solved #66, support default degrade rule.

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

@@ -0,0 +1,134 @@
+package com.alibaba.csp.sentinel.slots.block.degrade;
+
+import com.alibaba.csp.sentinel.log.RecordLog;
+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.slots.block.RuleConstant;
+import com.alibaba.csp.sentinel.slots.block.degrade.circuitbreaker.CircuitBreaker;
+import com.alibaba.csp.sentinel.slots.block.degrade.circuitbreaker.ExceptionCircuitBreaker;
+import com.alibaba.csp.sentinel.slots.block.degrade.circuitbreaker.ResponseTimeCircuitBreaker;
+import com.alibaba.csp.sentinel.util.StringUtil;
+
+import java.util.ArrayList;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.stream.Collectors;
+
+/**
+ * @author wuwen
+ */
+public class DefaultDegradeRuleManager {
+
+    public static final String DEFAULT_KEY = "*";
+
+    private static volatile Map<String, List<CircuitBreaker>> circuitBreakers = new ConcurrentHashMap<>();
+    private static volatile Set<DegradeRule> rules = new HashSet<>();
+
+    private static final DefaultDegradeRuleManager.RulePropertyListener LISTENER = new DefaultDegradeRuleManager.RulePropertyListener();
+    private static SentinelProperty<List<DegradeRule>> currentProperty
+            = new DynamicSentinelProperty<>();
+
+    static {
+        currentProperty.addListener(LISTENER);
+    }
+
+
+    static List<CircuitBreaker> getDefaultCircuitBreakers(String resourceName) {
+        List<CircuitBreaker> circuitBreakers = DefaultDegradeRuleManager.circuitBreakers.get(resourceName);
+        if (circuitBreakers == null && !rules.isEmpty()) {
+            return DefaultDegradeRuleManager.circuitBreakers.computeIfAbsent(resourceName,
+                    r -> rules.stream().map(DefaultDegradeRuleManager::newCircuitBreakerFrom).collect(Collectors.toList()));
+        }
+        return circuitBreakers;
+    }
+
+    /**
+     * Load {@link DegradeRule}s, former rules will be replaced.
+     *
+     * @param rules new rules to load.
+     */
+    public static void loadRules(List<DegradeRule> rules) {
+        try {
+            currentProperty.updateValue(rules);
+        } catch (Throwable e) {
+            RecordLog.error("[DefaultDegradeRuleManager] Unexpected error when loading degrade rules", e);
+        }
+    }
+
+    public static boolean isValidDefaultRule(DegradeRule rule) {
+        if (!DegradeRuleManager.isValidRule(rule)) {
+            return false;
+        }
+
+        return rule.getResource().equals(DEFAULT_KEY);
+    }
+
+    /**
+     * Create a circuit breaker instance from provided circuit breaking rule.
+     *
+     * @param rule a valid circuit breaking rule
+     * @return new circuit breaker based on provided rule; null if rule is invalid or unsupported type
+     */
+    private static CircuitBreaker newCircuitBreakerFrom(/*@Valid*/ DegradeRule rule) {
+        switch (rule.getGrade()) {
+            case RuleConstant.DEGRADE_GRADE_RT:
+                return new ResponseTimeCircuitBreaker(rule);
+            case RuleConstant.DEGRADE_GRADE_EXCEPTION_RATIO:
+            case RuleConstant.DEGRADE_GRADE_EXCEPTION_COUNT:
+                return new ExceptionCircuitBreaker(rule);
+            default:
+                return null;
+        }
+    }
+
+
+    private static class RulePropertyListener implements PropertyListener<List<DegradeRule>> {
+
+        private synchronized void reloadFrom(List<DegradeRule> list) {
+
+            if (list == null) {
+                return;
+            }
+
+            Set<DegradeRule> rules = new HashSet<>();
+            List<CircuitBreaker> cbs = new ArrayList<>();
+
+            for (DegradeRule rule : list) {
+                if (!isValidDefaultRule(rule)) {
+                    RecordLog.warn("[DefaultDegradeRuleManager] Ignoring invalid rule when loading new rules: {}", rule);
+                } else {
+
+                    if (StringUtil.isBlank(rule.getLimitApp())) {
+                        rule.setLimitApp(RuleConstant.LIMIT_APP_DEFAULT);
+                    }
+                    CircuitBreaker cb = newCircuitBreakerFrom(rule);
+                    cbs.add(cb);
+                    rules.add(rule);
+                }
+            }
+
+            Map<String, List<CircuitBreaker>> cbMap = new ConcurrentHashMap<>(8);
+
+            DefaultDegradeRuleManager.circuitBreakers.forEach((k, v) -> cbMap.put(k, cbs));
+
+            DefaultDegradeRuleManager.rules = rules;
+            DefaultDegradeRuleManager.circuitBreakers = cbMap;
+        }
+
+        @Override
+        public void configUpdate(List<DegradeRule> conf) {
+            reloadFrom(conf);
+            RecordLog.info("[DefaultDegradeRuleManager] Degrade rules has been updated to: {}", rules);
+        }
+
+        @Override
+        public void configLoad(List<DegradeRule> conf) {
+            reloadFrom(conf);
+            RecordLog.info("[DefaultDegradeRuleManager] Degrade rules loaded: {}", rules);
+        }
+    }
+}

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

@@ -0,0 +1,76 @@
+package com.alibaba.csp.sentinel.slots.block.degrade;
+
+import com.alibaba.csp.sentinel.Constants;
+import com.alibaba.csp.sentinel.Entry;
+import com.alibaba.csp.sentinel.context.Context;
+import com.alibaba.csp.sentinel.node.DefaultNode;
+import com.alibaba.csp.sentinel.slotchain.AbstractLinkedProcessorSlot;
+import com.alibaba.csp.sentinel.slotchain.ResourceWrapper;
+import com.alibaba.csp.sentinel.slots.block.BlockException;
+import com.alibaba.csp.sentinel.slots.block.degrade.circuitbreaker.CircuitBreaker;
+import com.alibaba.csp.sentinel.spi.Spi;
+
+import java.util.List;
+
+/**
+ * @author wuwen
+ */
+@Spi(order = Constants.ORDER_DEGRADE_SLOT + 100)
+public class DefaultDegradeSlot extends AbstractLinkedProcessorSlot<DefaultNode> {
+
+    @Override
+    public void entry(Context context, ResourceWrapper resourceWrapper, DefaultNode node, int count,
+                      boolean prioritized, Object... args) throws Throwable {
+        performChecking(context, resourceWrapper);
+
+        fireEntry(context, resourceWrapper, node, count, prioritized, args);
+    }
+
+    private void performChecking(Context context, ResourceWrapper r) throws BlockException {
+
+        if (DegradeRuleManager.hasConfig(r.getName())) {
+            return;
+        }
+
+        List<CircuitBreaker> circuitBreakers = DefaultDegradeRuleManager.getDefaultCircuitBreakers(r.getName());
+
+        if (circuitBreakers == null || circuitBreakers.isEmpty()) {
+            return;
+        }
+
+        for (CircuitBreaker cb : circuitBreakers) {
+            if (!cb.tryPass(context)) {
+                throw new DegradeException(cb.getRule().getLimitApp(), cb.getRule());
+            }
+        }
+    }
+
+    @Override
+    public void exit(Context context, ResourceWrapper r, int count, Object... args) {
+        Entry curEntry = context.getCurEntry();
+        if (curEntry.getBlockError() != null) {
+            fireExit(context, r, count, args);
+            return;
+        }
+
+        if (DegradeRuleManager.hasConfig(r.getName())) {
+            fireExit(context, r, count, args);
+            return;
+        }
+
+        List<CircuitBreaker> circuitBreakers = DefaultDegradeRuleManager.getDefaultCircuitBreakers(r.getName());
+
+        if (circuitBreakers == null || circuitBreakers.isEmpty()) {
+            return;
+        }
+
+        if (curEntry.getBlockError() == null) {
+            // passed request
+            for (CircuitBreaker circuitBreaker : circuitBreakers) {
+                circuitBreaker.onRequestComplete(context);
+            }
+        }
+
+        fireExit(context, r, count, args);
+    }
+}

sentinel-core/src/main/resources/META-INF/services/com.alibaba.csp.sentinel.slotchain.ProcessorSlot

@@ -6,4 +6,5 @@ com.alibaba.csp.sentinel.slots.statistic.StatisticSlot
 com.alibaba.csp.sentinel.slots.block.authority.AuthoritySlot
 com.alibaba.csp.sentinel.slots.system.SystemSlot
 com.alibaba.csp.sentinel.slots.block.flow.FlowSlot
-com.alibaba.csp.sentinel.slots.block.degrade.DegradeSlot
+com.alibaba.csp.sentinel.slots.block.degrade.DegradeSlot
+com.alibaba.csp.sentinel.slots.block.degrade.DefaultDegradeSlot

sentinel-core/src/test/java/com/alibaba/csp/sentinel/slots/DefaultSlotChainBuilderTest.java

@@ -18,6 +18,7 @@
 import com.alibaba.csp.sentinel.slotchain.AbstractLinkedProcessorSlot;
 import com.alibaba.csp.sentinel.slotchain.ProcessorSlotChain;
 import com.alibaba.csp.sentinel.slots.block.authority.AuthoritySlot;
+import com.alibaba.csp.sentinel.slots.block.degrade.DefaultDegradeSlot;
 import com.alibaba.csp.sentinel.slots.block.degrade.DegradeSlot;
 import com.alibaba.csp.sentinel.slots.block.flow.FlowSlot;
 import com.alibaba.csp.sentinel.slots.clusterbuilder.ClusterBuilderSlot;
@@ -70,6 +71,9 @@ public void testBuild() {
         next = next.getNext();
         assertTrue(next instanceof DegradeSlot);
 
+        next = next.getNext();
+        assertTrue(next instanceof DefaultDegradeSlot);
+
         next = next.getNext();
         assertNull(next);
 

sentinel-core/src/test/java/com/alibaba/csp/sentinel/slots/block/degrade/CircuitBreakingIntegrationTest.java

@@ -44,16 +44,17 @@ public class CircuitBreakingIntegrationTest extends AbstractTimeBasedTest {
 
     @Before
     public void setUp() {
-        DegradeRuleManager.loadRules(new ArrayList<DegradeRule>());
+        DegradeRuleManager.loadRules(new ArrayList<>());
     }
 
     @After
-    public void tearDown() throws Exception {
-        DegradeRuleManager.loadRules(new ArrayList<DegradeRule>());
+    public void tearDown() {
+        DegradeRuleManager.loadRules(new ArrayList<>());
+        DefaultDegradeRuleManager.loadRules(new ArrayList<>());
     }
 
     @Test
-    public void testSlowRequestMode() throws Exception {
+    public void testSlowRequestMode() {
         CircuitBreakerStateChangeObserver observer = mock(CircuitBreakerStateChangeObserver.class);
         setCurrentMillis(System.currentTimeMillis() / 1000 * 1000);
         int retryTimeoutSec = 5;
@@ -115,7 +116,69 @@ public void testSlowRequestMode() throws Exception {
     }
 
     @Test
-    public void testExceptionRatioMode() throws Exception {
+    public void testSlowRequestModeUseDefaultRule() {
+        CircuitBreakerStateChangeObserver observer = mock(CircuitBreakerStateChangeObserver.class);
+        setCurrentMillis(System.currentTimeMillis() / 1000 * 1000);
+        int retryTimeoutSec = 5;
+        int maxRt = 50;
+        int statIntervalMs = 20000;
+        int minRequestAmount = 10;
+        String res = "CircuitBreakingIntegrationTest_testSlowRequestModeUseDefaultRule";
+        EventObserverRegistry.getInstance().addStateChangeObserver(res, observer);
+
+        DefaultDegradeRuleManager.loadRules(Arrays.asList(
+                new DegradeRule(DefaultDegradeRuleManager.DEFAULT_KEY).setTimeWindow(retryTimeoutSec).setCount(maxRt)
+                        .setStatIntervalMs(statIntervalMs).setMinRequestAmount(minRequestAmount)
+                        .setSlowRatioThreshold(0.8d).setGrade(0)));
+
+        // Try first N requests where N = minRequestAmount.
+        for (int i = 0; i < minRequestAmount; i++) {
+            if (i < 7) {
+                assertTrue(entryAndSleepFor(res, maxRt + ThreadLocalRandom.current().nextInt(10, 20)));
+            } else {
+                assertTrue(entryAndSleepFor(res, maxRt + ThreadLocalRandom.current().nextInt(-20, -10)));
+            }
+        }
+
+        // Till now slow ratio should be 70%.
+        assertTrue(entryAndSleepFor(res, maxRt + ThreadLocalRandom.current().nextInt(10, 20)));
+        assertTrue(entryAndSleepFor(res, maxRt + ThreadLocalRandom.current().nextInt(10, 20)));
+        assertTrue(entryAndSleepFor(res, maxRt + ThreadLocalRandom.current().nextInt(10, 20)));
+        assertTrue(entryAndSleepFor(res, maxRt + ThreadLocalRandom.current().nextInt(10, 20)));
+        assertTrue(entryAndSleepFor(res, maxRt + ThreadLocalRandom.current().nextInt(10, 20)));
+        assertTrue(entryAndSleepFor(res, maxRt + ThreadLocalRandom.current().nextInt(10, 20)));
+        // Circuit breaker has transformed to OPEN since here.
+        verify(observer)
+                .onStateChange(eq(State.CLOSED), eq(State.OPEN), any(DegradeRule.class), anyDouble());
+        assertEquals(State.OPEN, DefaultDegradeRuleManager.getDefaultCircuitBreakers(res).get(0).currentState());
+        assertFalse(entryAndSleepFor(res, 1));
+
+        sleepSecond(1);
+        assertFalse(entryAndSleepFor(res, 1));
+        sleepSecond(retryTimeoutSec);
+        // Test HALF-OPEN to OPEN.
+        assertTrue(entryAndSleepFor(res, maxRt + ThreadLocalRandom.current().nextInt(10, 20)));
+
+        verify(observer)
+                .onStateChange(eq(State.OPEN), eq(State.HALF_OPEN), any(DegradeRule.class), nullable(Double.class));
+        verify(observer)
+                .onStateChange(eq(State.HALF_OPEN), eq(State.OPEN), any(DegradeRule.class), anyDouble());
+        // Wait for next retry timeout;
+        reset(observer);
+        sleepSecond(retryTimeoutSec + 1);
+        assertTrue(entryAndSleepFor(res, maxRt - ThreadLocalRandom.current().nextInt(10, 20)));
+        verify(observer)
+                .onStateChange(eq(State.OPEN), eq(State.HALF_OPEN), any(DegradeRule.class), nullable(Double.class));
+        verify(observer)
+                .onStateChange(eq(State.HALF_OPEN), eq(State.CLOSED), any(DegradeRule.class), nullable(Double.class));
+        // Now circuit breaker has been closed.
+        assertTrue(entryAndSleepFor(res, maxRt + ThreadLocalRandom.current().nextInt(10, 20)));
+
+        EventObserverRegistry.getInstance().removeStateChangeObserver(res);
+    }
+
+    @Test
+    public void testExceptionRatioMode() {
         CircuitBreakerStateChangeObserver observer = mock(CircuitBreakerStateChangeObserver.class);
         setCurrentMillis(System.currentTimeMillis() / 1000 * 1000);
         int retryTimeoutSec = 5;
@@ -169,7 +232,7 @@ public void testExceptionRatioMode() throws Exception {
     }
 
     @Test
-    public void testExceptionCountMode() throws Throwable {
+    public void testExceptionCountMode() {
         // TODO
     }
 
@@ -188,7 +251,7 @@ private void verifyState(List<CircuitBreaker> breakers, int target) {
     }
 
     @Test
-    public void testMultipleHalfOpenedBreakers() throws Exception {
+    public void testMultipleHalfOpenedBreakers() {
         CircuitBreakerStateChangeObserver observer = mock(CircuitBreakerStateChangeObserver.class);
         setCurrentMillis(System.currentTimeMillis() / 1000 * 1000);
         int retryTimeoutSec = 2;

sentinel-core/src/test/java/com/alibaba/csp/sentinel/spi/SpiLoaderTest.java

@@ -22,6 +22,7 @@
 import com.alibaba.csp.sentinel.slotchain.SlotChainBuilder;
 import com.alibaba.csp.sentinel.slots.DefaultSlotChainBuilder;
 import com.alibaba.csp.sentinel.slots.block.authority.AuthoritySlot;
+import com.alibaba.csp.sentinel.slots.block.degrade.DefaultDegradeSlot;
 import com.alibaba.csp.sentinel.slots.block.degrade.DegradeSlot;
 import com.alibaba.csp.sentinel.slots.block.flow.FlowSlot;
 import com.alibaba.csp.sentinel.slots.clusterbuilder.ClusterBuilderSlot;
@@ -98,13 +99,14 @@ public void testLoadInstanceList() {
         prototypeSlotClasses.add(NodeSelectorSlot.class);
         prototypeSlotClasses.add(ClusterBuilderSlot.class);
 
-        List<Class<? extends ProcessorSlot>> singletonSlotClasses = new ArrayList<>(6);
+        List<Class<? extends ProcessorSlot>> singletonSlotClasses = new ArrayList<>(7);
         singletonSlotClasses.add(LogSlot.class);
         singletonSlotClasses.add(StatisticSlot.class);
         singletonSlotClasses.add(AuthoritySlot.class);
         singletonSlotClasses.add(SystemSlot.class);
         singletonSlotClasses.add(FlowSlot.class);
         singletonSlotClasses.add(DegradeSlot.class);
+        singletonSlotClasses.add(DefaultDegradeSlot.class);
 
         for (int i = 0; i < slots1.size(); i++) {
             ProcessorSlot slot1 = slots1.get(i);
@@ -148,7 +150,7 @@ public void testLoadInstanceListSorted() {
         assertNotNull(sortedSlots);
 
         // Total 8 default slot in sentinel-core
-        assertEquals(8, sortedSlots.size());
+        assertEquals(9, sortedSlots.size());
 
         // Verify the order of slot
         int index = 0;
@@ -160,6 +162,7 @@ public void testLoadInstanceListSorted() {
         assertTrue(sortedSlots.get(index++) instanceof SystemSlot);
         assertTrue(sortedSlots.get(index++) instanceof FlowSlot);
         assertTrue(sortedSlots.get(index++) instanceof DegradeSlot);
+        assertTrue(sortedSlots.get(index++) instanceof DefaultDegradeSlot);
     }
 
     @Test
@@ -177,7 +180,7 @@ public void testLoadLowestPriorityInstance() {
         assertNotNull(slot);
 
         // NodeSelectorSlot is lowest order priority with @Spi(order = -1000) among all slots
-        assertTrue(slot instanceof DegradeSlot);
+        assertTrue(slot instanceof DefaultDegradeSlot);
     }
 
     @Test