From 210ab249e373c535796b1ff6f9ccfe1ab9c55a7b Mon Sep 17 00:00:00 2001
From: Oliver Drotbohm <odrotbohm@pivotal.io>
Date: Tue, 26 May 2020 18:05:26 +0200
Subject: [PATCH] DATACMNS-1734 - Defer initialization of Repositories in
 DomainClassConverter.

DomainClassConverter now delays the initialization of the Repositories instances used to avoid the premature initialization of repository instances as that can cause deadlocks if the infrastructure backing the repositories is initialized on a separate thread.

Refactored nested converter classes to allow them to be static ones.

Related issues: spring-projects/spring-boot#16230, spring-projects/spring-framework#25131.
Original pull request: #445.
---
 .../support/DomainClassConverter.java         | 38 ++++++++++++++-----
 .../DomainClassConverterUnitTests.java        |  2 +-
 2 files changed, 30 insertions(+), 10 deletions(-)

diff --git a/src/main/java/org/springframework/data/repository/support/DomainClassConverter.java b/src/main/java/org/springframework/data/repository/support/DomainClassConverter.java
index 740c99de4..01080cdfb 100644
--- a/src/main/java/org/springframework/data/repository/support/DomainClassConverter.java
+++ b/src/main/java/org/springframework/data/repository/support/DomainClassConverter.java
@@ -30,6 +30,7 @@ import org.springframework.core.convert.converter.ConverterRegistry;
 import org.springframework.data.repository.CrudRepository;
 import org.springframework.data.repository.core.EntityInformation;
 import org.springframework.data.repository.core.RepositoryInformation;
+import org.springframework.data.util.Lazy;
 import org.springframework.lang.Nullable;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
@@ -47,7 +48,7 @@ public class DomainClassConverter<T extends ConversionService & ConverterRegistr
 		implements ConditionalGenericConverter, ApplicationContextAware {
 
 	private final T conversionService;
-	private Repositories repositories = Repositories.NONE;
+	private Lazy<Repositories> repositories = Lazy.of(Repositories.NONE);
 	private Optional<ToEntityConverter> toEntityConverter = Optional.empty();
 	private Optional<ToIdConverter> toIdConverter = Optional.empty();
 
@@ -97,7 +98,7 @@ public class DomainClassConverter<T extends ConversionService & ConverterRegistr
 	 * @return
 	 */
 	private Optional<? extends ConditionalGenericConverter> getConverter(TypeDescriptor targetType) {
-		return repositories.hasRepositoryFor(targetType.getType()) ? toEntityConverter : toIdConverter;
+		return repositories.get().hasRepositoryFor(targetType.getType()) ? toEntityConverter : toIdConverter;
 	}
 
 	/*
@@ -106,13 +107,18 @@ public class DomainClassConverter<T extends ConversionService & ConverterRegistr
 	 */
 	public void setApplicationContext(ApplicationContext context) {
 
-		this.repositories = new Repositories(context);
+		this.repositories = Lazy.of(() -> {
 
-		this.toEntityConverter = Optional.of(new ToEntityConverter(this.repositories, this.conversionService));
-		this.toEntityConverter.ifPresent(it -> this.conversionService.addConverter(it));
+			Repositories repositories = new Repositories(context);
 
-		this.toIdConverter = Optional.of(new ToIdConverter());
-		this.toIdConverter.ifPresent(it -> this.conversionService.addConverter(it));
+			this.toEntityConverter = Optional.of(new ToEntityConverter(repositories, conversionService));
+			this.toEntityConverter.ifPresent(it -> conversionService.addConverter(it));
+
+			this.toIdConverter = Optional.of(new ToIdConverter(repositories, conversionService));
+			this.toIdConverter.ifPresent(it -> conversionService.addConverter(it));
+
+			return repositories;
+		});
 	}
 
 	/**
@@ -121,9 +127,11 @@ public class DomainClassConverter<T extends ConversionService & ConverterRegistr
 	 * @author Oliver Gierke
 	 * @since 1.10
 	 */
-	private class ToEntityConverter implements ConditionalGenericConverter {
+	private static class ToEntityConverter implements ConditionalGenericConverter {
 
 		private final RepositoryInvokerFactory repositoryInvokerFactory;
+		private final Repositories repositories;
+		private final ConversionService conversionService;
 
 		/**
 		 * Creates a new {@link ToEntityConverter} for the given {@link Repositories} and {@link ConversionService}.
@@ -132,7 +140,10 @@ public class DomainClassConverter<T extends ConversionService & ConverterRegistr
 		 * @param conversionService must not be {@literal null}.
 		 */
 		public ToEntityConverter(Repositories repositories, ConversionService conversionService) {
+
 			this.repositoryInvokerFactory = new DefaultRepositoryInvokerFactory(repositories, conversionService);
+			this.repositories = repositories;
+			this.conversionService = conversionService;
 		}
 
 		/*
@@ -206,7 +217,16 @@ public class DomainClassConverter<T extends ConversionService & ConverterRegistr
 	 * @author Oliver Gierke
 	 * @since 1.10
 	 */
-	class ToIdConverter implements ConditionalGenericConverter {
+	static class ToIdConverter implements ConditionalGenericConverter {
+
+		private final Repositories repositories;
+		private final ConversionService conversionService;
+
+		public ToIdConverter(Repositories repositories, ConversionService conversionService) {
+
+			this.repositories = repositories;
+			this.conversionService = conversionService;
+		}
 
 		/*
 		 * (non-Javadoc)
diff --git a/src/test/java/org/springframework/data/repository/support/DomainClassConverterUnitTests.java b/src/test/java/org/springframework/data/repository/support/DomainClassConverterUnitTests.java
index 65c1f9c94..0c8282d86 100755
--- a/src/test/java/org/springframework/data/repository/support/DomainClassConverterUnitTests.java
+++ b/src/test/java/org/springframework/data/repository/support/DomainClassConverterUnitTests.java
@@ -29,7 +29,6 @@ import org.mockito.Mock;
 import org.mockito.junit.jupiter.MockitoExtension;
 import org.mockito.junit.jupiter.MockitoSettings;
 import org.mockito.quality.Strictness;
-
 import org.springframework.aop.framework.Advised;
 import org.springframework.beans.factory.support.BeanDefinitionBuilder;
 import org.springframework.beans.factory.support.DefaultListableBeanFactory;
@@ -181,6 +180,7 @@ class DomainClassConverterUnitTests {
 	void toIdConverterDoesNotMatchIfTargetTypeIsAssignableFromSource() throws NoSuchMethodException {
 
 		converter.setApplicationContext(initContextWithRepo());
+		assertMatches(false);
 
 		@SuppressWarnings("rawtypes")
 		Optional<ToIdConverter> toIdConverter = (Optional<ToIdConverter>) ReflectionTestUtils.getField(converter,