From 5bb12ec2455320fb56afd2d3150ea335e4c7e4fc Mon Sep 17 00:00:00 2001
From: Dodecahedra <k.degeling@student.tue.nl>
Date: Fri, 4 Sep 2020 15:20:54 +0200
Subject: [PATCH] Add pre-loading setting to load OpenAPI early

Add configuration setting to `SpringDocConfigProperties` to enable pre-loading of OpenAPI. This setting is false by default. When instantiating `AbstractOpenApiResource` the OpenAPI is generated in a separate thread. Fixes #850
---
 .../org/springdoc/api/AbstractOpenApiResource.java  |  5 +++++
 .../springdoc/core/SpringDocConfigProperties.java   | 13 +++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/springdoc-openapi-common/src/main/java/org/springdoc/api/AbstractOpenApiResource.java b/springdoc-openapi-common/src/main/java/org/springdoc/api/AbstractOpenApiResource.java
index c9c90c918..3dc022aa3 100644
--- a/springdoc-openapi-common/src/main/java/org/springdoc/api/AbstractOpenApiResource.java
+++ b/springdoc-openapi-common/src/main/java/org/springdoc/api/AbstractOpenApiResource.java
@@ -37,6 +37,7 @@
 import java.util.Objects;
 import java.util.Optional;
 import java.util.Set;
+import java.util.concurrent.Executors;
 import java.util.stream.Collectors;
 
 import com.fasterxml.jackson.annotation.JsonView;
@@ -200,6 +201,10 @@ protected AbstractOpenApiResource(String groupName, ObjectFactory<OpenAPIBuilder
 			operationCustomizers.get().removeIf(Objects::isNull);
 		this.operationCustomizers = operationCustomizers;
 		this.actuatorProvider = actuatorProvider;
+		if (springDocConfigProperties.isPreLoadingEnabled()) {
+			Executors.newSingleThreadExecutor()
+					.execute(this::getOpenApi);
+		}
 	}
 
 	/**
diff --git a/springdoc-openapi-common/src/main/java/org/springdoc/core/SpringDocConfigProperties.java b/springdoc-openapi-common/src/main/java/org/springdoc/core/SpringDocConfigProperties.java
index ad0f3ff3a..572a62bcd 100644
--- a/springdoc-openapi-common/src/main/java/org/springdoc/core/SpringDocConfigProperties.java
+++ b/springdoc-openapi-common/src/main/java/org/springdoc/core/SpringDocConfigProperties.java
@@ -130,6 +130,11 @@ public class SpringDocConfigProperties {
 	 */
 	private boolean showLoginEndpoint;
 
+	/**
+	 * Allow for pre-loading OpenAPI
+	 */
+	private boolean preLoadingEnabled = false;
+
 	/**
 	 * Is use fqn boolean.
 	 *
@@ -472,6 +477,14 @@ public void setWriterWithDefaultPrettyPrinter(boolean writerWithDefaultPrettyPri
 		this.writerWithDefaultPrettyPrinter = writerWithDefaultPrettyPrinter;
 	}
 
+	public void setPreLoadingEnabled(boolean preLoadingEnabled) {
+		this.preLoadingEnabled = preLoadingEnabled;
+	}
+
+	public boolean isPreLoadingEnabled() {
+		return preLoadingEnabled;
+	}
+
 	/**
 	 * The type Model converters.
 	 */