SpringCloudRibbon（六）之服务实例过滤器ServerListFilter

一、服务实例过滤器ServerListFilter

服务实例过滤器&＃xff08;ServerListFilter&＃xff09;为负载均衡器&＃xff08;Loadbalancer&＃xff09;提供从服务实例列表&＃xff08;ServerList&＃xff09;获取的服务实例过滤出符合要求的服务实例。

负载均衡器&＃xff08;Loadbalancer&＃xff09;通过服务实例列表&＃xff08;ServerList&＃xff09;从注册中心&＃xff08;register&＃xff09;或者配置文件&＃xff08;yaml或properties&＃xff09;上读取全部服务实例&＃xff08;server&＃xff09;&＃xff0c;然后以服务实例过滤器&＃xff08;ServerListFilter&＃xff09;的过滤方式进行筛选留下满足条件的服务实例&＃xff0c;进而借助负载均衡策略&＃xff08;IRule&＃xff09;选择出一个合适的服务实例。

二、ServerListFilter实现类

ZoneAffinityServerListFilter     区区域相关性筛选服务实例列表过滤器

ZonePreferenceServerListFilter  首选本地区域服务实例列表过滤器

ServerListSubsetFilter   服务实例数限制为所有服务实例的子集 筛选过滤器

三、具体代码实现

&＃xff08;1&＃xff09;ZoneAffinityServerListFilter 

public class ZoneAffinityServerListFilter extendsAbstractServerListFilter implements IClientConfigAware {private volatile boolean zoneAffinity &＃61; DefaultClientConfigImpl.DEFAULT_ENABLE_ZONE_AFFINITY;private volatile boolean zoneExclusive &＃61; DefaultClientConfigImpl.DEFAULT_ENABLE_ZONE_EXCLUSIVITY;private DynamicDoubleProperty activeReqeustsPerServerThreshold;private DynamicDoubleProperty blackOutServerPercentageThreshold;private DynamicIntProperty availableServersThreshold;private Counter overrideCounter;private ZoneAffinityPredicate zoneAffinityPredicate &＃61; new ZoneAffinityPredicate();private static Logger logger &＃61; LoggerFactory.getLogger(ZoneAffinityServerListFilter.class);String zone;public ZoneAffinityServerListFilter() { }public ZoneAffinityServerListFilter(IClientConfig niwsClientConfig) {initWithNiwsConfig(niwsClientConfig);}&＃64;Overridepublic void initWithNiwsConfig(IClientConfig niwsClientConfig) {String sZoneAffinity &＃61; "" &＃43; niwsClientConfig.getProperty(CommonClientConfigKey.EnableZoneAffinity, false);if (sZoneAffinity !&＃61; null){zoneAffinity &＃61; Boolean.parseBoolean(sZoneAffinity);logger.debug("ZoneAffinity is set to {}", zoneAffinity);}String sZoneExclusive &＃61; "" &＃43; niwsClientConfig.getProperty(CommonClientConfigKey.EnableZoneExclusivity, false);if (sZoneExclusive !&＃61; null){zoneExclusive &＃61; Boolean.parseBoolean(sZoneExclusive);}if (ConfigurationManager.getDeploymentContext() !&＃61; null) {zone &＃61; ConfigurationManager.getDeploymentContext().getValue(ContextKey.zone);}activeReqeustsPerServerThreshold &＃61; DynamicPropertyFactory.getInstance().getDoubleProperty(niwsClientConfig.getClientName() &＃43; "." &＃43; niwsClientConfig.getNameSpace() &＃43; ".zoneAffinity.maxLoadPerServer", 0.6d);logger.debug("activeReqeustsPerServerThreshold: {}", activeReqeustsPerServerThreshold.get());blackOutServerPercentageThreshold &＃61; DynamicPropertyFactory.getInstance().getDoubleProperty(niwsClientConfig.getClientName() &＃43; "." &＃43; niwsClientConfig.getNameSpace() &＃43; ".zoneAffinity.maxBlackOutServesrPercentage", 0.8d);logger.debug("blackOutServerPercentageThreshold: {}", blackOutServerPercentageThreshold.get());availableServersThreshold &＃61; DynamicPropertyFactory.getInstance().getIntProperty(niwsClientConfig.getClientName() &＃43; "." &＃43; niwsClientConfig.getNameSpace() &＃43; ".zoneAffinity.minAvailableServers", 2);logger.debug("availableServersThreshold: {}", availableServersThreshold.get());overrideCounter &＃61; Monitors.newCounter("ZoneAffinity_OverrideCounter");Monitors.registerObject("NIWSServerListFilter_" &＃43; niwsClientConfig.getClientName());}private boolean shouldEnableZoneAffinity(List filtered) { if (!zoneAffinity && !zoneExclusive) {return false;}if (zoneExclusive) {return true;}LoadBalancerStats stats &＃61; getLoadBalancerStats();if (stats &＃61;&＃61; null) {return zoneAffinity;} else {logger.debug("Determining if zone affinity should be enabled with given server list: {}", filtered);ZoneSnapshot snapshot &＃61; stats.getZoneSnapshot(filtered);double loadPerServer &＃61; snapshot.getLoadPerServer();int instanceCount &＃61; snapshot.getInstanceCount(); int circuitBreakerTrippedCount &＃61; snapshot.getCircuitTrippedCount();if (((double) circuitBreakerTrippedCount) / instanceCount >&＃61; blackOutServerPercentageThreshold.get() || loadPerServer >&＃61; activeReqeustsPerServerThreshold.get()|| (instanceCount - circuitBreakerTrippedCount) getFilteredListOfServers(List servers) {if (zone !&＃61; null && (zoneAffinity || zoneExclusive) && servers !&＃61;null && servers.size() > 0){List filteredServers &＃61; Lists.newArrayList(Iterables.filter(servers, this.zoneAffinityPredicate.getServerOnlyPredicate()));if (shouldEnableZoneAffinity(filteredServers)) {return filteredServers;} else if (zoneAffinity) {overrideCounter.increment();}}return servers;}&＃64;Overridepublic String toString(){StringBuilder sb &＃61; new StringBuilder("ZoneAffinityServerListFilter:");sb.append(", zone: ").append(zone).append(", zoneAffinity:").append(zoneAffinity);sb.append(", zoneExclusivity:").append(zoneExclusive);return sb.toString(); }
}

&＃xff08;2&＃xff09;ZonePreferenceServerListFilter

public class ZonePreferenceServerListFilter extends ZoneAffinityServerListFilter {private String zone;&＃64;Overridepublic void initWithNiwsConfig(IClientConfig niwsClientConfig) {super.initWithNiwsConfig(niwsClientConfig);if (ConfigurationManager.getDeploymentContext() !&＃61; null) {this.zone &＃61; ConfigurationManager.getDeploymentContext().getValue(ContextKey.zone);}}&＃64;Overridepublic List getFilteredListOfServers(List servers) {List output &＃61; super.getFilteredListOfServers(servers);if (this.zone !&＃61; null && output.size() &＃61;&＃61; servers.size()) {List local &＃61; new ArrayList<>();for (Server server : output) {if (this.zone.equalsIgnoreCase(server.getZone())) {local.add(server);}}if (!local.isEmpty()) {return local;}}return output;}public String getZone() {return zone;}public void setZone(String zone) {this.zone &＃61; zone;}&＃64;Overridepublic boolean equals(Object o) {if (this &＃61;&＃61; o) {return true;}if (o &＃61;&＃61; null || getClass() !&＃61; o.getClass()) {return false;}ZonePreferenceServerListFilter that &＃61; (ZonePreferenceServerListFilter) o;return Objects.equals(zone, that.zone);}&＃64;Overridepublic int hashCode() {return Objects.hash(zone);}&＃64;Overridepublic String toString() {return new StringBuilder("ZonePreferenceServerListFilter{").append("zone&＃61;&＃39;").append(zone).append("&＃39;").append("}").toString();}}

&＃xff08;3&＃xff09;ServerListSubsetFilter 

public class ServerListSubsetFilter extends ZoneAffinityServerListFilter implements IClientConfigAware, Comparator{private Random random &＃61; new Random();private volatile Set currentSubset &＃61; Sets.newHashSet(); private DynamicIntProperty sizeProp &＃61; new DynamicIntProperty(DefaultClientConfigImpl.DEFAULT_PROPERTY_NAME_SPACE &＃43; ".ServerListSubsetFilter.size", 20);private DynamicFloatProperty eliminationPercent &＃61; new DynamicFloatProperty(DefaultClientConfigImpl.DEFAULT_PROPERTY_NAME_SPACE &＃43; ".ServerListSubsetFilter.forceEliminatePercent", 0.1f);private DynamicIntProperty eliminationFailureCountThreshold &＃61; new DynamicIntProperty(DefaultClientConfigImpl.DEFAULT_PROPERTY_NAME_SPACE &＃43; ".ServerListSubsetFilter.eliminationFailureThresold", 0);private DynamicIntProperty eliminationConnectionCountThreshold &＃61; new DynamicIntProperty(DefaultClientConfigImpl.DEFAULT_PROPERTY_NAME_SPACE &＃43; ".ServerListSubsetFilter.eliminationConnectionThresold", 0);&＃64;Overridepublic void initWithNiwsConfig(IClientConfig clientConfig) {super.initWithNiwsConfig(clientConfig);sizeProp &＃61; new DynamicIntProperty(clientConfig.getClientName() &＃43; "." &＃43; clientConfig.getNameSpace() &＃43; ".ServerListSubsetFilter.size", 20);eliminationPercent &＃61; new DynamicFloatProperty(clientConfig.getClientName() &＃43; "." &＃43; clientConfig.getNameSpace() &＃43; ".ServerListSubsetFilter.forceEliminatePercent", 0.1f);eliminationFailureCountThreshold &＃61; new DynamicIntProperty( clientConfig.getClientName() &＃43; "." &＃43; clientConfig.getNameSpace()&＃43; ".ServerListSubsetFilter.eliminationFailureThresold", 0);eliminationConnectionCountThreshold &＃61; new DynamicIntProperty(clientConfig.getClientName() &＃43; "." &＃43; clientConfig.getNameSpace()&＃43; ".ServerListSubsetFilter.eliminationConnectionThresold", 0);}/*** Given all the servers, keep only a stable subset of servers to use. This method* keeps the current list of subset in use and keep returning the same list, with exceptions* to relatively unhealthy servers, which are defined as the following:*

*

*
• Servers with their concurrent connection count exceeding the client configuration for * {&＃64;code ..ServerListSubsetFilter.eliminationConnectionThresold} (default is 0)*
• Servers with their failure count exceeding the client configuration for * {&＃64;code ..ServerListSubsetFilter.eliminationFailureThresold} (default is 0)*
• If the servers evicted above is less than the forced eviction percentage as defined by client configuration* {&＃64;code ..ServerListSubsetFilter.forceEliminatePercent} (default is 10%, or 0.1), the* remaining servers will be sorted by their health status and servers will worst health status will be* forced evicted.*

* After the elimination, new servers will be randomly chosen from all servers pool to keep the* number of the subset unchanged. * */&＃64;Overridepublic List getFilteredListOfServers(List servers) {List zoneAffinityFiltered &＃61; super.getFilteredListOfServers(servers);Set candidates &＃61; Sets.newHashSet(zoneAffinityFiltered);Set newSubSet &＃61; Sets.newHashSet(currentSubset);LoadBalancerStats lbStats &＃61; getLoadBalancerStats();for (T server: currentSubset) {// this server is either down or out of serviceif (!candidates.contains(server)) {newSubSet.remove(server);} else {ServerStats stats &＃61; lbStats.getSingleServerStat(server);// remove the servers that do not meet health criteriaif (stats.getActiveRequestsCount() > eliminationConnectionCountThreshold.get()|| stats.getFailureCount() > eliminationFailureCountThreshold.get()) {newSubSet.remove(server);// also remove from the general pool to avoid selecting them againcandidates.remove(server);}}}int targetedListSize &＃61; sizeProp.get();int numEliminated &＃61; currentSubset.size() - newSubSet.size();int minElimination &＃61; (int) (targetedListSize * eliminationPercent.get());int numToForceEliminate &＃61; 0;if (targetedListSize numEliminated) {numToForceEliminate &＃61; minElimination - numEliminated; }if (numToForceEliminate > newSubSet.size()) {numToForceEliminate &＃61; newSubSet.size();}if (numToForceEliminate > 0) {List sortedSubSet &＃61; Lists.newArrayList(newSubSet); Collections.sort(sortedSubSet, this);List forceEliminated &＃61; sortedSubSet.subList(0, numToForceEliminate);newSubSet.removeAll(forceEliminated);candidates.removeAll(forceEliminated);}// after forced elimination or elimination of unhealthy instances,// the size of the set may be less than the targeted size,// then we just randomly add servers from the big poolif (newSubSet.size() candidates.size()) {// Not enough healthy instances to choose, fallback to use the// total server poolcandidates &＃61; Sets.newHashSet(zoneAffinityFiltered);candidates.removeAll(newSubSet);}List chosen &＃61; randomChoose(Lists.newArrayList(candidates), numToChoose);for (T server: chosen) {newSubSet.add(server);}}currentSubset &＃61; newSubSet; return Lists.newArrayList(newSubSet); }/*** Randomly shuffle the beginning portion of server list (according to the number passed into the method) * and return them.* * &＃64;param servers* &＃64;param toChoose* &＃64;return*/private List randomChoose(List servers, int toChoose) {int size &＃61; servers.size();if (toChoose >&＃61; size || toChoose <0) {return servers;} for (int i &＃61; 0; i }