SPARK-1195: set map_input_file environment variable in PipedRDD

Hadoop uses the config mapreduce.map.input.file to indicate the input filename to the map when the input split is of type FileSplit. Some of the hadoop input and output formats set or use this config. This config can also be used by user code.
PipedRDD runs an external process and the configs aren't available to that process. Hadoop Streaming does something very similar and the way they make configs available is exporting them into the environment replacing '.' with '_'. Spark should also export this variable when launching the pipe command so the user code has access to that config.
Note that the config mapreduce.map.input.file is the new one, the old one which is deprecated but not yet removed is map.input.file. So we should handle both.

Perhaps it would be better to abstract this out somehow so it goes into the HadoopParition code?

Author: Thomas Graves <tgraves@apache.org>

Closes #94 from tgravescs/map_input_file and squashes the following commits:

cc97a6a [Thomas Graves] Update test to check for existence of command, add a getPipeEnvVars function to HadoopRDD
e3401dc [Thomas Graves] Merge remote-tracking branch 'upstream/master' into map_input_file
2ba805e [Thomas Graves] set map_input_file environment variable in PipedRDD

Author: tgravescs

core/src/main/scala/org/apache/spark/rdd/HadoopRDD.scala

@@ -18,8 +18,10 @@
 package org.apache.spark.rdd
 
 import java.io.EOFException
+import scala.collection.immutable.Map
 
 import org.apache.hadoop.conf.{Configurable, Configuration}
+import org.apache.hadoop.mapred.FileSplit
 import org.apache.hadoop.mapred.InputFormat
 import org.apache.hadoop.mapred.InputSplit
 import org.apache.hadoop.mapred.JobConf
@@ -43,6 +45,23 @@ private[spark] class HadoopPartition(rddId: Int, idx: Int, @transient s: InputSp
   override def hashCode(): Int = 41 * (41 + rddId) + idx
 
   override val index: Int = idx
+
+  /**
+   * Get any environment variables that should be added to the users environment when running pipes
+   * @return a Map with the environment variables and corresponding values, it could be empty
+   */
+  def getPipeEnvVars(): Map[String, String] = {
+    val envVars: Map[String, String] = if (inputSplit.value.isInstanceOf[FileSplit]) {
+      val is: FileSplit = inputSplit.value.asInstanceOf[FileSplit]
+      // map_input_file is deprecated in favor of mapreduce_map_input_file but set both
+      // since its not removed yet
+      Map("map_input_file" -> is.getPath().toString(),
+        "mapreduce_map_input_file" -> is.getPath().toString())
+    } else {
+      Map()
+    }
+    envVars
+  }
 }
 
 /**

core/src/main/scala/org/apache/spark/rdd/PipedRDD.scala

@@ -28,6 +28,7 @@ import scala.reflect.ClassTag
 
 import org.apache.spark.{Partition, SparkEnv, TaskContext}
 
+
 /**
  * An RDD that pipes the contents of each parent partition through an external command
  * (printing them one per line) and returns the output as a collection of strings.
@@ -59,6 +60,13 @@ class PipedRDD[T: ClassTag](
     val currentEnvVars = pb.environment()
     envVars.foreach { case (variable, value) => currentEnvVars.put(variable, value) }
 
+    // for compatibility with Hadoop which sets these env variables
+    // so the user code can access the input filename
+    if (split.isInstanceOf[HadoopPartition]) {
+      val hadoopSplit = split.asInstanceOf[HadoopPartition]
+      currentEnvVars.putAll(hadoopSplit.getPipeEnvVars())
+    }
+
     val proc = pb.start()
     val env = SparkEnv.get
 

core/src/test/scala/org/apache/spark/PipedRDDSuite.scala

@@ -19,74 +19,152 @@ package org.apache.spark
 
 import org.scalatest.FunSuite
 
+
+import org.apache.spark.rdd.{HadoopRDD, PipedRDD, HadoopPartition}
+import org.apache.hadoop.mapred.{JobConf, TextInputFormat, FileSplit}
+import org.apache.hadoop.fs.Path
+
+import scala.collection.Map
+import scala.sys.process._
+import scala.util.Try
+import org.apache.hadoop.io.{Text, LongWritable}
+
 class PipedRDDSuite extends FunSuite with SharedSparkContext {
 
   test("basic pipe") {
-    val nums = sc.makeRDD(Array(1, 2, 3, 4), 2)
+    if (testCommandAvailable("cat")) {
+      val nums = sc.makeRDD(Array(1, 2, 3, 4), 2)
 
-    val piped = nums.pipe(Seq("cat"))
+      val piped = nums.pipe(Seq("cat"))
 
-    val c = piped.collect()
-    assert(c.size === 4)
-    assert(c(0) === "1")
-    assert(c(1) === "2")
-    assert(c(2) === "3")
-    assert(c(3) === "4")
+      val c = piped.collect()
+      assert(c.size === 4)
+      assert(c(0) === "1")
+      assert(c(1) === "2")
+      assert(c(2) === "3")
+      assert(c(3) === "4")
+    } else {
+      assert(true)
+    }
   }
 
   test("advanced pipe") {
-    val nums = sc.makeRDD(Array(1, 2, 3, 4), 2)
-    val bl = sc.broadcast(List("0"))
-
-    val piped = nums.pipe(Seq("cat"),
-      Map[String, String](),
-      (f: String => Unit) => {bl.value.map(f(_));f("\u0001")},
-      (i:Int, f: String=> Unit) => f(i + "_"))
-
-    val c = piped.collect()
-
-    assert(c.size === 8)
-    assert(c(0) === "0")
-    assert(c(1) === "\u0001")
-    assert(c(2) === "1_")
-    assert(c(3) === "2_")
-    assert(c(4) === "0")
-    assert(c(5) === "\u0001")
-    assert(c(6) === "3_")
-    assert(c(7) === "4_")
-
-    val nums1 = sc.makeRDD(Array("a\t1", "b\t2", "a\t3", "b\t4"), 2)
-    val d = nums1.groupBy(str=>str.split("\t")(0)).
-      pipe(Seq("cat"),
-           Map[String, String](),
-           (f: String => Unit) => {bl.value.map(f(_));f("\u0001")},
-           (i:Tuple2[String, Seq[String]], f: String=> Unit) => {for (e <- i._2){ f(e + "_")}}).collect()
-    assert(d.size === 8)
-    assert(d(0) === "0")
-    assert(d(1) === "\u0001")
-    assert(d(2) === "b\t2_")
-    assert(d(3) === "b\t4_")
-    assert(d(4) === "0")
-    assert(d(5) === "\u0001")
-    assert(d(6) === "a\t1_")
-    assert(d(7) === "a\t3_")
+    if (testCommandAvailable("cat")) {
+      val nums = sc.makeRDD(Array(1, 2, 3, 4), 2)
+      val bl = sc.broadcast(List("0"))
+
+      val piped = nums.pipe(Seq("cat"),
+        Map[String, String](),
+        (f: String => Unit) => {
+          bl.value.map(f(_)); f("\u0001")
+        },
+        (i: Int, f: String => Unit) => f(i + "_"))
+
+      val c = piped.collect()
+
+      assert(c.size === 8)
+      assert(c(0) === "0")
+      assert(c(1) === "\u0001")
+      assert(c(2) === "1_")
+      assert(c(3) === "2_")
+      assert(c(4) === "0")
+      assert(c(5) === "\u0001")
+      assert(c(6) === "3_")
+      assert(c(7) === "4_")
+
+      val nums1 = sc.makeRDD(Array("a\t1", "b\t2", "a\t3", "b\t4"), 2)
+      val d = nums1.groupBy(str => str.split("\t")(0)).
+        pipe(Seq("cat"),
+          Map[String, String](),
+          (f: String => Unit) => {
+            bl.value.map(f(_)); f("\u0001")
+          },
+          (i: Tuple2[String, Seq[String]], f: String => Unit) => {
+            for (e <- i._2) {
+              f(e + "_")
+            }
+          }).collect()
+      assert(d.size === 8)
+      assert(d(0) === "0")
+      assert(d(1) === "\u0001")
+      assert(d(2) === "b\t2_")
+      assert(d(3) === "b\t4_")
+      assert(d(4) === "0")
+      assert(d(5) === "\u0001")
+      assert(d(6) === "a\t1_")
+      assert(d(7) === "a\t3_")
+    } else {
+      assert(true)
+    }
   }
 
   test("pipe with env variable") {
-    val nums = sc.makeRDD(Array(1, 2, 3, 4), 2)
-    val piped = nums.pipe(Seq("printenv", "MY_TEST_ENV"), Map("MY_TEST_ENV" -> "LALALA"))
-    val c = piped.collect()
-    assert(c.size === 2)
-    assert(c(0) === "LALALA")
-    assert(c(1) === "LALALA")
+    if (testCommandAvailable("printenv")) {
+      val nums = sc.makeRDD(Array(1, 2, 3, 4), 2)
+      val piped = nums.pipe(Seq("printenv", "MY_TEST_ENV"), Map("MY_TEST_ENV" -> "LALALA"))
+      val c = piped.collect()
+      assert(c.size === 2)
+      assert(c(0) === "LALALA")
+      assert(c(1) === "LALALA")
+    } else {
+      assert(true)
+    }
   }
 
   test("pipe with non-zero exit status") {
-    val nums = sc.makeRDD(Array(1, 2, 3, 4), 2)
-    val piped = nums.pipe(Seq("cat nonexistent_file", "2>", "/dev/null"))
-    intercept[SparkException] {
-      piped.collect()
+    if (testCommandAvailable("cat")) {
+      val nums = sc.makeRDD(Array(1, 2, 3, 4), 2)
+      val piped = nums.pipe(Seq("cat nonexistent_file", "2>", "/dev/null"))
+      intercept[SparkException] {
+        piped.collect()
+      }
+    } else {
+      assert(true)
     }
   }
 
+  test("test pipe exports map_input_file") {
+    testExportInputFile("map_input_file")
+  }
+
+  test("test pipe exports mapreduce_map_input_file") {
+    testExportInputFile("mapreduce_map_input_file")
+  }
+
+  def testCommandAvailable(command: String): Boolean = {
+    Try(Process(command) !!).isSuccess
+  }
+
+  def testExportInputFile(varName: String) {
+    if (testCommandAvailable("printenv")) {
+      val nums = new HadoopRDD(sc, new JobConf(), classOf[TextInputFormat], classOf[LongWritable],
+        classOf[Text], 2) {
+        override def getPartitions: Array[Partition] = Array(generateFakeHadoopPartition())
+
+        override val getDependencies = List[Dependency[_]]()
+
+        override def compute(theSplit: Partition, context: TaskContext) = {
+          new InterruptibleIterator[(LongWritable, Text)](context, Iterator((new LongWritable(1),
+            new Text("b"))))
+        }
+      }
+      val hadoopPart1 = generateFakeHadoopPartition()
+      val pipedRdd = new PipedRDD(nums, "printenv " + varName)
+      val tContext = new TaskContext(0, 0, 0, interrupted = false, runningLocally = false,
+        taskMetrics = null)
+      val rddIter = pipedRdd.compute(hadoopPart1, tContext)
+      val arr = rddIter.toArray
+      assert(arr(0) == "/some/path")
+    } else {
+      // printenv isn't available so just pass the test
+      assert(true)
+    }
+  }
+
+  def generateFakeHadoopPartition(): HadoopPartition = {
+    val split = new FileSplit(new Path("/some/path"), 0, 1,
+      Array[String]("loc1", "loc2", "loc3", "loc4", "loc5"))
+    new HadoopPartition(sc.newRddId(), 1, split)
+  }
+
 }