Submit PR #3276 against the 2.0.x branch (#3297)

* An enhancement when multiple HystrixConcurrencyStrategy detected. Fixes #3256

* replace exception with wran log

spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/hystrix/security/HystrixSecurityAutoConfiguration.java

@@ -18,6 +18,9 @@ package org.springframework.cloud.netflix.hystrix.security;
 
 import javax.annotation.PostConstruct;
 
+import com.netflix.hystrix.strategy.concurrency.HystrixConcurrencyStrategyDefault;
+import org.apache.commons.logging.Log;
+import org.apache.commons.logging.LogFactory;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.autoconfigure.condition.AllNestedConditions;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
@@ -42,6 +45,7 @@ import com.netflix.hystrix.strategy.properties.HystrixPropertiesStrategy;
 @Conditional(HystrixSecurityCondition.class)
 @ConditionalOnClass({ Hystrix.class, SecurityContext.class })
 public class HystrixSecurityAutoConfiguration {
+	private static final Log LOGGER = LogFactory.getLog(HystrixSecurityAutoConfiguration.class);
 	@Autowired(required = false)
 	private HystrixConcurrencyStrategy existingConcurrencyStrategy;
 
@@ -56,18 +60,36 @@ public class HystrixSecurityAutoConfiguration {
 				.getPropertiesStrategy();
 		HystrixCommandExecutionHook commandExecutionHook = HystrixPlugins.getInstance()
 				.getCommandExecutionHook();
+		HystrixConcurrencyStrategy concurrencyStrategy = detectRegisteredConcurrencyStrategy();
 
 		HystrixPlugins.reset();
 
 		// Registers existing plugins excepts the Concurrent Strategy plugin.
 		HystrixPlugins.getInstance().registerConcurrencyStrategy(
-				new SecurityContextConcurrencyStrategy(existingConcurrencyStrategy));
+				new SecurityContextConcurrencyStrategy(concurrencyStrategy));
 		HystrixPlugins.getInstance().registerEventNotifier(eventNotifier);
 		HystrixPlugins.getInstance().registerMetricsPublisher(metricsPublisher);
 		HystrixPlugins.getInstance().registerPropertiesStrategy(propertiesStrategy);
 		HystrixPlugins.getInstance().registerCommandExecutionHook(commandExecutionHook);
 	}
 
+	private HystrixConcurrencyStrategy detectRegisteredConcurrencyStrategy() {
+		HystrixConcurrencyStrategy registeredStrategy = HystrixPlugins.getInstance()
+				.getConcurrencyStrategy();
+		if (existingConcurrencyStrategy == null) {
+			return registeredStrategy;
+		}
+		//Hystrix registered a default Strategy.
+		if (registeredStrategy instanceof HystrixConcurrencyStrategyDefault){
+			return existingConcurrencyStrategy;
+		}
+		//If registeredStrategy not the default and not some use bean of existingConcurrencyStrategy.
+		if (!existingConcurrencyStrategy.equals(registeredStrategy)){
+			LOGGER.warn("Multiple HystrixConcurrencyStrategy detected. Bean of HystrixConcurrencyStrategy was used.");
+		}
+		return existingConcurrencyStrategy;
+	}
+
 	static class HystrixSecurityCondition extends AllNestedConditions {
 
 		public HystrixSecurityCondition() {

spring-cloud-netflix-core/src/test/java/org/springframework/cloud/netflix/hystrix/security/HystrixSecurityAutoConfigurationTest.java

@@ -0,0 +1,110 @@
+/*
+ * Copyright 2013-2018 the original author or authors.
+ *
+ * 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 org.springframework.cloud.netflix.hystrix.security;
+
+import com.netflix.hystrix.strategy.HystrixPlugins;
+import com.netflix.hystrix.strategy.concurrency.HystrixConcurrencyStrategy;
+import com.netflix.hystrix.strategy.concurrency.HystrixConcurrencyStrategyDefault;
+import com.netflix.hystrix.strategy.eventnotifier.HystrixEventNotifier;
+import com.netflix.hystrix.strategy.executionhook.HystrixCommandExecutionHook;
+import com.netflix.hystrix.strategy.metrics.HystrixMetricsPublisher;
+import com.netflix.hystrix.strategy.properties.HystrixPropertiesStrategy;
+import org.junit.Test;
+import org.mockito.internal.util.reflection.FieldSetter;
+
+import java.lang.reflect.Field;
+
+import static org.junit.Assert.assertEquals;
+
+/**
+ * @author : ailin.zhou
+ */
+public class HystrixSecurityAutoConfigurationTest {
+
+    @Test
+    public void testInit() throws NoSuchFieldException, IllegalAccessException {
+
+        //save test context
+        HystrixEventNotifier eventNotifier = HystrixPlugins.getInstance()
+                .getEventNotifier();
+        HystrixMetricsPublisher metricsPublisher = HystrixPlugins.getInstance()
+                .getMetricsPublisher();
+        HystrixPropertiesStrategy propertiesStrategy = HystrixPlugins.getInstance()
+                .getPropertiesStrategy();
+        HystrixCommandExecutionHook commandExecutionHook = HystrixPlugins.getInstance()
+                .getCommandExecutionHook();
+        HystrixConcurrencyStrategy concurrencyStrategy = HystrixPlugins.getInstance().getConcurrencyStrategy();
+
+        //test
+        testForMultiConcurrentStrategy();
+
+        //recover test context
+        HystrixPlugins.reset();
+        HystrixPlugins.getInstance().registerConcurrencyStrategy(concurrencyStrategy);
+        HystrixPlugins.getInstance().registerEventNotifier(eventNotifier);
+        HystrixPlugins.getInstance().registerMetricsPublisher(metricsPublisher);
+        HystrixPlugins.getInstance().registerPropertiesStrategy(propertiesStrategy);
+        HystrixPlugins.getInstance().registerCommandExecutionHook(commandExecutionHook);
+
+
+    }
+
+    private void testForMultiConcurrentStrategy() throws IllegalAccessException, NoSuchFieldException {
+        HystrixSecurityAutoConfiguration securityStrategy = new HystrixSecurityAutoConfiguration();
+
+        //1.existingConcurrencyStrategy is null, registeredStrategy is default
+        HystrixPlugins.reset();
+        securityStrategy.init();
+        //result is default
+        assertEquals(HystrixConcurrencyStrategyDefault.getInstance(), getOriginalInSecurityConcurrencyStrategy());
+
+        //2.existingConcurrencyStrategy is null, registered strategy is customized
+        HystrixPlugins.reset();
+        HystrixConcurrencyStrategy customized = new HystrixConcurrencyStrategy() {
+        };
+        HystrixPlugins.getInstance().registerConcurrencyStrategy(customized);
+        securityStrategy.init();
+        //result is customized
+        assertEquals(customized, getOriginalInSecurityConcurrencyStrategy());
+
+        //3.existingConcurrencyStrategy is not null, registeredStrategy is  default.
+        HystrixPlugins.reset();
+        HystrixConcurrencyStrategy existingConcurrencyStrategy = new HystrixConcurrencyStrategy() {
+        };
+        FieldSetter.setField(securityStrategy, securityStrategy.getClass().getDeclaredField("existingConcurrencyStrategy"), existingConcurrencyStrategy);
+        securityStrategy.init();
+        //result is existingConcurrencyStrategy
+        assertEquals(existingConcurrencyStrategy, getOriginalInSecurityConcurrencyStrategy());
+
+        //4.existingConcurrencyStrategy is not null, registeredStrategy is  customized.
+        HystrixPlugins.reset();
+        HystrixPlugins.getInstance().registerConcurrencyStrategy(customized);
+        FieldSetter.setField(securityStrategy, securityStrategy.getClass().getDeclaredField("existingConcurrencyStrategy"), existingConcurrencyStrategy);
+        securityStrategy.init();
+        assertEquals(existingConcurrencyStrategy, getOriginalInSecurityConcurrencyStrategy());
+    }
+
+    private HystrixConcurrencyStrategy getOriginalInSecurityConcurrencyStrategy() throws IllegalAccessException, NoSuchFieldException {
+        HystrixConcurrencyStrategy concurrencyStrategy = HystrixPlugins.getInstance().getConcurrencyStrategy();
+        Field existingConcurrencyStrategy = concurrencyStrategy.getClass().getDeclaredField("existingConcurrencyStrategy");
+        existingConcurrencyStrategy.setAccessible(true);
+        HystrixConcurrencyStrategy strategyInSecurityStrategy = (HystrixConcurrencyStrategy) existingConcurrencyStrategy.get(concurrencyStrategy);
+        return strategyInSecurityStrategy;
+    }
+
+}