Change "synchronized" to reentrant lock for virtual-threads

spring-cloud-function-adapters/spring-cloud-function-adapter-azure-web/src/main/java/org/springframework/cloud/function/adapter/azure/web/AzureWebProxyInvoker.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023-2023 the original author or authors.
+ * Copyright 2023-2024 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.
@@ -20,6 +20,7 @@
 import java.nio.charset.StandardCharsets;
 import java.util.Map.Entry;
 import java.util.Optional;
+import java.util.concurrent.locks.ReentrantLock;
 
 import com.microsoft.azure.functions.ExecutionContext;
 import com.microsoft.azure.functions.HttpMethod;
@@ -48,6 +49,7 @@
  *
  * @author Christian Tzolov
  * @author Oleg Zhurakousky
+ * @author Omer Celik
  *
  */
 public class AzureWebProxyInvoker implements FunctionInstanceInjector {
@@ -62,6 +64,8 @@ public class AzureWebProxyInvoker implements FunctionInstanceInjector {
 
 	private ServletContext servletContext;
 
+	private static final ReentrantLock globalLock = new ReentrantLock();
+
 	@SuppressWarnings("unchecked")
 	@Override
 	public <T> T getInstance(Class<T> functionClass) throws Exception {
@@ -72,13 +76,20 @@ public <T> T getInstance(Class<T> functionClass) throws Exception {
 	/**
 	 * Because the getInstance is called by Azure Java Function on every function request we need to cache the Spring
 	 * context initialization on the first function call.
+	 * Double-Checked Locking Optimization was used to avoid unnecessary locking overhead.
 	 * @throws ServletException error.
 	 */
 	private void initialize() throws ServletException {
-		synchronized (AzureWebProxyInvoker.class.getName()) {
-			if (mvc == null) {
-				Class<?> startClass = FunctionClassUtils.getStartClass();
-				this.mvc = ServerlessMVC.INSTANCE(startClass);
+		if (mvc == null) {
+			try {
+				globalLock.lock();
+				if (mvc == null) {
+					Class<?> startClass = FunctionClassUtils.getStartClass();
+					this.mvc = ServerlessMVC.INSTANCE(startClass);
+				}
+			}
+			finally {
+				globalLock.unlock();
 			}
 		}
 	}

spring-cloud-function-adapters/spring-cloud-function-adapter-azure/src/main/java/org/springframework/cloud/function/adapter/azure/AzureFunctionInstanceInjector.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2021-2022 the original author or authors.
+ * Copyright 2021-2024 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.
@@ -17,6 +17,7 @@
 package org.springframework.cloud.function.adapter.azure;
 
 import java.util.Map;
+import java.util.concurrent.locks.ReentrantLock;
 
 import com.microsoft.azure.functions.spi.inject.FunctionInstanceInjector;
 import org.apache.commons.logging.Log;
@@ -37,6 +38,7 @@
  * hook. The Azure Java Worker delegates scans the classpath for service definition and delegates the function class
  * creation to this instance factory.
  * @author Christian Tzolov
+ * @author Omer Celik
  * @since 3.2.9
  */
 public class AzureFunctionInstanceInjector implements FunctionInstanceInjector {
@@ -45,6 +47,8 @@ public class AzureFunctionInstanceInjector implements FunctionInstanceInjector {
 
 	private static ConfigurableApplicationContext APPLICATION_CONTEXT;
 
+	private static final ReentrantLock globalLock = new ReentrantLock();
+
 	/**
 	 * This method is called by the Azure Java Worker on every function invocation. The Worker sends in the classes
 	 * annotated with @FunctionName annotations and allows the Spring framework to initialize the function instance as a
@@ -83,13 +87,20 @@ public <T> T getInstance(Class<T> functionClass) throws Exception {
 
 	/**
 	 * Create a static Application Context instance shared between multiple function invocations.
+	 * Double-Checked Locking Optimization was used to avoid unnecessary locking overhead.
 	 */
 	private static void initialize() {
-		synchronized (AzureFunctionInstanceInjector.class.getName()) {
-			if (APPLICATION_CONTEXT == null) {
-				Class<?> springConfigurationClass = FunctionClassUtils.getStartClass();
-				logger.info("Initializing: " + springConfigurationClass);
-				APPLICATION_CONTEXT = springApplication(springConfigurationClass).run();
+		if (APPLICATION_CONTEXT == null) {
+			try {
+				globalLock.lock();
+				if (APPLICATION_CONTEXT == null) {
+					Class<?> springConfigurationClass = FunctionClassUtils.getStartClass();
+					logger.info("Initializing: " + springConfigurationClass);
+					APPLICATION_CONTEXT = springApplication(springConfigurationClass).run();
+				}
+			}
+			finally {
+				globalLock.unlock();
 			}
 		}
 	}

spring-cloud-function-adapters/spring-cloud-function-adapter-azure/src/main/java/org/springframework/cloud/function/adapter/azure/FunctionInvoker.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2021-2022 the original author or authors.
+ * Copyright 2021-2024 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.
@@ -25,6 +25,7 @@
 import java.util.Map;
 import java.util.Map.Entry;
 import java.util.Optional;
+import java.util.concurrent.locks.ReentrantLock;
 
 import com.fasterxml.jackson.databind.ObjectMapper;
 import com.microsoft.azure.functions.ExecutionContext;
@@ -66,6 +67,7 @@
  * @author Oleg Zhurakousky
  * @author Chris Bono
  * @author Christian Tzolov
+ * @author Omer Celik
  *
  * @since 3.2
  *
@@ -85,6 +87,8 @@ public class FunctionInvoker<I, O> {
 
 	private static JsonMapper OBJECT_MAPPER;
 
+	private static final ReentrantLock globalLock = new ReentrantLock();
+
 	public FunctionInvoker(Class<?> configurationClass) {
 		try {
 			initialize(configurationClass);
@@ -355,30 +359,38 @@ private MessageHeaders getHeaders(HttpRequestMessage<I> event) {
 		return new MessageHeaders(headers);
 	}
 
+	/**
+	 * Double-Checked Locking Optimization was used to avoid unnecessary locking overhead.
+	 */
 	private static void initialize(Class<?> configurationClass) {
-		synchronized (FunctionInvoker.class.getName()) {
-			if (FUNCTION_CATALOG == null) {
-				logger.info("Initializing: " + configurationClass);
-				SpringApplication builder = springApplication(configurationClass);
-				APPLICATION_CONTEXT = builder.run();
-
-				Map<String, FunctionCatalog> mf = APPLICATION_CONTEXT.getBeansOfType(FunctionCatalog.class);
-				if (CollectionUtils.isEmpty(mf)) {
-					OBJECT_MAPPER = new JacksonMapper(new ObjectMapper());
-					JsonMessageConverter jsonConverter = new JsonMessageConverter(OBJECT_MAPPER);
-					SmartCompositeMessageConverter messageConverter = new SmartCompositeMessageConverter(
+		if (FUNCTION_CATALOG == null) {
+			try {
+				globalLock.lock();
+				if (FUNCTION_CATALOG == null) {
+					logger.info("Initializing: " + configurationClass);
+					SpringApplication builder = springApplication(configurationClass);
+					APPLICATION_CONTEXT = builder.run();
+
+					Map<String, FunctionCatalog> mf = APPLICATION_CONTEXT.getBeansOfType(FunctionCatalog.class);
+					if (CollectionUtils.isEmpty(mf)) {
+						OBJECT_MAPPER = new JacksonMapper(new ObjectMapper());
+						JsonMessageConverter jsonConverter = new JsonMessageConverter(OBJECT_MAPPER);
+						SmartCompositeMessageConverter messageConverter = new SmartCompositeMessageConverter(
 							Collections.singletonList(jsonConverter));
-					FUNCTION_CATALOG = new SimpleFunctionRegistry(
+						FUNCTION_CATALOG = new SimpleFunctionRegistry(
 							APPLICATION_CONTEXT.getBeanFactory().getConversionService(),
 							messageConverter, OBJECT_MAPPER);
-				}
-				else {
-					OBJECT_MAPPER = APPLICATION_CONTEXT.getBean(JsonMapper.class);
-					FUNCTION_CATALOG = mf.values().iterator().next();
+					}
+					else {
+						OBJECT_MAPPER = APPLICATION_CONTEXT.getBean(JsonMapper.class);
+						FUNCTION_CATALOG = mf.values().iterator().next();
+					}
 				}
 			}
+			finally {
+				globalLock.unlock();
+			}
 		}
-
 	}
 
 	private static SpringApplication springApplication(Class<?> configurationClass) {

spring-cloud-function-adapters/spring-cloud-function-serverless-web/src/main/java/org/springframework/cloud/function/serverless/web/ServerlessAsyncContext.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023-2023 the original author or authors.
+ * Copyright 2023-2024 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.
@@ -19,6 +19,7 @@
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
+import java.util.concurrent.locks.ReentrantLock;
 
 import jakarta.servlet.AsyncContext;
 import jakarta.servlet.AsyncEvent;
@@ -39,6 +40,7 @@
  * Implementation of Async context for {@link ServerlessMVC}.
  *
  * @author Oleg Zhurakousky
+ * @author Omer Celik
  */
 public class ServerlessAsyncContext implements AsyncContext {
 	private final HttpServletRequest request;
@@ -55,6 +57,8 @@ public class ServerlessAsyncContext implements AsyncContext {
 
 	private final List<Runnable> dispatchHandlers = new ArrayList<>();
 
+	private final ReentrantLock globalLock = new ReentrantLock();
+
 
 	public ServerlessAsyncContext(ServletRequest request, @Nullable ServletResponse response) {
 		this.request = (HttpServletRequest) request;
@@ -64,14 +68,18 @@ public ServerlessAsyncContext(ServletRequest request, @Nullable ServletResponse
 
 	public void addDispatchHandler(Runnable handler) {
 		Assert.notNull(handler, "Dispatch handler must not be null");
-		synchronized (this) {
+		try {
+			this.globalLock.lock();
 			if (this.dispatchedPath == null) {
 				this.dispatchHandlers.add(handler);
 			}
 			else {
 				handler.run();
 			}
 		}
+		finally {
+			this.globalLock.unlock();
+		}
 	}
 
 	@Override
@@ -102,10 +110,14 @@ public void dispatch(String path) {
 
 	@Override
 	public void dispatch(@Nullable ServletContext context, String path) {
-		synchronized (this) {
+		try {
+			this.globalLock.lock();
 			this.dispatchedPath = path;
 			this.dispatchHandlers.forEach(Runnable::run);
 		}
+		finally {
+			this.globalLock.unlock();
+		}
 	}
 
 	@Nullable

spring-cloud-function-context/src/main/java/org/springframework/cloud/function/utils/JsonMasker.java

@@ -27,6 +27,7 @@
 import java.util.Map;
 import java.util.Set;
 import java.util.TreeSet;
+import java.util.concurrent.locks.ReentrantLock;
 
 import com.fasterxml.jackson.databind.ObjectMapper;
 import org.apache.commons.logging.Log;
@@ -39,6 +40,7 @@
 
 /**
  * @author Oleg Zhurakousky
+ * @author Omer Celik
  */
 public final class JsonMasker {
 
@@ -50,22 +52,41 @@ public final class JsonMasker {
 
 	private final Set<String> keysToMask;
 
+	private static final ReentrantLock globalLock = new ReentrantLock();
+
 	private JsonMasker() {
 		this.keysToMask = loadKeys();
 		this.mapper = new JacksonMapper(new ObjectMapper());
 
 	}
 
-	public synchronized static JsonMasker INSTANCE() {
+	/**
+	 * Double-Checked Locking Optimization was used to avoid unnecessary locking overhead.
+	 */
+	public static JsonMasker INSTANCE() {
 		if (jsonMasker == null) {
-			jsonMasker = new JsonMasker();
+			try {
+				globalLock.lock();
+				if (jsonMasker == null) {
+					jsonMasker = new JsonMasker();
+				}
+			}
+			finally {
+				globalLock.unlock();
+			}
 		}
 		return jsonMasker;
 	}
 
-	public synchronized static JsonMasker INSTANCE(Set<String> keysToMask) {
-		INSTANCE().addKeys(keysToMask);
-		return jsonMasker;
+	public static JsonMasker INSTANCE(Set<String> keysToMask) {
+		try {
+			globalLock.lock();
+			INSTANCE().addKeys(keysToMask);
+			return jsonMasker;
+		}
+		finally {
+			globalLock.unlock();
+		}
 	}
 
 	public String[] getKeysToMask() {

spring-cloud-function-integration/src/main/java/org/springframework/cloud/function/integration/dsl/FunctionLookupHelper.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2023-2023 the original author or authors.
+ * Copyright 2023-2024 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.
@@ -17,6 +17,7 @@
 package org.springframework.cloud.function.integration.dsl;
 
 import java.util.concurrent.atomic.AtomicReference;
+import java.util.concurrent.locks.ReentrantLock;
 import java.util.function.Consumer;
 import java.util.function.Function;
 import java.util.function.Supplier;
@@ -28,6 +29,7 @@
  * The helper class to lookup functions from the catalog in lazy manner and cache their instances.
  *
  * @author Artem Bilan
+ * @author Omer Celik
  *
  * @since 4.0.3
  */
@@ -72,16 +74,21 @@ private  <T> T requireNonNull(Class<?> functionType, String functionDefinition)
 	 */
 	private static <T> Supplier<T> memoize(Supplier<? extends T> delegate) {
 		AtomicReference<T> value = new AtomicReference<>();
+		ReentrantLock lock = new ReentrantLock();
 		return () -> {
 			T val = value.get();
 			if (val == null) {
-				synchronized (value) {
+				try {
+					lock.lock();
 					val = value.get();
 					if (val == null) {
 						val = delegate.get();
 						value.set(val);
 					}
 				}
+				finally {
+					lock.unlock();
+				}
 			}
 			return val;
 		};