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Enabling Long Polling for Amazon SQS Message Queues

Amazon SQS uses short polling by default, querying only a subset of the servers—based on a weighted random distribution—to determine whether any messages are available for inclusion in the response.

Long polling helps reduce your cost of using Amazon SQS by reducing the number of empty responses when there are no messages available to return in reply to a ReceiveMessage request sent to an Amazon SQS queue and eliminating false empty responses. You can set a long polling frequency from 1–20 seconds.

Prerequisites

Before you begin, we recommend you read Getting started using the Amazon SDK for C++.

Download the example code and build the solution as described in Get started on code examples.

To run the examples, the user profile your code uses to make the requests must have proper permissions in Amazon (for the service and the action). For more information, see Providing Amazon credentials.

Enable Long Polling when Creating a Queue

To enable long polling when creating an Amazon SQS queue, set the ReceiveMessageWaitTimeSeconds attribute on the CreateQueueRequest object before calling the SQSClient class’ CreateQueue member function.

Includes

#include <aws/core/Aws.h>
#include <aws/sqs/SQSClient.h>
#include <aws/sqs/model/CreateQueueRequest.h>
#include <iostream>

Code

    Aws::SQS::SQSClient sqsClient(clientConfiguration);

    Aws::SQS::Model::CreateQueueRequest request;
    request.SetQueueName(queueName);
    request.AddAttributes(
            Aws::SQS::Model::QueueAttributeName::ReceiveMessageWaitTimeSeconds,
            pollTimeSeconds);

    const Aws::SQS::Model::CreateQueueOutcome outcome = sqsClient.CreateQueue(request);
    if (outcome.IsSuccess()) {
        std::cout << "Successfully created queue " << queueName <<
                  std::endl;
    }
    else {
        std::cout << "Error creating queue " << queueName << ": " <<
                  outcome.GetError().GetMessage() << std::endl;
    }

See the complete example.

Enable Long Polling on an Existing Queue

In addition to enabling long polling when creating a queue, you can also enable it on an existing queue by setting ReceiveMessageWaitTimeSeconds on the SetQueueAttributesRequest before calling the SQSClient class’ SetQueueAttributes member function.

Includes

#include <aws/core/Aws.h>
#include <aws/sqs/SQSClient.h>
#include <aws/sqs/model/SetQueueAttributesRequest.h>
#include <iostream>

Code

    Aws::SQS::SQSClient sqsClient(clientConfiguration);

    Aws::SQS::Model::SetQueueAttributesRequest request;
    request.SetQueueUrl(queueURL);
    request.AddAttributes(
            Aws::SQS::Model::QueueAttributeName::ReceiveMessageWaitTimeSeconds,
            pollTimeSeconds);

    const Aws::SQS::Model::SetQueueAttributesOutcome outcome = sqsClient.SetQueueAttributes(
            request);
    if (outcome.IsSuccess()) {
        std::cout << "Successfully updated long polling time for queue " <<
                  queueURL << " to " << pollTimeSeconds << std::endl;
    }
    else {
        std::cout << "Error updating long polling time for queue " <<
                  queueURL << ": " << outcome.GetError().GetMessage() <<
                  std::endl;
    }

See the complete example.

Enable Long Polling on Message Receipt

You can enable long polling when receiving a message by setting the wait time in seconds on the ReceiveMessageRequest that you supply to the SQSClient class’ ReceiveMessage member function.

Includes

#include <aws/core/Aws.h>
#include <aws/sqs/SQSClient.h>
#include <aws/sqs/model/ReceiveMessageRequest.h>

Code

    Aws::SQS::SQSClient sqsClient(customConfiguration);

    Aws::SQS::Model::ReceiveMessageRequest request;
    request.SetQueueUrl(queueUrl);
    request.SetMaxNumberOfMessages(1);
    request.SetWaitTimeSeconds(waitTimeSeconds);

    auto outcome = sqsClient.ReceiveMessage(request);
    if (outcome.IsSuccess()) {
        const auto &messages = outcome.GetResult().GetMessages();
        if (messages.empty()) {
            std::cout << "No messages received from queue " << queueUrl <<
                      std::endl;
        }
        else {
            const auto &message = messages[0];
            std::cout << "Received message:" << std::endl;
            std::cout << "  MessageId: " << message.GetMessageId() << std::endl;
            std::cout << "  ReceiptHandle: " << message.GetReceiptHandle() << std::endl;
            std::cout << "  Body: " << message.GetBody() << std::endl << std::endl;
        }
    }
    else {
        std::cout << "Error receiving message from queue " << queueUrl << ": "
                  << outcome.GetError().GetMessage() << std::endl;
    }

See the complete example.

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