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https://issues.apache.org/jira/browse/FLINK-9311?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16688022#comment-16688022
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ASF GitHub Bot commented on FLINK-9311:
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zentol commented on a change in pull request #6594: [FLINK-9311] [pubsub] Added
PubSub source connector with support for checkpointing (ATLEAST_ONCE)
URL: https://github.com/apache/flink/pull/6594#discussion_r233826562
##########
File path:
flink-connectors/flink-connector-pubsub/src/main/java/org/apache/flink/streaming/connectors/pubsub/PubSubSource.java
##########
@@ -0,0 +1,315 @@
+/*
+ * 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.flink.streaming.connectors.pubsub;
+
+import org.apache.flink.api.common.functions.RuntimeContext;
+import org.apache.flink.api.common.functions.StoppableFunction;
+import org.apache.flink.api.common.serialization.DeserializationSchema;
+import org.apache.flink.api.common.typeinfo.TypeInformation;
+import org.apache.flink.api.java.tuple.Tuple2;
+import org.apache.flink.api.java.typeutils.ResultTypeQueryable;
+import org.apache.flink.configuration.Configuration;
+import
org.apache.flink.streaming.api.functions.source.MultipleIdsMessageAcknowledgingSourceBase;
+import org.apache.flink.streaming.api.functions.source.ParallelSourceFunction;
+import org.apache.flink.streaming.api.operators.StreamingRuntimeContext;
+import
org.apache.flink.streaming.connectors.pubsub.common.PubSubSubscriberFactory;
+import
org.apache.flink.streaming.connectors.pubsub.common.SerializableCredentialsProvider;
+
+import com.google.api.gax.core.CredentialsProvider;
+import com.google.auth.Credentials;
+import com.google.cloud.pubsub.v1.AckReplyConsumer;
+import com.google.cloud.pubsub.v1.Subscriber;
+import com.google.pubsub.v1.ProjectSubscriptionName;
+import com.google.pubsub.v1.PubsubMessage;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.io.IOException;
+import java.util.List;
+import java.util.Optional;
+
+/**
+ * PubSub Source, this Source will consume PubSub messages from a subscription
and Acknowledge them as soon as they have been received.
+ */
+public class PubSubSource<OUT> extends
MultipleIdsMessageAcknowledgingSourceBase<OUT, String, AckReplyConsumer>
+ implements ResultTypeQueryable<OUT>,
ParallelSourceFunction<OUT>, StoppableFunction {
+ private static final Logger LOG =
LoggerFactory.getLogger(PubSubSource.class);
+ protected DeserializationSchema<OUT> deserializationSchema;
+ protected SubscriberWrapper subscriberWrapper;
+
+ protected boolean running = true;
+ protected transient volatile SourceContext<OUT> sourceContext = null;
+
+ protected PubSubSource() {
+ super(String.class);
+ }
+
+ protected void setDeserializationSchema(DeserializationSchema<OUT>
deserializationSchema) {
+ this.deserializationSchema = deserializationSchema;
+ }
+
+ protected void setSubscriberWrapper(SubscriberWrapper
subscriberWrapper) {
+ this.subscriberWrapper = subscriberWrapper;
+ }
+
+ @Override
+ public void open(Configuration configuration) throws Exception {
+ super.open(configuration);
+ subscriberWrapper.initialize();
+ if (hasNoCheckpointingEnabled(getRuntimeContext())) {
+ throw new IllegalArgumentException("The PubSubSource
REQUIRES Checkpointing to be enabled and " +
+ "the checkpointing frequency must be MUCH lower
than the PubSub timeout for it to retry a message.");
+ }
+
+
getRuntimeContext().getMetricGroup().gauge("PubSubMessagesProcessedNotAcked",
this::getOutstandingMessagesToAck);
+
getRuntimeContext().getMetricGroup().gauge("PubSubMessagesReceivedNotProcessed",
subscriberWrapper::amountOfMessagesInBuffer);
+ }
+
+ private boolean hasNoCheckpointingEnabled(RuntimeContext
runtimeContext) {
+ return !(runtimeContext instanceof StreamingRuntimeContext &&
((StreamingRuntimeContext) runtimeContext).isCheckpointingEnabled());
+ }
+
+ @Override
+ protected void acknowledgeSessionIDs(List<AckReplyConsumer>
ackReplyConsumers) {
+ ackReplyConsumers.forEach(AckReplyConsumer::ack);
+ }
+
+ @Override
+ public void run(SourceContext<OUT> sourceContext) throws Exception {
+ this.sourceContext = sourceContext;
+ subscriberWrapper.start();
+
+ while (subscriberWrapper.isRunning()) {
+ try {
+ Optional.ofNullable(subscriberWrapper.take())
+
.ifPresent(this::processMessage);
+ } catch (InterruptedException e) {
+ LOG.debug("Interrupted - stop or cancel
called?");
+ }
+ }
+
+ nackOutstandingMessages();
+
+ LOG.debug("Waiting for PubSubSubscriber to terminate.");
+ subscriberWrapper.awaitTerminated();
+ }
+
+ void processMessage(Tuple2<PubsubMessage, AckReplyConsumer> input) {
+ PubsubMessage message = input.f0;
+ AckReplyConsumer ackReplyConsumer = input.f1;
+ if (sourceContext == null) {
+ ackReplyConsumer.nack();
+ return;
+ }
+
+ synchronized (sourceContext.getCheckpointLock()) {
+ boolean alreadyProcessed =
!addId(message.getMessageId());
+ if (alreadyProcessed) {
+ return;
+ }
+
+ sessionIds.add(ackReplyConsumer);
+ sourceContext.collect(deserializeMessage(message));
+ }
+ }
+
+ private Integer getOutstandingMessagesToAck() {
+ return this.sessionIdsPerSnapshot
+ .stream()
+ .mapToInt(tuple -> tuple.f1.size())
+ .sum() + this.sessionIds.size();
+ }
+
+ private void nackOutstandingMessages() {
+ LOG.debug("Going to nack {} processed but not checkpointed
pubsub messages.", getOutstandingMessagesToAck());
+ this.sessionIdsPerSnapshot.stream()
+
.flatMap(tuple -> tuple.f1.stream())
+
.forEach(AckReplyConsumer::nack);
+ this.sessionIds.forEach(AckReplyConsumer::nack);
+ LOG.debug("Finished nacking pubsub messages.");
+ }
+
+ @Override
+ public void cancel() {
+ sourceContext = null;
+ subscriberWrapper.stop();
+ running = false;
+ }
+
+ @Override
+ public void stop() {
+ subscriberWrapper.stop();
+ running = false;
+ }
+
+ private OUT deserializeMessage(PubsubMessage message) {
+ try {
+ return
deserializationSchema.deserialize(message.getData().toByteArray());
+ } catch (IOException e) {
+ throw new RuntimeException(e);
+ }
+ }
+
+ @Override
+ public TypeInformation<OUT> getProducedType() {
+ return deserializationSchema.getProducedType();
+ }
+
+ public static <OUT> PubSubSourceBuilder<OUT, ? extends
PubSubSource<OUT>, ? extends PubSubSourceBuilder<OUT, ?, ?>> newBuilder() {
+ return new PubSubSourceBuilder<>(new PubSubSource<>());
+ }
+
+ /**
+ * Builder to create PubSubSource.
+ *
+ * @param <OUT> The type of objects which will be read
+ * @param <PSS> The type of PubSubSource
+ * @param <BUILDER> The type of Builder to create the PubSubSource
+ */
+ @SuppressWarnings("unchecked")
+ public static class PubSubSourceBuilder<OUT, PSS extends
PubSubSource<OUT>, BUILDER extends PubSubSourceBuilder<OUT, PSS, BUILDER>> {
+ protected PSS sourceUnderConstruction;
+
+ private PubSubSubscriberFactory pubSubSubscriberFactory;
+ private SerializableCredentialsProvider
serializableCredentialsProvider;
+ private DeserializationSchema<OUT> deserializationSchema;
+ private String projectName;
+ private String subscriptionName;
+ private String hostAndPort;
+
+ protected PubSubSourceBuilder(PSS sourceUnderConstruction) {
+ this.sourceUnderConstruction = sourceUnderConstruction;
+ }
+
+ /**
+ * Set the credentials.
+ * If this is not used then the credentials are picked up from
the environment variables.
+ *
+ * @param credentials the Credentials needed to connect.
+ * @return The current PubSubSourceBuilder instance
+ */
+ public BUILDER withCredentials(Credentials credentials) {
+ this.serializableCredentialsProvider = new
SerializableCredentialsProvider(credentials);
+ return (BUILDER) this;
+ }
+
+ /**
+ * Set the CredentialsProvider.
+ * If this is not used then the credentials are picked up from
the environment variables.
+ *
+ * @param credentialsProvider the custom
SerializableCredentialsProvider instance.
+ * @return The current PubSubSourceBuilder instance
+ */
+ public BUILDER withCredentialsProvider(CredentialsProvider
credentialsProvider) throws IOException {
+ return
withCredentials(credentialsProvider.getCredentials());
+ }
+
+ /**
+ * Set the credentials to be absent.
+ * This means that no credentials are to be used at all.
+ *
+ * @return The current PubSubSourceBuilder instance
+ */
+ public BUILDER withoutCredentials() {
+ this.serializableCredentialsProvider =
SerializableCredentialsProvider.withoutCredentials();
+ return (BUILDER) this;
+ }
+
+ /**
+ * @param deserializationSchema Instance of a
DeserializationSchema that converts the OUT into a byte[]
+ * @return The current PubSubSourceBuilder instance
+ */
+ public BUILDER
withDeserializationSchema(DeserializationSchema<OUT> deserializationSchema) {
+ this.deserializationSchema = deserializationSchema;
+ return (BUILDER) this;
+ }
+
+ /**
+ * @param projectName The name of the project in
GoogleCloudPlatform
+ * @param subscriptionName The name of the subscription in
PubSub
+ * @return The current PubSubSourceBuilder instance
+ */
+ public BUILDER withProjectSubscriptionName(String projectName,
String subscriptionName) {
+ this.projectName = projectName;
+ this.subscriptionName = subscriptionName;
+ return (BUILDER) this;
+ }
+
+ /**
+ * Set the custom hostname/port combination of PubSub.
+ * The ONLY reason to use this is during tests with the
emulator provided by Google.
+ *
+ * @param hostAndPort The combination of hostname and port to
connect to ("hostname:1234")
+ * @return The current PubSubSourceBuilder instance
+ */
+ public BUILDER withHostAndPort(String hostAndPort) {
+ this.hostAndPort = hostAndPort;
+ return (BUILDER) this;
+ }
+
+ /**
+ * Set a PubSubSubscriberFactory
+ * This allows for custom Subscriber options to be set.
+ * Cannot be used in combination with withHostAndPort().
+ *
+ * @param pubSubSubscriberFactory A factory to create a {@link
Subscriber}
+ * @return The current PubSubSourceBuilder instance
+ */
+ public BUILDER
withPubSubSubscriberFactory(PubSubSubscriberFactory pubSubSubscriberFactory) {
+ this.pubSubSubscriberFactory = pubSubSubscriberFactory;
+ return (BUILDER) this;
+ }
+
+ /**
+ * Actually build the desired instance of the
PubSubSourceBuilder.
+ *
+ * @return a brand new SourceFunction
+ * @throws IOException incase of a problem getting
the credentials
+ * @throws IllegalArgumentException incase required fields were
not specified.
+ */
+ public PSS build() throws IOException {
+ if (serializableCredentialsProvider == null) {
+ serializableCredentialsProvider =
SerializableCredentialsProvider.credentialsProviderFromEnvironmentVariables();
+ }
+ if (deserializationSchema == null) {
+ throw new IllegalArgumentException("The
deserializationSchema has not been specified.");
+ }
+
+ if (pubSubSubscriberFactory != null && hostAndPort !=
null) {
+ throw new
IllegalArgumentException(("withPubSubSubscriberFactory() and withHostAndPort()
both called, only one may be called."));
+ }
+
+ if (projectName == null || subscriptionName == null) {
+ throw new IllegalArgumentException("ProjectName
or SubscriptionName has not been specified.");
+ }
+
+ if (pubSubSubscriberFactory == null) {
+ pubSubSubscriberFactory = new
DefaultPubSubSubscriberFactory();
+ if (hostAndPort != null) {
+ ((DefaultPubSubSubscriberFactory)
pubSubSubscriberFactory).withHostAndPort(hostAndPort);
+ }
+ }
+
+ SubscriberWrapper subscriberWrapper = new
SubscriberWrapper(serializableCredentialsProvider,
ProjectSubscriptionName.of(projectName, subscriptionName),
pubSubSubscriberFactory);
+
sourceUnderConstruction.setSubscriberWrapper(subscriberWrapper);
+
sourceUnderConstruction.setDeserializationSchema(deserializationSchema);
Review comment:
This issue still remains. It's the same issue that existed for the sink
builder.
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us...@infra.apache.org
> PubSub connector
> ----------------
>
> Key: FLINK-9311
> URL: https://issues.apache.org/jira/browse/FLINK-9311
> Project: Flink
> Issue Type: New Feature
> Components: Streaming Connectors
> Reporter: Richard Deurwaarder
> Assignee: Niels Basjes
> Priority: Minor
> Labels: pull-request-available
>
> I would like start adding some google cloud connectors starting with a PubSub
> Source. I have a basic implementation ready but I want it to be able to:
> * easily scale up (should I have it extend RichParallelSourceFunction for
> this?)
> * Make it easier to provide the google cloud credentials. This would require
> being able to send some json string / ServiceAccount to the nodes when
> starting up this source.
> Could this be something that would be useful for others and added to the
> flink connectors repo?
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