org.example.service.CircuitBreakerCommand Maven / Gradle / Ivy

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/*
 *  Copyright (c) 2005-2014, WSO2 Inc. (http://www.wso2.org) All Rights Reserved.
 *
 *  WSO2 Inc. 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.example.service;

import com.netflix.hystrix.HystrixCommand;
import com.netflix.hystrix.HystrixCommandGroupKey;
import com.netflix.hystrix.HystrixCommandKey;
import com.netflix.hystrix.HystrixCommandMetrics;
import com.netflix.hystrix.HystrixCommandProperties;

public class CircuitBreakerCommand extends HystrixCommand {

    private StockQuoteDatabase db;
    private final String symbol;

    CircuitBreakerCommand(StockQuoteDatabase db, String symbol) {
        super(HystrixCommand.Setter.withGroupKey(HystrixCommandGroupKey.Factory.asKey("MyGroup"))
                .andCommandPropertiesDefaults(
                        HystrixCommandProperties.Setter()
                                .withCircuitBreakerEnabled(true)
                                .withCircuitBreakerRequestVolumeThreshold(50)
                                .withExecutionTimeoutEnabled(true)
                                .withExecutionTimeoutInMilliseconds(10)
                ));
        this.db = db;
        this.symbol = symbol;
    }

    @Override
    protected Stock run() {
        printMetrics();
        return db.getStock(symbol);
    }

    @Override
    protected Stock getFallback() {
        if (isCircuitBreakerOpen()) {
            System.out.println("Circuit is open");
        }
        printMetrics();
        return db.getCachedStock(symbol);
    }

    private void printMetrics() {
        HystrixCommandMetrics metrics =
                HystrixCommandMetrics.
                        getInstance(HystrixCommandKey.Factory.asKey(this.getClass().getSimpleName()));
        StringBuilder m = new StringBuilder();
        if (metrics != null) {
            HystrixCommandMetrics.HealthCounts health = metrics.getHealthCounts();
            m.append("Requests: ").append(health.getTotalRequests()).append(" ");
            m.append("Errors: ").append(health.getErrorCount()).append(" (").
                    append(health.getErrorPercentage()).append("%)   ");
            m.append("Mean: ").append(metrics.getExecutionTimePercentile(50)).append(" ");
            m.append("75th: ").append(metrics.getExecutionTimePercentile(75)).append(" ");
            m.append("90th: ").append(metrics.getExecutionTimePercentile(90)).append(" ");
            m.append("99th: ").append(metrics.getExecutionTimePercentile(99)).append(" ");
        }
        System.out.println(m);
    }
}