cache boot version results from maven central to avoid too many unnecessary requests

headless-services/spring-boot-language-server/src/main/java/org/springframework/ide/vscode/boot/app/BootVersionValidator.java

@@ -28,6 +28,7 @@ import org.springframework.stereotype.Component;
 public class BootVersionValidator {
 
 	private static final Logger log = LoggerFactory.getLogger(BootVersionValidator.class);
+
 	private SimpleLanguageServer server;
 	private BootJavaConfig config;
 	

headless-services/spring-boot-language-server/src/main/java/org/springframework/ide/vscode/boot/validation/generations/BootVersionsFromMavenCentral.java

@@ -15,6 +15,8 @@ import java.util.Collections;
 import java.util.List;
 import java.util.Map;
 
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 import org.springframework.http.HttpEntity;
 import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
@@ -26,26 +28,32 @@ import org.springframework.web.client.RestTemplate;
 
 public class BootVersionsFromMavenCentral {
 	
+	private static final Logger log = LoggerFactory.getLogger(BootVersionsFromMavenCentral.class);
 	private static final String URL = "https://search.maven.org/solrsearch/select?q=g:org.springframework.boot+AND+a:spring-boot-starter-parent&core=gav&rows=200&wt=json";
 	
 	@SuppressWarnings({ "rawtypes", "unchecked" })
-	public static List<Version> getBootVersions() {
+	public static List<Version> getBootVersions() throws Exception {
 		HttpHeaders headers = new HttpHeaders();
-
 		headers.setAccept(MediaType.parseMediaTypes("application/json"));
 
 		HttpEntity<?> entity = new HttpEntity(headers);
-
 		RestTemplate restTemplate = new RestTemplate();
-		try {
-			ResponseEntity<Map> responseEntity = restTemplate.exchange(URL, HttpMethod.GET, entity, Map.class);
+		
+		log.info("search maven central for Spring Boot release information via: " + URL);
+
+		ResponseEntity<Map> responseEntity = restTemplate.exchange(URL, HttpMethod.GET, entity, Map.class);
+		int status = responseEntity.getStatusCodeValue();
+
+		log.info("search maven central response code: " + status);
+
+		if (status == 200) {
 			Map<String, Object> json = responseEntity.getBody();
 			Map<String, Object> response = (Map<String, Object>) json.get("response");
 			if (response != null) {
 				List<Version> versions = new ArrayList<>();
 				Object docs = response.get("docs");
+
 				if (docs instanceof List) {
-					
 					for (Object o : (List<?>) docs) {
 						if (o instanceof Map) {
 							Map<String, Object> e = (Map<String, Object>) o;
@@ -62,10 +70,13 @@ public class BootVersionsFromMavenCentral {
 				Collections.sort(versions);
 				return versions;
 			}
-		} catch (Exception e) {
-			// Error case
+			else {
+				throw new Exception("unable to access Spring Boot versions from Maven Central, empty response");
+			}
+		}
+		else {
+			throw new Exception("unable to access Spring Boot versions from Maven Central, query returned " + status);
 		}
-		return null;
 	}
 	
 }

headless-services/spring-boot-language-server/src/main/java/org/springframework/ide/vscode/boot/validation/generations/CachedBootVersionsFromMavenCentral.java

@@ -0,0 +1,58 @@
+/*******************************************************************************
+ * Copyright (c) 2022 VMware, Inc.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *     VMware, Inc. - initial API and implementation
+ *******************************************************************************/
+package org.springframework.ide.vscode.boot.validation.generations;
+
+import java.time.Duration;
+import java.util.List;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+import org.springframework.ide.vscode.commons.java.Version;
+
+import com.google.common.cache.CacheBuilder;
+import com.google.common.cache.CacheLoader;
+import com.google.common.cache.LoadingCache;
+import com.google.common.collect.ImmutableList;
+
+public class CachedBootVersionsFromMavenCentral {
+	
+	private static final Logger log = LoggerFactory.getLogger(CachedBootVersionsFromMavenCentral.class);
+	
+	private static final String KEY = "cacheKey";
+	private static final Duration EXPIRES_AFTER = Duration.ofMinutes(60);
+	
+	private static final LoadingCache<String, List<Version>> cache = CacheBuilder.newBuilder()
+			.expireAfterWrite(EXPIRES_AFTER)
+			.build(new CacheLoader<String, List<Version>>() {
+
+		@Override
+		public List<Version> load(String key) {
+			try {
+				return BootVersionsFromMavenCentral.getBootVersions();
+			}
+			catch (Exception e) {
+				return ImmutableList.of();
+			}
+		}
+		
+	});
+	
+	public static List<Version> getBootVersions() {
+		try {
+			return cache.get(KEY);
+		}
+		catch (Exception e) {
+			log.error("failed to load Spring Boot release information from maven central", e);
+			return ImmutableList.of();
+		}
+	}
+
+}

headless-services/spring-boot-language-server/src/main/java/org/springframework/ide/vscode/boot/validation/generations/json/ResolvedSpringProject.java

@@ -12,7 +12,7 @@ package org.springframework.ide.vscode.boot.validation.generations.json;
 
 import java.util.List;
 
-import org.springframework.ide.vscode.boot.validation.generations.BootVersionsFromMavenCentral;
+import org.springframework.ide.vscode.boot.validation.generations.CachedBootVersionsFromMavenCentral;
 import org.springframework.ide.vscode.boot.validation.generations.SpringProjectsClient;
 import org.springframework.ide.vscode.commons.java.Version;
 
@@ -22,7 +22,6 @@ public class ResolvedSpringProject extends SpringProject {
 
 	private final SpringProjectsClient client;
 	private Generations generations;
-	private List<Version> releases;
 
 	public ResolvedSpringProject(SpringProject project, SpringProjectsClient client) {
 		this.client = client;
@@ -53,10 +52,7 @@ public class ResolvedSpringProject extends SpringProject {
 	 * @throws Exception
 	 */
 	public List<Version> getReleases() throws Exception {
-		// cache the releases to prevent frequent calls to the client
-		if (this.releases == null) {
-			this.releases = BootVersionsFromMavenCentral.getBootVersions();
-		}
-		return this.releases != null ? this.releases : ImmutableList.of();
+		return CachedBootVersionsFromMavenCentral.getBootVersions();
 	}
+
 }