QueueBufferConfig.java

/*
 * Copyright 2012-2024 Amazon.com, Inc. or its affiliates. All Rights Reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License").
 * You may not use this file except in compliance with the License.
 * A copy of the License is located at
 *
 *  http://aws.amazon.com/apache2.0
 *
 * or in the "license" file accompanying this file. This file 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.amazonaws.services.sqs.buffered;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import com.amazonaws.AmazonClientException;
import com.amazonaws.handlers.AsyncHandler;
import com.amazonaws.services.sqs.model.DeleteMessageRequest;
import com.amazonaws.services.sqs.model.DeleteMessageResult;

public class QueueBufferConfig {

    public static final int MAX_BATCH_SIZE_DEFAULT = 10;

    /** the maximum number of entries in a batch command */
    private int maxBatchSize;

    /** Updated as the service now supports messages of size max 256 KiB. */
    public static final long SERVICE_MAX_BATCH_SIZE_BYTES = 256 * 1024;

    /**
     * The maximum time (milliseconds) a send batch is held open for additional outbound requests.
     * The longer this timeout, the longer messages wait for other messages to be added to the
     * batch. Increasing this timeout reduces the number of calls made and increases throughput, but
     * also increases average message latency.
     */
    private long maxBatchOpenMs;

    /** 200 milliseconds */
    public static final long MAX_BATCH_OPEN_MS_DEFAULT = 200;

    /**
     * If true, even synchronous calls to delete messages will be made using background
     * asynchronous batches. The client will return results indicating that the messages were deleted successfully
     * even if the background calls eventually fail; the actual errors will be logged instead.
     * This can be beneficial for decreasing message acknowledgement latency at the cost of potential
     * duplicate messages (which can be produced by SQS itself anyway).
     */
    private boolean deleteInBackground = false;

    /**
     * Should we use long polling or not?
     */
    private boolean longPoll;

    /** true */
    private static final boolean LONG_POLL_DEFAULT = true;

    /**
     * The maximum number of concurrent batches for each type of outbound request. The greater the
     * number, the greater the throughput that can be achieved (at the expense of consuming more
     * threads).
     */
    private int maxInflightOutboundBatches;

    /** 5 batches */
    public static final int MAX_INFLIGHT_OUTBOUND_BATCHES_DEFAULT = 5;

    /**
     * The maximum number of concurrent receive message batches. The greater this number, the faster
     * the queue will be pulling messages from the SQS servers (at the expense of consuming more
     * threads).
     */
    private int maxInflightReceiveBatches;

    /** 10 batches */
    public static final int MAX_INFLIGHT_RECEIVE_BATCHES_DEFAULT = 10;

    /**
     * If more than that number of completed receive batches are waiting in the buffer, the querying
     * for new messages will stop. The larger this number, the more messages the buffer queue will
     * pre-fetch and keep in the buffer on the client side, and the faster receive requests will be
     * satisfied. The visibility timeout of a pre-fetched message starts at the point of pre-fetch,
     * which means that while the message is in the local buffer it is unavailable for other clients
     * to process, and when this client retrieves it, part of the visibility timeout may have
     * already expired. The number of messages prefetched will not exceed maxBatchSize *
     * maxDoneReceiveBatches.
     */
    private int maxDoneReceiveBatches;

    /** 10 batches */
    public static final int MAX_DONE_RECEIVE_BATCHES_DEFAULT = 10;

    /**
     * Maximum permitted size of a SendMessage or SendMessageBatch message, in bytes
     */
    private long maxBatchSizeBytes;

    /** 256 kilobytes */
    public static final long MAX_BATCH_SIZE_BYTES_DEFAULT = SERVICE_MAX_BATCH_SIZE_BYTES;

    /**
     * Custom visibility timeout to use when retrieving messages from SQS. If set to a value greater
     * than zero, this timeout will override the default visibility timeout set on the SQS queue.
     * Set it to -1 to use the default visiblity timeout of the queue. Visibility timeout of 0
     * seconds is not supported.
     */
    private int visibilityTimeoutSeconds;

    /** -1, which means use the visibility timeout of the queue */
    public static final int VISIBILITY_TIMEOUT_SECONDS_DEFAULT = -1;

    /**
     * Specifies the amount of time, in seconds, the receive call will block on the server waiting
     * for messages to arrive if the queue is empty when the receive call is first made. This
     * setting has no effect if long polling is disabled.
     */
    private int longPollWaitTimeoutSeconds;

    public static final int LONGPOLL_WAIT_TIMEOUT_SECONDS_DEFAULT = 20;

    /**
     * Configures the minimum wait time for incoming receive message requests. Without a non-zero
     * minimum wait time, threads can easily waste CPU time busy-waiting against empty local buffers.
     * Avoid setting this to 0 unless you are confident threads will do useful work in-between
     * each call to receive messages!
     * <p></p>
     * This will be applied to both requests that explicitly set WaitTimeSeconds and
     * those that inherit the ReceiveMessageWaitTimeSeconds queue attribute.
     */
    private int minReceiveWaitTimeMs = MIN_RECEIVE_WAIT_TIME_MS_DEFAULT;

    /** 50 ms, which is in the ballpark for typical latency contacting a remote service like SQS */
    public static final int MIN_RECEIVE_WAIT_TIME_MS_DEFAULT = 50;

    /**
     * Specifies the message attributes receive calls will request. Only receive message requests that
     * request the same set of attributes will be satisfied from the receive buffers.
     * <p>
     * The default value is an empty list, so any receive requests that require message attributes
     * will not be fulfilled from buffers.
     */
    private List<String> receiveMessageAttributeNames = RECEIVE_MESSAGE_ATTRIBUTE_NAMES_DEFAULT;

    public static final List<String> RECEIVE_MESSAGE_ATTRIBUTE_NAMES_DEFAULT = Collections.emptyList();

    /**
     * Specifies the attributes receive calls will request. Only receive message requests that
     * request the same set of attributes will be satisfied from the receive buffers.
     * <p>
     * The default value is an empty list, so any receive requests that require attributes
     * will not be fulfilled from buffers.
     */
    private List<String> receiveAttributeNames = RECEIVE_ATTRIBUTE_NAMES_DEFAULT;

    public static final List<String> RECEIVE_ATTRIBUTE_NAMES_DEFAULT = Collections.emptyList();

    /**
     * If set, prefetching will be scaled with the number of in-flight incoming receive requests
     * made to the client. The advantage of this is reducing the number of outgoing requests
     * made to SQS when incoming requests are reduced: in particular, if all incoming requests
     * stop no future requests to SQS will be made. The disadvantage is increased latency when
     * incoming requests first start occurring.
     */
    private boolean adaptivePrefetching = ADAPTIVE_PREFETCHING_DEFAULT;

    public static final boolean ADAPTIVE_PREFETCHING_DEFAULT = false;

    /**
     * Option to configure flushOnShutdown. Enabling this option will flush the pending requests in the
     * {@link SendQueueBuffer} during shutdown.
     * <p>
     * The default value is false which indicates flushOnShutdown is disabled.
     * </p>
     */
    private boolean flushOnShutdown = false;

    public QueueBufferConfig(long maxBatchOpenMs, int maxInflightOutboundBatches, int maxInflightReceiveBatches,
            int maxDoneReceiveBatches, boolean paramLongPoll, long maxBatchSizeBytes, int visibilityTimeout,
            int longPollTimeout, int maxBatch) {
        super();
        this.maxBatchOpenMs = maxBatchOpenMs;
        this.maxInflightOutboundBatches = maxInflightOutboundBatches;
        this.maxInflightReceiveBatches = maxInflightReceiveBatches;
        this.maxDoneReceiveBatches = maxDoneReceiveBatches;
        this.longPoll = paramLongPoll;
        this.maxBatchSizeBytes = maxBatchSizeBytes;
        this.visibilityTimeoutSeconds = visibilityTimeout;
        this.longPollWaitTimeoutSeconds = longPollTimeout;
        this.maxBatchSize = maxBatch;
    }

    public QueueBufferConfig() {
        this(MAX_BATCH_OPEN_MS_DEFAULT, MAX_INFLIGHT_OUTBOUND_BATCHES_DEFAULT, MAX_INFLIGHT_RECEIVE_BATCHES_DEFAULT,
                MAX_DONE_RECEIVE_BATCHES_DEFAULT, LONG_POLL_DEFAULT, MAX_BATCH_SIZE_BYTES_DEFAULT,
                VISIBILITY_TIMEOUT_SECONDS_DEFAULT, LONGPOLL_WAIT_TIMEOUT_SECONDS_DEFAULT, MAX_BATCH_SIZE_DEFAULT);
    }

    /** copy constructor */
    public QueueBufferConfig(QueueBufferConfig other) {
        longPoll = other.longPoll;
        longPollWaitTimeoutSeconds = other.longPollWaitTimeoutSeconds;
        minReceiveWaitTimeMs = other.minReceiveWaitTimeMs;
        maxBatchOpenMs = other.maxBatchOpenMs;
        maxBatchSize = other.maxBatchSize;
        maxBatchSizeBytes = other.maxBatchSizeBytes;
        maxDoneReceiveBatches = other.maxDoneReceiveBatches;
        maxInflightOutboundBatches = other.maxInflightOutboundBatches;
        maxInflightReceiveBatches = other.maxInflightReceiveBatches;
        visibilityTimeoutSeconds = other.visibilityTimeoutSeconds;
        flushOnShutdown = other.flushOnShutdown;
        receiveAttributeNames = other.receiveAttributeNames;
        receiveMessageAttributeNames = other.receiveMessageAttributeNames;
        adaptivePrefetching = other.adaptivePrefetching;
        deleteInBackground = other.deleteInBackground;
    }

    @Override
    public String toString() {
        return "QueueBufferConfig [maxBatchSize=" + maxBatchSize + ", maxBatchOpenMs=" + maxBatchOpenMs + ", longPoll="
                + longPoll + ", maxInflightOutboundBatches=" + maxInflightOutboundBatches
                + ", maxInflightReceiveBatches=" + maxInflightReceiveBatches + ", maxDoneReceiveBatches="
                + maxDoneReceiveBatches + ", maxBatchSizeBytes=" + maxBatchSizeBytes + ", visibilityTimeoutSeconds="
                + visibilityTimeoutSeconds + ", longPollWaitTimeoutSeconds=" + longPollWaitTimeoutSeconds + "]";
    }

    /**
     * The maximum time (milliseconds) a send batch is held open for additional outbound requests.
     * The longer this timeout, the longer messages wait for other messages to be added to the
     * batch. Increasing this timeout reduces the number of calls made and increases throughput, but
     * also increases average message latency.
     */
    public long getMaxBatchOpenMs() {
        return maxBatchOpenMs;
    }

    /**
     * The maximum time (milliseconds) a send batch is held open for additional outbound requests.
     * The longer this timeout, the longer messages wait for other messages to be added to the
     * batch. Increasing this timeout reduces the number of calls made and increases throughput, but
     * also increases average message latency.
     */
    public void setMaxBatchOpenMs(long maxBatchOpenMs) {
        this.maxBatchOpenMs = maxBatchOpenMs;
    }

    /**
     * The maximum time (milliseconds) a send batch is held open for additional outbound requests.
     * The longer this timeout, the longer messages wait for other messages to be added to the
     * batch. Increasing this timeout reduces the number of calls made and increases throughput, but
     * also increases average message latency.
     */
    public QueueBufferConfig withMaxBatchOpenMs(long maxBatchOpenMs) {
        setMaxBatchOpenMs(maxBatchOpenMs);
        return this;
    }

    /**
     * If set, even synchronous calls to delete messages will be made using background
     * asynchronous batches. The client will return results indicating that the messages were deleted successfully
     * even if the background calls eventually fail; the actual result of the deletions will be reported
     * through the given handler instead (often just logging errors). This can be beneficial for decreasing message
     * acknowledgement latency at the cost of potential duplicate messages (which can be produced by SQS itself anyway).
     */
    public boolean isDeleteInBackground() {
        return deleteInBackground;
    }

    /**
     * If set, even synchronous calls to delete messages will be made using background
     * asynchronous batches. The client will return results indicating that the messages were deleted successfully
     * even if the background calls eventually fail; any errors result of the deletions will be reported
     * through the given handler instead (often just logging errors). This can be beneficial for decreasing message
     * acknowledgement latency at the cost of potential duplicate messages (which can be produced by SQS itself anyway).
     */
    public void setDeleteInBackground(boolean deleteInBackground) {
        this.deleteInBackground = deleteInBackground;
    }

    /**
     * If set, even synchronous calls to delete messages will be made using background
     * asynchronous batches. The client will return results indicating that the messages were deleted successfully
     * even if the background calls eventually fail; the actual result of the deletions will be reported
     * through the given handler instead (often just logging errors). This can be beneficial for decreasing message
     * acknowledgement latency at the cost of potential duplicate messages (which can be produced by SQS itself anyway).
     */
    public QueueBufferConfig withDeleteInBackground(boolean deleteInBackground) {
        setDeleteInBackground(deleteInBackground);
        return this;
    }

    /**
     * @return true if the queue buffer will use long polling while retrieving messages from the
     *         SQS server, false otherwise.
     */
    public boolean isLongPoll() {
        return longPoll;
    }

    /**
     * Specify "true" for receive requests to use long polling.
     */
    public void setLongPoll(boolean longPoll) {
        this.longPoll = longPoll;
    }

    /**
     * Specify "true" for receive requests to use long polling.
     */
    public QueueBufferConfig withLongPoll(boolean longPoll) {
        setLongPoll(longPoll);
        return this;
    }

    /**
     * The maximum number of concurrent batches for each type of outbound request. The greater the
     * number, the greater the throughput that can be achieved (at the expense of consuming more
     * threads).
     */
    public int getMaxInflightOutboundBatches() {
        return maxInflightOutboundBatches;
    }

    /**
     * The maximum number of concurrent batches for each type of outbound request. The greater the
     * number, the greater the throughput that can be achieved (at the expense of consuming more
     * threads).
     */
    public void setMaxInflightOutboundBatches(int maxInflightOutboundBatches) {
        this.maxInflightOutboundBatches = maxInflightOutboundBatches;
    }

    /**
     * The maximum number of concurrent batches for each type of outbound request. The greater the
     * number, the greater the throughput that can be achieved (at the expense of consuming more
     * threads).
     */
    public QueueBufferConfig withMaxInflightOutboundBatches(int maxInflightOutboundBatches) {
        setMaxInflightOutboundBatches(maxInflightOutboundBatches);
        return this;
    }

    /**
     * The maximum number of concurrent receive message batches. The greater this number, the faster
     * the queue will be pulling messages from the SQS servers (at the expense of consuming more
     * threads).
     */
    public int getMaxInflightReceiveBatches() {
        return maxInflightReceiveBatches;
    }

    /**
     * The maximum number of concurrent receive message batches. The greater this number, the faster
     * the queue will be pulling messages from the SQS servers (at the expense of consuming more
     * threads).
     */
    public void setMaxInflightReceiveBatches(int maxInflightReceiveBatches) {
        this.maxInflightReceiveBatches = maxInflightReceiveBatches;
    }

    /**
     * The maximum number of concurrent receive message batches. The greater this number, the faster
     * the queue will be pulling messages from the SQS servers (at the expense of consuming more
     * threads).
     */
    public QueueBufferConfig withMaxInflightReceiveBatches(int maxInflightReceiveBatches) {
        setMaxInflightReceiveBatches(maxInflightReceiveBatches);
        return this;
    }

    /**
     * If more than that number of completed receive batches are waiting in the buffer, the querying
     * for new messages will stop.<br>
     * The larger this number, the more messages the queue buffer will pre-fetch and keep in the
     * buffer on the client side, and the faster receive requests will be satisfied. <br>
     * The visibility timeout of a pre-fetched message starts at the point of pre-fetch, which means
     * that while the message is in the local buffer it is unavailable for other clients to process,
     * and when this client retrieves it, part of the visibility timeout may have already expired.<br>
     * The number of messages prefetched will not exceed 10 * maxDoneReceiveBatches, as there can be
     * a maximum of 10 messages per batch.<br>
     */
    public int getMaxDoneReceiveBatches() {
        return maxDoneReceiveBatches;
    }

    /**
     * If more than that number of completed receive batches are waiting in the buffer, the querying
     * for new messages will stop. The larger this number, the more messages the buffer queue will
     * pre-fetch and keep in the buffer on the client side, and the faster receive requests will be
     * satisfied. The visibility timeout of a pre-fetched message starts at the point of pre-fetch,
     * which means that while the message is in the local buffer it is unavailable for other clients
     * to process, and when this client retrieves it, part of the visibility timeout may have
     * already expired. The number of messages prefetched will not exceed maxBatchSize *
     * maxDoneReceiveBatches.
     */
    public void setMaxDoneReceiveBatches(int maxDoneReceiveBatches) {
        this.maxDoneReceiveBatches = maxDoneReceiveBatches;
    }

    /**
     * If more than that number of completed receive batches are waiting in the buffer, the querying
     * for new messages will stop. The larger this number, the more messages the buffer queue will
     * pre-fetch and keep in the buffer on the client side, and the faster receive requests will be
     * satisfied. The visibility timeout of a pre-fetched message starts at the point of pre-fetch,
     * which means that while the message is in the local buffer it is unavailable for other clients
     * to process, and when this client retrieves it, part of the visibility timeout may have
     * already expired. The number of messages prefetched will not exceed maxBatchSize *
     * maxDoneReceiveBatches.
     */
    public QueueBufferConfig withMaxDoneReceiveBatches(int maxDoneReceiveBatches) {
        setMaxDoneReceiveBatches(maxDoneReceiveBatches);
        return this;
    }

    /**
     * Maximum permitted size of a SendMessage or SendMessageBatch message, in bytes. This setting
     * is also enforced on the server, and if this client submits a request of a size larger than
     * the server can support, the server will reject the request.
     */
    public long getMaxBatchSizeBytes() {
        return maxBatchSizeBytes;
    }

    /**
     * Maximum permitted size of a SendMessage or SendMessageBatch message, in bytes. This setting
     * is also enforced on the server, and if this client submits a request of a size larger than
     * the server can support, the server will reject the request.
     * 
     * @throws IllegalArgumentException
     *             if the size being set is greater than the service allowed size for message body.
     */
    public void setMaxBatchSizeBytes(long maxBatchSizeBytes) {
        if (maxBatchSizeBytes > SERVICE_MAX_BATCH_SIZE_BYTES) {
            throw new IllegalArgumentException(
                    "Maximum Size of the message cannot be greater than the allowed limit of "
                            + SERVICE_MAX_BATCH_SIZE_BYTES + " bytes");
        }
        this.maxBatchSizeBytes = maxBatchSizeBytes;
    }

    /**
     * Maximum permitted size of a SendMessage or SendMessageBatch message, in bytes. This setting
     * is also enforced on the server, and if this client submits a request of a size larger than
     * the server can support, the server will reject the request.
     * 
     * @throws IllegalArgumentException
     *             if the size being set is greater than the service allowed size for message body.
     */
    public QueueBufferConfig withMaxBatchSizeBytes(long maxBatchSizeBytes) {
        setMaxBatchSizeBytes(maxBatchSizeBytes);
        return this;
    }

    /**
     * Custom visibility timeout to use when retrieving messages from SQS. If set to a value greater
     * than zero, this timeout will override the default visibility timeout set on the SQS queue.
     * Set it to -1 to use the default visiblity timeout of the queue. Visibility timeout of 0
     * seconds is not supported.
     */
    public int getVisibilityTimeoutSeconds() {
        return visibilityTimeoutSeconds;
    }

    /**
     * Custom visibility timeout to use when retrieving messages from SQS. If set to a value greater
     * than zero, this timeout will override the default visibility timeout set on the SQS queue.
     * Set it to -1 to use the default visiblity timeout of the queue. Visibility timeout of 0
     * seconds is not supported.
     */
    public void setVisibilityTimeoutSeconds(int visibilityTimeoutSeconds) {
        this.visibilityTimeoutSeconds = visibilityTimeoutSeconds;
    }

    /**
     * Custom visibility timeout to use when retrieving messages from SQS. If set to a value greater
     * than zero, this timeout will override the default visibility timeout set on the SQS queue.
     * Set it to -1 to use the default visiblity timeout of the queue. Visibility timeout of 0
     * seconds is not supported.
     */
    public QueueBufferConfig withVisibilityTimeoutSeconds(int visibilityTimeoutSeconds) {
        setVisibilityTimeoutSeconds(visibilityTimeoutSeconds);
        return this;
    }

    /**
     * Specifies the amount of time, in seconds, the receive call will block on the server waiting
     * for messages to arrive if the queue is empty when the receive call is first made. This
     * setting has no effect if long polling is disabled.
     */
    public void setLongPollWaitTimeoutSeconds(int longPollWaitTimeoutSeconds) {
        this.longPollWaitTimeoutSeconds = longPollWaitTimeoutSeconds;
    }

    /**
     * Specifies the amount of time, in seconds, the receive call will block on the server waiting
     * for messages to arrive if the queue is empty when the receive call is first made. This
     * setting has no effect if long polling is disabled.
     */
    public int getLongPollWaitTimeoutSeconds() {
        return longPollWaitTimeoutSeconds;
    }

    /**
     * Specifies the amount of time, in seconds, the receive call will block on the server waiting
     * for messages to arrive if the queue is empty when the receive call is first made. This
     * setting has no effect if long polling is disabled.
     */
    public QueueBufferConfig withLongPollWaitTimeoutSeconds(int longPollWaitTimeoutSeconds) {
        setLongPollWaitTimeoutSeconds(longPollWaitTimeoutSeconds);
        return this;
    }

    /**
     * Configures the minimum wait time for incoming receive message requests. Without a non-zero
     * minimum wait time, threads can easily waste CPU time busy-waiting against empty local buffers.
     * Avoid setting this to 0 unless you are confident threads will do useful work in-between
     * each call to receive messages!
     * <p></p>
     * This will be applied to both requests that explicitly set WaitTimeSeconds and
     * those that inherit the ReceiveMessageWaitTimeSeconds queue attribute.
     */
    public int getMinReceiveWaitTimeMs() {
        return minReceiveWaitTimeMs;
    }

    /**
     * Configures the minimum wait time for incoming receive message requests. Without a non-zero
     * minimum wait time, threads can easily waste CPU time busy-waiting against empty local buffers.
     * Avoid setting this to 0 unless you are confident threads will do useful work in-between
     * each call to receive messages!
     * <p></p>
     * This will be applied to both requests that explicitly set WaitTimeSeconds and
     * those that inherit the ReceiveMessageWaitTimeSeconds queue attribute.
     */
    public void setMinReceiveWaitTimeMs(int minReceiveWaitTimeMs) {
        this.minReceiveWaitTimeMs = minReceiveWaitTimeMs;
    }

    /**
     * Configures the minimum wait time for incoming receive message requests. Without a non-zero
     * minimum wait time, threads can easily waste CPU time busy-waiting against empty local buffers.
     * Avoid setting this to 0 unless you are confident threads will do useful work in-between
     * each call to receive messages!
     * <p></p>
     * This will be applied to both requests that explicitly set WaitTimeSeconds and
     * those that inherit the ReceiveMessageWaitTimeSeconds queue attribute.
     */
    public QueueBufferConfig withMinReceiveWaitTimeMs(int minReceiveWaitTimeMs) {
        setMinReceiveWaitTimeMs(minReceiveWaitTimeMs);
        return this;
    }

    /**
     * Specifies the maximum number of entries the buffered client will put in a single batch
     * request.
     */
    public int getMaxBatchSize() {
        return maxBatchSize;
    }

    /**
     * Specifies the maximum number of entries the buffered client will put in a single batch
     * request.
     */
    public void setMaxBatchSize(int maxBatchSize) {
        this.maxBatchSize = maxBatchSize;
    }

    /**
     * Specifies the maximum number of entries the buffered client will put in a single batch
     * request.
     */
    public QueueBufferConfig withMaxBatchSize(int maxBatchSize) {
        setMaxBatchSize(maxBatchSize);
        return this;
    }

    /**
     * Specifies the attributes receive calls will request. Only receive message requests that
     * request the same set of attributes will be satisfied from the receive buffers.
     * <p>
     * The default value is an empty list, so any receive requests that require attributes
     * will not be fulfilled from buffers.
     */
    public List<String> getReceiveAttributeNames() {
        return receiveAttributeNames;
    }

    /**
     * Specifies the attributes receive calls will request. Only receive message requests that
     * request the same set of attributes will be satisfied from the receive buffers.
     * <p>
     * The default value is an empty list, so any receive requests that require attributes
     * will not be fulfilled from buffers.
     */
    public void setReceiveAttributeNames(List<String> receiveAttributeNames) {
        if (receiveAttributeNames == null) {
            this.receiveAttributeNames = Collections.emptyList();
        } else {
            this.receiveAttributeNames = Collections.unmodifiableList(new ArrayList<String>(receiveAttributeNames));
        }
    }

    /**
     * Specifies the attributes receive calls will request. Only receive message requests that
     * request the same set of attributes will be satisfied from the receive buffers.
     * <p>
     * The default value is an empty list, so any receive requests that require attributes
     * will not be fulfilled from buffers.
     */
    public QueueBufferConfig withReceiveAttributeNames(List<String> receiveAttributes) {
        setReceiveAttributeNames(receiveAttributes);
        return this;
    }

    /**
     * Specifies the message attributes receive calls will request. Only receive message requests that
     * request the same set of attributes will be satisfied from the receive buffers.
     * <p>
     * The default value is an empty list, so any receive requests that require message attributes
     * will not be fulfilled from buffers.
     */
    public List<String> getReceiveMessageAttributeNames() {
        return receiveMessageAttributeNames;
    }

    /**
     * Specifies the message attributes receive calls will request. Only receive message requests that
     * request the same set of attributes will be satisfied from the receive buffers.
     * <p>
     * The default value is an empty list, so any receive requests that require message attributes
     * will not be fulfilled from buffers.
     */
    public void setReceiveMessageAttributeNames(List<String> receiveMessageAttributeNames) {
        if (receiveMessageAttributeNames == null) {
            this.receiveMessageAttributeNames = Collections.emptyList();
        } else {
            this.receiveMessageAttributeNames = Collections.unmodifiableList(new ArrayList<String>(receiveMessageAttributeNames));
        }
    }

    /**
     * Specifies the message attributes receive calls will request. Only receive message requests that
     * request the same set of attributes will be satisfied from the receive buffers.
     * <p>
     * The default value is an empty list, so any receive requests that require message attributes
     * will not be fulfilled from buffers.
     */
    public QueueBufferConfig withReceiveMessageAttributeNames(List<String> receiveMessageAttributes) {
        setReceiveMessageAttributeNames(receiveMessageAttributes);
        return this;
    }

    /**
     * If set, prefetching will be scaled with the number of in-flight incoming receive requests
     * made to the client. The advantage of this is reducing the number of outgoing requests
     * made to SQS when incoming requests are reduced: in particular, if all incoming requests
     * stop no future requests to SQS will be made. The disadvantage is increased latency when
     * incoming requests first start occurring.
     */
    public void setAdaptivePrefetching(boolean adaptivePrefetching) {
        this.adaptivePrefetching = adaptivePrefetching;
    }

    /**
     * If set, prefetching will be scaled with the number of in-flight incoming receive requests
     * made to the client. The advantage of this is reducing the number of outgoing requests
     * made to SQS when incoming requests are reduced: in particular, if all incoming requests
     * stop no future requests to SQS will be made. The disadvantage is increased latency when
     * incoming requests first start occurring.
     */
    public boolean isAdapativePrefetching() {
        return adaptivePrefetching;
    }

    /**
     * If set, prefetching will be scaled with the number of in-flight incoming receive requests
     * made to the client. The advantage of this is reducing the number of outgoing requests
     * made to SQS when incoming requests are reduced: in particular, if all incoming requests
     * stop no future requests to SQS will be made. The disadvantage is increased latency when
     * incoming requests first start occurring.
     */
    public QueueBufferConfig withAdapativePrefetching(boolean adaptivePrefetching) {
        setAdaptivePrefetching(adaptivePrefetching);
        return this;
    }

    /**
     * Returns the flushOnShutdown value. The default value is false which indicates flushOnShutdown is disabled.
     *
     * Enabling this option will flush the pending requests in the {@link SendQueueBuffer} during shutdown.
     *
     * @return true if flushOnShutdown is enabled, otherwise false.
     */
    public boolean isFlushOnShutdown() {
        return flushOnShutdown;
    }

    /**
     * Sets the flushOnShutdown option. The default value is false which indicates flushOnShutdown is disabled.
     *
     * Enabling this option will flush the pending requests in the {@link SendQueueBuffer} during shutdown.
     *
     * @param flushOnShutdown boolean value to configure flushOnShutdown.
     */
    public void setFlushOnShutdown(boolean flushOnShutdown) {
        this.flushOnShutdown = flushOnShutdown;
    }

    /**
     * Sets the flushOnShutdown option. The default value is false which indicates flushOnShutdown is disabled.
     *
     * Enabling this option will flush the pending requests in the {@link SendQueueBuffer} during shutdown.
     *
     * @param flushOnShutdown boolean value to configure flushOnShutdown.
     * @return This object for method chaining.
     */
    public QueueBufferConfig withFlushOnShutdown(boolean flushOnShutdown) {
        setFlushOnShutdown(flushOnShutdown);
        return this;
    }

    /**
     * this method checks the config for validity. If the config is deemed to be invalid, an
     * informative exception is thrown.
     * 
     * @throws AmazonClientException
     *             with a message explaining why the config was invalid
     */
    void validate() {
        if (visibilityTimeoutSeconds == 0) {
            throw new AmazonClientException("Visibility timeout value may not be equal to zero ");
        }
    }

}