Merge pull request #3024: Add traffic routing capability

* Support traffic routing capability.

sentinel-core/src/main/java/com/alibaba/csp/sentinel/traffic/AbstractLoadBalancer.java

@@ -0,0 +1,36 @@
+/*
+ * 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.csp.sentinel.traffic;
+
+import java.util.List;
+
+/**
+ * @author panxiaojun233
+ */
+public abstract class AbstractLoadBalancer implements LoadBalancer {
+    @Override
+    public Instance select(List<Instance> instances, TrafficContext trafficContext) throws TrafficException {
+        if (instances == null || instances.size() == 0) {
+            return null;
+        }
+        if (instances.size() == 1) {
+            return instances.get(0);
+        }
+        return doSelect(instances, trafficContext);
+    }
+
+    protected abstract Instance doSelect(List<Instance> instances, TrafficContext trafficContext);
+}

sentinel-core/src/main/java/com/alibaba/csp/sentinel/traffic/ClusterManager.java

@@ -0,0 +1,129 @@
+/*
+ * 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.csp.sentinel.traffic;
+
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+import com.alibaba.csp.sentinel.traffic.rule.router.TrafficRouterRuleManager;
+
+/**
+ * @author panxiaojun233
+ */
+public class ClusterManager implements InstanceListener {
+    private List<RouterFilter> routerFilterList;
+    private LoadBalancer loadBalancer;
+    private InstanceManager instanceManager;
+    private volatile Set<String> remoteAppName = Collections.emptySet();
+
+    public ClusterManager(List<RouterFilter> routerFilterList, LoadBalancer loadBalancer, InstanceManager instanceManager) {
+        this.routerFilterList = routerFilterList;
+        this.loadBalancer = loadBalancer;
+        this.instanceManager = instanceManager;
+    }
+
+    public Set<String> getRemoteAppName() {
+        return remoteAppName;
+    }
+
+    public ClusterManager(List<RouterFilter> routerFilterList) {
+        this.routerFilterList = routerFilterList;
+    }
+
+    public ClusterManager(InstanceManager instanceManager) {
+        this.instanceManager = instanceManager;
+    }
+
+    /**
+     * Select one invoker in list, routing first, then load balancing.
+     *
+     * @param context traffic context.
+     * @return selected instance.
+     */
+    public Instance selectOneInstance(TrafficContext context) {
+        return loadBalancer.select(route(context), context);
+    }
+
+    /**
+     * Select one invoker in list.
+     *
+     * @param context   traffic context.
+     * @param instances instance List.
+     * @return selected instance.
+     */
+    public Instance loadBalance(TrafficContext context, List<Instance> instances) {
+        return loadBalancer.select(instances, context);
+    }
+
+    public Instance loadBalance(TrafficContext context) {
+        return loadBalancer.select(instanceManager.getInstances(), context);
+    }
+
+    /**
+     * Filter instances form instanceManager by current routing rule and traffic context.
+     *
+     * @param context traffic context
+     * @return instance List
+     */
+    public List<Instance> route(TrafficContext context) {
+        List<Instance> instances = instanceManager.getInstances();
+        for (RouterFilter routerFilter : routerFilterList) {
+            instances = routerFilter.filter(instances, context);
+        }
+        return instances;
+    }
+
+    /**
+     * Register the application in the instance List.
+     *
+     * @param instances instance List
+     */
+    private void registerAppRule(List<Instance> instances) {
+        Set<String> currentApplication = new HashSet<>();
+        if (instances != null && instances.size() > 0) {
+            for (Instance instance : instances) {
+                String applicationName = instance.getAppName();
+                if (applicationName != null && applicationName.length() > 0) {
+                    currentApplication.add(applicationName);
+                }
+            }
+        }
+
+        if (!remoteAppName.equals(currentApplication)) {
+            synchronized (this) {
+                Set<String> current = new HashSet<>(currentApplication);
+                Set<String> previous = new HashSet<>(remoteAppName);
+                previous.removeAll(currentApplication);
+                current.removeAll(remoteAppName);
+                for (String app : current) {
+                    TrafficRouterRuleManager.register(app);
+                }
+                for (String app : previous) {
+                    TrafficRouterRuleManager.unregister(app);
+                }
+                remoteAppName = currentApplication;
+            }
+        }
+    }
+
+    @Override
+    public void notify(List<Instance> instances) {
+        registerAppRule(instances);
+        instanceManager.storeInstances(instances);
+    }
+}

sentinel-core/src/main/java/com/alibaba/csp/sentinel/traffic/DefaultInstanceListener.java

@@ -0,0 +1,35 @@
+/*
+ * 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.csp.sentinel.traffic;
+
+import java.util.List;
+
+/**
+ * @author panxiaojun233
+ */
+public class DefaultInstanceListener implements InstanceListener {
+
+    private InstanceManager instanceManager;
+
+    public DefaultInstanceListener(InstanceManager instanceManager) {
+        this.instanceManager = instanceManager;
+    }
+
+    @Override
+    public void notify(List<Instance> instances) {
+        instanceManager.storeInstances(instances);
+    }
+}

sentinel-core/src/main/java/com/alibaba/csp/sentinel/traffic/DefaultInstanceManager.java

@@ -0,0 +1,41 @@
+/*
+ * 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.csp.sentinel.traffic;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+
+/**
+ * @author panxiaojun233
+ */
+public class DefaultInstanceManager implements InstanceManager {
+
+    private volatile List<Instance> instanceList = Collections.emptyList();
+
+    @Override
+    public void storeInstances(List<Instance> instances) {
+        if (instances == null || instances.size() == 0) {
+            return;
+        }
+        instanceList = new ArrayList<>(instances);
+    }
+
+    @Override
+    public List<Instance> getInstances() {
+        return instanceList;
+    }
+}

sentinel-core/src/main/java/com/alibaba/csp/sentinel/traffic/Instance.java

@@ -0,0 +1,80 @@
+/*
+ * 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.csp.sentinel.traffic;
+
+import java.util.Map;
+
+/**
+ * @author panxiaojun233
+ */
+public class Instance {
+    private String appName;
+    private String host;
+    private Integer port;
+    private Map<String, String> metadata;
+    private Object targetInstance;
+
+    public String getAppName() {
+        return appName;
+    }
+
+    public void setAppName(String appName) {
+        this.appName = appName;
+    }
+
+    public Object getTargetInstance() {
+        return targetInstance;
+    }
+
+    public void setTargetInstance(Object targetInstance) {
+        this.targetInstance = targetInstance;
+    }
+
+    public String getHost() {
+        return host;
+    }
+
+    public void setHost(String host) {
+        this.host = host;
+    }
+
+    public Integer getPort() {
+        return port;
+    }
+
+    public void setPort(Integer port) {
+        this.port = port;
+    }
+
+    public Map<String, String> getMetadata() {
+        return metadata;
+    }
+
+    public void setMetadata(Map<String, String> metadata) {
+        this.metadata = metadata;
+    }
+
+    @Override
+    public String toString() {
+        return "Instance{" +
+                "appName='" + appName + '\'' +
+                ", host='" + host + '\'' +
+                ", port=" + port +
+                ", metadata=" + metadata +
+                ", targetInstance=" + targetInstance +
+                '}';
+    }
+}

sentinel-core/src/main/java/com/alibaba/csp/sentinel/traffic/InstanceListener.java

@@ -0,0 +1,31 @@
+/*
+ * 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.csp.sentinel.traffic;
+
+import java.util.List;
+
+/**
+ * @author panxiaojun233
+ */
+public interface InstanceListener {
+
+    /**
+     * Notify the {@link ClusterManager} the instance list. Instance list may change from time to time.
+     *
+     * @param instances instance list.
+     */
+    void notify(List<Instance> instances);
+}

sentinel-core/src/main/java/com/alibaba/csp/sentinel/traffic/InstanceManager.java

@@ -0,0 +1,33 @@
+/*
+ * 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.csp.sentinel.traffic;
+
+import java.util.List;
+
+/**
+ * @author panxiaojun233
+ */
+public interface InstanceManager {
+
+    /**
+     * store the instance list from {@link InstanceListener#notify(List)}.
+     *
+     * @param instances
+     */
+    void storeInstances(List<Instance> instances);
+
+    List<Instance> getInstances();
+}