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/*
 * Copyright 2016 Google LLC
 *
 * Licensed 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 com.google.cloud.pubsub.v1;

import com.google.api.core.AbstractApiService;
import com.google.api.core.ApiClock;
import com.google.api.core.ApiService;
import com.google.api.core.BetaApi;
import com.google.api.core.CurrentMillisClock;
import com.google.api.core.InternalApi;
import com.google.api.gax.batching.FlowControlSettings;
import com.google.api.gax.batching.FlowController;
import com.google.api.gax.batching.FlowController.LimitExceededBehavior;
import com.google.api.gax.core.BackgroundResource;
import com.google.api.gax.core.CredentialsProvider;
import com.google.api.gax.core.Distribution;
import com.google.api.gax.core.ExecutorAsBackgroundResource;
import com.google.api.gax.core.ExecutorProvider;
import com.google.api.gax.core.InstantiatingExecutorProvider;
import com.google.api.gax.rpc.HeaderProvider;
import com.google.api.gax.rpc.NoHeaderProvider;
import com.google.api.gax.rpc.TransportChannelProvider;
import com.google.auth.oauth2.GoogleCredentials;
import com.google.cloud.pubsub.v1.stub.GrpcSubscriberStub;
import com.google.cloud.pubsub.v1.stub.SubscriberStub;
import com.google.cloud.pubsub.v1.stub.SubscriberStubSettings;
import com.google.common.base.Optional;
import com.google.common.base.Preconditions;
import com.google.common.util.concurrent.ThreadFactoryBuilder;
import com.google.pubsub.v1.ProjectSubscriptionName;
import com.google.pubsub.v1.PubsubMessage;
import io.opentelemetry.api.OpenTelemetry;
import io.opentelemetry.api.trace.Tracer;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.Executors;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.annotation.Nullable;
import org.threeten.bp.Duration;

/**
 * A Cloud Pub/Sub subscriber that is
 * associated with a specific subscription at creation.
 *
 * 

A {@link Subscriber} allows you to provide an implementation of a {@link MessageReceiver * receiver} to which messages are going to be delivered as soon as they are received by the * subscriber. The delivered messages then can be {@link AckReplyConsumer#ack() acked} or {@link * AckReplyConsumer#nack() nacked} at will as they get processed by the receiver. Nacking a messages * implies a later redelivery of such message. * *

The subscriber handles the ack management, by automatically extending the ack deadline while * the message is being processed, to then issue the ack or nack of such message when the processing * is done (see {@link Builder#setMaxAckExtensionPeriod(Duration)}). Note: message * redelivery is still possible. * *

It also provides customizable options that control: * *

    *
  • Ack deadline extension: such as the amount of time ahead to trigger the extension of * message acknowledgement expiration. *
  • Flow control: such as the maximum outstanding messages or maximum outstanding bytes to keep * in memory before the receiver either ack or nack them. *
* *

{@link Subscriber} will use the credentials set on the channel, which uses application default * credentials through {@link GoogleCredentials#getApplicationDefault} by default. * *

{@code Subscriber} is implemented using Guava's * Service and provides the same methods. See Guava documentation for more * details. */ public class Subscriber extends AbstractApiService implements SubscriberInterface { private static final int THREADS_PER_CHANNEL = 5; private static final int MAX_INBOUND_MESSAGE_SIZE = 20 * 1024 * 1024; // 20MB API maximum message size. private static final int MAX_INBOUND_METADATA_SIZE = 4 * 1024 * 1024; // 4MB API maximum metadata size @InternalApi static final Duration DEFAULT_MAX_ACK_EXTENSION_PERIOD = Duration.ofMinutes(60); @InternalApi static final Duration DEFAULT_MIN_ACK_DEADLINE_EXTENSION_EXACTLY_ONCE_DELIVERY = Duration.ofMinutes(1); @InternalApi static final Duration DEFAULT_MIN_ACK_DEADLINE_EXTENSION = Duration.ofMinutes(0); @InternalApi static final Duration DEFAULT_MAX_ACK_DEADLINE_EXTENSION = Duration.ofSeconds(0); @InternalApi static final Duration MIN_STREAM_ACK_DEADLINE = Duration.ofSeconds(10); @InternalApi static final Duration MAX_STREAM_ACK_DEADLINE = Duration.ofSeconds(600); @InternalApi static final Duration STREAM_ACK_DEADLINE_DEFAULT = Duration.ofSeconds(60); @InternalApi static final Duration STREAM_ACK_DEADLINE_EXACTLY_ONCE_DELIVERY_DEFAULT = Duration.ofSeconds(60); @InternalApi static final Duration ACK_EXPIRATION_PADDING_DEFAULT = Duration.ofSeconds(5); private static final Logger logger = Logger.getLogger(Subscriber.class.getName()); private static final String OPEN_TELEMETRY_TRACER_NAME = "com.google.cloud.pubsub.v1"; private final String subscriptionName; private final FlowControlSettings flowControlSettings; private final boolean useLegacyFlowControl; private final Duration maxAckExtensionPeriod; private final Duration maxDurationPerAckExtension; private final boolean maxDurationPerAckExtensionDefaultUsed; private final Duration minDurationPerAckExtension; private final boolean minDurationPerAckExtensionDefaultUsed; // The ExecutorProvider used to generate executors for processing messages. private final ExecutorProvider executorProvider; // An instantiation of the SystemExecutorProvider used for processing acks // and other system actions. @Nullable private final ScheduledExecutorService alarmsExecutor; private final Distribution ackLatencyDistribution = new Distribution(Math.toIntExact(MAX_STREAM_ACK_DEADLINE.getSeconds()) + 1); private SubscriberStub subscriberStub; private final SubscriberStubSettings subStubSettings; private final FlowController flowController; private final int numPullers; private final MessageReceiver receiver; private final MessageReceiverWithAckResponse receiverWithAckResponse; private final List streamingSubscriberConnections; private final ApiClock clock; private final List backgroundResources = new ArrayList<>(); private final boolean enableOpenTelemetryTracing; private final OpenTelemetry openTelemetry; private OpenTelemetryPubsubTracer tracer = new OpenTelemetryPubsubTracer(null, false); private Subscriber(Builder builder) { receiver = builder.receiver; receiverWithAckResponse = builder.receiverWithAckResponse; flowControlSettings = builder.flowControlSettings; useLegacyFlowControl = builder.useLegacyFlowControl; subscriptionName = builder.subscription; maxAckExtensionPeriod = builder.maxAckExtensionPeriod; maxDurationPerAckExtension = builder.maxDurationPerAckExtension; maxDurationPerAckExtensionDefaultUsed = builder.maxDurationPerAckExtensionDefaultUsed; minDurationPerAckExtension = builder.minDurationPerAckExtension; minDurationPerAckExtensionDefaultUsed = builder.minDurationPerAckExtensionDefaultUsed; clock = builder.clock.isPresent() ? builder.clock.get() : CurrentMillisClock.getDefaultClock(); flowController = new FlowController( builder .flowControlSettings .toBuilder() .setLimitExceededBehavior(LimitExceededBehavior.Block) .build()); this.numPullers = builder.parallelPullCount; executorProvider = builder.executorProvider; ExecutorProvider systemExecutorProvider = builder.systemExecutorProvider; alarmsExecutor = systemExecutorProvider.getExecutor(); if (systemExecutorProvider.shouldAutoClose()) { backgroundResources.add(new ExecutorAsBackgroundResource((alarmsExecutor))); } TransportChannelProvider channelProvider = builder.channelProvider; if (channelProvider.acceptsPoolSize()) { channelProvider = channelProvider.withPoolSize(numPullers); } try { this.subStubSettings = SubscriberStubSettings.newBuilder() .setExecutorProvider(systemExecutorProvider) .setCredentialsProvider(builder.credentialsProvider) .setTransportChannelProvider(channelProvider) .setHeaderProvider(builder.headerProvider) .setEndpoint(builder.endpoint) .setUniverseDomain(builder.universeDomain) .build(); // TODO(pongad): what about internal header?? } catch (Exception e) { throw new IllegalStateException(e); } this.enableOpenTelemetryTracing = builder.enableOpenTelemetryTracing; this.openTelemetry = builder.openTelemetry; if (this.openTelemetry != null && this.enableOpenTelemetryTracing) { Tracer openTelemetryTracer = builder.openTelemetry.getTracer(OPEN_TELEMETRY_TRACER_NAME); if (openTelemetryTracer != null) { this.tracer = new OpenTelemetryPubsubTracer(openTelemetryTracer, this.enableOpenTelemetryTracing); } } streamingSubscriberConnections = new ArrayList(numPullers); // We regularly look up the distribution for a good subscription deadline. // So we seed the distribution with the minimum value to start with. // Distribution is percentile-based, so this value will eventually lose importance. ackLatencyDistribution.record(Math.toIntExact(MIN_STREAM_ACK_DEADLINE.getSeconds())); } /** * Constructs a new {@link Builder}. * * @param subscription Cloud Pub/Sub subscription to bind the subscriber to * @param receiver an implementation of {@link MessageReceiver} used to process the received * messages */ public static Builder newBuilder(ProjectSubscriptionName subscription, MessageReceiver receiver) { return newBuilder(subscription.toString(), receiver); } public static Builder newBuilder( ProjectSubscriptionName subscription, MessageReceiverWithAckResponse receiver) { return newBuilder(subscription.toString(), receiver); } /** * Constructs a new {@link Builder}. * * @param subscription Cloud Pub/Sub subscription to bind the subscriber to * @param receiver an implementation of {@link MessageReceiver} used to process the received * messages */ public static Builder newBuilder(String subscription, MessageReceiver receiver) { return new Builder(subscription, receiver); } public static Builder newBuilder(String subscription, MessageReceiverWithAckResponse receiver) { return new Builder(subscription, receiver); } /** Returns the delivery attempt count for a received {@link PubsubMessage} */ public static Integer getDeliveryAttempt(PubsubMessage message) { if (!message.containsAttributes("googclient_deliveryattempt")) { return null; } return Integer.parseInt(message.getAttributesOrThrow("googclient_deliveryattempt")); } /** Subscription which the subscriber is subscribed to. */ public String getSubscriptionNameString() { return subscriptionName; } /** The flow control settings the Subscriber is configured with. */ public FlowControlSettings getFlowControlSettings() { return flowControlSettings; } /** * Initiates service startup and returns immediately. * *

Example of receiving a specific number of messages. * *

{@code
   * Subscriber subscriber = Subscriber.newBuilder(subscription, receiver).build();
   * subscriber.addListener(new Subscriber.Listener() {
   *   public void failed(Subscriber.State from, Throwable failure) {
   *     // Handle error.
   *   }
   * }, executor);
   * subscriber.startAsync();
   *
   * // Wait for a stop signal.
   * // In a server, this might be a signal to stop serving.
   * // In this example, the signal is just a dummy Future.
   * //
   * // By default, Subscriber uses daemon threads (see
   * // https://docs.oracle.com/javase/7/docs/api/java/lang/Thread.html).
   * // Consequently, once other threads have terminated, Subscriber will not stop the JVM from
   * // exiting.
   * // If the Subscriber should simply run forever, either use the setExecutorProvider method in
   * // Subscriber.Builder
   * // to use non-daemon threads or run
   * //   for (;;) {
   * //     Thread.sleep(Long.MAX_VALUE);
   * //   }
   * // at the end of main() to previent the main thread from exiting.
   * done.get();
   * subscriber.stopAsync().awaitTerminated();
   * }
*/ @Override public ApiService startAsync() { // Override only for the docs. return super.startAsync(); } @Override protected void doStart() { logger.log(Level.FINE, "Starting subscriber group."); try { this.subscriberStub = GrpcSubscriberStub.create(subStubSettings); } catch (IOException e) { // doesn't matter what we throw, the Service will just catch it and fail to start. throw new IllegalStateException(e); } // When started, connections submit tasks to the executor. // These tasks must finish before the connections can declare themselves running. // If we have a single-thread executor and call startStreamingConnections from the // same executor, it will deadlock: the thread will be stuck waiting for connections // to start but cannot start the connections. // For this reason, we spawn a dedicated thread. Starting subscriber should be rare. new Thread( new Runnable() { @Override public void run() { try { startStreamingConnections(); notifyStarted(); } catch (Throwable t) { notifyFailed(t); } } }) .start(); } @Override protected void doStop() { new Thread( new Runnable() { @Override public void run() { try { // stop connection is no-op if connections haven't been started. runShutdown(); notifyStopped(); } catch (Exception e) { notifyFailed(e); } } }) .start(); } private void runShutdown() { stopAllStreamingConnections(); shutdownBackgroundResources(); subscriberStub.shutdownNow(); } private void startStreamingConnections() { synchronized (streamingSubscriberConnections) { for (int i = 0; i < numPullers; i++) { final ScheduledExecutorService executor = executorProvider.getExecutor(); if (executorProvider.shouldAutoClose()) { backgroundResources.add(new ExecutorAsBackgroundResource((executor))); } StreamingSubscriberConnection.Builder streamingSubscriberConnectionBuilder; if (receiverWithAckResponse != null) { streamingSubscriberConnectionBuilder = StreamingSubscriberConnection.newBuilder(receiverWithAckResponse); } else { streamingSubscriberConnectionBuilder = StreamingSubscriberConnection.newBuilder(receiver); } StreamingSubscriberConnection streamingSubscriberConnection = streamingSubscriberConnectionBuilder .setSubscription(subscriptionName) .setAckExpirationPadding(ACK_EXPIRATION_PADDING_DEFAULT) .setMaxAckExtensionPeriod(maxAckExtensionPeriod) .setMinDurationPerAckExtension(minDurationPerAckExtension) .setMinDurationPerAckExtensionDefaultUsed(minDurationPerAckExtensionDefaultUsed) .setMaxDurationPerAckExtension(maxDurationPerAckExtension) .setMaxDurationPerAckExtensionDefaultUsed(maxDurationPerAckExtensionDefaultUsed) .setAckLatencyDistribution(ackLatencyDistribution) .setSubscriberStub(subscriberStub) .setChannelAffinity(i) .setFlowControlSettings(flowControlSettings) .setFlowController(flowController) .setUseLegacyFlowControl(useLegacyFlowControl) .setExecutor(executor) .setSystemExecutor(alarmsExecutor) .setClock(clock) .setEnableOpenTelemetryTracing(enableOpenTelemetryTracing) .setTracer(tracer) .build(); streamingSubscriberConnections.add(streamingSubscriberConnection); } startConnections( streamingSubscriberConnections, new Listener() { @Override public void failed(State from, Throwable failure) { // If a connection failed is because of a fatal error, we should fail the // whole subscriber. runShutdown(); try { notifyFailed(failure); } catch (IllegalStateException e) { if (isRunning()) { throw e; } // It could happen that we are shutting down while some channels fail. } } }); } } private void stopAllStreamingConnections() { stopConnections(streamingSubscriberConnections); } private void shutdownBackgroundResources() { for (BackgroundResource resource : backgroundResources) { resource.shutdown(); } } private void startConnections( List connections, final ApiService.Listener connectionsListener) { for (ApiService subscriber : connections) { subscriber.addListener(connectionsListener, alarmsExecutor); subscriber.startAsync(); } for (ApiService subscriber : connections) { subscriber.awaitRunning(); } } private void stopConnections(List connections) { ArrayList liveConnections; synchronized (connections) { liveConnections = new ArrayList(connections); connections.clear(); } for (ApiService subscriber : liveConnections) { subscriber.stopAsync(); } for (ApiService subscriber : liveConnections) { try { subscriber.awaitTerminated(); } catch (IllegalStateException e) { // If the service fails, awaitTerminated will throw an exception. // However, we could be stopping services because at least one // has already failed, so we just ignore this exception. } } } /** Builder of {@link Subscriber Subscribers}. */ public static final class Builder { static final FlowControlSettings DEFAULT_FLOW_CONTROL_SETTINGS = FlowControlSettings.newBuilder() .setMaxOutstandingElementCount(1000L) .setMaxOutstandingRequestBytes(100L * 1024L * 1024L) // 100MB .build(); private static final ExecutorProvider DEFAULT_EXECUTOR_PROVIDER = InstantiatingExecutorProvider.newBuilder() .setExecutorThreadCount(THREADS_PER_CHANNEL) .build(); private static final AtomicInteger SYSTEM_EXECUTOR_COUNTER = new AtomicInteger(); private String subscription; private MessageReceiver receiver; private MessageReceiverWithAckResponse receiverWithAckResponse; private Duration maxAckExtensionPeriod = DEFAULT_MAX_ACK_EXTENSION_PERIOD; private Duration minDurationPerAckExtension = DEFAULT_MIN_ACK_DEADLINE_EXTENSION; private boolean minDurationPerAckExtensionDefaultUsed = true; private Duration maxDurationPerAckExtension = DEFAULT_MAX_ACK_DEADLINE_EXTENSION; private boolean maxDurationPerAckExtensionDefaultUsed = true; private boolean useLegacyFlowControl = false; private FlowControlSettings flowControlSettings = DEFAULT_FLOW_CONTROL_SETTINGS; private ExecutorProvider executorProvider = DEFAULT_EXECUTOR_PROVIDER; private ExecutorProvider systemExecutorProvider = null; private TransportChannelProvider channelProvider = SubscriptionAdminSettings.defaultGrpcTransportProviderBuilder() .setMaxInboundMessageSize(MAX_INBOUND_MESSAGE_SIZE) .setMaxInboundMetadataSize(MAX_INBOUND_METADATA_SIZE) .setKeepAliveTime(Duration.ofMinutes(5)) .build(); private HeaderProvider headerProvider = new NoHeaderProvider(); private CredentialsProvider credentialsProvider = SubscriptionAdminSettings.defaultCredentialsProviderBuilder().build(); private Optional clock = Optional.absent(); private int parallelPullCount = 1; private String endpoint = null; private String universeDomain = null; private boolean enableOpenTelemetryTracing = false; private OpenTelemetry openTelemetry = null; Builder(String subscription, MessageReceiver receiver) { this.subscription = subscription; this.receiver = receiver; } Builder(String subscription, MessageReceiverWithAckResponse receiverWithAckResponse) { this.subscription = subscription; this.receiverWithAckResponse = receiverWithAckResponse; } /** * {@code ChannelProvider} to use to create Channels, which must point at Cloud Pub/Sub * endpoint. * *

For performance, this client benefits from having multiple channels open at once. Users * are encouraged to provide instances of {@code ChannelProvider} that creates new channels * instead of returning pre-initialized ones. */ public Builder setChannelProvider(TransportChannelProvider channelProvider) { this.channelProvider = Preconditions.checkNotNull(channelProvider); return this; } /** * Sets the static header provider. The header provider will be called during client * construction only once. The headers returned by the provider will be cached and supplied as * is for each request issued by the constructed client. Some reserved headers can be overridden * (e.g. Content-Type) or merged with the default value (e.g. User-Agent) by the underlying * transport layer. * * @param headerProvider the header provider * @return the builder */ @BetaApi public Builder setHeaderProvider(HeaderProvider headerProvider) { this.headerProvider = Preconditions.checkNotNull(headerProvider); return this; } /** * Sets the flow control settings. * *

In the example below, the {@link Subscriber} will make sure that * *

    *
  • there are at most ten thousand outstanding messages, and *
  • the combined size of outstanding messages does not exceed 1GB. *
* * "Outstanding messages" here means the messages that have already been given to {@link * MessageReceiver} but not yet {@code acked()} or {@code nacked()}. * *
{@code
     * FlowControlSettings flowControlSettings =
     *  FlowControlSettings.newBuilder()
     *      .setMaxOutstandingElementCount(10_000L)
     *      .setMaxOutstandingRequestBytes(1_000_000_000L)
     *      .build();
     * Subscriber subscriber =
     *     Subscriber.newBuilder(subscriptionName, receiver)
     *         .setFlowControlSettings(flowControlSettings)
     *         .build();
     * }
*/ public Builder setFlowControlSettings(FlowControlSettings flowControlSettings) { this.flowControlSettings = Preconditions.checkNotNull(flowControlSettings); return this; } /** * Disables enforcing flow control settings at the Cloud PubSub server and uses the less * accurate method of only enforcing flow control at the client side. */ public Builder setUseLegacyFlowControl(boolean value) { this.useLegacyFlowControl = value; return this; } /** * Set the maximum period a message ack deadline will be extended. Defaults to one hour. * *

It is recommended to set this value to a reasonable upper bound of the subscriber time to * process any message. This maximum period avoids messages to be locked by a subscriber * in cases when the ack reply is lost. * *

A zero duration effectively disables auto deadline extensions. */ public Builder setMaxAckExtensionPeriod(Duration maxAckExtensionPeriod) { Preconditions.checkArgument(maxAckExtensionPeriod.toMillis() >= 0); this.maxAckExtensionPeriod = maxAckExtensionPeriod; return this; } /** * Set the upper bound for a single mod ack extention period. * *

The ack deadline will continue to be extended by up to this duration until * MaxAckExtensionPeriod is reached. Setting MaxDurationPerAckExtension bounds the maximum * amount of time before a mesage re-delivery in the event the Subscriber fails to extend the * deadline. * *

MaxDurationPerAckExtension configuration can be disabled by specifying a zero duration. */ public Builder setMaxDurationPerAckExtension(Duration maxDurationPerAckExtension) { // If a non-default min is set, make sure min is less than max Preconditions.checkArgument( maxDurationPerAckExtension.toMillis() >= 0 && (this.minDurationPerAckExtensionDefaultUsed || (this.minDurationPerAckExtension.toMillis() < maxDurationPerAckExtension.toMillis()))); this.maxDurationPerAckExtension = maxDurationPerAckExtension; this.maxDurationPerAckExtensionDefaultUsed = false; return this; } /** * Set the lower bound for a single mod ack extention period. * *

The ack deadline will continue to be extended by up to this duration until * MinAckExtensionPeriod is reached. Setting MinDurationPerAckExtension bounds the minimum * amount of time before a mesage re-delivery in the event the Subscriber fails to extend the * deadline. * *

MinDurationPerAckExtension configuration can be disabled by specifying a zero duration. */ public Builder setMinDurationPerAckExtension(Duration minDurationPerAckExtension) { // If a non-default max is set, make sure min is less than max Preconditions.checkArgument( minDurationPerAckExtension.toMillis() >= 0 && (this.maxDurationPerAckExtensionDefaultUsed || (minDurationPerAckExtension.toMillis() < this.maxDurationPerAckExtension.toMillis()))); this.minDurationPerAckExtension = minDurationPerAckExtension; this.minDurationPerAckExtensionDefaultUsed = false; return this; } /** * Gives the ability to set a custom executor. {@link ExecutorProvider#getExecutor()} will be * called {@link Builder#parallelPullCount} times. */ public Builder setExecutorProvider(ExecutorProvider executorProvider) { this.executorProvider = Preconditions.checkNotNull(executorProvider); return this; } /** {@code CredentialsProvider} to use to create Credentials to authenticate calls. */ public Builder setCredentialsProvider(CredentialsProvider credentialsProvider) { this.credentialsProvider = Preconditions.checkNotNull(credentialsProvider); return this; } /** * Gives the ability to set a custom executor for managing lease extensions. If none is provided * a shared one will be used by all {@link Subscriber} instances. */ public Builder setSystemExecutorProvider(ExecutorProvider executorProvider) { this.systemExecutorProvider = Preconditions.checkNotNull(executorProvider); return this; } /** * Sets the number of StreamingPull streams to pull messages from the subscription. Defaults to * one. */ public Builder setParallelPullCount(int parallelPullCount) { this.parallelPullCount = parallelPullCount; return this; } /** Gives the ability to override the gRPC endpoint. */ public Builder setEndpoint(String endpoint) { this.endpoint = endpoint; return this; } /** Gives the ability to override the universe domain. */ public Builder setUniverseDomain(String universeDomain) { this.universeDomain = universeDomain; return this; } /** Gives the ability to set a custom clock. */ Builder setClock(ApiClock clock) { this.clock = Optional.of(clock); return this; } /** * OpenTelemetry will be enabled if setEnableOpenTelemetry is true and and instance of * OpenTelemetry has been provied. Warning: traces are subject to change. The name and * attributes of a span might change without notice. Only use run traces interactively. Don't * use in automation. Running non-interactive traces can cause problems if the underlying trace * architecture changes without notice. */ /** Gives the ability to enable Open Telemetry Tracing */ public Builder setEnableOpenTelemetryTracing(boolean enableOpenTelemetryTracing) { this.enableOpenTelemetryTracing = enableOpenTelemetryTracing; return this; } /** Sets the instance of OpenTelemetry for the Publisher class. */ public Builder setOpenTelemetry(OpenTelemetry openTelemetry) { this.openTelemetry = openTelemetry; return this; } /** Returns the default FlowControlSettings used by the client if settings are not provided. */ public static FlowControlSettings getDefaultFlowControlSettings() { return DEFAULT_FLOW_CONTROL_SETTINGS; } public Subscriber build() { if (systemExecutorProvider == null) { ThreadFactory threadFactory = new ThreadFactoryBuilder() .setDaemon(true) .setNameFormat("Subscriber-SE-" + SYSTEM_EXECUTOR_COUNTER.incrementAndGet() + "-%d") .build(); int threadCount = Math.max(6, 2 * parallelPullCount); final ScheduledExecutorService executor = Executors.newScheduledThreadPool(threadCount, threadFactory); systemExecutorProvider = new ExecutorProvider() { @Override public boolean shouldAutoClose() { return true; } @Override public ScheduledExecutorService getExecutor() { return executor; } }; } return new Subscriber(this); } } }





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