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Support degrade by exception count (#174)
* Add a new DegradeRule type, degrade by exception count in the last 60 seconds * Add demo about degrading by exception count
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...-basic/src/main/java/com/alibaba/csp/sentinel/demo/degrade/ExceptionCountDegradeDemo.java
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| package com.alibaba.csp.sentinel.demo.degrade; | ||
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| import java.util.ArrayList; | ||
| import java.util.List; | ||
| import java.util.concurrent.TimeUnit; | ||
| import java.util.concurrent.atomic.AtomicInteger; | ||
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| import com.alibaba.csp.sentinel.Entry; | ||
| import com.alibaba.csp.sentinel.SphU; | ||
| import com.alibaba.csp.sentinel.Tracer; | ||
| 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.util.TimeUtil; | ||
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| /** | ||
| * <p> | ||
| * Degrade is used when the resources are in an unstable state, these resources | ||
| * will be degraded within the next defined time window. There are three ways to | ||
| * measure whether a resource is stable or not: | ||
| * <ul> | ||
| * <li> | ||
| * Exception count: When the exception count in the last 60 seconds greats than | ||
| * or equals to the threshold, access to the resource will be blocked in the | ||
| * coming time window. | ||
| * </li> | ||
| * <li> | ||
| * Exception ratio, see {@link ExceptionRatioDegradeDemo}. | ||
| * </li> | ||
| * <li> | ||
| * For average response time, see {@link RtDegradeDemo}. | ||
| * </li> | ||
| * </ul> | ||
| * </p> | ||
| * <p> | ||
| * Note: When degrading by {@link RuleConstant#DEGRADE_GRADE_EXCEPTION_COUNT}, time window | ||
| * less than 60 seconds will not work as expected. Because the exception count is | ||
| * summed by minute, when a short time window elapsed, the degradation condition | ||
| * may still be satisfied. | ||
| * </p> | ||
| * | ||
| * @author Carpenter Lee | ||
| */ | ||
| public class ExceptionCountDegradeDemo { | ||
| private static final String KEY = "abc"; | ||
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| private static AtomicInteger total = new AtomicInteger(); | ||
| private static AtomicInteger pass = new AtomicInteger(); | ||
| private static AtomicInteger block = new AtomicInteger(); | ||
| private static AtomicInteger bizException = new AtomicInteger(); | ||
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| private static volatile boolean stop = false; | ||
| private static final int threadCount = 1; | ||
| private static int seconds = 60 + 40; | ||
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| public static void main(String[] args) throws Exception { | ||
| tick(); | ||
| initDegradeRule(); | ||
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| for (int i = 0; i < threadCount; i++) { | ||
| Thread entryThread = new Thread(new Runnable() { | ||
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| @Override | ||
| public void run() { | ||
| int count = 0; | ||
| while (true) { | ||
| count++; | ||
| Entry entry = null; | ||
| try { | ||
| Thread.sleep(20); | ||
| entry = SphU.entry(KEY); | ||
| // token acquired, means pass | ||
| pass.addAndGet(1); | ||
| if (count % 2 == 0) { | ||
| // biz code raise an exception. | ||
| throw new RuntimeException("throw runtime "); | ||
| } | ||
| } catch (BlockException e) { | ||
| block.addAndGet(1); | ||
| } catch (Throwable t) { | ||
| bizException.incrementAndGet(); | ||
| Tracer.trace(t); | ||
| } finally { | ||
| total.addAndGet(1); | ||
| if (entry != null) { | ||
| entry.exit(); | ||
| } | ||
| } | ||
| } | ||
| } | ||
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| }); | ||
| entryThread.setName("working-thread"); | ||
| entryThread.start(); | ||
| } | ||
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| } | ||
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| private static void initDegradeRule() { | ||
| List<DegradeRule> rules = new ArrayList<DegradeRule>(); | ||
| DegradeRule rule = new DegradeRule(); | ||
| rule.setResource(KEY); | ||
| // set limit exception count to 4 | ||
| rule.setCount(4); | ||
| rule.setGrade(RuleConstant.DEGRADE_GRADE_EXCEPTION_COUNT); | ||
| /** | ||
| * When degrading by {@link RuleConstant#DEGRADE_GRADE_EXCEPTION_COUNT}, time window | ||
| * less than 60 seconds will not work as expected. Because the exception count is | ||
| * summed by minute, when a short time window elapsed, the degradation condition | ||
| * may still be satisfied. | ||
| */ | ||
| rule.setTimeWindow(10); | ||
| rules.add(rule); | ||
| DegradeRuleManager.loadRules(rules); | ||
| } | ||
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| private static void tick() { | ||
| Thread timer = new Thread(new TimerTask()); | ||
| timer.setName("sentinel-timer-task"); | ||
| timer.start(); | ||
| } | ||
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| static class TimerTask implements Runnable { | ||
| @Override | ||
| public void run() { | ||
| long start = System.currentTimeMillis(); | ||
| System.out.println("begin to statistic!!!"); | ||
| long oldTotal = 0; | ||
| long oldPass = 0; | ||
| long oldBlock = 0; | ||
| long oldBizException = 0; | ||
| while (!stop) { | ||
| try { | ||
| TimeUnit.SECONDS.sleep(1); | ||
| } catch (InterruptedException e) { | ||
| } | ||
| long globalTotal = total.get(); | ||
| long oneSecondTotal = globalTotal - oldTotal; | ||
| oldTotal = globalTotal; | ||
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| long globalPass = pass.get(); | ||
| long oneSecondPass = globalPass - oldPass; | ||
| oldPass = globalPass; | ||
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| long globalBlock = block.get(); | ||
| long oneSecondBlock = globalBlock - oldBlock; | ||
| oldBlock = globalBlock; | ||
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| long globalBizException = bizException.get(); | ||
| long oneSecondBizException = globalBizException - oldBizException; | ||
| oldBizException = globalBizException; | ||
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| System.out.println(TimeUtil.currentTimeMillis() + ", oneSecondTotal:" + oneSecondTotal | ||
| + ", oneSecondPass:" + oneSecondPass | ||
| + ", oneSecondBlock:" + oneSecondBlock | ||
| + ", oneSecondBizException:" + oneSecondBizException); | ||
| if (seconds-- <= 0) { | ||
| stop = true; | ||
| } | ||
| } | ||
| long cost = System.currentTimeMillis() - start; | ||
| System.out.println("time cost: " + cost + " ms"); | ||
| System.out.println("total:" + total.get() + ", pass:" + pass.get() | ||
| + ", block:" + block.get() + ", bizException:" + bizException.get()); | ||
| System.exit(0); | ||
| } | ||
| } | ||
| } |
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