程序员保护协会

public interface Valve {
  public Valve getNext();
  public void setNext(Valve valve);
  public void invoke(Request request, Response response)
}

* Because TreeNodes are about twice the size of regular nodes, we
* use them only when bins contain enough nodes to warrant use
* (see TREEIFY_THRESHOLD). And when they become too small (due to
* removal or resizing) they are converted back to plain bins.  In
* usages with well-distributed user hashCodes, tree bins are
* rarely used.  Ideally, under random hashCodes, the frequency of
* nodes in bins follows a Poisson distribution
* (http://en.wikipedia.org/wiki/Poisson_distribution) with a
* parameter of about 0.5 on average for the default resizing
* threshold of 0.75, although with a large variance because of
* resizing granularity. Ignoring variance, the expected
* occurrences of list size k are (exp(-0.5) * pow(0.5, k) /
* factorial(k)). The first values are:
*
* 0:    0.60653066
* 1:    0.30326533
* 2:    0.07581633
* 3:    0.01263606
* 4:    0.00157952
* 5:    0.00015795
* 6:    0.00001316
* 7:    0.00000094
* 8:    0.00000006
* more: less than 1 in ten million

static final int hash(Object key) {
    int h;
    return (key == null) ? 0 : (h = key.hashCode()) ^ (h >>> 16);
}

static final int hash(Object key) {
        int h;
        return (key == null) ? 0 : (h = key.hashCode()) ^ (h >>> 16);
    }

System.out.println((129/128) ==(129 & 127));

static final int hash(Object key) {
        int h;
        return (key == null) ? 0 : (h = key.hashCode()) ^ (h >>> 16);
    }

public class TowSum {

    public int[] twoSum(int[] nums, int target) {
        Map<Integer, Integer> map = new HashMap<>();
        for (int i = 0; i < nums.length; i++) {
            int j = target - nums[i];
            if (map.containsKey(j)) {
                return new int[]{map.get(j), i};
            }
            map.put(nums[i], i);
        }
        return null;
    }
}

private void initScheduledTasks() {
      // 如果允许获取注册信息,那么拉取注册信息到本地
        if (clientConfig.shouldFetchRegistry()) {
            // registry cache refresh timer
            int registryFetchIntervalSeconds = clientConfig.getRegistryFetchIntervalSeconds();
            int expBackOffBound = clientConfig.getCacheRefreshExecutorExponentialBackOffBound();
            scheduler.schedule(
                    new TimedSupervisorTask(
                            "cacheRefresh",
                            scheduler,
                            cacheRefreshExecutor,
                            registryFetchIntervalSeconds,
                            TimeUnit.SECONDS,
                            expBackOffBound,
                            new CacheRefreshThread()
                    ),
                    registryFetchIntervalSeconds, TimeUnit.SECONDS);
        }

 //如果允许注册到eureka，
        if (clientConfig.shouldRegisterWithEureka()) {
            int renewalIntervalInSecs = instanceInfo.getLeaseInfo().getRenewalIntervalInSecs();
            int expBackOffBound = clientConfig.getHeartbeatExecutorExponentialBackOffBound();
            logger.info("Starting heartbeat executor: " + "renew interval is: " + renewalIntervalInSecs);

//定时续约
            // Heartbeat timer
            scheduler.schedule(
                    new TimedSupervisorTask(
                            "heartbeat",
                            scheduler,
                            heartbeatExecutor,
                            renewalIntervalInSecs,
                            TimeUnit.SECONDS,
                            expBackOffBound,
                            new HeartbeatThread()
                    ),
                    renewalIntervalInSecs, TimeUnit.SECONDS);

            // InstanceInfo replicator
            instanceInfoReplicator = new InstanceInfoReplicator(
                    this,
                    instanceInfo,
                    clientConfig.getInstanceInfoReplicationIntervalSeconds(),
                    2); // burstSize

            statusChangeListener = new ApplicationInfoManager.StatusChangeListener() {
                @Override
                public String getId() {
                    return "statusChangeListener";
                }

                @Override
                public void notify(StatusChangeEvent statusChangeEvent) {
                    if (InstanceStatus.DOWN == statusChangeEvent.getStatus() ||
                            InstanceStatus.DOWN == statusChangeEvent.getPreviousStatus()) {
                        // log at warn level if DOWN was involved
                        logger.warn("Saw local status change event {}", statusChangeEvent);
                    } else {
                        logger.info("Saw local status change event {}", statusChangeEvent);
                    }
                    instanceInfoReplicator.onDemandUpdate();
                }
            };

            if (clientConfig.shouldOnDemandUpdateStatusChange()) {
                applicationInfoManager.registerStatusChangeListener(statusChangeListener);
            }

           
//注册	         instanceInfoReplicator.start(clientConfig.getInitialInstanceInfoReplicationIntervalSeconds());
        } else {
            logger.info("Not registering with Eureka server per configuration");
        }
    }

public synchronized void shutdown() {
        if (isShutdown.compareAndSet(false, true)) {
            logger.info("Shutting down DiscoveryClient ...");

            if (statusChangeListener != null && applicationInfoManager != null) {
                applicationInfoManager.unregisterStatusChangeListener(statusChangeListener.getId());
            }

            cancelScheduledTasks();

            // If APPINFO was registered
            if (applicationInfoManager != null && clientConfig.shouldRegisterWithEureka()) {
                applicationInfoManager.setInstanceStatus(InstanceStatus.DOWN);
                unregister();
            }

            if (eurekaTransport != null) {
                eurekaTransport.shutdown();
            }

            heartbeatStalenessMonitor.shutdown();
            registryStalenessMonitor.shutdown();

            logger.info("Completed shut down of DiscoveryClient");
        }
    }