eureka服務下架、服務續期及eureka源碼分析

 

服務下架

如上圖所示一路debug走InstanceRegistry(發佈事件)——>AbstractInstanceRegistry（真正操作）——>PeerAwareInstanceRegistryImpl（集羣同步），設計採取責任鏈模式遵循單一職責原則.

InstanceResource #cancelLease()
——>InstanceRegistry#cancel發佈事件EurekaInstanceCanceledEvent
——>AbstractInstanceRegistry#cancel 真正進行服務下架操作
——>PeerAwareInstanceRegistryImpl#cancel 集羣同步

 

真正進行服務下架操作

protected boolean internalCancel(String appName, String id, boolean isReplication) {
        try {
            read.lock();
            CANCEL.increment(isReplication);
            //從registry拿到appName的微服務組
            Map<String, Lease<InstanceInfo>> gMap = registry.get(appName);
            Lease<InstanceInfo> leaseToCancel = null;
            if (gMap != null) {
                //從appName的微服務組拿到id的微服務實例
                leaseToCancel = gMap.remove(id);
            }
            synchronized (recentCanceledQueue) {
                 //最近下架的微服務的queue
                recentCanceledQueue.add(new Pair<Long, String>(System.currentTimeMillis(), appName + "(" + id + ")"));
            }
            InstanceStatus instanceStatus = overriddenInstanceStatusMap.remove(id);
            if (instanceStatus != null) {
                logger.debug("Removed instance id {} from the overridden map which has value {}", id, instanceStatus.name());
            }
            if (leaseToCancel == null) {
                //下架失敗
                CANCEL_NOT_FOUND.increment(isReplication);
                logger.warn("DS: Registry: cancel failed because Lease is not registered for: {}/{}", appName, id);
                return false;
            } else {
                //調用lease的cancel記錄evictionTimestamp
                leaseToCancel.cancel();
                //微服務實例
                InstanceInfo instanceInfo = leaseToCancel.getHolder();
                String vip = null;
                String svip = null;
                if (instanceInfo != null) {
                    //設置微服務狀態delete
                    instanceInfo.setActionType(ActionType.DELETED);
                    //近三分鐘發生改動的微服務的queue，用於增量更新使用返回給客戶端
                    recentlyChangedQueue.add(new RecentlyChangedItem(leaseToCancel));
                    //最後更新的時間戳
                    instanceInfo.setLastUpdatedTimestamp();
                    vip = instanceInfo.getVIPAddress();
                    svip = instanceInfo.getSecureVipAddress();
                }

                // 更新緩存數據
                invalidateCache(appName, vip, svip);
                logger.info("Cancelled instance {}/{} (replication={})", appName, id, isReplication);
                return true;
            }
        } finally {
            read.unlock();
        }
    }

 

 

服務續期

 

一樣是發佈事件，續期操作，集羣同步，這裏只看續期最低層方法renew

   public boolean renew(String appName, String id, boolean isReplication) {
        RENEW.increment(isReplication);
//從registry拿到appName的微服務組
        Map<String, Lease<InstanceInfo>> gMap = registry.get(appName);
        Lease<InstanceInfo> leaseToRenew = null;
        if (gMap != null) {
        //從appName的微服務組拿到id的微服務實例
            leaseToRenew = gMap.get(id);
        }
        //續期失敗
        if (leaseToRenew == null) {
            RENEW_NOT_FOUND.increment(isReplication);
            logger.warn("DS: Registry: lease doesn't exist, registering resource: {} - {}", appName, id);
            return false;
        } else {
            //微服務實例
            InstanceInfo instanceInfo = leaseToRenew.getHolder();
            if (instanceInfo != null) {
                // touchASGCache(instanceInfo.getASGName());
                InstanceStatus overriddenInstanceStatus = this.getOverriddenInstanceStatus(
                        instanceInfo, leaseToRenew, isReplication);
                if (overriddenInstanceStatus == InstanceStatus.UNKNOWN) {
                    logger.info("Instance status UNKNOWN possibly due to deleted override for instance {}"
                            + "; re-register required", instanceInfo.getId());
                    RENEW_NOT_FOUND.increment(isReplication);
                    return false;
                }
                if (!instanceInfo.getStatus().equals(overriddenInstanceStatus)) {
                    logger.info(
                            "The instance status {} is different from overridden instance status {} for instance {}. "
                                    + "Hence setting the status to overridden status", instanceInfo.getStatus().name(),
                                    instanceInfo.getOverriddenStatus().name(),
                                    instanceInfo.getId());
                    instanceInfo.setStatusWithoutDirty(overriddenInstanceStatus);

                }
            }
            
            renewsLastMin.increment();
            //執行lease的renew進行續期
            leaseToRenew.renew();
            return true;
        }
    }

總結

服務下架：發佈下架事件，下架操作gMap.remove,lease.cancel, 集羣同步
服務續期：發佈續期事件，續期操作lease.renew，集羣同步