With SPARK-20236, FileCommitProtocol.instantiate() looks for a three argument constructor, passing in the dynamicPartitionOverwrite parameter. If there is no such constructor, it falls back to the classic two-arg one.

When InsertIntoHadoopFsRelationCommand passes down that dynamicPartitionOverwrite flag to FileCommitProtocol.instantiate(), it assumes that the instantiated protocol supports the specific requirements of dynamic partition overwrite. It does not notice when this does not hold, and so the output generated may be incorrect.

This patch changes  FileCommitProtocol.instantiate() so  when dynamicPartitionOverwrite == true, it requires the protocol implementation to have a 3-arg constructor.

Tests verify that

* classes with only 2-arg constructor cannot be used with dynamic overwrite
* classes with only 2-arg constructor can be used without dynamic overwrite
* classes with 3 arg constructors can be used with both
* the fallback to any two arg ctor takes place after the attempt to load the 3-arg ctor,
* passing in invalid class types fail as expected (regression tests on expected behavior)

Change-Id: I694868aecf865cfa552e031ea3f6dde8b600fa7b

Author: steveloughran

core/src/main/scala/org/apache/spark/internal/io/FileCommitProtocol.scala

@@ -20,6 +20,7 @@ package org.apache.spark.internal.io
 import org.apache.hadoop.fs._
 import org.apache.hadoop.mapreduce._
 
+import org.apache.spark.internal.Logging
 import org.apache.spark.util.Utils
 
 
@@ -132,7 +133,7 @@ abstract class FileCommitProtocol {
 }
 
 
-object FileCommitProtocol {
+object FileCommitProtocol extends Logging {
   class TaskCommitMessage(val obj: Any) extends Serializable
 
   object EmptyTaskCommitMessage extends TaskCommitMessage(null)
@@ -145,15 +146,23 @@ object FileCommitProtocol {
       jobId: String,
       outputPath: String,
       dynamicPartitionOverwrite: Boolean = false): FileCommitProtocol = {
+
+    logDebug(s"Creating committer $className; job $jobId; output=$outputPath;" +
+      s" dynamic=$dynamicPartitionOverwrite")
     val clazz = Utils.classForName(className).asInstanceOf[Class[FileCommitProtocol]]
     // First try the constructor with arguments (jobId: String, outputPath: String,
     // dynamicPartitionOverwrite: Boolean).
     // If that doesn't exist, try the one with (jobId: string, outputPath: String).
     try {
       val ctor = clazz.getDeclaredConstructor(classOf[String], classOf[String], classOf[Boolean])
+      logDebug("Using (String, String, Boolean) constructor")
       ctor.newInstance(jobId, outputPath, dynamicPartitionOverwrite.asInstanceOf[java.lang.Boolean])
     } catch {
       case _: NoSuchMethodException =>
+        logDebug("Falling back to (String, String) constructor")
+        require(!dynamicPartitionOverwrite,
+          "Dynamic Partition Overwrite is enabled but" +
+            s" the committer ${className} does not have the appropriate constructor")
         val ctor = clazz.getDeclaredConstructor(classOf[String], classOf[String])
         ctor.newInstance(jobId, outputPath)
     }

core/src/test/scala/org/apache/spark/internal/io/FileCommitProtocolInstantiationSuite.scala

@@ -0,0 +1,146 @@
+/*
+ * 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.spark.internal.io
+
+import org.apache.spark.SparkFunSuite
+
+/**
+ * Unit tests for instantiation of FileCommitProtocol implementations.
+ */
+class FileCommitProtocolInstantiationSuite extends SparkFunSuite {
+
+  test("Dynamic partitions require appropriate constructor") {
+
+    // you cannot instantiate a two-arg client with dynamic partitions
+    // enabled.
+    val ex = intercept[IllegalArgumentException] {
+      instantiateClassic(true)
+    }
+    // check the contents of the message and rethrow if unexpected
+    if (!ex.toString.contains("Dynamic Partition Overwrite")) {
+      throw ex
+    }
+  }
+
+  test("Standard partitions work with classic constructor") {
+    instantiateClassic(false)
+  }
+
+  test("Three arg constructors have priority") {
+    assert(3 == instantiateNew(false).argCount,
+      "Wrong constructor argument count")
+  }
+
+  test("Three arg constructors have priority when dynamic") {
+    assert(3 == instantiateNew(true).argCount,
+      "Wrong constructor argument count")
+  }
+
+  test("The protocol must be of the correct class") {
+    intercept[ClassCastException] {
+      FileCommitProtocol.instantiate(
+        classOf[Other].getCanonicalName,
+        "job",
+        "path",
+        false)
+    }
+  }
+
+  test("If there is no matching constructor, class hierarchy is irrelevant") {
+    intercept[NoSuchMethodException] {
+      FileCommitProtocol.instantiate(
+        classOf[NoMatchingArgs].getCanonicalName,
+        "job",
+        "path",
+        false)
+    }
+  }
+
+  /**
+   * Create a classic two-arg protocol instance.
+   * @param dynamic dyanmic partitioning mode
+   * @return the instance
+   */
+  private def instantiateClassic(dynamic: Boolean): ClassicConstructorCommitProtocol = {
+    FileCommitProtocol.instantiate(
+      classOf[ClassicConstructorCommitProtocol].getCanonicalName,
+      "job",
+      "path",
+      dynamic).asInstanceOf[ClassicConstructorCommitProtocol]
+  }
+
+  /**
+   * Create a three-arg protocol instance.
+   * @param dynamic dyanmic partitioning mode
+   * @return the instance
+   */
+  private def instantiateNew(
+    dynamic: Boolean): FullConstructorCommitProtocol = {
+    FileCommitProtocol.instantiate(
+      classOf[FullConstructorCommitProtocol].getCanonicalName,
+      "job",
+      "path",
+      dynamic).asInstanceOf[FullConstructorCommitProtocol]
+  }
+
+}
+
+/**
+ * This protocol implementation does not have the new three-arg
+ * constructor.
+ */
+private class ClassicConstructorCommitProtocol(arg1: String, arg2: String)
+  extends HadoopMapReduceCommitProtocol(arg1, arg2) {
+}
+
+/**
+ * This protocol implementation does have the new three-arg constructor
+ * alongside the original, and a 4 arg one for completeness.
+ * The final value of the real constructor is the number of arguments
+ * used in the 2- and 3- constructor, for test assertions.
+ */
+private class FullConstructorCommitProtocol(
+  arg1: String,
+  arg2: String,
+  b: Boolean,
+  val argCount: Int)
+  extends HadoopMapReduceCommitProtocol(arg1, arg2, b) {
+
+  def this(arg1: String, arg2: String)=  {
+    this(arg1, arg2, false, 2)
+  }
+
+  def this(arg1: String, arg2: String, b: Boolean) = {
+    this(arg1, arg2, false, 3)
+  }
+}
+
+/**
+ * This has the 2-arity constructor, but isn't the right class.
+ */
+private class Other(arg1: String, arg2: String) {
+
+}
+
+/**
+ * This has no matching arguments
+ */
+private class NoMatchingArgs() {
+
+}
+