testAppendTo() {
+    JobID jobId = new JobID("1234", 1);
+    StringBuilder builder = new StringBuilder();
+
+    for (TaskType type : TaskType.values()) {
+      builder.setLength(0);
+      TaskID taskId = new TaskID(jobId, type, 0);
+      String str = String.format("_1234_0001_%c_000000",
+          TaskID.getRepresentingCharacter(type));
+
+      assertEquals("The appendTo() method appended the wrong value",
+          str, taskId.appendTo(builder).toString());
+    }
+
+    try {
+      new TaskID().appendTo(null);
+      fail("The appendTo() method allowed a null builder");
+    } catch (NullPointerException ex) {
+      // Expected
+    }
+  }
+
+  /**
+   * Test of hashCode method, of class TaskID.
+   */
+  @Test
+  public void testHashCode() {
+    TaskType[] types = TaskType.values();
+
+    for (int i = 0; i < types.length; i++) {
+      JobID jobId = new JobID("1234" + i, i);
+      TaskID taskId1 = new TaskID(jobId, types[i], i);
+      TaskID taskId2 = new TaskID(jobId, types[i], i);
+
+      assertTrue("The hashcode() method gave unequal hash codes for two equal "
+          + "task IDs", taskId1.hashCode() == taskId2.hashCode());
+    }
+  }
+
+  /**
+   * Test of readFields method, of class TaskID.
+   */
+  @Test
+  public void testReadFields() throws Exception {
+    DataOutputByteBuffer out = new DataOutputByteBuffer();
+
+    out.writeInt(0);
+    out.writeInt(1);
+    WritableUtils.writeVInt(out, 4);
+    out.write(new byte[] { 0x31, 0x32, 0x33, 0x34});
+    WritableUtils.writeEnum(out, TaskType.REDUCE);
+
+    DataInputByteBuffer in = new DataInputByteBuffer();
+
+    in.reset(out.getData());
+
+    TaskID instance = new TaskID();
+
+    instance.readFields(in);
+
+    assertEquals("The readFields() method did not produce the expected task ID",
+        "task_1234_0001_r_000000", instance.toString());
+  }
+
+  /**
+   * Test of write method, of class TaskID.
+   */
+  @Test
+  public void testWrite() throws Exception {
+    JobID jobId = new JobID("1234", 1);
+    TaskID taskId = new TaskID(jobId, TaskType.JOB_SETUP, 0);
+    DataOutputByteBuffer out = new DataOutputByteBuffer();
+
+    taskId.write(out);
+
+    DataInputByteBuffer in = new DataInputByteBuffer();
+    byte[] buffer = new byte[4];
+
+    in.reset(out.getData());
+
+    assertEquals("The write() method did not write the expected task ID",
+        0, in.readInt());
+    assertEquals("The write() method did not write the expected job ID",
+        1, in.readInt());
+    assertEquals("The write() method did not write the expected job "
+        + "identifier length", 4, WritableUtils.readVInt(in));
+    in.readFully(buffer, 0, 4);
+    assertEquals("The write() method did not write the expected job "
+        + "identifier length", "1234", new String(buffer));
+    assertEquals("The write() method did not write the expected task type",
+        TaskType.JOB_SETUP, WritableUtils.readEnum(in, TaskType.class));
+  }
+
+  /**
+   * Test of forName method, of class TaskID.
+   */
+  @Test
+  public void testForName() {
+    assertEquals("The forName() method did not parse the task ID string "
+        + "correctly", "task_1_0001_m_000000",
+        TaskID.forName("task_1_0001_m_000").toString());
+    assertEquals("The forName() method did not parse the task ID string "
+        + "correctly", "task_23_0002_r_000001",
+        TaskID.forName("task_23_0002_r_0001").toString());
+    assertEquals("The forName() method did not parse the task ID string "
+        + "correctly", "task_345_0003_s_000002",
+        TaskID.forName("task_345_0003_s_00002").toString());
+    assertEquals("The forName() method did not parse the task ID string "
+        + "correctly", "task_6789_0004_c_000003",
+        TaskID.forName("task_6789_0004_c_000003").toString());
+    assertEquals("The forName() method did not parse the task ID string "
+        + "correctly", "task_12345_0005_t_4000000",
+        TaskID.forName("task_12345_0005_t_4000000").toString());
+
+    try {
+      TaskID.forName("tisk_12345_0005_t_4000000");
+      fail("The forName() method parsed an invalid job ID: "
+          + "tisk_12345_0005_t_4000000");
+    } catch (IllegalArgumentException ex) {
+      // Expected
+    }
+
+    try {
+      TaskID.forName("tisk_12345_0005_t_4000000");
+      fail("The forName() method parsed an invalid job ID: "
+          + "tisk_12345_0005_t_4000000");
+    } catch (IllegalArgumentException ex) {
+      // Expected
+    }
+
+    try {
+      TaskID.forName("task_abc_0005_t_4000000");
+      fail("The forName() method parsed an invalid job ID: "
+          + "task_abc_0005_t_4000000");
+    } catch (IllegalArgumentException ex) {
+      // Expected
+    }
+
+    try {
+      TaskID.forName("task_12345_xyz_t_4000000");
+      fail("The forName() method parsed an invalid job ID: "
+          + "task_12345_xyz_t_4000000");
+    } catch (IllegalArgumentException ex) {
+      // Expected
+    }
+
+    try {
+      TaskID.forName("task_12345_0005_x_4000000");
+      fail("The forName() method parsed an invalid job ID: "
+          + "task_12345_0005_x_4000000");
+    } catch (IllegalArgumentException ex) {
+      // Expected
+    }
+
+    try {
+      TaskID.forName("task_12345_0005_t_jkl");
+      fail("The forName() method parsed an invalid job ID: "
+          + "task_12345_0005_t_jkl");
+    } catch (IllegalArgumentException ex) {
+      // Expected
+    }
+
+    try {
+      TaskID.forName("task_12345_0005_t");
+      fail("The forName() method parsed an invalid job ID: "
+          + "task_12345_0005_t");
+    } catch (IllegalArgumentException ex) {
+      // Expected
+    }
+
+    try {
+      TaskID.forName("task_12345_0005_4000000");
+      fail("The forName() method parsed an invalid job ID: "
+          + "task_12345_0005_4000000");
+    } catch (IllegalArgumentException ex) {
+      // Expected
+    }
+
+    try {
+      TaskID.forName("task_12345_t_4000000");
+      fail("The forName() method parsed an invalid job ID: "
+          + "task_12345_t_4000000");
+    } catch (IllegalArgumentException ex) {
+      // Expected
+    }
+
+    try {
+      TaskID.forName("12345_0005_t_4000000");
+      fail("The forName() method parsed an invalid job ID: "
+          + "12345_0005_t_4000000");
+    } catch (IllegalArgumentException ex) {
+      // Expected
+    }
+  }
+
+  /**
+   * Test of getRepresentingCharacter method, of class TaskID.
+   */
+  @Test
+  public void testGetRepresentingCharacter() {
+    assertEquals("The getRepresentingCharacter() method did not return the "
+        + "expected character", 'm',
+        TaskID.getRepresentingCharacter(TaskType.MAP));
+    assertEquals("The getRepresentingCharacter() method did not return the "
+        + "expected character", 'r',
+        TaskID.getRepresentingCharacter(TaskType.REDUCE));
+    assertEquals("The getRepresentingCharacter() method did not return the "
+        + "expected character", 's',
+        TaskID.getRepresentingCharacter(TaskType.JOB_SETUP));
+    assertEquals("The getRepresentingCharacter() method did not return the "
+        + "expected character", 'c',
+        TaskID.getRepresentingCharacter(TaskType.JOB_CLEANUP));
+    assertEquals("The getRepresentingCharacter() method did not return the "
+        + "expected character", 't',
+        TaskID.getRepresentingCharacter(TaskType.TASK_CLEANUP));
+  }
+
+  /**
+   * Test of getTaskType method, of class TaskID.
+   */
+  @Test
+  public void testGetTaskType_char() {
+    assertEquals("The getTaskType() method did not return the expected type",
+        TaskType.MAP,
+        TaskID.getTaskType('m'));
+    assertEquals("The getTaskType() method did not return the expected type",
+        TaskType.REDUCE,
+        TaskID.getTaskType('r'));
+    assertEquals("The getTaskType() method did not return the expected type",
+        TaskType.JOB_SETUP,
+        TaskID.getTaskType('s'));
+    assertEquals("The getTaskType() method did not return the expected type",
+        TaskType.JOB_CLEANUP,
+        TaskID.getTaskType('c'));
+    assertEquals("The getTaskType() method did not return the expected type",
+        TaskType.TASK_CLEANUP,
+        TaskID.getTaskType('t'));
+    assertNull("The getTaskType() method did not return null for an unknown "
+        + "type", TaskID.getTaskType('x'));
+  }
+
+  /**
+   * Test of getAllTaskTypes method, of class TaskID.
+   */
+  @Test
+  public void testGetAllTaskTypes() {
+    assertEquals("The getAllTaskTypes method did not return the expected "
+        + "string", "(m|r|s|c|t)", TaskID.getAllTaskTypes());
+  }
+}