[feature] Expose jmx endpoint for sentinel.

pom.xml

@@ -164,7 +164,13 @@
                 <artifactId>sentinel-adapter</artifactId>
                 <version>${project.version}</version>
             </dependency>
-
+
+            <dependency>
+                <groupId>com.alibaba.csp</groupId>
+                <artifactId>sentinel-metric-exporter</artifactId>
+                <version>${project.version}</version>
+            </dependency>
+
             <dependency>
                 <groupId>com.alibaba</groupId>
                 <artifactId>fastjson</artifactId>

sentinel-core/src/main/java/com/alibaba/csp/sentinel/slots/block/flow/FlowRuleManager.java

@@ -15,23 +15,23 @@
  */
 package com.alibaba.csp.sentinel.slots.block.flow;
 
-import java.util.ArrayList;
-import java.util.HashMap;
-import java.util.List;
-import java.util.Map;
-import java.util.concurrent.Executors;
-import java.util.concurrent.ScheduledExecutorService;
-import java.util.concurrent.TimeUnit;
-
 import com.alibaba.csp.sentinel.concurrent.NamedThreadFactory;
 import com.alibaba.csp.sentinel.config.SentinelConfig;
 import com.alibaba.csp.sentinel.log.RecordLog;
-import com.alibaba.csp.sentinel.util.AssertUtil;
-import com.alibaba.csp.sentinel.util.StringUtil;
 import com.alibaba.csp.sentinel.node.metric.MetricTimerListener;
 import com.alibaba.csp.sentinel.property.DynamicSentinelProperty;
 import com.alibaba.csp.sentinel.property.PropertyListener;
 import com.alibaba.csp.sentinel.property.SentinelProperty;
+import com.alibaba.csp.sentinel.util.AssertUtil;
+import com.alibaba.csp.sentinel.util.StringUtil;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.TimeUnit;
 
 /**
  * <p>
@@ -53,6 +53,7 @@ public class FlowRuleManager {
     private static final FlowPropertyListener LISTENER = new FlowPropertyListener();
     private static SentinelProperty<List<FlowRule>> currentProperty = new DynamicSentinelProperty<List<FlowRule>>();
 
+    /** the corePool size of SCHEDULER must be set at 1, so the two task ({@link #startMetricTimerListener()} can run orderly by the SCHEDULER **/
     @SuppressWarnings("PMD.ThreadPoolCreationRule")
     private static final ScheduledExecutorService SCHEDULER = Executors.newScheduledThreadPool(1,
         new NamedThreadFactory("sentinel-metrics-record-task", true));
@@ -61,7 +62,7 @@ public class FlowRuleManager {
         currentProperty.addListener(LISTENER);
         startMetricTimerListener();
     }
-
+    
     /**
      * <p> Start the MetricTimerListener
      * <ol>

sentinel-extension/pom.xml

@@ -24,6 +24,7 @@
         <module>sentinel-datasource-etcd</module>
         <module>sentinel-datasource-eureka</module>
         <module>sentinel-annotation-cdi-interceptor</module>
+        <module>sentinel-metric-exporter</module>
     </modules>
 
 </project>

sentinel-extension/sentinel-metric-exporter/pom.xml

@@ -0,0 +1,27 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <parent>
+        <groupId>com.alibaba.csp</groupId>
+        <artifactId>sentinel-extension</artifactId>
+        <version>1.8.2-SNAPSHOT</version>
+    </parent>
+    <modelVersion>4.0.0</modelVersion>
+
+    <artifactId>sentinel-metric-exporter</artifactId>
+    <packaging>jar</packaging>
+
+    <dependencies>
+        <dependency>
+            <groupId>com.alibaba.csp</groupId>
+            <artifactId>sentinel-core</artifactId>
+        </dependency>
+
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+</project>

sentinel-extension/sentinel-metric-exporter/src/main/java/com/alibaba/csp/sentinel/metric/MetricExporterInit.java

@@ -0,0 +1,81 @@
+/*
+ *  Copyright 1999-2021 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.metric;
+
+import com.alibaba.csp.sentinel.init.InitFunc;
+import com.alibaba.csp.sentinel.log.RecordLog;
+import com.alibaba.csp.sentinel.metric.collector.MetricCollector;
+import com.alibaba.csp.sentinel.metric.exporter.MetricExporter;
+import com.alibaba.csp.sentinel.metric.exporter.jmx.JMXMetricExporter;
+
+import java.util.ArrayList;
+import java.util.List;
+
+/**
+ * The{@link MetricExporterInit} work on load Metric exporters.
+ *
+ * @author chenglu
+ * @date 2021-07-01 19:58
+ * @since 1.8.3
+ */
+public class MetricExporterInit implements InitFunc {
+
+    /**
+     * the list of metric exporters.
+     */
+    private static List<MetricExporter> metricExporters = new ArrayList<>();
+
+    /**
+     * the metric collector.
+     */
+    private static MetricCollector metricCollector = new MetricCollector();
+
+    /*
+      load metric exporters.
+     */
+    static {
+        // now we use this simple way to load MetricExporter.
+        metricExporters.add(new JMXMetricExporter(metricCollector));
+    }
+
+    @Override
+    public void init() throws Exception {
+        RecordLog.info("[MetricExporterInit] MetricExporter start init.");
+        // start the metric exporters.
+        for (MetricExporter metricExporter : metricExporters) {
+           try {
+               metricExporter.start();
+           } catch (Exception e) {
+               RecordLog.warn("[MetricExporterInit] MetricExporterInit start the metricExport[{}] failed, will ignore it.",
+                       metricExporter.getClass().getName(), e);
+           }
+        }
+
+        // add shutdown hook.
+        Runtime.getRuntime().addShutdownHook(new Thread(
+                () -> metricExporters.forEach(metricExporter -> {
+                    try {
+                        metricExporter.shutdown();
+                    } catch (Exception e) {
+                        RecordLog.warn("[MetricExporterInit] MetricExporterInit shutdown the metricExport[{}] failed, will ignore it.",
+                                metricExporter.getClass().getName(), e);
+                    }
+                })
+        ));
+    }
+}

sentinel-extension/sentinel-metric-exporter/src/main/java/com/alibaba/csp/sentinel/metric/collector/MetricCollector.java

@@ -0,0 +1,92 @@
+/*
+ *  Copyright 1999-2021 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.metric.collector;
+
+import com.alibaba.csp.sentinel.Constants;
+import com.alibaba.csp.sentinel.node.ClusterNode;
+import com.alibaba.csp.sentinel.node.metric.MetricNode;
+import com.alibaba.csp.sentinel.slotchain.ResourceWrapper;
+import com.alibaba.csp.sentinel.slots.clusterbuilder.ClusterBuilderSlot;
+import com.alibaba.csp.sentinel.util.TimeUtil;
+
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+
+/**
+ * The {@link MetricCollector} work on collecting metrics in {@link MetricNode}.
+ *
+ * @author chenglu
+ * @date 2021-07-01 20:01
+ * @since 1.8.3
+ */
+public class MetricCollector {
+
+    /**
+     * collect the metrics in {@link MetricNode}.
+     *
+     * @return the metric grouped by resource name.
+     */
+    public Map<String, MetricNode> collectMetric() {
+        Map<String, MetricNode> metricNodeMap = new HashMap<>();
+        for (Map.Entry<ResourceWrapper, ClusterNode> e : ClusterBuilderSlot.getClusterNodeMap().entrySet()) {
+            ClusterNode node = e.getValue();
+            List<MetricNode> metrics = getLastMetrics(node);
+            aggregate(metricNodeMap, metrics, node);
+        }
+        aggregate(metricNodeMap, getLastMetrics(Constants.ENTRY_NODE), Constants.ENTRY_NODE);
+        return metricNodeMap;
+    }
+
+
+    /**
+     * Get the last second {@link MetricNode} of {@link ClusterNode}
+     * @param node {@link ClusterNode}
+     * @return the list of {@link MetricNode}
+     */
+    private List<MetricNode> getLastMetrics(ClusterNode node) {
+        final long currentTime = TimeUtil.currentTimeMillis();
+        final long maxTime = currentTime - currentTime % 1000;
+        final long minTime = maxTime - 1000;
+        return node.rawMetricsInMin(time -> time >= minTime && time < maxTime);
+    }
+
+
+    /**
+     * aggregate the metrics, the metrics under the same resource will left the lasted value
+     * @param metricNodeMap metrics map
+     * @param metrics metrics info group by timestamp
+     * @param node the node
+     */
+    private void aggregate(Map<String, MetricNode> metricNodeMap, List<MetricNode> metrics, ClusterNode node) {
+        if (metrics == null || metrics.size() == 0) {
+            return;
+        }
+        for (MetricNode metricNode : metrics) {
+            String resource = node.getName();
+            metricNode.setResource(resource);
+            metricNode.setClassification(node.getResourceType());
+            MetricNode existMetricNode = metricNodeMap.get(resource);
+            // always keep the MetricNode is the last
+            if (existMetricNode != null && existMetricNode.getTimestamp() > metricNode.getTimestamp()) {
+                continue;
+            }
+            metricNodeMap.put(resource, metricNode);
+        }
+    }
+}

sentinel-extension/sentinel-metric-exporter/src/main/java/com/alibaba/csp/sentinel/metric/exporter/MetricExporter.java

@@ -0,0 +1,49 @@
+/*
+ *  Copyright 1999-2021 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.metric.exporter;
+
+/**
+ * {@link MetricExporter} work on export metric to target monitor.
+ * you can implement your export ways by this class.
+ *
+ * @author chenglu
+ * @date 2021-07-01 21:16
+ */
+public interface MetricExporter {
+
+    /**
+     * start the {@link MetricExporter}.
+     *
+     * @throws Exception start exception.
+     */
+    void start() throws Exception;
+
+    /**
+     * export the data to target monitor by the implement.
+     *
+     * @throws Exception export exception.
+     */
+    void export() throws Exception;
+
+    /**
+     * shutdown the {@link MetricExporter}.
+     *
+     * @throws Exception shutdown exception.
+     */
+    void shutdown() throws Exception;
+}