init

sentinel/sentinel-demo/sentinel-demo-slotchain-spi/pom.xml

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+<?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>
+        <artifactId>sentinel-demo</artifactId>
+        <groupId>com.alibaba.csp</groupId>
+        <version>1.8.3</version>
+    </parent>
+    <modelVersion>4.0.0</modelVersion>
+
+    <artifactId>sentinel-demo-slotchain-spi</artifactId>
+</project>

sentinel/sentinel-demo/sentinel-demo-slotchain-spi/src/main/java/com/alibaba/csp/sentinel/demo/slotchain/DemoDegradeRuleApplication.java

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+/*
+ * 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.demo.slotchain;
+
+import com.alibaba.csp.sentinel.Entry;
+import com.alibaba.csp.sentinel.SphU;
+import com.alibaba.csp.sentinel.slots.block.BlockException;
+import com.alibaba.csp.sentinel.slots.block.degrade.DegradeRule;
+import com.alibaba.csp.sentinel.slots.block.degrade.DegradeRuleManager;
+import com.alibaba.csp.sentinel.slots.block.degrade.circuitbreaker.CircuitBreakerStrategy;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Demo for degrade rule using custom SlotChainBuilder {@link DemoSlotChainBuilder}.
+ *
+ * You will see this in sentinel-record.log, indicating that the custom slot chain builder is activated:
+ * [SlotChainProvider] Global slot chain builder resolved: com.alibaba.csp.sentinel.demo.slotchain.DemoSlotChainBuilder
+ *
+ * @author cdfive
+ */
+public class DemoDegradeRuleApplication {
+
+    private static final String RESOURCE_KEY = "abc";
+
+    public static void main(String[] args) throws Exception {
+        initDegradeRule();
+
+        for (int i = 1; i <= 100; i++) {
+            Entry entry = null;
+            try {
+                entry = SphU.entry(RESOURCE_KEY);
+                TimeUnit.MILLISECONDS.sleep(ThreadLocalRandom.current().nextInt(10, 100));
+                System.out.println(i + "=>" + " passed");
+            } catch (BlockException ex) {
+                System.out.println(i + "=>" + " blocked by " + ex.getClass().getSimpleName());
+            } finally {
+                if (entry != null) {
+                    entry.exit();
+                }
+            }
+        }
+    }
+
+    private static void initDegradeRule() {
+        List<DegradeRule> rules = new ArrayList<>();
+        DegradeRule rule = new DegradeRule(RESOURCE_KEY)
+                .setGrade(CircuitBreakerStrategy.SLOW_REQUEST_RATIO.getType())
+                // Max allowed response time
+                .setCount(20)
+                // Retry timeout (in second)
+                .setTimeWindow(10)
+                // Circuit breaker opens when slow request ratio > 20%
+                .setSlowRatioThreshold(0.2)
+                .setMinRequestAmount(10)
+                .setStatIntervalMs(20000);
+        rules.add(rule);
+
+        DegradeRuleManager.loadRules(rules);
+        System.out.println("Degrade rule loaded: " + rules);
+    }
+}

sentinel/sentinel-demo/sentinel-demo-slotchain-spi/src/main/java/com/alibaba/csp/sentinel/demo/slotchain/DemoFlowRuleApplication.java

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+/*
+ * 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.demo.slotchain;
+
+import com.alibaba.csp.sentinel.Entry;
+import com.alibaba.csp.sentinel.SphU;
+import com.alibaba.csp.sentinel.slots.block.BlockException;
+import com.alibaba.csp.sentinel.slots.block.RuleConstant;
+import com.alibaba.csp.sentinel.slots.block.degrade.DegradeRule;
+import com.alibaba.csp.sentinel.slots.block.degrade.DegradeRuleManager;
+import com.alibaba.csp.sentinel.slots.block.degrade.circuitbreaker.CircuitBreakerStrategy;
+import com.alibaba.csp.sentinel.slots.block.flow.FlowRule;
+import com.alibaba.csp.sentinel.slots.block.flow.FlowRuleManager;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.ThreadLocalRandom;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Demo for flow rule using custom SlotChainBuilder {@link DemoSlotChainBuilder}.
+ *
+ * You will see this in sentinel-record.log, indicating that the custom slot chain builder is activated:
+ * [SlotChainProvider] Global slot chain builder resolved: com.alibaba.csp.sentinel.demo.slotchain.DemoSlotChainBuilder
+ *
+ * @author cdfive
+ */
+public class DemoFlowRuleApplication {
+
+    private static final String RESOURCE_KEY = "abc";
+
+    public static void main(String[] args) throws Exception {
+        initFlowQpsRule();
+
+        for (int i = 1; i <= 100; i++) {
+            Entry entry = null;
+            try {
+                entry = SphU.entry(RESOURCE_KEY);
+                TimeUnit.MILLISECONDS.sleep(ThreadLocalRandom.current().nextInt(10, 100));
+                System.out.println(i + "=>" + " passed");
+            } catch (BlockException ex) {
+                System.out.println(i + "=>" + " blocked by " + ex.getClass().getSimpleName());
+            } finally {
+                if (entry != null) {
+                    entry.exit();
+                }
+            }
+        }
+    }
+
+    private static void initFlowQpsRule() {
+        List<FlowRule> rules = new ArrayList<FlowRule>();
+        FlowRule rule1 = new FlowRule();
+        rule1.setResource(RESOURCE_KEY);
+        // set limit qps to 5
+        rule1.setCount(5);
+        rule1.setGrade(RuleConstant.FLOW_GRADE_QPS);
+        rule1.setLimitApp("default");
+        rules.add(rule1);
+        FlowRuleManager.loadRules(rules);
+        System.out.println("Flow rule loaded: " + rules);
+    }
+}

sentinel/sentinel-demo/sentinel-demo-slotchain-spi/src/main/java/com/alibaba/csp/sentinel/demo/slotchain/DemoSlotChainBuilder.java

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+/*
+ * 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.demo.slotchain;
+
+import com.alibaba.csp.sentinel.Constants;
+import com.alibaba.csp.sentinel.log.RecordLog;
+import com.alibaba.csp.sentinel.slotchain.*;
+import com.alibaba.csp.sentinel.slots.DefaultSlotChainBuilder;
+import com.alibaba.csp.sentinel.slots.block.degrade.DegradeSlot;
+import com.alibaba.csp.sentinel.spi.Spi;
+import com.alibaba.csp.sentinel.spi.SpiLoader;
+
+import java.util.List;
+
+/**
+ * A demo {@link SlotChainBuilder} for build custom slot chain.
+ * Two ways to build slot chain are demonstrated.
+ *
+ * Pay attention to that `ProcessorSlotChain` is not a SPI, but the `SlotChainBuilder`.
+ *
+ * Most of the time, we don't need to customize `SlotChainBuilder`,
+ * maybe customize `ProcessorSlot` is enough, refer to `sentinel-demo-slot-spi` module.
+ *
+ * Note that the sentinel's default slots and the order of them are very important, be careful when customizing,
+ * refer to the constants for slot order definitions in {@link Constants}.
+ * You may also refer to {@link DefaultSlotChainBuilder}.
+ *
+ * @author cdfive
+ */
+@Spi
+public class DemoSlotChainBuilder implements SlotChainBuilder {
+
+    @Override
+    public ProcessorSlotChain build() {
+        ProcessorSlotChain chain = new DefaultProcessorSlotChain();
+
+        List<ProcessorSlot> sortedSlotList = SpiLoader.of(ProcessorSlot.class).loadInstanceListSorted();
+        // Filter out `DegradeSlot`
+        // Test for `DemoDegradeRuleApplication`, the demo will not be blocked by `DegradeException`
+        sortedSlotList.removeIf(o -> DegradeSlot.class.equals(o.getClass()));
+        for (ProcessorSlot slot : sortedSlotList) {
+            if (!(slot instanceof AbstractLinkedProcessorSlot)) {
+                RecordLog.warn("The ProcessorSlot(" + slot.getClass().getCanonicalName() + ") is not an instance of AbstractLinkedProcessorSlot, can't be added into ProcessorSlotChain");
+                continue;
+            }
+
+            chain.addLast((AbstractLinkedProcessorSlot<?>) slot);
+        }
+
+        return chain;
+    }
+
+    /**
+     * Another way to build the slot chain, add slot one by one with `SpiLoader#loadInstance`.
+     * Note that the sentinel's default slots and the order of them are very important, be careful when customizing,
+     * refer to the constants for slot order definitions in {@link com.alibaba.csp.sentinel.Constants}.
+     */
+    /*
+    @Override
+    public ProcessorSlotChain build() {
+        ProcessorSlotChain chain = new DefaultProcessorSlotChain();
+
+        // Create a `SpiLoader` instance
+        SpiLoader<ProcessorSlot> spiLoader = SpiLoader.of(ProcessorSlot.class);
+
+        // Add `NodeSelectorSlot`, load by class
+        chain.addLast((AbstractLinkedProcessorSlot<?>) spiLoader.loadInstance(NodeSelectorSlot.class));
+
+        // Add `ClusterBuilderSlot`, load by aliasname(default is classname)
+        chain.addLast((AbstractLinkedProcessorSlot<?>) spiLoader.loadInstance("com.alibaba.csp.sentinel.slots.clusterbuilder.ClusterBuilderSlot"));
+
+        // Add `StatisticSlot`
+        chain.addLast((AbstractLinkedProcessorSlot<?>) spiLoader.loadInstance(StatisticSlot.class));
+
+        // Add `FlowSlot`
+        chain.addLast((AbstractLinkedProcessorSlot<?>) spiLoader.loadInstance(FlowSlot.class));
+
+        // Add `DegradeSlot`
+        // Test for `DemoDegradeRuleApplication`
+        // If we don't add `DegradeSlot`, the demo will not be blocked by `DegradeException`
+        // If it's added, we can see the expected DegradeException
+//        chain.addLast((AbstractLinkedProcessorSlot<?>) spiLoader.loadInstance(DegradeSlot.class));
+        return chain;
+    }
+    */
+}

sentinel/sentinel-demo/sentinel-demo-slotchain-spi/src/main/resources/META-INF/services/com.alibaba.csp.sentinel.slotchain.SlotChainBuilder

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+# Custom SlotChainBuilder to build slot chain
+com.alibaba.csp.sentinel.demo.slotchain.DemoSlotChainBuilder