Github user pwendell commented on a diff in the pull request:
https://github.com/apache/spark/pull/42#discussion_r10272860
--- Diff: core/src/main/scala/org/apache/spark/ui/UISparkListener.scala ---
@@ -0,0 +1,231 @@
+/*
+ * 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.ui
+
+import scala.collection.mutable
+import scala.collection.mutable.ArrayBuffer
+
+import org.json4s.jackson.JsonMethods._
+
+import org.apache.spark.SparkContext
+import org.apache.spark.scheduler._
+import org.apache.spark.storage._
+import org.apache.spark.util.FileLogger
+import org.apache.spark.util.JsonProtocol
+
+private[ui] trait UISparkListener extends SparkListener
+
+/**
+ * A SparkListener that serves as an entry point for all events posted to
the UI.
+ *
+ * GatewayUISparkListener achieves two functions:
+ *
+ * (1) If the UI is live, GatewayUISparkListener posts each event to all
attached listeners
+ * then logs it as JSON. This centralizes event logging and avoids
having all attached
+ * listeners log the events on their own.
+ *
+ * (2) If the UI is rendered from disk, GatewayUISparkListener replays
each event deserialized
+ * from the event logs to all attached listeners.
+ *
+ * Event logging is specified by three configurable parameters:
+ *
+ * spark.eventLog.enabled - Whether event logging is enabled.
+ * spark.eventLog.dir - Path to the directory in which events are logged.
+ * spark.eventLog.overwrite - Whether to overwrite any existing files.
+ */
+private[ui] class GatewayUISparkListener(parent: SparkUI, sc:
SparkContext) extends SparkListener {
+
+ // Log events only if the UI is live and event logging is enabled
+ private val logger: Option[FileLogger] = {
+ if (sc != null && sc.conf.getBoolean("spark.eventLog.enabled", false))
{
+ val logDir = sc.conf.get("spark.eventLog.dir", "/tmp/spark-events")
+ val appName = sc.appName.replaceAll("[ /]", "_").toLowerCase
--- End diff --
I think here we'd want a nonce also (e.g. timestamp) because otherwise if
someone runs the same app twice the files will overwrite eachother.
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