| /* |
| * 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.samza.system.kafka |
| |
| |
| import java.util.concurrent.atomic.AtomicReference |
| import java.util.concurrent.TimeUnit |
| |
| import org.apache.kafka.clients.producer.Callback |
| import org.apache.kafka.clients.producer.Producer |
| import org.apache.kafka.clients.producer.ProducerRecord |
| import org.apache.kafka.clients.producer.RecordMetadata |
| import org.apache.kafka.common.PartitionInfo |
| import org.apache.samza.system.OutgoingMessageEnvelope |
| import org.apache.samza.system.SystemProducer |
| import org.apache.samza.system.SystemProducerException |
| import org.apache.samza.util.ExponentialSleepStrategy |
| import org.apache.samza.util.KafkaUtil |
| import org.apache.samza.util.Logging |
| import org.apache.samza.util.TimerUtil |
| |
| class KafkaSystemProducer(systemName: String, |
| retryBackoff: ExponentialSleepStrategy = new ExponentialSleepStrategy, |
| getProducer: () => Producer[Array[Byte], Array[Byte]], |
| metrics: KafkaSystemProducerMetrics, |
| val clock: () => Long = () => System.nanoTime, |
| val dropProducerExceptions: Boolean = false) extends SystemProducer with Logging with TimerUtil { |
| |
| // Represents a fatal error that caused the producer to close. |
| val fatalException: AtomicReference[SystemProducerException] = new AtomicReference[SystemProducerException]() |
| val producerRef: AtomicReference[Producer[Array[Byte], Array[Byte]]] = new AtomicReference[Producer[Array[Byte], Array[Byte]]]() |
| val producerCreationLock: Object = new Object |
| @volatile var stopped = false |
| |
| def start(): Unit = { |
| producerRef.set(getProducer()) |
| } |
| |
| def stop() { |
| info("Stopping producer for system: " + this.systemName) |
| |
| stopped = true |
| val currentProducer = producerRef.getAndSet(null) |
| try { |
| if (currentProducer != null) { |
| currentProducer.close // Also performs the equivalent of a flush() |
| } |
| |
| val exception = fatalException.get() |
| if (exception != null) { |
| error("Observed an earlier send() error while closing producer", exception) |
| } |
| } catch { |
| case e: Exception => error("Error while closing producer for system: " + systemName, e) |
| } |
| } |
| |
| def register(source: String) { |
| } |
| |
| def send(source: String, envelope: OutgoingMessageEnvelope) { |
| trace("Enqueuing message: %s, %s." format (source, envelope)) |
| |
| val topicName = envelope.getSystemStream.getStream |
| if (topicName == null || topicName.isEmpty) { |
| throw new IllegalArgumentException("Invalid system stream: " + envelope.getSystemStream) |
| } |
| |
| val globalProducerException = fatalException.get() |
| if (globalProducerException != null) { |
| metrics.sendFailed.inc |
| throw new SystemProducerException("Producer was unable to recover from previous exception.", globalProducerException) |
| } |
| |
| val currentProducer = getOrCreateCurrentProducer |
| |
| // Java-based Kafka producer API requires an "Integer" type partitionKey and does not allow custom overriding of Partitioners |
| // Any kind of custom partitioning has to be done on the client-side |
| val partitions: java.util.List[PartitionInfo] = currentProducer.partitionsFor(topicName) |
| val partitionKey = if (envelope.getPartitionKey != null) KafkaUtil.getIntegerPartitionKey(envelope, partitions) else null |
| val record = new ProducerRecord(envelope.getSystemStream.getStream, |
| partitionKey, |
| envelope.getKey.asInstanceOf[Array[Byte]], |
| envelope.getMessage.asInstanceOf[Array[Byte]]) |
| |
| try { |
| currentProducer.send(record, new Callback { |
| def onCompletion(metadata: RecordMetadata, exception: Exception): Unit = { |
| if (exception == null) { |
| metrics.sendSuccess.inc |
| } else { |
| val producerException = new SystemProducerException("Failed to send message for Source: %s on System:%s Topic:%s Partition:%s" |
| .format(source, systemName, topicName, partitionKey), exception) |
| |
| handleFatalSendException(currentProducer, producerException) |
| } |
| } |
| }) |
| metrics.sends.inc |
| } catch { |
| case originalException : Exception => |
| val producerException = new SystemProducerException("Failed to send message for Source: %s on System:%s Topic:%s Partition:%s" |
| .format(source, systemName, topicName, partitionKey), originalException) |
| |
| metrics.sendFailed.inc |
| error("Got a synchronous error from Kafka producer.", producerException) |
| // Synchronous exceptions are always recoverable so propagate it up and let the user decide |
| throw producerException |
| } |
| } |
| |
| def flush(source: String) { |
| updateTimer(metrics.flushNs) { |
| metrics.flushes.inc |
| |
| val currentProducer = producerRef.get() |
| if (currentProducer == null) { |
| if (dropProducerExceptions) { |
| // No producer to flush, but we're ignoring exceptions so just return. |
| warn("Skipping flush because the Kafka producer is null.") |
| metrics.flushFailed.inc |
| return |
| } |
| throw new SystemProducerException("Kafka producer is null.") |
| } |
| |
| // Flush only throws InterruptedException, all other errors are handled in send() callbacks |
| currentProducer.flush() |
| |
| // Invariant: At this point either |
| // 1. The producer is fine and there are no exceptions to handle OR |
| // 2. The producer is closed and one or more sources have exceptions to handle |
| // 2a. All new sends get a ProducerClosedException or IllegalStateException (depending on kafka version) |
| // 2b. There are no messages in flight because the producer is closed |
| |
| // We must check for an exception AFTER flush() because when flush() returns all callbacks for messages sent |
| // in that flush() are guaranteed to have completed and we update the exception in the callback. |
| // If there is an exception, we rethrow it here to prevent the checkpoint. |
| val exception = fatalException.get() |
| if (exception != null) { |
| metrics.flushFailed.inc |
| throw new SystemProducerException("Flush failed. One or more batches of messages were not sent!", exception) |
| } |
| trace("Flushed %s." format source) |
| } |
| } |
| |
| |
| /** |
| * Handles a fatal exception by closing the producer and either recreating it or storing the exception |
| * to rethrow later, depending on the value of dropProducerExceptions. |
| * |
| * @param currentProducer the current producer for which the exception occurred. Must not be null. |
| * @param producerException the exception to handle. |
| */ |
| private def handleFatalSendException(currentProducer: Producer[Array[Byte], Array[Byte]], producerException: SystemProducerException): Unit = { |
| metrics.sendFailed.inc |
| error(producerException) |
| // The SystemProducer API is synchronous, so there's no way for us to guarantee that an exception will |
| // be handled by the Task before we recreate the producer, and if it isn't handled, a concurrent send() from another |
| // Task could send on the new producer before the first Task properly handled the exception and produce out of order messages. |
| // So we have to handle it right here in the SystemProducer. |
| if (dropProducerExceptions) { |
| warn("Ignoring producer exception. All messages in the failed producer request will be dropped!") |
| |
| // Prevent each callback from closing and nulling producer for the same failure. |
| if (currentProducer == producerRef.get()) { |
| info("Closing producer for system %s." format systemName) |
| try { |
| // send()s can get ProducerClosedException if the producer is stopped after they get the currentProducer |
| // reference but before producer.send() returns. That's ONLY ok when dropProducerExceptions is true. |
| // Also, when producer.close(0) is invoked on the Kafka IO thread, when it returns there will be no more |
| // messages sent over the wire. This is key to ensuring no out-of-order messages as a result of recreating |
| // the producer. |
| currentProducer.close(0, TimeUnit.MILLISECONDS) |
| } catch { |
| case exception: Exception => error("Exception while closing producer.", exception) |
| } |
| producerRef.compareAndSet(currentProducer, null) |
| } |
| } else { |
| // If there is an exception in the callback, it means that the Kafka producer has exhausted the max-retries |
| // Close producer to ensure messages queued in-flight are not sent and hence, avoid re-ordering |
| // This works because there is only 1 IO thread and no IO can be done until the callback returns. |
| // Do not create a new producer here! It cannot be done without data loss for all concurrency modes. |
| fatalException.compareAndSet(null, producerException) |
| try { |
| currentProducer.close(0, TimeUnit.MILLISECONDS) |
| } catch { |
| case exception: Exception => error("Exception while closing producer.", exception) |
| } |
| } |
| } |
| |
| /** |
| * @return the current producer. Never returns null. |
| */ |
| private def getOrCreateCurrentProducer = { |
| var currentProducer = producerRef.get |
| |
| if (currentProducer == null) { |
| if (dropProducerExceptions && !stopped) { |
| // Note: While this lock prevents others from creating a new producer, they could still set it to null. |
| producerCreationLock.synchronized { |
| currentProducer = producerRef.get |
| if (currentProducer == null) { |
| currentProducer = getProducer() |
| producerRef.set(currentProducer) |
| } |
| } |
| // Invariant: currentProducer must not be null at this point. |
| } else { |
| throw new SystemProducerException("Kafka producer is null.") |
| } |
| } |
| currentProducer |
| } |
| } |
