refactor: Get the max allowed RT directly from SentinelConfig.statisticMaxRt() (#1173)

- to avoid the dependency chain: Constants -> SentinelConfig

Signed-off-by: Eric Zhao <sczyh16@gmail.com>

sentinel-core/src/main/java/com/alibaba/csp/sentinel/Constants.java

@@ -15,18 +15,19 @@
  */
 package com.alibaba.csp.sentinel;
 
-import com.alibaba.csp.sentinel.config.SentinelConfig;
 import com.alibaba.csp.sentinel.node.ClusterNode;
 import com.alibaba.csp.sentinel.node.DefaultNode;
 import com.alibaba.csp.sentinel.node.EntranceNode;
 import com.alibaba.csp.sentinel.slotchain.StringResourceWrapper;
-import com.alibaba.csp.sentinel.slots.system.SystemRule;
 import com.alibaba.csp.sentinel.util.VersionUtil;
 
 /**
+ * Universal constants of Sentinel.
+ *
  * @author qinan.qn
  * @author youji.zj
  * @author jialiang.linjl
+ * @author Eric Zhao
  */
 public final class Constants {
 
@@ -60,16 +61,10 @@ public final class Constants {
         new ClusterNode(ROOT_ID, ResourceTypeConstants.COMMON));
 
     /**
-     * Global statistic node for inbound traffic. Usually used for {@link SystemRule} checking.
+     * Global statistic node for inbound traffic. Usually used for {@code SystemRule} checking.
      */
     public final static ClusterNode ENTRY_NODE = new ClusterNode(TOTAL_IN_RESOURCE_NAME, ResourceTypeConstants.COMMON);
 
-    /**
-     * Response time that exceeds TIME_DROP_VALVE will be calculated as TIME_DROP_VALVE. Default value is 4900 ms.
-     * It can be configured by property file or JVM parameter via {@code -Dcsp.sentinel.statistic.max.rt=xxx}.
-     */
-    public static final int TIME_DROP_VALVE = SentinelConfig.statisticMaxRt();
-
     /**
      * The global switch for Sentinel.
      */

sentinel-core/src/main/java/com/alibaba/csp/sentinel/config/SentinelConfig.java

@@ -18,6 +18,7 @@ package com.alibaba.csp.sentinel.config;
 import com.alibaba.csp.sentinel.log.RecordLog;
 import com.alibaba.csp.sentinel.util.AppNameUtil;
 import com.alibaba.csp.sentinel.util.AssertUtil;
+import com.alibaba.csp.sentinel.util.StringUtil;
 
 import java.util.Map;
 import java.util.Properties;
@@ -30,7 +31,7 @@ import java.util.concurrent.ConcurrentHashMap;
  * @author leyou
  * @author Eric Zhao
  */
-public class SentinelConfig {
+public final class SentinelConfig {
 
     /**
      * The default application type.
@@ -54,7 +55,8 @@ public class SentinelConfig {
     static final long DEFAULT_SINGLE_METRIC_FILE_SIZE = 1024 * 1024 * 50;
     static final int DEFAULT_TOTAL_METRIC_FILE_COUNT = 6;
     static final int DEFAULT_COLD_FACTOR = 3;
-    static final int DEFAULT_STATISTIC_MAX_RT = 4900;
+
+    public static final int DEFAULT_STATISTIC_MAX_RT = 4900;
 
     static {
         try {
@@ -186,13 +188,28 @@ public class SentinelConfig {
         }
     }
 
+    /**
+     * <p>Get the max RT value that Sentinel could accept.</p>
+     * <p>Response time that exceeds {@code statisticMaxRt} will be recorded as this value.
+     * The default value is {@link #DEFAULT_STATISTIC_MAX_RT}.</p>
+     *
+     * @return the max allowed RT value
+     * @since 1.4.1
+     */
     public static int statisticMaxRt() {
+        String v = props.get(STATISTIC_MAX_RT);
         try {
-            return Integer.parseInt(props.get(STATISTIC_MAX_RT));
+            if (StringUtil.isEmpty(v)) {
+                return DEFAULT_STATISTIC_MAX_RT;
+            }
+            return Integer.parseInt(v);
         } catch (Throwable throwable) {
-            RecordLog.warn("[SentinelConfig] Parse statisticMaxRt fail, use default value: "
-                    + DEFAULT_STATISTIC_MAX_RT, throwable);
+            RecordLog.warn("[SentinelConfig] Invalid statisticMaxRt value: {0}, using the default value instead: "
+                    + DEFAULT_STATISTIC_MAX_RT, v, throwable);
+            SentinelConfig.setConfig(STATISTIC_MAX_RT, String.valueOf(DEFAULT_STATISTIC_MAX_RT));
             return DEFAULT_STATISTIC_MAX_RT;
         }
     }
+
+    private SentinelConfig() {}
 }

sentinel-core/src/main/java/com/alibaba/csp/sentinel/slots/block/degrade/DegradeRuleManager.java

@@ -23,7 +23,7 @@ import java.util.Map;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 
-import com.alibaba.csp.sentinel.Constants;
+import com.alibaba.csp.sentinel.config.SentinelConfig;
 import com.alibaba.csp.sentinel.context.Context;
 import com.alibaba.csp.sentinel.log.RecordLog;
 import com.alibaba.csp.sentinel.node.DefaultNode;
@@ -211,7 +211,7 @@ public final class DegradeRuleManager {
         if (!baseValid) {
             return false;
         }
-        int maxAllowedRt = Constants.TIME_DROP_VALVE;
+        int maxAllowedRt = SentinelConfig.statisticMaxRt();
         if (rule.getGrade() == RuleConstant.DEGRADE_GRADE_RT) {
             if (rule.getRtSlowRequestAmount() <= 0) {
                 return false;

sentinel-core/src/main/java/com/alibaba/csp/sentinel/slots/statistic/StatisticSlot.java

@@ -17,6 +17,7 @@ package com.alibaba.csp.sentinel.slots.statistic;
 
 import java.util.Collection;
 
+import com.alibaba.csp.sentinel.config.SentinelConfig;
 import com.alibaba.csp.sentinel.slotchain.ProcessorSlotEntryCallback;
 import com.alibaba.csp.sentinel.slotchain.ProcessorSlotExitCallback;
 import com.alibaba.csp.sentinel.slots.block.flow.PriorityWaitException;
@@ -133,10 +134,11 @@ public class StatisticSlot extends AbstractLinkedProcessorSlot<DefaultNode> {
         DefaultNode node = (DefaultNode)context.getCurNode();
 
         if (context.getCurEntry().getError() == null) {
-            // Calculate response time (max RT is TIME_DROP_VALVE).
+            // Calculate response time (max RT is statisticMaxRt from SentinelConfig).
             long rt = TimeUtil.currentTimeMillis() - context.getCurEntry().getCreateTime();
-            if (rt > Constants.TIME_DROP_VALVE) {
-                rt = Constants.TIME_DROP_VALVE;
+            int maxStatisticRt = SentinelConfig.statisticMaxRt();
+            if (rt > maxStatisticRt) {
+                rt = maxStatisticRt;
             }
 
             // Record response time and success count.

sentinel-core/src/main/java/com/alibaba/csp/sentinel/slots/statistic/data/MetricBucket.java

@@ -15,7 +15,7 @@
  */
 package com.alibaba.csp.sentinel.slots.statistic.data;
 
-import com.alibaba.csp.sentinel.Constants;
+import com.alibaba.csp.sentinel.config.SentinelConfig;
 import com.alibaba.csp.sentinel.slots.statistic.MetricEvent;
 import com.alibaba.csp.sentinel.slots.statistic.base.LongAdder;
 
@@ -50,7 +50,7 @@ public class MetricBucket {
     }
 
     private void initMinRt() {
-        this.minRt = Constants.TIME_DROP_VALVE;
+        this.minRt = SentinelConfig.statisticMaxRt();
     }
 
     /**

sentinel-core/src/main/java/com/alibaba/csp/sentinel/slots/statistic/metric/ArrayMetric.java

@@ -18,7 +18,7 @@ package com.alibaba.csp.sentinel.slots.statistic.metric;
 import java.util.ArrayList;
 import java.util.List;
 
-import com.alibaba.csp.sentinel.Constants;
+import com.alibaba.csp.sentinel.config.SentinelConfig;
 import com.alibaba.csp.sentinel.node.metric.MetricNode;
 import com.alibaba.csp.sentinel.slots.statistic.MetricEvent;
 import com.alibaba.csp.sentinel.slots.statistic.base.LeapArray;
@@ -141,7 +141,7 @@ public class ArrayMetric implements Metric {
     @Override
     public long minRt() {
         data.currentWindow();
-        long rt = Constants.TIME_DROP_VALVE;
+        long rt = SentinelConfig.statisticMaxRt();
         List<MetricBucket> list = data.values();
         for (MetricBucket window : list) {
             if (window.minRt() < rt) {

sentinel-core/src/test/java/com/alibaba/csp/sentinel/ConstantsTest.java

@@ -1,25 +0,0 @@
-package com.alibaba.csp.sentinel;
-
-import org.junit.Test;
-
-import static org.junit.Assert.assertEquals;
-
-/**
- * Test cases for {@link Constants}.
- *
- * @author cdfive
- */
-public class ConstantsTest {
-
-    @Test
-    public void testDefaultTimeDropValue() {
-        assertEquals(4900, Constants.TIME_DROP_VALVE);
-    }
-
-//    add JVM parameter
-//    -Dcsp.sentinel.statistic.max.rt=10000
-//    @Test
-    public void testCustomTimeDropValue() {
-        assertEquals(10000, Constants.TIME_DROP_VALVE);
-    }
-}

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

@@ -15,7 +15,7 @@
  */
 package com.alibaba.csp.sentinel.node;
 
-import com.alibaba.csp.sentinel.Constants;
+import com.alibaba.csp.sentinel.config.SentinelConfig;
 import com.alibaba.csp.sentinel.util.TimeUtil;
 import org.junit.Assert;
 import org.junit.Test;
@@ -111,7 +111,7 @@ public class StatisticNodeTest {
         assertEquals(totalRequest, node.totalSuccess());
 
         // now there are no data in time span, so the minRT should be equals to TIME_DROP_VALVE
-        assertEquals(node.minRt(), Constants.TIME_DROP_VALVE, 0.01);
+        assertEquals(node.minRt(), SentinelConfig.statisticMaxRt(), 0.01);
 
         log("====================================================");
         log("testStatisticThreadNumAndQps done, cost " + (TimeUtil.currentTimeMillis() - testStartTime) + "ms");