disruptor 笔记之一:快速入门
// Copy LICENSE
tasks.withType(Jar) {
from(project.rootDir) {
include 'LICENSE'
into 'META-INF'
}
}
// 写入到 MANIFEST.MF 中的内容
jar {
manifest {
attributes(
'Created-By': "{System.properties['java.vendor']} ${System.properties['java.vm.version']})".toString(),
'Built-By': 'travis',
'Build-Date': buildDate,
'Build-Time': buildTime,
'Built-OS': "${System.properties['os.name']}",
'Build-Revision': buildRevision,
'Specification-Title': project.name,
'Specification-Version': projectVersion,
'Specification-Vendor': 'Will Zhao',
'Implementation-Title': project.name,
'Implementation-Version': projectVersion,
'Implementation-Vendor': 'Will Zhao'
)
}
}
repositories {
mavenCentral()
// 如果有私服就在此配置,如果没有请注释掉
maven {
url 'http://192.168.50.43:8081/repository/aliyun-proxy/'
}
// 阿里云
maven {
url 'http://maven.aliyun.com/nexus/content/groups/public/'
}
jcenter()
}
buildscript {
repositories {
maven { url 'https://plugins.gradle.org/m2/' }
}
}
}
allprojects { project ->
buildscript {
dependencyManagement {
imports {
mavenBom "org.springframework.boot:spring-boot-starter-parent:${springBootVersion}"
mavenBom "org.junit:junit-bom:5.7.0"
}
dependencies {
dependency 'org.projectlombok:lombok:1.16.16'
dependency 'org.apache.commons:commons-lang3:3.11'
dependency 'commons-collections:commons-collections:3.2.2'
dependency 'com.lmax:disruptor:3.4.4'
}
}
ext {
springFrameworkVersion = dependencyManagement.importedProperties['spring-framework.version']
}
}
}
group = 'bolingcavalry'
version = projectVersion
接下来编写消息发布和消费的代码;
新建 module
前面新建了整个《Disruptor 笔记》系列的父工程,现在新建名为 basic-event 的 module,其 build.gradle 内容如下:
plugins {
id 'org.springframework.boot'
}
dependencies {
implementation 'org.projectlombok:lombok'
implementation 'org.springframework.boot:spring-boot-starter'
implementation 'org.springframework.boot:spring-boot-starter-web'
implementation 'com.lmax:disruptor'
testImplementation('org.springframework.boot:spring-boot-starter-test')
}
这个 module 是个 springboot 应用,启动类如下:
package com.bolingcavalry;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
@SpringBootApplication
public class BasicEventApplication {
public static void main(String[] args) {
SpringApplication.run(BasicEventApplication.class, args);
}
}
接下来按照前面总结的套路行事;
事件的定义
事件定义类 StringEvent.java,可见就是个普普通通的 java bean:
package com.bolingcavalry.service;
import lombok.Data;
import lombok.NoArgsConstructor;
import lombok.ToString;
@Data
@ToString
@NoArgsConstructor
public class StringEvent {
private String value;
}
事件工厂
事件工厂的作用,是让 disruptor 知道如何在内存中创建一个事件实例,不过,该实例和业务还没有任何关系,本篇的事件工厂如下,可见就是创建 StringEvent 实例,并没有特别的操作:
package com.bolingcavalry.service;
import com.lmax.disruptor.EventFactory;
public class StringEventFactory implements EventFactory<StringEvent> {
@Override
public StringEvent newInstance() {
return new StringEvent();
}
}
事件处理
时间处理类的作用是定义一个事件如何被消费,里面是具体的业务代码,每个事件都会执行此类的 onEvent 方法;
本篇的事件处理类做的事情是打印事件内容,再用 sleep 消耗 100 毫秒,然后再调用外部传入的 Consumer 实现类的 accept 方法:
package com.bolingcavalry.service;
import com.lmax.disruptor.EventHandler;
import lombok.Setter;
import lombok.extern.slf4j.Slf4j;
import java.util.function.Consumer;
@Slf4j
public class StringEventHandler implements EventHandler<StringEvent> {
public StringEventHandler(Consumer<?> consumer) {
this.consumer = consumer;
}
// 外部可以传入 Consumer 实现类,每处理一条消息的时候,consumer 的 accept 方法就会被执行一次
private Consumer<?> consumer;
@Override
public void onEvent(StringEvent event, long sequence, boolean endOfBatch) throws Exception {
log.info("sequence [{}], endOfBatch [{}], event : {}", sequence, endOfBatch, event);
// 这里延时 100ms,模拟消费事件的逻辑的耗时
Thread.sleep(100);
// 如果外部传入了 consumer,就要执行一次 accept 方法
if (null!=consumer) {
consumer.accept(null);
}
}
}
事件生产者
每当业务要生产一个事件时,就会调用事件生产者的 onData 方法,将业务数据作为入参传进来,此时生产者会从环形队列中取出一个事件实例(就是前面的事件工厂创建的),把业务数据传给这个实例,再把实例正式发布出去:
package com.bolingcavalry.service;
import com.lmax.disruptor.RingBuffer;
public class StringEventProducer {
// 存储数据的环形队列
private final RingBuffer<StringEvent> ringBuffer;
public StringEventProducer(RingBuffer<StringEvent> ringBuffer) {
this.ringBuffer = ringBuffer;
}
public void onData(String content) {
// ringBuffer 是个队列,其 next 方法返回的是下最后一条记录之后的位置,这是个可用位置
long sequence = ringBuffer.next();
try {
// sequence 位置取出的事件是空事件
StringEvent stringEvent = ringBuffer.get(sequence);
// 空事件添加业务信息
stringEvent.setValue(content);
} finally {
// 发布
ringBuffer.publish(sequence);
}
}
}
初始化逻辑
开发一个 spring bean,这里面有 disruptor 的初始化逻辑,有几处需要关注的地方稍后会说到:
package com.bolingcavalry.service.impl;
import com.bolingcavalry.service.*;
import com.lmax.disruptor.RingBuffer;
import com.lmax.disruptor.dsl.Disruptor;
import com.lmax.disruptor.util.DaemonThreadFactory;
import lombok.extern.slf4j.Slf4j;
import org.springframework.scheduling.concurrent.CustomizableThreadFactory;
import org.springframework.stereotype.Service;
import javax.annotation.PostConstruct;
import java.time.LocalDateTime;
import java.util.concurrent.Executor;
import java.util.concurrent.Executors;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicLong;
import java.util.function.Consumer;
@Service
@Slf4j
public class BasicEventServiceImpl implements BasicEventService {
private static final int BUFFER_SIZE = 16;
private Disruptor<StringEvent> disruptor;
private StringEventProducer producer;
/**
统计消息总数
*/
private final AtomicLong eventCount = new AtomicLong();
@PostConstruct
private void init() {
Executor executor = Executors.newCachedThreadPool();
// 实例化
disruptor = new Disruptor<>(new StringEventFactory(),
BUFFER_SIZE,
new CustomizableThreadFactory("event-handler-"));
// 准备一个匿名类,传给 disruptor 的事件处理类,
// 这样每次处理事件时,都会将已经处理事件的总数打印出来
Consumer<?> eventCountPrinter = new Consumer<Object>() {
@Override
public void accept(Object o) {
long count = eventCount.incrementAndGet();
log.info("receive [{}] event", count);
}
};
// 指定处理类
disruptor.handleEventsWith(new StringEventHandler(eventCountPrinter));
// 启动
disruptor.start();
// 生产者
producer = new StringEventProducer(disruptor.getRingBuffer());
}
@Override
public void publish(String value) {
producer.onData(value);
}
@Override
public long eventCount() {
return eventCount.get();
}
}
上述代码有以下几点需要注意:
publish 方法给外部调用,用于发布一个事件;
eventCountPrinter 是 Consumer 的实现类,被传给了 StringEventHandler,这样 StringEventHandler 消费消息的时候,eventCount 就会增加,也就记下了已经处理的事件总数;
Disruptor 的构造方法中,BUFFER_SIZE 表示环形队列的大小,这里故意设置为 16,这样可以轻易的将环形队列填满,此时再发布事件会不会导致环形队列上的数据被覆盖呢?稍后咱们可以测一下;
记得调用 start 方法;
web 接口
再写一个 web 接口类,这样就可以通过浏览器验证前面的代码了:
package com.bolingcavalry.controller;
import com.bolingcavalry.service.BasicEventService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.*;
import java.time.LocalDateTime;
@RestController
public class BasicEventController {
@Autowired
BasicEventService basicEventService;
@RequestMapping(value = "/{value}", method = RequestMethod.GET)
public String publish(@PathVariable("value") String va
lue) {
basicEventService.publish(value);
return "success, " + LocalDateTime.now().toString();
}
}
业务逻辑
现在生产事件的接口已准备好,消费事件的代码也完成了,接下来就是如何调用生产事件的接口来验证生产和消费是否正常,这里我选择使用单元测试来验证;
在 disruptor-tutorials\basic-event\src\test\java 目录下新增测试类 BasicEventServiceImplTest.java,测试逻辑是发布了一百个事件,再验证消费事件的数量是否也等于一百:
package com.bolingcavalry.service.impl;
import com.bolingcavalry.service.BasicEventService;
import lombok.extern.slf4j.Slf4j;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;
import static org.junit.Assert.assertEquals;
@RunWith(SpringRunner.class)
@SpringBootTest
@Slf4j
public class BasicEventServiceImplTest {
@Autowired
BasicEventService basicEventService;
@Test
public void publish() throws InterruptedException {
log.info("start publich test");
int count = 100;
for(int i=0;i<count;i++) {
log.info("publich {}", i);
basicEventService.publish(String.valueOf(i));
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