微服务笔记之Eureka03(服务注册分析)

服务注册接口源码分析：

com.netflix.eureka.resources.ApplicationResource#addInstance

public Response addInstance(InstanceInfo info,
                                @HeaderParam(PeerEurekaNode.HEADER_REPLICATION) String isReplication) {
	//注册
        registry.register(info, "true".equals(isReplication));
        return Response.status(204).build();  // 204 to be backwards compatible
}

com.netflix.eureka.registry.PeerAwareInstanceRegistryImpl#register

public void register(final InstanceInfo info, final boolean isReplication) {
	// 心跳检测周期默认90s
        int leaseDuration = Lease.DEFAULT_DURATION_IN_SECS;
    	// 配置文件设置该时间，就用配置文件的设置时间
	if (info.getLeaseInfo() != null && info.getLeaseInfo().getDurationInSecs() > 0) {
            leaseDuration = info.getLeaseInfo().getDurationInSecs();
        }
	// 调用父方法
        super.register(info, leaseDuration, isReplication);
    	// 复制到集群其他节点
	replicateToPeers(Action.Register, info.getAppName(), info.getId(), info, null, isReplication);
}

com.netflix.eureka.registry.AbstractInstanceRegistry#register

public void register(InstanceInfo registrant, int leaseDuration, boolean isReplication) {
        try {
            read.lock();
	    // 从注册表中获取实例信息
            Map<String, Lease<InstanceInfo>> gMap = registry.get(registrant.getAppName());
            REGISTER.increment(isReplication);
	    // 第一次注册时，gMap是null
            if (gMap == null) {
		// 定义一个Map
                final ConcurrentHashMap<String, Lease<InstanceInfo>> gNewMap = new ConcurrentHashMap<String, Lease<InstanceInfo>>();
		// 进行put操作
                gMap = registry.putIfAbsent(registrant.getAppName(), gNewMap);
                if (gMap == null) {
                    gMap = gNewMap;
                }
            }
	    // 根据实例ID获取注册信息，第一次注册获取为空
            Lease<InstanceInfo> existingLease = gMap.get(registrant.getId());
            // 不为空，说明已注册但实例信息发生变化
            if (existingLease != null && (existingLease.getHolder() != null)) {
                Long existingLastDirtyTimestamp = existingLease.getHolder().getLastDirtyTimestamp();
                Long registrationLastDirtyTimestamp = registrant.getLastDirtyTimestamp();
                logger.debug("Existing lease found (existing={}, provided={}", existingLastDirtyTimestamp, registrationLastDirtyTimestamp);

                //
                if (existingLastDirtyTimestamp > registrationLastDirtyTimestamp) {
                    logger.warn("There is an existing lease and the existing lease's dirty timestamp {} is greater" +
                            " than the one that is being registered {}", existingLastDirtyTimestamp, registrationLastDirtyTimestamp);
                    logger.warn("Using the existing instanceInfo instead of the new instanceInfo as the registrant");
                    registrant = existingLease.getHolder();
                }
            } else {
                // 该租约不存在，因此它是一个新的注册
                synchronized (lock) {
                    if (this.expectedNumberOfClientsSendingRenews > 0) {
                        // 因为客户机想要注册它，所以要增加发送更新的客户机的数量
                        this.expectedNumberOfClientsSendingRenews = this.expectedNumberOfClientsSendingRenews + 1;
                        updateRenewsPerMinThreshold();
                    }
                }
                logger.debug("No previous lease information found; it is new registration");
            }
            Lease<InstanceInfo> lease = new Lease<InstanceInfo>(registrant, leaseDuration);
            if (existingLease != null) {
                lease.setServiceUpTimestamp(existingLease.getServiceUpTimestamp());
            }
	    // 将实例信息加入map中
            gMap.put(registrant.getId(), lease);
            synchronized (recentRegisteredQueue) {
                recentRegisteredQueue.add(new Pair<Long, String>(
                        System.currentTimeMillis(),
                        registrant.getAppName() + "(" + registrant.getId() + ")"));
            }
            // 更新状态信息
            if (!InstanceStatus.UNKNOWN.equals(registrant.getOverriddenStatus())) {
                logger.debug("Found overridden status {} for instance {}. Checking to see if needs to be add to the "
                                + "overrides", registrant.getOverriddenStatus(), registrant.getId());
                if (!overriddenInstanceStatusMap.containsKey(registrant.getId())) {
                    logger.info("Not found overridden id {} and hence adding it", registrant.getId());
                    overriddenInstanceStatusMap.put(registrant.getId(), registrant.getOverriddenStatus());
                }
            }
            InstanceStatus overriddenStatusFromMap = overriddenInstanceStatusMap.get(registrant.getId());
            if (overriddenStatusFromMap != null) {
                logger.info("Storing overridden status {} from map", overriddenStatusFromMap);
                registrant.setOverriddenStatus(overriddenStatusFromMap);
            }

            InstanceStatus overriddenInstanceStatus = getOverriddenInstanceStatus(registrant, existingLease, isReplication);
            registrant.setStatusWithoutDirty(overriddenInstanceStatus);

            if (InstanceStatus.UP.equals(registrant.getStatus())) {
                lease.serviceUp();
            }
            registrant.setActionType(ActionType.ADDED);
            recentlyChangedQueue.add(new RecentlyChangedItem(lease));
            registrant.setLastUpdatedTimestamp();
            invalidateCache(registrant.getAppName(), registrant.getVIPAddress(), registrant.getSecureVipAddress());
            logger.info("Registered instance {}/{} with status {} (replication={})",
                    registrant.getAppName(), registrant.getId(), registrant.getStatus(), isReplication);
        } finally {
            read.unlock();
        }
    }

com.netflix.eureka.registry.PeerAwareInstanceRegistryImpl#replicateToPeers

将注册信息同步到集群中其他节点

private void replicateToPeers(Action action, String appName, String id,
                                  InstanceInfo info /* optional */,
                                  InstanceStatus newStatus /* optional */, boolean isReplication) {
        Stopwatch tracer = action.getTimer().start();
        try {
            if (isReplication) {
                numberOfReplicationsLastMin.increment();
            }
            // 如果它已经是一个复制，不要再次复制
            if (peerEurekaNodes == Collections.EMPTY_LIST || isReplication) {
                return;
            }

            for (final PeerEurekaNode node : peerEurekaNodes.getPeerEurekaNodes()) {
                // 如果url表示此主机，则不要复制到自己.
                if (peerEurekaNodes.isThisMyUrl(node.getServiceUrl())) {
                    continue;
                }
		// 复制操作
                replicateInstanceActionsToPeers(action, appName, id, info, newStatus, node);
            }
        } finally {
            tracer.stop();
        }
    }

com.netflix.eureka.registry.PeerAwareInstanceRegistryImpl#replicateInstanceActionsToPeers

复制操作

private void replicateInstanceActionsToPeers(Action action, String appName,
                                                 String id, InstanceInfo info, InstanceStatus newStatus,
                                                 PeerEurekaNode node) {
        try {
            InstanceInfo infoFromRegistry = null;
            CurrentRequestVersion.set(Version.V2);
            switch (action) {
                case Cancel: // 下线
                    node.cancel(appName, id);
                    break;
                case Heartbeat://心跳
                    InstanceStatus overriddenStatus = overriddenInstanceStatusMap.get(id);
                    infoFromRegistry = getInstanceByAppAndId(appName, id, false);
                    node.heartbeat(appName, id, infoFromRegistry, overriddenStatus, false);
                    break;
                case Register://注册
                    node.register(info);
                    break;
                case StatusUpdate:// 状态更新
                    infoFromRegistry = getInstanceByAppAndId(appName, id, false);
                    node.statusUpdate(appName, id, newStatus, infoFromRegistry);
                    break;
                case DeleteStatusOverride:
                    infoFromRegistry = getInstanceByAppAndId(appName, id, false);
                    node.deleteStatusOverride(appName, id, infoFromRegistry);
                    break;
            }
        } catch (Throwable t) {
            logger.error("Cannot replicate information to {} for action {}", node.getServiceUrl(), action.name(), t);
        }
    }