Github user andrewor14 commented on a diff in the pull request:
https://github.com/apache/spark/pull/718#discussion_r13630434
--- Diff:
core/src/main/scala/org/apache/spark/deploy/history/FsHistoryProvider.scala ---
@@ -0,0 +1,210 @@
+/*
+ * 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.FileNotFoundException
+
+import scala.collection.mutable
+
+import org.apache.hadoop.fs.{FileStatus, Path}
+
+import org.apache.spark.{Logging, SecurityManager, SparkConf}
+import org.apache.spark.scheduler._
+import org.apache.spark.ui.SparkUI
+import org.apache.spark.util.Utils
+
+private[history] class FsHistoryProvider(conf: SparkConf) extends
ApplicationHistoryProvider
+ with Logging {
+
+ // Interval between each check for event log updates
+ private val UPDATE_INTERVAL_MS =
conf.getInt("spark.history.fs.updateInterval",
+ conf.getInt("spark.history.updateInterval", 10)) * 1000
+
+ private val logDir = conf.get("spark.history.fs.logDirectory")
+ private val fs = Utils.getHadoopFileSystem(logDir)
+
+ // A timestamp of when the disk was last accessed to check for log
updates
+ private var lastLogCheckTimeMs = -1L
+
+ // List of applications, in order from newest to oldest.
+ @volatile private var appList: Seq[ApplicationHistoryInfo] = Nil
+
+ /**
+ * A background thread that periodically checks for event log updates on
disk.
+ *
+ * If a log check is invoked manually in the middle of a period, this
thread re-adjusts the
+ * time at which it performs the next log check to maintain the same
period as before.
+ *
+ * TODO: Add a mechanism to update manually.
+ */
+ private val logCheckingThread = new Thread("LogCheckingThread") {
+ override def run() = Utils.logUncaughtExceptions {
+ while (true) {
+ val now = getMonotonicTimeMs()
+ if (now - lastLogCheckTimeMs > UPDATE_INTERVAL_MS) {
+ Thread.sleep(UPDATE_INTERVAL_MS)
+ } else {
+ // If the user has manually checked for logs recently, wait until
+ // UPDATE_INTERVAL_MS after the last check time
+ Thread.sleep(lastLogCheckTimeMs + UPDATE_INTERVAL_MS - now)
+ }
+ checkForLogs()
+ }
+ }
+ }
+
+ initialize()
+
+ private def initialize() {
+ // Validate the log directory.
+ val path = new Path(logDir)
+ if (!fs.exists(path)) {
+ throw new IllegalArgumentException(
+ "Logging directory specified does not exist: %s".format(logDir))
+ }
+ if (!fs.getFileStatus(path).isDir) {
+ throw new IllegalArgumentException(
+ "Logging directory specified is not a directory:
%s".format(logDir))
+ }
+
+ checkForLogs()
+ logCheckingThread.setDaemon(true)
+ logCheckingThread.start()
+ }
+
+ override def getListing() = appList
+
+ override def getAppUI(appId: String): SparkUI = {
+ try {
+ val appLogDir = fs.getFileStatus(new Path(logDir, appId))
+ loadAppInfo(appLogDir, true)._2
+ } catch {
+ case e: FileNotFoundException => null
+ }
+ }
+
+ override def getConfig(): Map[String, String] =
+ Map(("Event Log Location" -> logDir))
+
+ /**
+ * Builds the application list based on the current contents of the log
directory.
+ * Tries to reuse as much of the data already in memory as possible, by
not reading
+ * applications that haven't been updated since last time the logs were
checked.
+ */
+ private def checkForLogs() = {
+ lastLogCheckTimeMs = getMonotonicTimeMs()
+ logDebug("Checking for logs. Time is now
%d.".format(lastLogCheckTimeMs))
+ try {
+ val logStatus = fs.listStatus(new Path(logDir))
+ val logDirs = if (logStatus != null) logStatus.filter(_.isDir).toSeq
else Seq[FileStatus]()
+ val logInfos = logDirs
+ .filter {
+ dir => fs.isFile(new Path(dir.getPath(),
EventLoggingListener.APPLICATION_COMPLETE))
+ }
+
+ val currentApps = Map[String, ApplicationHistoryInfo](
+ appList.map(app => (app.id -> app)):_*)
+
+ // For any application that either (i) is not listed or (ii) has
changed since the last time
+ // the listing was created (defined by the log dir's modification
time), load the app's info.
+ // Otherwise just reuse what's already in memory.
+ val newApps = new
mutable.ArrayBuffer[ApplicationHistoryInfo](logInfos.size)
+ for (dir <- logInfos) {
+ val curr = currentApps.getOrElse(dir.getPath().getName(), null)
+ if (curr == null || curr.lastUpdated < getModificationTime(dir)) {
+ try {
+ newApps += loadAppInfo(dir, false)._1
+ } catch {
+ case e: Exception => logError(s"Failed to load app info from
directory $dir.")
+ }
+ } else {
+ newApps += curr
+ }
+ }
+
+ appList = newApps.sortBy { info => -info.endTime }
+ } catch {
+ case t: Throwable => logError("Exception in checking for event log
updates", t)
+ }
+ }
+
+ /**
+ * Parse the application's logs to find out the information we need to
build the
+ * listing page.
+ *
+ * When creating the listing of available apps, there is no need to load
the whole UI for the
+ * application. The UI is requested by the HistoryServer (by calling
getAppInfo()) when the user
+ * clicks on a specific application.
+ *
+ * @param logDir Directory with application's log files.
+ * @param renderUI Whether to create the SparkUI for the application.
+ * @return A 2-tuple `(app info, ui)`. `ui` will be null if `renderUI`
is false.
--- End diff --
I see, we still get the view ACLs for rendering the UI.
I think the ugliness of returning a tuple should be avoided, even if it is
not user facing. These are really two separate cases anyway, so the correct way
to do this is to abstract out the duplicate part (i.e. the instantiation of the
ReplayBus), and then have both `getAppUI` and `getAppInfo` use the same method.
Right now, based on the method signature, it seems that the caller needs both
items of the tuple, which is not true.
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