Local root directory and jar caching in PathMatchingResourcePatternResolver

Closes gh-21190

spring-context/src/main/java/org/springframework/context/support/AbstractApplicationContext.java

@@ -1021,6 +1021,14 @@ public abstract class AbstractApplicationContext extends DefaultResourceLoader
 		CachedIntrospectionResults.clearClassLoader(getClassLoader());
 	}
 
+	@Override
+	public void clearResourceCaches() {
+		super.clearResourceCaches();
+		if (this.resourcePatternResolver instanceof PathMatchingResourcePatternResolver pmrpr) {
+			pmrpr.clearCache();
+		}
+	}
+
 
 	/**
 	 * Register a shutdown hook {@linkplain Thread#getName() named}

spring-core/src/main/java/org/springframework/core/io/support/PathMatchingResourcePatternResolver.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2023 the original author or authors.
+ * Copyright 2002-2024 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.
@@ -40,8 +40,11 @@ import java.util.Collections;
 import java.util.Enumeration;
 import java.util.LinkedHashSet;
 import java.util.Map;
+import java.util.NavigableSet;
 import java.util.Objects;
 import java.util.Set;
+import java.util.TreeSet;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.function.Predicate;
 import java.util.jar.JarEntry;
 import java.util.jar.JarFile;
@@ -247,6 +250,10 @@ public class PathMatchingResourcePatternResolver implements ResourcePatternResol
 
 	private PathMatcher pathMatcher = new AntPathMatcher();
 
+	private final Map<String, Resource[]> rootDirCache = new ConcurrentHashMap<>();
+
+	private final Map<String, NavigableSet<String>> jarEntryCache = new ConcurrentHashMap<>();
+
 
 	/**
 	 * Create a {@code PathMatchingResourcePatternResolver} with a
@@ -355,6 +362,16 @@ public class PathMatchingResourcePatternResolver implements ResourcePatternResol
 		}
 	}
 
+	/**
+	 * Clear the local resource cache, removing all cached classpath/jar structures.
+	 * @since 6.2
+	 */
+	public void clearCache() {
+		this.rootDirCache.clear();
+		this.jarEntryCache.clear();
+	}
+
+
 	/**
 	 * Find all class location resources with the given location via the ClassLoader.
 	 * <p>Delegates to {@link #doFindAllClassPathResources(String)}.
@@ -567,9 +584,73 @@ public class PathMatchingResourcePatternResolver implements ResourcePatternResol
 	protected Resource[] findPathMatchingResources(String locationPattern) throws IOException {
 		String rootDirPath = determineRootDir(locationPattern);
 		String subPattern = locationPattern.substring(rootDirPath.length());
-		Resource[] rootDirResources = getResources(rootDirPath);
-		Set<Resource> result = new LinkedHashSet<>(16);
+
+		// Look for pre-cached root dir resources, either a direct match
+		// or for a parent directory in the same classpath locations.
+		Resource[] rootDirResources = this.rootDirCache.get(rootDirPath);
+		String actualRootPath = null;
+		if (rootDirResources == null) {
+			// No direct match -> search for parent directory match.
+			String commonPrefix = null;
+			String existingPath = null;
+			boolean commonUnique = true;
+			for (String path : this.rootDirCache.keySet()) {
+				String currentPrefix = null;
+				for (int i = 0; i < path.length(); i++) {
+					if (i == rootDirPath.length() || path.charAt(i) != rootDirPath.charAt(i)) {
+						currentPrefix = path.substring(0, path.lastIndexOf('/', i - 1) + 1);
+						break;
+					}
+				}
+				if (currentPrefix != null) {
+					// A prefix match found, potentially to be turned into a common parent cache entry.
+					if (commonPrefix == null || !commonUnique || currentPrefix.length() > commonPrefix.length()) {
+						commonPrefix = currentPrefix;
+						existingPath = path;
+					}
+					else if (currentPrefix.equals(commonPrefix)) {
+						commonUnique = false;
+					}
+				}
+				else if (actualRootPath == null || path.length() > actualRootPath.length()) {
+					// A direct match found for a parent directory -> use it.
+					rootDirResources = this.rootDirCache.get(path);
+					actualRootPath = path;
+				}
+			}
+			if (rootDirResources == null & StringUtils.hasLength(commonPrefix)) {
+				// Try common parent directory as long as it points to the same classpath locations.
+				rootDirResources = getResources(commonPrefix);
+				Resource[] existingResources = this.rootDirCache.get(existingPath);
+				if (existingResources != null && rootDirResources.length == existingResources.length) {
+					// Replace existing subdirectory cache entry with common parent directory.
+					this.rootDirCache.remove(existingPath);
+					this.rootDirCache.put(commonPrefix, rootDirResources);
+					actualRootPath = commonPrefix;
+				}
+				else if (commonPrefix.equals(rootDirPath)) {
+					// The identified common directory is equal to the currently requested path ->
+					// worth caching specifically, even if it cannot replace the existing sub-entry.
+					this.rootDirCache.put(rootDirPath, rootDirResources);
+				}
+				else {
+					// Mismatch: parent directory points to more classpath locations.
+					rootDirResources = null;
+				}
+			}
+			if (rootDirResources == null) {
+				// Lookup for specific directory, creating a cache entry for it.
+				rootDirResources = getResources(rootDirPath);
+				this.rootDirCache.put(rootDirPath, rootDirResources);
+			}
+		}
+
+		Set<Resource> result = new LinkedHashSet<>(64);
 		for (Resource rootDirResource : rootDirResources) {
+			if (actualRootPath != null && actualRootPath.length() < rootDirPath.length()) {
+				// Create sub-resource for requested sub-location from cached common root directory.
+				rootDirResource = rootDirResource.createRelative(rootDirPath.substring(actualRootPath.length()));
+			}
 			rootDirResource = resolveRootDirResource(rootDirResource);
 			URL rootDirUrl = rootDirResource.getURL();
 			if (equinoxResolveMethod != null && rootDirUrl.getProtocol().startsWith("bundle")) {
@@ -672,10 +753,37 @@ public class PathMatchingResourcePatternResolver implements ResourcePatternResol
 	protected Set<Resource> doFindPathMatchingJarResources(Resource rootDirResource, URL rootDirUrl, String subPattern)
 			throws IOException {
 
+		String jarFileUrl = null;
+		String rootEntryPath = null;
+
+		String urlFile = rootDirUrl.getFile();
+		int separatorIndex = urlFile.indexOf(ResourceUtils.WAR_URL_SEPARATOR);
+		if (separatorIndex == -1) {
+			separatorIndex = urlFile.indexOf(ResourceUtils.JAR_URL_SEPARATOR);
+		}
+		if (separatorIndex != -1) {
+			jarFileUrl = urlFile.substring(0, separatorIndex);
+			rootEntryPath = urlFile.substring(separatorIndex + 2);  // both separators are 2 chars
+			NavigableSet<String> entryCache = this.jarEntryCache.get(jarFileUrl);
+			if (entryCache != null) {
+				Set<Resource> result = new LinkedHashSet<>(64);
+				// Search sorted entries from first entry with rootEntryPath prefix
+				for (String entryPath : entryCache.tailSet(rootEntryPath, false)) {
+					if (!entryPath.startsWith(rootEntryPath)) {
+						// We are beyond the potential matches in the current TreeSet.
+						break;
+					}
+					String relativePath = entryPath.substring(rootEntryPath.length());
+					if (getPathMatcher().match(subPattern, relativePath)) {
+						result.add(rootDirResource.createRelative(relativePath));
+					}
+				}
+				return result;
+			}
+		}
+
 		URLConnection con = rootDirUrl.openConnection();
 		JarFile jarFile;
-		String jarFileUrl;
-		String rootEntryPath;
 		boolean closeJarFile;
 
 		if (con instanceof JarURLConnection jarCon) {
@@ -691,15 +799,8 @@ public class PathMatchingResourcePatternResolver implements ResourcePatternResol
 			// We'll assume URLs of the format "jar:path!/entry", with the protocol
 			// being arbitrary as long as following the entry format.
 			// We'll also handle paths with and without leading "file:" prefix.
-			String urlFile = rootDirUrl.getFile();
 			try {
-				int separatorIndex = urlFile.indexOf(ResourceUtils.WAR_URL_SEPARATOR);
-				if (separatorIndex == -1) {
-					separatorIndex = urlFile.indexOf(ResourceUtils.JAR_URL_SEPARATOR);
-				}
-				if (separatorIndex != -1) {
-					jarFileUrl = urlFile.substring(0, separatorIndex);
-					rootEntryPath = urlFile.substring(separatorIndex + 2);  // both separators are 2 chars
+				if (jarFileUrl != null) {
 					jarFile = getJarFile(jarFileUrl);
 				}
 				else {
@@ -726,10 +827,12 @@ public class PathMatchingResourcePatternResolver implements ResourcePatternResol
 				// The Sun JRE does not return a slash here, but BEA JRockit does.
 				rootEntryPath = rootEntryPath + "/";
 			}
-			Set<Resource> result = new LinkedHashSet<>(8);
-			for (Enumeration<JarEntry> entries = jarFile.entries(); entries.hasMoreElements();) {
+			Set<Resource> result = new LinkedHashSet<>(64);
+			NavigableSet<String> entryCache = new TreeSet<>();
+			for (Enumeration<JarEntry> entries = jarFile.entries(); entries.hasMoreElements(); ) {
 				JarEntry entry = entries.nextElement();
 				String entryPath = entry.getName();
+				entryCache.add(entryPath);
 				if (entryPath.startsWith(rootEntryPath)) {
 					String relativePath = entryPath.substring(rootEntryPath.length());
 					if (getPathMatcher().match(subPattern, relativePath)) {
@@ -737,6 +840,8 @@ public class PathMatchingResourcePatternResolver implements ResourcePatternResol
 					}
 				}
 			}
+			// Cache jar entries in TreeSet for efficient searching on re-encounter.
+			this.jarEntryCache.put(jarFileUrl, entryCache);
 			return result;
 		}
 		finally {
@@ -777,7 +882,7 @@ public class PathMatchingResourcePatternResolver implements ResourcePatternResol
 	protected Set<Resource> doFindPathMatchingFileResources(Resource rootDirResource, String subPattern)
 			throws IOException {
 
-		Set<Resource> result = new LinkedHashSet<>();
+		Set<Resource> result = new LinkedHashSet<>(64);
 		URI rootDirUri;
 		try {
 			rootDirUri = rootDirResource.getURI();
@@ -886,7 +991,7 @@ public class PathMatchingResourcePatternResolver implements ResourcePatternResol
 	 * @see PathMatcher#match(String, String)
 	 */
 	protected Set<Resource> findAllModulePathResources(String locationPattern) throws IOException {
-		Set<Resource> result = new LinkedHashSet<>(16);
+		Set<Resource> result = new LinkedHashSet<>(64);
 
 		// Skip scanning the module path when running in a native image.
 		if (NativeDetector.inNativeImage()) {
@@ -987,7 +1092,7 @@ public class PathMatchingResourcePatternResolver implements ResourcePatternResol
 
 		private final String rootPath;
 
-		private final Set<Resource> resources = new LinkedHashSet<>();
+		private final Set<Resource> resources = new LinkedHashSet<>(64);
 
 		public PatternVirtualFileVisitor(String rootPath, String subPattern, PathMatcher pathMatcher) {
 			this.subPattern = subPattern;
@@ -1000,15 +1105,17 @@ public class PathMatchingResourcePatternResolver implements ResourcePatternResol
 		public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
 			String methodName = method.getName();
 			if (Object.class == method.getDeclaringClass()) {
-				switch(methodName) {
-					case "equals":
+				switch (methodName) {
+					case "equals" -> {
 						// Only consider equal when proxies are identical.
 						return (proxy == args[0]);
-					case "hashCode":
+					}
+					case "hashCode" -> {
 						return System.identityHashCode(proxy);
+					}
 				}
 			}
-			return switch(methodName) {
+			return switch (methodName) {
 				case "getAttributes" -> getAttributes();
 				case "visit" -> {
 					visit(args[0]);