loadbalancer

目录

loadbalancer

u1s1,感觉代码质量不咋样….主要内容,负载均衡策略,从eureka中拉取信息等
然后,如果想弃用ribbon,需要增加spring.cloud.loadbalancer.ribbon.enabled=false.
大体流程,BlockingLoadBalancerClient(新版本用了webflux,然后mono获取的时候block了.貌似这个原因所以叫blockingLoadBalancer??).在内部通过loadBalancerClientFactory去选择不同的服务的负载均衡配置.实际只有RoudRobin轮询的实现…..

BlockingLoadBalancerClient

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@Override
public ServiceInstance choose(String serviceId) {
	ReactiveLoadBalancer<ServiceInstance> loadBalancer = loadBalancerClientFactory
			.getInstance(serviceId);
	if (loadBalancer == null) {
		return null;
	}
	Response<ServiceInstance> loadBalancerResponse = Mono.from(loadBalancer.choose())
			.block();
	if (loadBalancerResponse == null) {
		return null;
	}
	return loadBalancerResponse.getServer();
}

RoundRobinLoadBalancer

eeeeee.这个

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public class RoundRobinLoadBalancer implements ReactorServiceInstanceLoadBalancer {
    // 创建的时候随机
	private final AtomicInteger position;

	@SuppressWarnings("rawtypes")
	@Override
	// see original
	// https://github.com/Netflix/ocelli/blob/master/ocelli-core/
	// src/main/java/netflix/ocelli/loadbalancer/RoundRobinLoadBalancer.java
	public Mono<Response<ServiceInstance>> choose(Request request) {
		// TODO: move supplier to Request?
		// Temporary conditional logic till deprecated members are removed.
		if (serviceInstanceListSupplierProvider != null) {
			ServiceInstanceListSupplier supplier = serviceInstanceListSupplierProvider
					.getIfAvailable(NoopServiceInstanceListSupplier::new);
			return supplier.get().next().map(this::getInstanceResponse);
		}
		ServiceInstanceSupplier supplier = this.serviceInstanceSupplier
				.getIfAvailable(NoopServiceInstanceSupplier::new);
		return supplier.get().collectList().map(this::getInstanceResponse);
	}

    // 哎,每次请求会将position+1,然后取余去获取instance.
    private Response<ServiceInstance> getInstanceResponse(
			List<ServiceInstance> instances) {
		if (instances.isEmpty()) {
			log.warn("No servers available for service: " + this.serviceId);
			return new EmptyResponse();
		}
		// TODO: enforce order?
		int pos = Math.abs(this.position.incrementAndGet());

		ServiceInstance instance = instances.get(pos % instances.size());

		return new DefaultResponse(instance);
	}
}

从eureka拉取信息

通过discoveryClient去从eureka拉取信息….

BlockingSupportConfiguration

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@Bean
@ConditionalOnBean(DiscoveryClient.class)
@ConditionalOnMissingBean
@ConditionalOnProperty(value = "spring.cloud.loadbalancer.configurations",
		havingValue = "default", matchIfMissing = true)
public ServiceInstanceListSupplier discoveryClientServiceInstanceListSupplier(
		ConfigurableApplicationContext context) {
	return ServiceInstanceListSupplier.builder().withBlockingDiscoveryClient()
			.withCaching().build(context);
}
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public ServiceInstanceListSupplierBuilder withBlockingDiscoveryClient() {
	if (baseCreator != null && LOG.isWarnEnabled()) {
		LOG.warn(
				"Overriding a previously set baseCreator with a blocking DiscoveryClient baseCreator.");
	}
	this.baseCreator = context -> {
		DiscoveryClient discoveryClient = context.getBean(DiscoveryClient.class);

		return new DiscoveryClientServiceInstanceListSupplier(discoveryClient,
				context.getEnvironment());
	};
	return this;
}