Spring Cloud 2.2.2 源码之九Eureka服务端处理注册服务

大致流程图

服务端接受服务注册

ApplicationResource的addInstance用来接受客户端发来的POST请求：

主要的是最后的注册到注册表，第二个参数是表示是否要进行集群同步复制，因为如果是其他结点同步过来的信息，就不需要再同步给其他结点了，就重复了，如果是客户端发来的信息，那就要给其他节点同步了。

PeerAwareInstanceRegistryImpl的register

先进行注册，然后同步到其他结点。

    @Override
    public void register(final InstanceInfo info, final boolean isReplication) {
        int leaseDuration = Lease.DEFAULT_DURATION_IN_SECS;
        if (info.getLeaseInfo() != null && info.getLeaseInfo().getDurationInSecs() > 0) {
            leaseDuration = info.getLeaseInfo().getDurationInSecs();
        }
        super.register(info, leaseDuration, isReplication);
        replicateToPeers(Action.Register, info.getAppName(), info.getId(), info, null, isReplication);//同步给其他结点
    }

AbstractInstanceRegistry的register

首先看注册表有没有，没有的话就创建一个，然后获取是否有相同的实例在了，有的话就进行数据的更新，然后创建一个新的续约，更新事件，最后让读写缓存失效。

public void register(InstanceInfo registrant, int leaseDuration, boolean isReplication) {
        try {
            read.lock();
            Map<String, Lease<InstanceInfo>> gMap = registry.get(registrant.getAppName());//注册表获取
            REGISTER.increment(isReplication);
            if (gMap == null) {//第一次为空
                final ConcurrentHashMap<String, Lease<InstanceInfo>> gNewMap = new ConcurrentHashMap<String, Lease<InstanceInfo>>();
                gMap = registry.putIfAbsent(registrant.getAppName(), gNewMap);//不存在就放入gNewMap
                if (gMap == null) {//没映射
                    gMap = gNewMap;
                }
            }
            Lease<InstanceInfo> existingLease = gMap.get(registrant.getId());//获取实例id对应的租约信息
            // Retain the last dirty timestamp without overwriting it, if there is already a lease
            if (existingLease != null && (existingLease.getHolder() != null)) {//存在的话
                Long existingLastDirtyTimestamp = existingLease.getHolder().getLastDirtyTimestamp();
                Long registrationLastDirtyTimestamp = registrant.getLastDirtyTimestamp();
                logger.debug("Existing lease found (existing={}, provided={}", existingLastDirtyTimestamp, registrationLastDirtyTimestamp);

                // this is a > instead of a >= because if the timestamps are equal, we still take the remote transmitted
                // InstanceInfo instead of the server local copy.
                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();//取最新的
                }
            } else {
                // The lease does not exist and hence it is a new registration
                synchronized (lock) {//更新续约数量，注册一个新的实例
                    if (this.expectedNumberOfClientsSendingRenews > 0) {
                        // Since the client wants to register it, increase the number of clients sending renews
                        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);//创建租约
            if (existingLease != null) {
                lease.setServiceUpTimestamp(existingLease.getServiceUpTimestamp());
            }
            gMap.put(registrant.getId(), lease);//放进实例名和租约的映射集合
            recentRegisteredQueue.add(new Pair<Long, String>(
                    System.currentTimeMillis(),
                    registrant.getAppName() + "(" + registrant.getId() + ")"));//加入到租约注册队列中
            // This is where the initial state transfer of overridden status happens
            if (!InstanceStatus.UNKNOWN.equals(registrant.getOverriddenStatus())) {//覆盖信息不为unknow的要添加到overriddenInstanceStatusMap
                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);//设置覆盖信息
            }

            // Set the status based on the overridden status rules
            InstanceStatus overriddenInstanceStatus = getOverriddenInstanceStatus(registrant, existingLease, isReplication);
            registrant.setStatusWithoutDirty(overriddenInstanceStatus);

            // If the lease is registered with UP status, set lease service up timestamp
            if (InstanceStatus.UP.equals(registrant.getStatus())) {
                lease.serviceUp();//记录启动时间
            }
            registrant.setActionType(ActionType.ADDED);//标记为添加
            recentlyChangedQueue.add(new RecentlyChangedItem(lease));
            registrant.setLastUpdatedTimestamp();//设置最后更新时间
            invalidateCache(registrant.getAppName(), registrant.getVIPAddress(), registrant.getSecureVipAddress());//失效缓存
            logger.info("Registered instance {}/{} with status {} (replication={})",
                    registrant.getAppName(), registrant.getId(), registrant.getStatus(), isReplication);
        } finally {
            read.unlock();
        }
    }

invalidateCache失效缓存

缓存是存在在ResponseCache中的。

失效很多中缓存，比如增量，全量，服务等。

这些信息都存在读写锁里readWriteCacheMap，这个是一个谷歌缓存框架提供的类：

PeerAwareInstanceRegistryImpl的replicateToPeers

会同步到除去自己的其他结点中，最后调用replicateInstanceActionsToPeers：

放在一个批处理的处理器当中发送，最后还是jersey去完成发送：

好了，今天就到这里了，希望对学习理解有帮助，大神看见勿喷，仅为自己的学习理解，能力有限，请多包涵。