[SPARK-1133] Add whole text files reader in MLlib

mllib/src/main/scala/org/apache/spark/mllib/MLContext.scala

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+/*
+ * 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.mllib
+
+import org.apache.spark.mllib.input.WholeTextFileInputFormat
+import org.apache.spark.rdd.RDD
+import org.apache.spark.SparkContext
+
+/**
+ * Extra functions available on SparkContext of mllib through an implicit conversion. Import
+ * `org.apache.spark.mllib.MLContext._` at the top of your program to use these functions.
+ */
+class MLContext(self: SparkContext) {
+
+  /**
+   * Read a directory of text files from HDFS, a local file system (available on all nodes), or any
+   * Hadoop-supported file system URI. Each file is read as a single record and returned in a
+   * key-value pair, where the key is the path of each file, the value is the content of each file.
+   *
+   * <p> For example, if you have the following files:
+   * {{{
+   * hdfs://a-hdfs-path/part-00000
+   * hdfs://a-hdfs-path/part-00001
+   * ...
+   * hdfs://a-hdfs-path/part-nnnnn
+   * }}}
+   *
+   * Do `val rdd = mlContext.wholeTextFile("hdfs://a-hdfs-path")`,
+   *
+   * <p> then `rdd` contains
+   * {{{
+   * (a-hdfs-path/part-00000, its content)
+   * (a-hdfs-path/part-00001, its content)
+   * ...
+   * (a-hdfs-path/part-nnnnn, its content)
+   * }}}
+   */
+  def wholeTextFile(path: String): RDD[(String, String)] = {
+    self.newAPIHadoopFile(
+      path,
+      classOf[WholeTextFileInputFormat],
+      classOf[String],
+      classOf[String])
+  }
+}
+
+/**
+ * The MLContext object contains a number of implicit conversions and parameters for use with
+ * various mllib features.
+ */
+object MLContext {
+  implicit def sparkContextToMLContext(sc: SparkContext) = new MLContext(sc)
+}

mllib/src/main/scala/org/apache/spark/mllib/input/WholeTextFileInputFormat.scala

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+/*
+ * 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.mllib.input
+
+import org.apache.hadoop.fs.Path
+import org.apache.hadoop.mapreduce.InputSplit
+import org.apache.hadoop.mapreduce.JobContext
+import org.apache.hadoop.mapreduce.lib.input.CombineFileInputFormat
+import org.apache.hadoop.mapreduce.RecordReader
+import org.apache.hadoop.mapreduce.TaskAttemptContext
+import org.apache.hadoop.mapreduce.lib.input.CombineFileRecordReader
+import org.apache.hadoop.mapreduce.lib.input.CombineFileSplit
+
+/**
+ * A [[org.apache.hadoop.mapreduce.lib.input.CombineFileInputFormat CombineFileInputFormat]] for
+ * reading whole text files. Each file is read as key-value pair, where the key is the file path and
+ * the value is the entire content of file.
+ */
+
+private[mllib] class WholeTextFileInputFormat extends CombineFileInputFormat[String, String] {
+  override protected def isSplitable(context: JobContext, file: Path): Boolean = false
+
+  override def createRecordReader(
+      split: InputSplit,
+      context: TaskAttemptContext): RecordReader[String, String] = {
+
+    new CombineFileRecordReader[String, String](
+    split.asInstanceOf[CombineFileSplit],
+    context,
+    classOf[WholeTextFileRecordReader])
+  }
+}

mllib/src/main/scala/org/apache/spark/mllib/input/WholeTextFileRecordReader.scala

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+/*
+ * 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.mllib.input
+
+import com.google.common.io.{ByteStreams, Closeables}
+
+import org.apache.hadoop.io.Text
+import org.apache.hadoop.mapreduce.InputSplit
+import org.apache.hadoop.mapreduce.lib.input.CombineFileSplit
+import org.apache.hadoop.mapreduce.RecordReader
+import org.apache.hadoop.mapreduce.TaskAttemptContext
+
+/**
+ * A [[org.apache.hadoop.mapreduce.RecordReader RecordReader]] for reading a single whole text file
+ * out in a key-value pair, where the key is the file path and the value is the entire content of
+ * the file.
+ */
+private[mllib] class WholeTextFileRecordReader(
+    split: CombineFileSplit,
+    context: TaskAttemptContext,
+    index: Integer)
+  extends RecordReader[String, String] {
+
+  private val path = split.getPath(index)
+  private val fs = path.getFileSystem(context.getConfiguration)
+
+  // True means the current file has been processed, then skip it.
+  private var processed = false
+
+  private val key = path.toString
+  private var value: String = null
+
+  override def initialize(split: InputSplit, context: TaskAttemptContext) = {}
+
+  override def close() = {}
+
+  override def getProgress = if (processed) 1.0f else 0.0f
+
+  override def getCurrentKey = key
+
+  override def getCurrentValue = value
+
+  override def nextKeyValue = {
+    if (!processed) {
+      val fileIn = fs.open(path)
+      val innerBuffer = ByteStreams.toByteArray(fileIn)
+
+      value = new Text(innerBuffer).toString
+      Closeables.close(fileIn, false)
+
+      processed = true
+      true
+    } else {
+      false
+    }
+  }
+}

mllib/src/test/scala/org/apache/spark/mllib/input/WholeTextFileRecordReaderSuite.scala

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+/*
+ * 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.mllib.input
+
+import java.io.DataOutputStream
+import java.io.File
+import java.io.FileOutputStream
+
+import scala.collection.immutable.IndexedSeq
+
+import com.google.common.io.Files
+
+import org.scalatest.BeforeAndAfterAll
+import org.scalatest.FunSuite
+
+import org.apache.hadoop.io.Text
+
+import org.apache.spark.SparkContext
+import org.apache.spark.mllib.MLContext._
+
+/**
+ * Tests the correctness of
+ * [[org.apache.spark.mllib.input.WholeTextFileRecordReader WholeTextFileRecordReader]]. A temporary
+ * directory is created as fake input. Temporal storage would be deleted in the end.
+ */
+class WholeTextFileRecordReaderSuite extends FunSuite with BeforeAndAfterAll {
+  private var sc: SparkContext = _
+
+  override def beforeAll() {
+    sc = new SparkContext("local", "test")
+  }
+
+  override def afterAll() {
+    sc.stop()
+  }
+
+  private def createNativeFile(inputDir: File, fileName: String, contents: Array[Byte]) = {
+    val out = new DataOutputStream(new FileOutputStream(s"${inputDir.toString}/$fileName"))
+    out.write(contents, 0, contents.length)
+    out.close()
+  }
+
+  /**
+   * This code will test the behaviors of WholeTextFileRecordReader based on local disk. There are
+   * three aspects to check:
+   *   1) Whether all files are read;
+   *   2) Whether paths are read correctly;
+   *   3) Does the contents be the same.
+   */
+  test("Correctness of WholeTextFileRecordReader.") {
+
+    val dir = Files.createTempDir()
+    println(s"Local disk address is ${dir.toString}.")
+
+    WholeTextFileRecordReaderSuite.files.foreach { case (filename, contents) =>
+      createNativeFile(dir, filename, contents)
+    }
+
+    val res = sc.wholeTextFile(dir.toString).collect()
+
+    assert(res.size === WholeTextFileRecordReaderSuite.fileNames.size,
+      "Number of files read out does not fit with the actual value.")
+
+    for ((filename, contents) <- res) {
+      val shortName = filename.split('/').last
+      assert(WholeTextFileRecordReaderSuite.fileNames.contains(shortName),
+        s"Missing file name $filename.")
+      assert(contents === new Text(WholeTextFileRecordReaderSuite.files(shortName)).toString,
+        s"file $filename contents can not match.")
+    }
+
+    dir.delete()
+  }
+}
+
+/**
+ * Files to be tested are defined here.
+ */
+object WholeTextFileRecordReaderSuite {
+  private val testWords: IndexedSeq[Byte] = "Spark is easy to use.\n".map(_.toByte)
+
+  private val fileNames = Array("part-00000", "part-00001", "part-00002")
+  private val fileLengths = Array(10, 100, 1000)
+
+  private val files = fileLengths.zip(fileNames).map { case (upperBound, filename) =>
+    filename -> Stream.continually(testWords.toList.toStream).flatten.take(upperBound).toArray
+  }.toMap
+}