Github user pwendell commented on a diff in the pull request:
https://github.com/apache/spark/pull/3026#discussion_r19696931
--- Diff:
streaming/src/main/scala/org/apache/spark/streaming/scheduler/ReceivedBlockTracker.scala
---
@@ -0,0 +1,205 @@
+/*
+ * 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.streaming.scheduler
+
+import java.nio.ByteBuffer
+
+import scala.collection.mutable
+import scala.language.implicitConversions
+
+import org.apache.hadoop.conf.Configuration
+import org.apache.hadoop.fs.Path
+
+import org.apache.spark.{Logging, SparkConf}
+import org.apache.spark.streaming.Time
+import org.apache.spark.streaming.util.{Clock, WriteAheadLogManager}
+import org.apache.spark.util.Utils
+
+/** Trait representing any event in the ReceivedBlockTracker that updates
its state. */
+private[streaming] sealed trait ReceivedBlockTrackerLogEvent
+
+private[streaming] case class BlockAdditionEvent(receivedBlockInfo:
ReceivedBlockInfo)
+ extends ReceivedBlockTrackerLogEvent
+private[streaming] case class BatchAllocationEvent(time: Time,
allocatedBlocks: AllocatedBlocks)
+ extends ReceivedBlockTrackerLogEvent
+private[streaming] case class BatchCleanupEvent(times: Seq[Time])
+ extends ReceivedBlockTrackerLogEvent
+
+
+/** Class representing the blocks of all the streams allocated to a batch
*/
+private[streaming] case class AllocatedBlocks(streamIdToAllocatedBlocks:
Map[Int, Seq[ReceivedBlockInfo]]) {
+ def getBlockForStream(streamId: Int) =
streamIdToAllocatedBlocks(streamId)
+}
+
+/**
+ * Class that keep track of all the received blocks, and allocate them to
batches
+ * when required. All actions taken by this class can be saved to a write
ahead log
+ * (if a checkpoint directory has been provided), so that the state of the
tracker
+ * (received blocks and block-to-batch allocations) can be recovered after
driver failure.
+ *
+ * Note that when any instance of this class is created with a checkpoint
directory,
+ * it will try reading events from logs in the directory.
+ */
+private[streaming] class ReceivedBlockTracker(
+ conf: SparkConf,
+ hadoopConf: Configuration,
+ streamIds: Seq[Int],
+ clock: Clock,
+ checkpointDirOption: Option[String])
+ extends Logging {
+
+ private type ReceivedBlockQueue = mutable.Queue[ReceivedBlockInfo]
+
+ private val streamIdToUnallocatedBlockQueues = new mutable.HashMap[Int,
ReceivedBlockQueue]
+ private val timeToAllocatedBlocks = new mutable.HashMap[Time,
AllocatedBlocks]
+
+ private val logManagerRollingIntervalSecs = conf.getInt(
+
"spark.streaming.receivedBlockTracker.writeAheadLog.rotationIntervalSecs", 60)
+ private val logManagerOption = checkpointDirOption.map { checkpointDir =>
+ new WriteAheadLogManager(
+ ReceivedBlockTracker.checkpointDirToLogDir(checkpointDir),
+ hadoopConf,
+ rollingIntervalSecs = logManagerRollingIntervalSecs,
+ callerName = "ReceivedBlockHandlerMaster",
+ clock = clock
+ )
+ }
+
+ // Recover block information from write ahead logs
+ recoverFromWriteAheadLogs()
+
+ /** Add received block. This event will get written to the write ahead
log (if enabled). */
+ def addBlock(receivedBlockInfo: ReceivedBlockInfo): Boolean =
synchronized {
+ try {
+ writeToLog(BlockAdditionEvent(receivedBlockInfo))
+ getReceivedBlockQueue(receivedBlockInfo.streamId) +=
receivedBlockInfo
+ logDebug(s"Stream ${receivedBlockInfo.streamId} received " +
+ s"block ${receivedBlockInfo.blockStoreResult.blockId}")
+ true
+ } catch {
+ case e: Exception =>
+ logError(s"Error adding block $receivedBlockInfo", e)
+ false
+ }
+ }
+
+ /**
+ * Allocate all unallocated blocks to the given batch.
+ * This event will get written to the write ahead log (if enabled).
+ */
+ def allocateBlocksToBatch(batchTime: Time): Unit = synchronized {
+ val allocatedBlocks = AllocatedBlocks(streamIds.map { streamId =>
--- End diff --
This is a really dense expression. Can this be broken out into simpler
experesssions that make it easier to read?
```
val streamsWithBlocks = streamIds.map { streamId =>
(streamId, getReceivedBlockQueue(streamId).dequeueAll(_ => true))
}
val streamToBlocks = streamsWithBlocks.toMap
val allocatedBlocks = AllocatedBlocks(streamToBlocks)
```
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