FaultInjectionRequestHandler.java

/*
* Copyright 2014-2015 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.dynamodbv2.client;

import java.util.Map;
import java.util.Random;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import com.amazonaws.Request;
import com.amazonaws.Response;
import com.amazonaws.handlers.RequestHandler2;
import com.amazonaws.services.dynamodbv2.AmazonDynamoDBClient;
import com.amazonaws.services.dynamodbv2.model.AttributeValue;
import com.amazonaws.services.dynamodbv2.model.GetItemRequest;
import com.amazonaws.services.dynamodbv2.model.GetItemResult;
import com.amazonaws.services.dynamodbv2.model.ProvisionedThroughputExceededException;
import com.amazonaws.services.dynamodbv2.model.PutItemRequest;

public class FaultInjectionRequestHandler extends RequestHandler2
{

    private AmazonDynamoDBClient dynamoDBClient;
    private static final Random rnd = new Random(1234);
    private static final Log logger = LogFactory.getLog(FaultInjectionRequestHandler.class);

    public FaultInjectionRequestHandler(AmazonDynamoDBClient dynamoDBClient)
    {
        this.dynamoDBClient = dynamoDBClient;
    }

    @Override
    public void beforeRequest(Request<?> request)
    {

        /* Things to do just before a request is executed */
        if (request.getOriginalRequest() instanceof PutItemRequest)
        {

            /* Throw throuhgput exceeded exception for 50% of put requests */
            if (rnd.nextInt(2) == 0)
            {

                logger.info("Injecting ProvisionedThroughputExceededException");
                throw new ProvisionedThroughputExceededException("Injected Error");
            }
        }

        /* Add latency to some Get requests */
        if (request.getOriginalRequest() instanceof GetItemRequest)
        {

            /* Delay 50% of GetItem requests by 500 ms */
            if (rnd.nextInt(2) == 0)
            {
                /* Delay on average 50% of the requests from client perspective */
                try
                {

                    logger.info("Injecting 500 ms delay");
                    Thread.sleep(500);
                }
                catch (InterruptedException ie)
                {
                    logger.info(ie);
                    throw new RuntimeException(ie);
                }
            }
        }
    }

    @Override
    public void afterResponse(Request<?> request, Response<?> response)
    {
        /*
         * The following is a hit and miss for multi-threaded clients as the
         * cache size is only 50 entries
         */
        String awsRequestId = dynamoDBClient.getCachedResponseMetadata(request.getOriginalRequest()).getRequestId();
        logger.info("AWS RequestID: " + awsRequestId);

        /*
         * Here you could inspect and alter the response object to see how your
         * application behaves for specific data
         */
        if (request.getOriginalRequest() instanceof GetItemRequest)
        {
            GetItemResult result = (GetItemResult) response.getAwsResponse();

            Map<String, AttributeValue> item = result.getItem();

            if (item.get("name").getS().equals("Airplane"))
            {

                // Alter the item
                item.put("name", new AttributeValue("newAirplane"));
                item.put("new attr", new AttributeValue("new attr"));

                // Add some delay
                try
                {
                    Thread.sleep(500);
                }
                catch (InterruptedException ie)
                {
                    logger.info(ie);
                    throw new RuntimeException(ie);
                }
            }
        }
    }

    @Override
    public void afterError(Request<?> request, Response<?> response, Exception e)
    {
        // TODO Auto-generated method stub
    }
}