[#3117]Just Sink the Notify implementation into common module and optimize some parts

common/src/main/java/com/alibaba/nacos/common/NotThreadSafe.java

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+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.alibaba.nacos.common;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+/**
+ * Annotation that marks a method as not thread safe.
+ *
+ * @author zongtanghu
+ */
+@Documented
+@Target({ElementType.TYPE, ElementType.METHOD})
+@Retention(RetentionPolicy.SOURCE)
+public @interface NotThreadSafe {
+
+}

common/src/main/java/com/alibaba/nacos/common/notify/DefaultPublisher.java

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+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.alibaba.nacos.common.notify;
+
+import com.alibaba.nacos.common.notify.listener.Subscriber;
+import com.alibaba.nacos.common.utils.ConcurrentHashSet;
+import com.alibaba.nacos.common.utils.ThreadUtils;
+import com.alibaba.nacos.common.utils.CollectionUtils;
+import com.alibaba.nacos.common.utils.ClassUtils;
+import com.alibaba.nacos.common.utils.Objects;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import java.util.concurrent.ArrayBlockingQueue;
+import java.util.concurrent.BlockingQueue;
+import java.util.concurrent.Executor;
+import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
+
+import static com.alibaba.nacos.common.notify.NotifyCenter.ringBufferSize;
+
+/**
+ * The default event publisher implementation.
+ *
+ * <p>Internally, use {@link ArrayBlockingQueue <Event/>} as a message staging queue.
+ *
+ * @author <a href="mailto:liaochuntao@live.com">liaochuntao</a>
+ * @author zongtanghu
+ */
+public class DefaultPublisher extends Thread implements EventPublisher {
+
+    private static final Logger LOGGER = LoggerFactory.getLogger(NotifyCenter.class);
+
+    private volatile boolean initialized = false;
+
+    private volatile boolean shutdown = false;
+
+    private Class<? extends Event> eventType;
+
+    private final ConcurrentHashSet<Subscriber> subscribers = new ConcurrentHashSet<Subscriber>();
+
+    private int queueMaxSize = -1;
+
+    private BlockingQueue<Event> queue;
+
+    private volatile Long lastEventSequence = -1L;
+
+    private final AtomicReferenceFieldUpdater<DefaultPublisher, Long> updater = AtomicReferenceFieldUpdater
+            .newUpdater(DefaultPublisher.class, Long.class, "lastEventSequence");
+
+    @Override
+    public void init(Class<? extends Event> type, int bufferSize) {
+        setDaemon(true);
+        setName("nacos.publisher-" + type.getName());
+        this.eventType = type;
+        this.queueMaxSize = bufferSize;
+        this.queue = new ArrayBlockingQueue<Event>(bufferSize);
+        start();
+    }
+
+    public ConcurrentHashSet<Subscriber> getSubscribers() {
+        return subscribers;
+    }
+
+    @Override
+    public synchronized void start() {
+        if (!initialized) {
+            // start just called once
+            super.start();
+            if (queueMaxSize == -1) {
+                queueMaxSize = ringBufferSize;
+            }
+            initialized = true;
+        }
+    }
+
+    public long currentEventSize() {
+        return queue.size();
+    }
+
+    @Override
+    public void run() {
+        openEventHandler();
+    }
+
+    void openEventHandler() {
+        try {
+            // To ensure that messages are not lost, enable EventHandler when
+            // waiting for the first Subscriber to register
+            for (; ; ) {
+                if (shutdown || hasSubscriber()) {
+                    break;
+                }
+                ThreadUtils.sleep(1000L);
+            }
+
+            for (; ; ) {
+                if (shutdown) {
+                    break;
+                }
+                final Event event = queue.take();
+                receiveEvent(event);
+                updater.compareAndSet(this, lastEventSequence, Math.max(lastEventSequence, event.sequence()));
+            }
+        } catch (Throwable ex) {
+            LOGGER.error("Event listener exception : {}", ex);
+        }
+    }
+
+    private boolean hasSubscriber() {
+        return CollectionUtils.isNotEmpty(subscribers);
+    }
+
+    @Override
+    public void addSubscriber(Subscriber subscriber) {
+        subscribers.add(subscriber);
+    }
+
+    @Override
+    public void removeSubscriber(Subscriber subscriber) {
+        subscribers.remove(subscriber);
+    }
+
+    @Override
+    public boolean publish(Event event) {
+        checkIsStart();
+        boolean success = this.queue.offer(event);
+        if (!success) {
+            LOGGER.warn("Unable to plug in due to interruption, synchronize sending time, event : {}", event);
+            receiveEvent(event);
+            return true;
+        }
+        return true;
+    }
+
+    void checkIsStart() {
+        if (!initialized) {
+            throw new IllegalStateException("Publisher does not start");
+        }
+    }
+
+    @Override
+    public void shutdown() {
+        this.shutdown = true;
+        this.queue.clear();
+    }
+
+    public boolean isInitialized() {
+        return initialized;
+    }
+
+    void receiveEvent(Event event) {
+        final long currentEventSequence = event.sequence();
+        final String sourceName = ClassUtils.getName(event);
+
+        // Notification single event listener
+        for (Subscriber subscriber : subscribers) {
+            // Whether to ignore expiration events
+            if (subscriber.ignoreExpireEvent() && lastEventSequence > currentEventSequence) {
+                LOGGER.debug("[NotifyCenter] the {} is unacceptable to this subscriber, because had expire",
+                        event.getClass());
+                continue;
+            }
+
+            final String targetName = ClassUtils.getName(subscriber.subscribeType());
+            if (!Objects.equals(sourceName, targetName)) {
+                continue;
+            }
+            notifySubscriber(subscriber, event);
+        }
+    }
+
+    @Override
+    public void notifySubscriber(final Subscriber subscriber, final Event event) {
+
+        LOGGER.debug("[NotifyCenter] the {} will received by {}", event, subscriber);
+
+        final Runnable job = new Runnable() {
+            @Override
+            public void run() {
+                subscriber.onEvent(event);
+            }
+        };
+
+        final Executor executor = subscriber.executor();
+
+        if (executor != null) {
+            executor.execute(job);
+        } else {
+            try {
+                job.run();
+            } catch (Throwable e) {
+                LOGGER.error("Event callback exception : {}", e);
+            }
+        }
+    }
+}

common/src/main/java/com/alibaba/nacos/common/notify/Event.java

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+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.alibaba.nacos.common.notify;
+
+import java.io.Serializable;
+import java.util.concurrent.atomic.AtomicLong;
+
+/**
+ * An abstract class for event.
+ *
+ * @author <a href="mailto:liaochuntao@live.com">liaochuntao</a>
+ * @author zongtanghu
+ */
+@SuppressWarnings({"PMD.AbstractClassShouldStartWithAbstractNamingRule"})
+public abstract class Event implements Serializable {
+
+    private static final AtomicLong SEQUENCE = new AtomicLong(0);
+
+    private final long sequence = SEQUENCE.getAndIncrement();
+
+    /**
+     * Event sequence number, which can be used to handle the sequence of events.
+     *
+     * @return sequence num, It's best to make sure it's monotone.
+     */
+    public long sequence() {
+        return sequence;
+    }
+
+}
+

common/src/main/java/com/alibaba/nacos/common/notify/EventPublisher.java

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+/*
+ * Copyright 1999-2018 Alibaba Group Holding Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.alibaba.nacos.common.notify;
+
+import com.alibaba.nacos.common.lifecycle.Closeable;
+import com.alibaba.nacos.common.notify.listener.Subscriber;
+
+/**
+ * Event publisher.
+ *
+ * @author <a href="mailto:liaochuntao@live.com">liaochuntao</a>
+ * @author zongtanghu
+ */
+public interface EventPublisher extends Closeable {
+
+    /**
+     * Initializes the event publisher.
+     *
+     * @param type       {@link Event >}
+     * @param bufferSize Message staging queue size
+     */
+    void init(Class<? extends Event> type, int bufferSize);
+
+    /**
+     * The number of currently staged events.
+     *
+     * @return event size
+     */
+    long currentEventSize();
+
+    /**
+     * Add listener.
+     *
+     * @param subscriber {@link Subscriber}
+     */
+    void addSubscriber(Subscriber subscriber);
+
+    /**
+     * Remove listener.
+     *
+     * @param subscriber {@link Subscriber}
+     */
+    void removeSubscriber(Subscriber subscriber);
+
+    /**
+     * publish event.
+     *
+     * @param event {@link Event}
+     * @return publish event is success
+     */
+    boolean publish(Event event);
+
+    /**
+     * Notify listener.
+     *
+     * @param subscriber {@link Subscriber}
+     * @param event      {@link Event}
+     */
+    void notifySubscriber(Subscriber subscriber, Event event);
+}