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@ -6,74 +6,104 @@ import org.springframework.cloud.client.ServiceInstance; |
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import org.springframework.cloud.client.loadbalancer.DefaultResponse; |
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import org.springframework.cloud.client.loadbalancer.EmptyResponse; |
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import org.springframework.cloud.client.loadbalancer.Request; |
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import org.springframework.cloud.client.loadbalancer.RequestDataContext; |
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import org.springframework.cloud.client.loadbalancer.Response; |
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import org.springframework.cloud.loadbalancer.core.NoopServiceInstanceListSupplier; |
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import org.springframework.cloud.loadbalancer.core.ReactorServiceInstanceLoadBalancer; |
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import org.springframework.cloud.loadbalancer.core.ServiceInstanceListSupplier; |
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import org.springframework.http.HttpHeaders; |
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import reactor.core.publisher.Mono; |
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import java.util.Arrays; |
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import java.util.Collections; |
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import java.util.List; |
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/** |
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* 优先级负载均衡器 - 首选优先策略 |
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* 优先级负载均衡器 - 按角色顺序选择实例 |
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* <p> |
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* 根据配置文件中实例的声明顺序确定优先级， |
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* 始终选择优先级最高的健康实例。 |
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* 从请求 header {@value #HEADER_ROLE_ORDER} 读取角色优先级列表（由 PreferredRoleFilter 从路由 metadata 注入）， |
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* 依次在 Nacos 拉到的健康实例中匹配 metadata {@value #METADATA_ROLE_KEY}，命中即返回； |
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* 若列表中所有角色均未命中，则回退取第一个健康实例作为兜底。 |
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* <p> |
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* 健康检查并发执行后返回结果顺序不确定， |
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* 因此通过 preferredOrder 显式匹配配置中的优先级顺序。 |
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* 完全替代原有静态 SimpleDiscoveryProperties 方案，同时保留“首选优先 + 兜底容错”语义。 |
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* |
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* @author zdxt |
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*/ |
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@Slf4j |
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public class PreferredFirstLoadBalancer implements ReactorServiceInstanceLoadBalancer { |
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/** 路由 metadata 中优先级顺序注入到请求头的名称 */ |
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public static final String HEADER_ROLE_ORDER = "X-Preferred-Role-Order"; |
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/** Nacos 实例 metadata 中标识角色的 key（与 admin 服务 application.yml 保持一致） |
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* 注意:不使用点号(Spring Boot 会把点号视为嵌套路径拆分 Map key) */ |
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public static final String METADATA_ROLE_KEY = "zdxt-role"; |
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private final String serviceId; |
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private final ObjectProvider<ServiceInstanceListSupplier> serviceInstanceListSupplierProvider; |
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/** 配置中声明的实例顺序（host:port），索引越小优先级越高 */ |
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private final List<String> preferredOrder; |
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public PreferredFirstLoadBalancer( |
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ObjectProvider<ServiceInstanceListSupplier> serviceInstanceListSupplierProvider, |
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String serviceId, |
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List<String> preferredOrder) { |
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String serviceId) { |
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this.serviceId = serviceId; |
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this.serviceInstanceListSupplierProvider = serviceInstanceListSupplierProvider; |
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this.preferredOrder = preferredOrder; |
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log.info("[{}] 优先级顺序: {}", serviceId, preferredOrder); |
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log.info("[{}] PreferredFirstLoadBalancer 已启用，将按请求头 {} 指定的角色顺序优先选择实例", |
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serviceId, HEADER_ROLE_ORDER); |
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} |
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@Override |
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public Mono<Response<ServiceInstance>> choose(Request request) { |
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List<String> roleOrder = extractRoleOrder(request); |
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ServiceInstanceListSupplier supplier = serviceInstanceListSupplierProvider |
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.getIfAvailable(NoopServiceInstanceListSupplier::new); |
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return supplier.get(request) |
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.next() |
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.map(this::selectInstance); |
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.map(instances -> selectByRoleOrder(instances, roleOrder)); |
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} |
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private Response<ServiceInstance> selectInstance(List<ServiceInstance> instances) { |
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private Response<ServiceInstance> selectByRoleOrder(List<ServiceInstance> instances, List<String> roleOrder) { |
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if (instances.isEmpty()) { |
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log.warn("[{}] 无可用服务实例", serviceId); |
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return new EmptyResponse(); |
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} |
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// 按配置优先级顺序遍历，找到第一个在健康列表中的实例
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for (String preferred : preferredOrder) { |
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// 按 roleOrder 顺序遍历，找到第一个匹配角色且健康的实例
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for (String role : roleOrder) { |
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for (ServiceInstance instance : instances) { |
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String key = instance.getHost() + ":" + instance.getPort(); |
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if (preferred.equals(key)) { |
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log.debug("[{}] 选择优先实例: {}, 健康实例数: {}", |
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serviceId, key, instances.size()); |
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String instanceRole = instance.getMetadata().get(METADATA_ROLE_KEY); |
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if (role.equals(instanceRole)) { |
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log.debug("[{}] 命中优先角色 [{}] -> {}:{} (metadata={})", |
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serviceId, role, instance.getHost(), instance.getPort(), instance.getMetadata()); |
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return new DefaultResponse(instance); |
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} |
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} |
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} |
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// 如果配置顺序中的实例都不在健康列表中（不应发生），取健康列表第一个
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// 兜底：所有优先角色都不健康，取列表首个健康实例
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ServiceInstance fallback = instances.get(0); |
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log.warn("[{}] 未匹配到配置优先级实例，回退使用: {}:{}", |
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serviceId, fallback.getHost(), fallback.getPort()); |
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log.warn("[{}] roleOrder={} 未匹配到任何健康实例，回退到首个健康实例 {}:{} (role={})", |
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serviceId, roleOrder, fallback.getHost(), fallback.getPort(), |
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fallback.getMetadata().get(METADATA_ROLE_KEY)); |
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return new DefaultResponse(fallback); |
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} |
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/** |
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* 从请求头 X-Preferred-Role-Order 提取角色优先级列表（逗号分隔） |
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*/ |
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private List<String> extractRoleOrder(Request<?> request) { |
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Object context = request.getContext(); |
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if (context instanceof RequestDataContext rdc) { |
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HttpHeaders headers = rdc.getClientRequest().getHeaders(); |
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if (headers != null) { |
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String raw = headers.getFirst(HEADER_ROLE_ORDER); |
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if (raw != null && !raw.isBlank()) { |
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return Arrays.stream(raw.split(",")) |
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.map(String::trim) |
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.filter(s -> !s.isEmpty()) |
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.toList(); |
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} |
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} |
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} |
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return Collections.emptyList(); |
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} |
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} |
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