apache
diff --git a/‎core/src/main/scala/org/apache/spark/deploy/history/EventLogFileReaders.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.deploy.history
+
+import java.io.{BufferedInputStream, InputStream}
+import java.util.concurrent.ConcurrentHashMap
+import java.util.zip.{ZipEntry, ZipOutputStream}
+
+import com.google.common.io.ByteStreams
+import org.apache.hadoop.fs.{FileStatus, FileSystem, Path}
+import org.apache.hadoop.hdfs.DFSInputStream
+
+import org.apache.spark.SparkConf
+import org.apache.spark.deploy.history.EventLogFileWriter.codecName
+import org.apache.spark.io.CompressionCodec
+import org.apache.spark.util.Utils
+
+/** The base class of reader which will read the information of event log file(s). */
+abstract class EventLogFileReader(
+    protected val fileSystem: FileSystem,
+    val rootPath: Path) {
+
+  protected def fileSizeForDFS(path: Path): Option[Long] = {
+    Utils.tryWithResource(fileSystem.open(path)) { in =>
+      in.getWrappedStream match {
+        case dfsIn: DFSInputStream => Some(dfsIn.getFileLength)
+        case _ => None
+      }
+    }
+  }
+
+  protected def addFileAsZipEntry(
+      zipStream: ZipOutputStream,
+      path: Path,
+      entryName: String): Unit = {
+    Utils.tryWithResource(fileSystem.open(path, 1 * 1024 * 1024)) { inputStream =>
+      zipStream.putNextEntry(new ZipEntry(entryName))
+      ByteStreams.copy(inputStream, zipStream)
+      zipStream.closeEntry()
+    }
+  }
+
+  /** Returns the last index of event log files. None for single event log file. */
+  def lastIndex: Option[Long]
+
+  /**
+   * Returns the size of file for the last index of event log files. Returns its size for
+   * single event log file.
+   */
+  def fileSizeForLastIndex: Long
+
+  /** Returns whether the application is completed. */
+  def completed: Boolean
+
+  /**
+   * Returns the size of file for the last index (itself for single event log file) of event log
+   * files, only when underlying input stream is DFSInputStream. Otherwise returns None.
+   */
+  def fileSizeForLastIndexForDFS: Option[Long]
+
+  /**
+   * Returns the modification time for the last index (itself for single event log file)
+   * of event log files.
+   */
+  def modificationTime: Long
+
+  /**
+   * This method compresses the files passed in, and writes the compressed data out into the
+   * ZipOutputStream passed in. Each file is written as a new ZipEntry with its name being
+   * the name of the file being compressed.
+   */
+  def zipEventLogFiles(zipStream: ZipOutputStream): Unit
+
+  /** Returns all available event log files. */
+  def listEventLogFiles: Seq[FileStatus]
+
+  /** Returns the short compression name if being used. None if it's uncompressed. */
+  def compressionCodec: Option[String]
+
+  /** Returns the size of all event log files. */
+  def totalSize: Long
+}
+
+object EventLogFileReader {
+  // A cache for compression codecs to avoid creating the same codec many times
+  private val codecMap = new ConcurrentHashMap[String, CompressionCodec]()
+
+  def apply(
+      fs: FileSystem,
+      path: Path,
+      lastIndex: Option[Long]): EventLogFileReader = {
+    lastIndex match {
+      case Some(_) => new RollingEventLogFilesFileReader(fs, path)
+      case None => new SingleFileEventLogFileReader(fs, path)
+    }
+  }
+
+  def apply(fs: FileSystem, path: Path): Option[EventLogFileReader] = {
+    apply(fs, fs.getFileStatus(path))
+  }
+
+  def apply(fs: FileSystem, status: FileStatus): Option[EventLogFileReader] = {
+    if (isSingleEventLog(status)) {
+      Some(new SingleFileEventLogFileReader(fs, status.getPath))
+    } else if (isRollingEventLogs(status)) {
+      Some(new RollingEventLogFilesFileReader(fs, status.getPath))
+    } else {
+      None
+    }
+  }
+
+  /**
+   * Opens an event log file and returns an input stream that contains the event data.
+   *
+   * @return input stream that holds one JSON record per line.
+   */
+  def openEventLog(log: Path, fs: FileSystem): InputStream = {
+    val in = new BufferedInputStream(fs.open(log))
+    try {
+      val codec = codecName(log).map { c =>
+        codecMap.computeIfAbsent(c, CompressionCodec.createCodec(new SparkConf, _))
+      }
+      codec.map(_.compressedContinuousInputStream(in)).getOrElse(in)
+    } catch {
+      case e: Throwable =>
+        in.close()
+        throw e
+    }
+  }
+
+  private def isSingleEventLog(status: FileStatus): Boolean = {
+    !status.isDirectory &&
+      // FsHistoryProvider used to generate a hidden file which can't be read.  Accidentally
+      // reading a garbage file is safe, but we would log an error which can be scary to
+      // the end-user.
+      !status.getPath.getName.startsWith(".")
+  }
+
+  private def isRollingEventLogs(status: FileStatus): Boolean = {
+    RollingEventLogFilesWriter.isEventLogDir(status)
+  }
+}
+
+/**
+ * The reader which will read the information of single event log file.
+ *
+ * This reader gets the status of event log file only once when required;
+ * It may not give "live" status of file that could be changing concurrently, and
+ * FileNotFoundException could occur if the log file is renamed before getting the
+ * status of log file.
+ */
+class SingleFileEventLogFileReader(
+    fs: FileSystem,
+    path: Path) extends EventLogFileReader(fs, path) {
+  private lazy val status = fileSystem.getFileStatus(rootPath)
+
+  override def lastIndex: Option[Long] = None
+
+  override def fileSizeForLastIndex: Long = status.getLen
+
+  override def completed: Boolean = !rootPath.getName.endsWith(EventLogFileWriter.IN_PROGRESS)
+
+  override def fileSizeForLastIndexForDFS: Option[Long] = {
+    if (completed) {
+      Some(fileSizeForLastIndex)
+    } else {
+      fileSizeForDFS(rootPath)
+    }
+  }
+
+  override def modificationTime: Long = status.getModificationTime
+
+  override def zipEventLogFiles(zipStream: ZipOutputStream): Unit = {
+    addFileAsZipEntry(zipStream, rootPath, rootPath.getName)
+  }
+
+  override def listEventLogFiles: Seq[FileStatus] = Seq(status)
+
+  override def compressionCodec: Option[String] = EventLogFileWriter.codecName(rootPath)
+
+  override def totalSize: Long = fileSizeForLastIndex
+}
+
+/**
+ * The reader which will read the information of rolled multiple event log files.
+ *
+ * This reader lists the files only once; if caller would like to play with updated list,
+ * it needs to create another reader instance.
+ */
+class RollingEventLogFilesFileReader(
+    fs: FileSystem,
+    path: Path) extends EventLogFileReader(fs, path) {
+  import RollingEventLogFilesWriter._
+
+  private lazy val files: Seq[FileStatus] = {
+    val ret = fs.listStatus(rootPath).toSeq
+    require(ret.exists(isEventLogFile), "Log directory must contain at least one event log file!")
+    require(ret.exists(isAppStatusFile), "Log directory must contain an appstatus file!")
+    ret
+  }
+
+  private lazy val appStatusFile = files.find(isAppStatusFile).get
+
+  private lazy val eventLogFiles: Seq[FileStatus] = {
+    val eventLogFiles = files.filter(isEventLogFile).sortBy { status =>
+      getIndex(status.getPath.getName)
+    }
+    val indices = eventLogFiles.map { file => getIndex(file.getPath.getName) }.sorted
+    require((indices.head to indices.last) == indices, "Found missing event log file, expected" +
+      s" indices: ${(indices.head to indices.last)}, actual: ${indices}")
+    eventLogFiles
+  }
+
+  override def lastIndex: Option[Long] = Some(getIndex(lastEventLogFile.getPath.getName))
+
+  override def fileSizeForLastIndex: Long = lastEventLogFile.getLen
+
+  override def completed: Boolean = {
+    !appStatusFile.getPath.getName.endsWith(EventLogFileWriter.IN_PROGRESS)
+  }
+
+  override def fileSizeForLastIndexForDFS: Option[Long] = {
+    if (completed) {
+      Some(fileSizeForLastIndex)
+    } else {
+      fileSizeForDFS(lastEventLogFile.getPath)
+    }
+  }
+
+  override def modificationTime: Long = lastEventLogFile.getModificationTime
+
+  override def zipEventLogFiles(zipStream: ZipOutputStream): Unit = {
+    val dirEntryName = rootPath.getName + "/"
+    zipStream.putNextEntry(new ZipEntry(dirEntryName))
+    files.foreach { file =>
+      addFileAsZipEntry(zipStream, file.getPath, dirEntryName + file.getPath.getName)
+    }
+  }
+
+  override def listEventLogFiles: Seq[FileStatus] = eventLogFiles
+
+  override def compressionCodec: Option[String] = {
+    EventLogFileWriter.codecName(eventLogFiles.head.getPath)
+  }
+
+  override def totalSize: Long = eventLogFiles.map(_.getLen).sum
+
+  private def lastEventLogFile: FileStatus = eventLogFiles.last
+}