feature: add metric exporter interface

sentinel-core/src/main/java/com/alibaba/csp/sentinel/node/metric/MetricTimerListener.java

@@ -25,16 +25,34 @@
 import com.alibaba.csp.sentinel.config.SentinelConfig;
 import com.alibaba.csp.sentinel.log.RecordLog;
 import com.alibaba.csp.sentinel.node.ClusterNode;
+import com.alibaba.csp.sentinel.node.metric.export.DefaultExporter;
+import com.alibaba.csp.sentinel.node.metric.export.MetricExporter;
 import com.alibaba.csp.sentinel.slotchain.ResourceWrapper;
 import com.alibaba.csp.sentinel.slots.clusterbuilder.ClusterBuilderSlot;
+import com.alibaba.csp.sentinel.spi.SpiLoader;
 
 /**
  * @author jialiang.linjl
  */
 public class MetricTimerListener implements Runnable {
 
-    private static final MetricWriter metricWriter = new MetricWriter(SentinelConfig.singleMetricFileSize(),
-        SentinelConfig.totalMetricFileCount());
+    private static MetricExporter exporter = null;
+
+    static {
+        MetricExporter instance = null;
+        try {
+            instance = SpiLoader.of(MetricExporter.class).loadFirstInstance();
+        } catch (Throwable t) {
+            RecordLog.info("[MetricTimerListener] Fail to load metric exporter", t);
+        }
+        if (instance == null) {
+            MetricTimerListener.exporter = new DefaultExporter();
+        } else {
+            MetricTimerListener.exporter = instance;
+        }
+        RecordLog.info("[MetricTimerListener] Active exporter: {}", MetricTimerListener.exporter.getClass());
+    }
+
 
     @Override
     public void run() {
@@ -46,12 +64,10 @@ public void run() {
         }
         aggregate(maps, Constants.ENTRY_NODE.metrics(), Constants.ENTRY_NODE);
         if (!maps.isEmpty()) {
-            for (Entry<Long, List<MetricNode>> entry : maps.entrySet()) {
-                try {
-                    metricWriter.write(entry.getKey(), entry.getValue());
-                } catch (Exception e) {
-                    RecordLog.warn("[MetricTimerListener] Write metric error", e);
-                }
+            try {
+                exporter.export(maps);
+            } catch (Exception e) {
+                RecordLog.warn("[MetricTimerListener] Write metric error", e);
             }
         }
     }

sentinel-core/src/main/java/com/alibaba/csp/sentinel/node/metric/export/DefaultExporter.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright 1999-2024 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.node.metric.export;
+
+import com.alibaba.csp.sentinel.config.SentinelConfig;
+import com.alibaba.csp.sentinel.log.RecordLog;
+import com.alibaba.csp.sentinel.node.metric.MetricNode;
+import com.alibaba.csp.sentinel.node.metric.MetricWriter;
+
+import java.util.List;
+import java.util.Map;
+
+/**
+ * Origin way to export metrics.
+ *
+ * @author Daydreamer-ia
+ */
+public class DefaultExporter implements MetricExporter {
+
+    private static final MetricWriter metricWriter = new MetricWriter(SentinelConfig.singleMetricFileSize(),
+            SentinelConfig.totalMetricFileCount());
+
+    @Override
+    public void export(Map<Long, List<MetricNode>> metrics) {
+        for (Map.Entry<Long, List<MetricNode>> entry : metrics.entrySet()) {
+            try {
+                metricWriter.write(entry.getKey(), entry.getValue());
+            } catch (Exception e) {
+                RecordLog.warn("[DefaultExporter] Write metric error", e);
+            }
+        }
+    }
+
+}

sentinel-core/src/main/java/com/alibaba/csp/sentinel/node/metric/export/MetricExporter.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright 1999-2024 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.node.metric.export;
+
+import com.alibaba.csp.sentinel.node.metric.MetricNode;
+
+import java.util.List;
+import java.util.Map;
+
+/**
+ * Used to export metric.
+ *
+ * @author Daydreamer-ia
+ */
+public interface MetricExporter {
+
+    /**
+     * export metrics.
+     *
+     * @param metrics metrics.
+     */
+    void export(Map<Long, List<MetricNode>> metrics);
+}

sentinel-core/src/test/java/com/alibaba/csp/sentinel/node/metric/MetricExporterTest.java

@@ -0,0 +1,38 @@
+/*
+ * Copyright 1999-2024 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.node.metric;
+
+import org.junit.Test;
+
+import java.lang.reflect.Field;
+
+import static org.junit.Assert.assertTrue;
+
+/**
+ * @author Daydreamer-ia.
+ */
+public class MetricExporterTest {
+
+    @Test
+    public void testExporter() throws NoSuchFieldException, IllegalAccessException {
+        Field exporter = MetricTimerListener.class.getDeclaredField("exporter");
+        exporter.setAccessible(true);
+        Object o = exporter.get(exporter);
+        assertTrue(o instanceof TestMetricExporter);
+    }
+
+}

sentinel-core/src/test/java/com/alibaba/csp/sentinel/node/metric/TestMetricExporter.java

@@ -0,0 +1,33 @@
+/*
+ * Copyright 1999-2024 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.node.metric;
+
+import com.alibaba.csp.sentinel.node.metric.export.MetricExporter;
+
+import java.util.List;
+import java.util.Map;
+
+/**
+ * @author Daydreamer-ia
+ */
+public class TestMetricExporter implements MetricExporter {
+
+    @Override
+    public void export(Map<Long, List<MetricNode>> metrics) {
+
+    }
+}

sentinel-core/src/test/resources/META-INF/services/com.alibaba.csp.sentinel.node.metric.export.MetricExporter

@@ -0,0 +1,17 @@
+#
+#  Copyright 1999-2024 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.
+#
+
+com.alibaba.csp.sentinel.node.metric.TestMetricExporter