Copy content of KinesisReceiver implementation from Spark original …

…repository at the following point in time (`branch-2.4`):

https://github.com/apache/spark/blob/4be566062defa249435c4d72eb106fe7b933e023/external/kinesis-asl/src/main/scala/org/apache/spark/streaming/kinesis/KinesisReceiver.scala

This commit can be used as a point of reference to easily see the changes we applied to the original implementation.

spark-kinesis-dynamodb/src/main/scala/org/apache/spark/streaming/kinesis/KinesisCheckpointer.scala

@@ -0,0 +1,146 @@
+/*
+ * 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.kinesis
+
+import java.util.concurrent._
+
+import scala.util.control.NonFatal
+
+import com.amazonaws.services.kinesis.clientlibrary.interfaces.IRecordProcessorCheckpointer
+import com.amazonaws.services.kinesis.clientlibrary.lib.worker.ShutdownReason
+
+import org.apache.spark.internal.Logging
+import org.apache.spark.streaming.Duration
+import org.apache.spark.streaming.util.RecurringTimer
+import org.apache.spark.util.{Clock, SystemClock}
+
+/**
+ * This is a helper class for managing Kinesis checkpointing.
+ *
+ * @param receiver The receiver that keeps track of which sequence numbers we can checkpoint
+ * @param checkpointInterval How frequently we will checkpoint to DynamoDB
+ * @param workerId Worker Id of KCL worker for logging purposes
+ * @param clock In order to use ManualClocks for the purpose of testing
+ */
+private[kinesis] class KinesisCheckpointer(
+    receiver: KinesisReceiver[_],
+    checkpointInterval: Duration,
+    workerId: String,
+    clock: Clock = new SystemClock) extends Logging {
+
+  // a map from shardId's to checkpointers
+  private val checkpointers = new ConcurrentHashMap[String, IRecordProcessorCheckpointer]()
+
+  private val lastCheckpointedSeqNums = new ConcurrentHashMap[String, String]()
+
+  private val checkpointerThread: RecurringTimer = startCheckpointerThread()
+
+  /** Update the checkpointer instance to the most recent one for the given shardId. */
+  def setCheckpointer(shardId: String, checkpointer: IRecordProcessorCheckpointer): Unit = {
+    checkpointers.put(shardId, checkpointer)
+  }
+
+  /**
+   * Stop tracking the specified shardId.
+   *
+   * If a checkpointer is provided, e.g. on IRecordProcessor.shutdown [[ShutdownReason.TERMINATE]],
+   * we will use that to make the final checkpoint. If `null` is provided, we will not make the
+   * checkpoint, e.g. in case of [[ShutdownReason.ZOMBIE]].
+   */
+  def removeCheckpointer(shardId: String, checkpointer: IRecordProcessorCheckpointer): Unit = {
+    synchronized {
+      checkpointers.remove(shardId)
+    }
+    if (checkpointer != null) {
+      try {
+        // We must call `checkpoint()` with no parameter to finish reading shards.
+        // See a URL below for details:
+        // https://forums.aws.amazon.com/thread.jspa?threadID=244218
+        KinesisRecordProcessor.retryRandom(checkpointer.checkpoint(), 4, 100)
+      } catch {
+        case NonFatal(e) =>
+          logError(s"Exception:  WorkerId $workerId encountered an exception while checkpointing" +
+            s"to finish reading a shard of $shardId.", e)
+          // Rethrow the exception to the Kinesis Worker that is managing this RecordProcessor
+          throw e
+      }
+    }
+  }
+
+  /** Perform the checkpoint. */
+  private def checkpoint(shardId: String, checkpointer: IRecordProcessorCheckpointer): Unit = {
+    try {
+      if (checkpointer != null) {
+        receiver.getLatestSeqNumToCheckpoint(shardId).foreach { latestSeqNum =>
+          val lastSeqNum = lastCheckpointedSeqNums.get(shardId)
+          // Kinesis sequence numbers are monotonically increasing strings, therefore we can do
+          // safely do the string comparison
+          if (lastSeqNum == null || latestSeqNum > lastSeqNum) {
+            /* Perform the checkpoint */
+            KinesisRecordProcessor.retryRandom(checkpointer.checkpoint(latestSeqNum), 4, 100)
+            logDebug(s"Checkpoint:  WorkerId $workerId completed checkpoint at sequence number" +
+              s" $latestSeqNum for shardId $shardId")
+            lastCheckpointedSeqNums.put(shardId, latestSeqNum)
+          }
+        }
+      } else {
+        logDebug(s"Checkpointing skipped for shardId $shardId. Checkpointer not set.")
+      }
+    } catch {
+      case NonFatal(e) =>
+        logWarning(s"Failed to checkpoint shardId $shardId to DynamoDB.", e)
+    }
+  }
+
+  /** Checkpoint the latest saved sequence numbers for all active shardId's. */
+  private def checkpointAll(): Unit = synchronized {
+    // if this method throws an exception, then the scheduled task will not run again
+    try {
+      val shardIds = checkpointers.keys()
+      while (shardIds.hasMoreElements) {
+        val shardId = shardIds.nextElement()
+        checkpoint(shardId, checkpointers.get(shardId))
+      }
+    } catch {
+      case NonFatal(e) =>
+        logWarning("Failed to checkpoint to DynamoDB.", e)
+    }
+  }
+
+  /**
+   * Start the checkpointer thread with the given checkpoint duration.
+   */
+  private def startCheckpointerThread(): RecurringTimer = {
+    val period = checkpointInterval.milliseconds
+    val threadName = s"Kinesis Checkpointer - Worker $workerId"
+    val timer = new RecurringTimer(clock, period, _ => checkpointAll(), threadName)
+    timer.start()
+    logDebug(s"Started checkpointer thread: $threadName")
+    timer
+  }
+
+  /**
+   * Shutdown the checkpointer. Should be called on the onStop of the Receiver.
+   */
+  def shutdown(): Unit = {
+    // the recurring timer checkpoints for us one last time.
+    checkpointerThread.stop(interruptTimer = false)
+    checkpointers.clear()
+    lastCheckpointedSeqNums.clear()
+    logInfo("Successfully shutdown Kinesis Checkpointer.")
+  }
+}