server push java_聊聊nacos server的PushService
序
本文主要研究一下nacos server的PushService
PushService
nacos-1.1.3/naming/src/main/java/com/alibaba/nacos/naming/push/PushService.java
@Component
public class PushService implements ApplicationContextAware, ApplicationListener {
@Autowired
private SwitchDomain switchDomain;
private ApplicationContext applicationContext;
private static final long ACK_TIMEOUT_NANOS = TimeUnit.SECONDS.toNanos(10L);
private static final int MAX_RETRY_TIMES = 1;
private static volatile ConcurrentMap ackMap
= new ConcurrentHashMap();
private static ConcurrentMap> clientMap
= new ConcurrentHashMap>();
private static volatile ConcurrentHashMap udpSendTimeMap = new ConcurrentHashMap();
public static volatile ConcurrentHashMap pushCostMap = new ConcurrentHashMap();
private static int totalPush = 0;
private static int failedPush = 0;
private static ConcurrentHashMap lastPushMillisMap = new ConcurrentHashMap<>();
private static DatagramSocket udpSocket;
private static Map futureMap = new ConcurrentHashMap<>();
private static ScheduledExecutorService executorService = Executors.newSingleThreadScheduledExecutor(new ThreadFactory() {
@Override
public Thread newThread(Runnable r) {
Thread t = new Thread(r);
t.setDaemon(true);
t.setName("com.alibaba.nacos.naming.push.retransmitter");
return t;
}
});
private static ScheduledExecutorService udpSender = Executors.newSingleThreadScheduledExecutor(new ThreadFactory() {
@Override
public Thread newThread(Runnable r) {
Thread t = new Thread(r);
t.setDaemon(true);
t.setName("com.alibaba.nacos.naming.push.udpSender");
return t;
}
});
static {
try {
udpSocket = new DatagramSocket();
Receiver receiver = new Receiver();
Thread inThread = new Thread(receiver);
inThread.setDaemon(true);
inThread.setName("com.alibaba.nacos.naming.push.receiver");
inThread.start();
executorService.scheduleWithFixedDelay(new Runnable() {
@Override
public void run() {
try {
removeClientIfZombie();
} catch (Throwable e) {
Loggers.PUSH.warn("[NACOS-PUSH] failed to remove client zombie");
}
}
}, 0, 20, TimeUnit.SECONDS);
} catch (SocketException e) {
Loggers.SRV_LOG.error("[NACOS-PUSH] failed to init push service");
}
}
@Override
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
this.applicationContext = applicationContext;
}
//......
public static void removeClientIfZombie() {
int size = 0;
for (Map.Entry> entry : clientMap.entrySet()) {
ConcurrentMap clientConcurrentMap = entry.getValue();
for (Map.Entry entry1 : clientConcurrentMap.entrySet()) {
PushClient client = entry1.getValue();
if (client.zombie()) {
clientConcurrentMap.remove(entry1.getKey());
}
}
size += clientConcurrentMap.size();
}
if (Loggers.PUSH.isDebugEnabled()) {
Loggers.PUSH.debug("[NACOS-PUSH] clientMap size: {}", size);
}
}
//......
}
PushService实现了ApplicationContextAware、ApplicationListener接口；它有两个ScheduledExecutorService，一个用于retransmitter，一个用于udpSender；其static代码块创建了一个deamon线程执行Receiver，同时注册了一个定时任务执行removeClientIfZombie，它会遍历clientMap，移除zombie的client
Receiver
nacos-1.1.3/naming/src/main/java/com/alibaba/nacos/naming/push/PushService.java
public static class Receiver implements Runnable {
@Override
public void run() {
while (true) {
byte[] buffer = new byte[1024 * 64];
DatagramPacket packet = new DatagramPacket(buffer, buffer.length);
try {
udpSocket.receive(packet);
String json = new String(packet.getData(), 0, packet.getLength(), Charset.forName("UTF-8")).trim();
AckPacket ackPacket = JSON.parseObject(json, AckPacket.class);
InetSocketAddress socketAddress = (InetSocketAddress) packet.getSocketAddress();
String ip = socketAddress.getAddress().getHostAddress();
int port = socketAddress.getPort();
if (System.nanoTime() - ackPacket.lastRefTime > ACK_TIMEOUT_NANOS) {
Loggers.PUSH.warn("ack takes too long from {} ack json: {}", packet.getSocketAddress(), json);
}
String ackKey = getACKKey(ip, port, ackPacket.lastRefTime);
AckEntry ackEntry = ackMap.remove(ackKey);
if (ackEntry == null) {
throw new IllegalStateException("unable to find ackEntry for key: " + ackKey
+ ", ack json: " + json);
}
long pushCost = System.currentTimeMillis() - udpSendTimeMap.get(ackKey);
Loggers.PUSH.info("received ack: {} from: {}:, cost: {} ms, unacked: {}, total push: {}",
json, ip, port, pushCost, ackMap.size(), totalPush);
pushCostMap.put(ackKey, pushCost);
udpSendTimeMap.remove(ackKey);
} catch (Throwable e) {
Loggers.PUSH.error("[NACOS-PUSH] error while receiving ack data", e);
}
}
}
//......
public static class AckPacket {
public String type;
public long lastRefTime;
public String data;
}
}
Receiver实现了Runnable接口，其run方法使用while true循环来执行udpSocket.receive，之后解析AckPacket，从ackMap移除该ackKey，更新pushCostMap，同时从udpSendTimeMap移除该ackKey
PushClient
nacos-1.1.3/naming/src/main/java/com/alibaba/nacos/naming/push/PushService.java
public class PushClient {
private String namespaceId;
private String serviceName;
private String clusters;
private String agent;
private String tenant;
private String app;
private InetSocketAddress socketAddr;
private DataSource dataSource;
private Map params;
public Map getParams() {
return params;
}
public void setParams(Map params) {
this.params = params;
}
public long lastRefTime = System.currentTimeMillis();
public PushClient(String namespaceId,
String serviceName,
String clusters,
String agent,
InetSocketAddress socketAddr,
DataSource dataSource,
String tenant,
String app) {
this.namespaceId = namespaceId;
this.serviceName = serviceName;
this.clusters = clusters;
this.agent = agent;
this.socketAddr = socketAddr;
this.dataSource = dataSource;
this.tenant = tenant;
this.app = app;
}
public DataSource getDataSource() {
return dataSource;
}
public PushClient(InetSocketAddress socketAddr) {
this.socketAddr = socketAddr;
}
public boolean zombie() {
return System.currentTimeMillis() - lastRefTime > switchDomain.getPushCacheMillis(serviceName);
}
@Override
public String toString() {
return "serviceName: " + serviceName
+ ", clusters: " + clusters
+ ", ip: " + socketAddr.getAddress().getHostAddress()
+ ", port: " + socketAddr.getPort()
+ ", agent: " + agent;
}
public String getAgent() {
return agent;
}
public String getAddrStr() {
return socketAddr.getAddress().getHostAddress() + ":" + socketAddr.getPort();
}
public String getIp() {
return socketAddr.getAddress().getHostAddress();
}
@Override
public int hashCode() {
return Objects.hash(serviceName, clusters, socketAddr);
}
@Override
public boolean equals(Object obj) {
if (!(obj instanceof PushClient)) {
return false;
}
PushClient other = (PushClient) obj;
return serviceName.equals(other.serviceName) && clusters.equals(other.clusters) && socketAddr.equals(other.socketAddr);
}
public String getClusters() {
return clusters;
}
public void setClusters(String clusters) {
this.clusters = clusters;
}
public String getNamespaceId() {
return namespaceId;
}
public void setNamespaceId(String namespaceId) {
this.namespaceId = namespaceId;
}
public String getServiceName() {
return serviceName;
}
public void setServiceName(String serviceName) {
this.serviceName = serviceName;
}
public String getTenant() {
return tenant;
}
public void setTenant(String tenant) {
this.tenant = tenant;
}
public String getApp() {
return app;
}
public void setApp(String app) {
this.app = app;
}
public InetSocketAddress getSocketAddr() {
return socketAddr;
}
public void refresh() {
lastRefTime = System.currentTimeMillis();
}
}
PushClient封装了要推送的目标服务地址等信息，它提供了zombie方法来判断目标服务是否zombie，它判断距离lastRefTime的时间差是否超过switchDomain指定的该serviceName的PushCacheMillis(默认为10秒)，超过则判定为zombie
PushService.onApplicationEvent
@Component
public class PushService implements ApplicationContextAware, ApplicationListener {
//......
@Override
public void onApplicationEvent(ServiceChangeEvent event) {
Service service = event.getService();
String serviceName = service.getName();
String namespaceId = service.getNamespaceId();
Future future = udpSender.schedule(new Runnable() {
@Override
public void run() {
try {
Loggers.PUSH.info(serviceName + " is changed, add it to push queue.");
ConcurrentMap clients = clientMap.get(UtilsAndCommons.assembleFullServiceName(namespaceId, serviceName));
if (MapUtils.isEmpty(clients)) {
return;
}
Map cache = new HashMap<>(16);
long lastRefTime = System.nanoTime();
for (PushClient client : clients.values()) {
if (client.zombie()) {
Loggers.PUSH.debug("client is zombie: " + client.toString());
clients.remove(client.toString());
Loggers.PUSH.debug("client is zombie: " + client.toString());
continue;
}
Receiver.AckEntry ackEntry;
Loggers.PUSH.debug("push serviceName: {} to client: {}", serviceName, client.toString());
String key = getPushCacheKey(serviceName, client.getIp(), client.getAgent());
byte[] compressData = null;
Map data = null;
if (switchDomain.getDefaultPushCacheMillis() >= 20000 && cache.containsKey(key)) {
org.javatuples.Pair pair = (org.javatuples.Pair) cache.get(key);
compressData = (byte[]) (pair.getValue0());
data = (Map) pair.getValue1();
Loggers.PUSH.debug("[PUSH-CACHE] cache hit: {}:{}", serviceName, client.getAddrStr());
}
if (compressData != null) {
ackEntry = prepareAckEntry(client, compressData, data, lastRefTime);
} else {
ackEntry = prepareAckEntry(client, prepareHostsData(client), lastRefTime);
if (ackEntry != null) {
cache.put(key, new org.javatuples.Pair<>(ackEntry.origin.getData(), ackEntry.data));
}
}
Loggers.PUSH.info("serviceName: {} changed, schedule push for: {}, agent: {}, key: {}",
client.getServiceName(), client.getAddrStr(), client.getAgent(), (ackEntry == null ? null : ackEntry.key));
udpPush(ackEntry);
}
} catch (Exception e) {
Loggers.PUSH.error("[NACOS-PUSH] failed to push serviceName: {} to client, error: {}", serviceName, e);
} finally {
futureMap.remove(UtilsAndCommons.assembleFullServiceName(namespaceId, serviceName));
}
}
}, 1000, TimeUnit.MILLISECONDS);
futureMap.put(UtilsAndCommons.assembleFullServiceName(namespaceId, serviceName), future);
}
//......
public void serviceChanged(Service service) {
// merge some change events to reduce the push frequency:
if (futureMap.containsKey(UtilsAndCommons.assembleFullServiceName(service.getNamespaceId(), service.getName()))) {
return;
}
this.applicationContext.publishEvent(new ServiceChangeEvent(this, service));
}
//......
}
onApplicationEvent会处理ServiceChangeEvent，它会注册一个延时任务并将该future放入futureMap；该延时任务会从clientMap获取指定namespaceId, serviceName的clients；然后遍历clients判断是否是zombie，如果是的话则移除该client，否则创建Receiver.AckEntry，然后执行udpPush(ackEntry)，最后从futureMap移除该future；serviceChanged方法提供给外部调用发布ServiceChangeEvent
PushService.udpPush
nacos-1.1.3/naming/src/main/java/com/alibaba/nacos/naming/push/PushService.java
@Component
public class PushService implements ApplicationContextAware, ApplicationListener {
//......
public static class Receiver implements Runnable {
//......
public static class AckEntry {
public AckEntry(String key, DatagramPacket packet) {
this.key = key;
this.origin = packet;
}
public void increaseRetryTime() {
retryTimes.incrementAndGet();
}
public int getRetryTimes() {
return retryTimes.get();
}
public String key;
public DatagramPacket origin;
private AtomicInteger retryTimes = new AtomicInteger(0);
public Map data;
}
//......
}
private static Receiver.AckEntry udpPush(Receiver.AckEntry ackEntry) {
if (ackEntry == null) {
Loggers.PUSH.error("[NACOS-PUSH] ackEntry is null.");
return null;
}
if (ackEntry.getRetryTimes() > MAX_RETRY_TIMES) {
Loggers.PUSH.warn("max re-push times reached, retry times {}, key: {}", ackEntry.retryTimes, ackEntry.key);
ackMap.remove(ackEntry.key);
udpSendTimeMap.remove(ackEntry.key);
failedPush += 1;
return ackEntry;
}
try {
if (!ackMap.containsKey(ackEntry.key)) {
totalPush++;
}
ackMap.put(ackEntry.key, ackEntry);
udpSendTimeMap.put(ackEntry.key, System.currentTimeMillis());
Loggers.PUSH.info("send udp packet: " + ackEntry.key);
udpSocket.send(ackEntry.origin);
ackEntry.increaseRetryTime();
executorService.schedule(new Retransmitter(ackEntry), TimeUnit.NANOSECONDS.toMillis(ACK_TIMEOUT_NANOS),
TimeUnit.MILLISECONDS);
return ackEntry;
} catch (Exception e) {
Loggers.PUSH.error("[NACOS-PUSH] failed to push data: {} to client: {}, error: {}",
ackEntry.data, ackEntry.origin.getAddress().getHostAddress(), e);
ackMap.remove(ackEntry.key);
udpSendTimeMap.remove(ackEntry.key);
failedPush += 1;
return null;
}
}
//......
}
udpPush方法会根据Receiver.AckEntry的信息进行判断，如果其重试次数大于MAX_RETRY_TIMES则终止push，将其从ackMap、udpSendTimeMap中移除；如果可以重试则将其ackEntry.key放入ackMap及udpSendTimeMap，然后执行udpSocket.send(ackEntry.origin)及ackEntry.increaseRetryTime()，并注册Retransmitter的延时任务；如果出现异常则将其从ackMap、udpSendTimeMap移除
Retransmitter
nacos-1.1.3/naming/src/main/java/com/alibaba/nacos/naming/push/PushService.java
public static class Retransmitter implements Runnable {
Receiver.AckEntry ackEntry;
public Retransmitter(Receiver.AckEntry ackEntry) {
this.ackEntry = ackEntry;
}
@Override
public void run() {
if (ackMap.containsKey(ackEntry.key)) {
Loggers.PUSH.info("retry to push data, key: " + ackEntry.key);
udpPush(ackEntry);
}
}
}
Retransmitter实现了Runnable方法，其run方法在ackMap包含ackEntry.key的条件下执行udpPush重试
小结
PushService实现了ApplicationContextAware、ApplicationListener接口
其static代码块创建了一个deamon线程执行Receiver，同时注册了一个定时任务执行removeClientIfZombie，它会遍历clientMap，移除zombie的client
其onApplicationEvent会处理ServiceChangeEvent，它会注册一个延时任务并将该future放入futureMap；该延时任务会从clientMap获取指定namespaceId, serviceName的clients；然后遍历clients判断是否是zombie，如果是的话则移除该client，否则创建Receiver.AckEntry，然后执行udpPush(ackEntry)，最后从futureMap移除该future；serviceChanged方法提供给外部调用发布ServiceChangeEvent
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