WIP

pom4ide.xml

@@ -172,6 +172,18 @@
 			<version>3.5</version>
 			<scope>test</scope>
 		</dependency>
+		<dependency>
+			<groupId>com.netflix.hystrix</groupId>
+			<artifactId>hystrix-core</artifactId>
+			<version>1.5.18</version>
+			<scope>test</scope>
+		</dependency>
+		<dependency>
+			<groupId>org.springframework.cloud</groupId>
+			<artifactId>spring-cloud-starter-hystrix</artifactId>
+			<version>1.4.7.RELEASE</version>
+			<scope>test</scope>
+		</dependency>
 	</dependencies>
 
 	<distributionManagement>

src/test/java/com/alibaba/demo/hystrix/EmployeeService.java

+package com.alibaba.demo.hystrix;
+
+import org.springframework.stereotype.Component;
+
+@Component
+public abstract class EmployeeService {
+    public abstract void getEmployee(int employeeId);
+
+    public void fallbackMethod(int employeeid) {
+        ThreadLocalUtil.addDataToThreadLocalMap("ErrorResponse", "Fallback response:: No employee details available temporarily");
+    }
+}

src/test/java/com/alibaba/demo/hystrix/EmployeeServiceImpl.java

+package com.alibaba.demo.hystrix;
+
+import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
+import com.netflix.hystrix.contrib.javanica.annotation.HystrixProperty;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.core.ParameterizedTypeReference;
+import org.springframework.stereotype.Service;
+
+@Service
+public class EmployeeServiceImpl extends EmployeeService {
+
+    @HystrixCommand(fallbackMethod = "fallbackMethod", commandProperties = {
+            @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "900"),
+            @HystrixProperty(name = "circuitBreaker.errorThresholdPercentage", value = "10") })
+    public void getEmployee(int employeeId) {
+        System.out.println("Getting Employee details for " + employeeId + ", threadLocalUtil : " + ThreadLocalUtil.getDataFromThreadLocalMap("EMPLOYEE_ID"));
+        String response = restTemplate.exchange("http://localhost:8011/findEmployeeDetails/{employeeid}",
+                HttpMethod.GET, null, new ParameterizedTypeReference<String>() {
+                }, employeeId).getBody();
+
+        ThreadLocalUtil.addDataToThreadLocalMap("Response", response);
+    }
+
+    @Autowired
+    RestTemplate restTemplate;
+}

src/test/java/com/alibaba/demo/hystrix/HystrixHook.java

+package com.alibaba.demo.hystrix;
+
+import com.netflix.hystrix.HystrixInvokable;
+import com.netflix.hystrix.exception.HystrixRuntimeException;
+import com.netflix.hystrix.strategy.concurrency.HystrixRequestContext;
+import com.netflix.hystrix.strategy.concurrency.HystrixRequestVariableDefault;
+import com.netflix.hystrix.strategy.executionhook.HystrixCommandExecutionHook;
+
+import java.util.concurrent.ConcurrentHashMap;
+
+public class HystrixHook extends HystrixCommandExecutionHook {
+
+    private HystrixRequestVariableDefault<ConcurrentHashMap<String, Object>> hrv = new HystrixRequestVariableDefault<>();
+
+    @Override
+    public <T> void onStart(HystrixInvokable<T> commandInstance) {
+        HystrixRequestContext.initializeContext();
+        getThreadLocals();
+    }
+
+    @Override
+    public <T> void onExecutionStart(HystrixInvokable<T> commandInstance) {
+        setThreadLocals();
+    }
+
+
+    @Override
+    public <T> void onFallbackStart(HystrixInvokable<T> commandInstance) {
+        setThreadLocals();
+    }
+
+
+    @Override
+    public <T> void onSuccess(HystrixInvokable<T> commandInstance) {
+        HystrixRequestContext.getContextForCurrentThread().shutdown();
+        super.onSuccess(commandInstance);
+    }
+
+    @Override
+    public <T> Exception onError(HystrixInvokable<T> commandInstance, HystrixRuntimeException.FailureType failureType, Exception e) {
+        HystrixRequestContext.getContextForCurrentThread().shutdown();
+        return super.onError(commandInstance, failureType, e);
+    }
+
+    private void getThreadLocals() {
+        hrv.set(ThreadLocalUtil.getThreadLocalData());
+    }
+
+    private void setThreadLocals() {
+        ThreadLocalUtil.setThreadLocalData(hrv.get());
+    }
+}

src/test/java/com/alibaba/demo/hystrix/MainApplication.java

+package com.alibaba.demo.hystrix;
+
+import com.netflix.hystrix.strategy.HystrixPlugins;
+import org.springframework.boot.SpringApplication;
+
+public class MainApplication {
+    public static void main(String[] args) {
+        HystrixPlugins.getInstance().registerCommandExecutionHook(new HystrixHook());
+        SpringApplication.run(Abc.class, args);
+    }
+}

src/test/java/com/alibaba/demo/hystrix/ThreadLocalUtil.java

+package com.alibaba.demo.hystrix;
+
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
+public class ThreadLocalUtil {
+
+    private static ThreadLocal<ConcurrentHashMap<String, Object>> transmittableThreadLocal = new ThreadLocal<>();
+
+    public static ConcurrentHashMap<String, Object> getThreadLocalData() {
+        return transmittableThreadLocal.get();
+    }
+
+    public static void setThreadLocalData(ConcurrentHashMap<String, Object> data) {
+        transmittableThreadLocal.set(data);
+    }
+
+    public static void addDataToThreadLocalMap(String key, Object value) {
+        Map<String, Object> existingDataMap = transmittableThreadLocal.get();
+        if (value != null) {
+            existingDataMap.put(key, value);
+        }
+    }
+
+    public static Object getDataFromThreadLocalMap(String key) {
+        Map<String, Object> existingDataMap = transmittableThreadLocal.get();
+        return existingDataMap.get(key);
+    }
+
+    public static void clearThreadLocalDataMap() {
+        if (transmittableThreadLocal != null) 
+            transmittableThreadLocal.remove();
+    }
+
+    public static Object getRequestData(String key) {
+        Map<String, Object> existingDataMap = transmittableThreadLocal.get();
+        if (existingDataMap != null) {
+            return existingDataMap.get(key);
+        }
+        return "-1";
+    }
+
+
+
+    public static void initThreadLocals() {
+        transmittableThreadLocal.set(new ConcurrentHashMap<>());
+        String requestId = "REQUEST_ID_" + System.currentTimeMillis();
+        addDataToThreadLocalMap("REQUEST_ID", requestId);
+    }
+}