Fix NPE when on the bootclasspath (fixes #481)

To reduce runtime overhead due to fields needed only by certain configurations, code generation is used and reflection loads the optimal implementation classes. This trades off a small amount of disk space for reduced memory usage. Unfortunately the wrong classloader method was used, which is not available on the bootclasspath (null value). This fails when the cache is used by a compiler, e.g. ErrorProne's javac fork. Instead Class.forName is now used which should resolve to a non-null, acceptable class loader. It appears as if this should be the same loader as before, or else the system loader if on the bootclasspath.
ben-manes · Dec 8, 2020 · c1ed088 · c1ed088
1 parent f77b9e2
commit c1ed088
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Showing 3 changed files with 13 additions and 9 deletions.
diff --git a/caffeine/src/javaPoet/java/com/github/benmanes/caffeine/cache/LocalCacheSelectorCode.java b/caffeine/src/javaPoet/java/com/github/benmanes/caffeine/cache/LocalCacheSelectorCode.java
@@ -99,8 +99,7 @@ private LocalCacheSelectorCode expires() {
   private LocalCacheSelectorCode selector() {
     block
         .beginControlFlow("try")
-            .addStatement("$T<?> clazz = $T.class.getClassLoader().loadClass(sb.toString())",
-                Class.class, LOCAL_CACHE_FACTORY)
+            .addStatement("Class<?> clazz = Class.forName(sb.toString())")
             .addStatement("$T<?> ctor = clazz.getDeclaredConstructor($T.class, $T.class, $T.class)",
                 Constructor.class, BUILDER, CACHE_LOADER.rawType, TypeName.BOOLEAN)
             .add("@SuppressWarnings($S)\n", "unchecked")

diff --git a/caffeine/src/javaPoet/java/com/github/benmanes/caffeine/cache/NodeSelectorCode.java b/caffeine/src/javaPoet/java/com/github/benmanes/caffeine/cache/NodeSelectorCode.java
@@ -94,8 +94,7 @@ private NodeSelectorCode maximum() {
   private NodeSelectorCode selector() {
     block
         .beginControlFlow("try")
-            .addStatement("$T<?> clazz = $T.class.getClassLoader().loadClass(sb.toString())",
-                Class.class, NODE_FACTORY.rawType)
+            .addStatement("Class<?> clazz = Class.forName(sb.toString())")
             .add("@SuppressWarnings($S)\n", "unchecked")
             .addStatement("$1T factory = ($1T) clazz.getDeclaredConstructor().newInstance()",
                 NODE_FACTORY)

diff --git a/jcache/src/main/java/com/github/benmanes/caffeine/jcache/spi/CaffeineCachingProvider.java b/jcache/src/main/java/com/github/benmanes/caffeine/jcache/spi/CaffeineCachingProvider.java
@@ -180,7 +180,7 @@ public JCacheClassLoader() {
     public Class<?> loadClass(String name) throws ClassNotFoundException {
       ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();
       ClassNotFoundException error = null;
-      if (contextClassLoader != null && contextClassLoader != DEFAULT_CLASS_LOADER) {
+      if ((contextClassLoader != null) && (contextClassLoader != DEFAULT_CLASS_LOADER)) {
         try {
           return contextClassLoader.loadClass(name);
         } catch (ClassNotFoundException e) {
@@ -198,7 +198,9 @@ public Class<?> loadClass(String name) throws ClassNotFoundException {
       }
 
       ClassLoader parentClassLoader = getParent();
-      if (parentClassLoader != null && parentClassLoader != contextClassLoader && parentClassLoader != classClassLoader) {
+      if ((parentClassLoader != null)
+          && (parentClassLoader != classClassLoader)
+          && (parentClassLoader != contextClassLoader)) {
         return parentClassLoader.loadClass(name);
       }
       throw (error == null) ? new ClassNotFoundException(name) : error;
@@ -207,7 +209,7 @@ public Class<?> loadClass(String name) throws ClassNotFoundException {
     @Override
     public @Nullable URL getResource(String name) {
       ClassLoader contextClassLoader = Thread.currentThread().getContextClassLoader();
-      if (contextClassLoader != null && contextClassLoader != DEFAULT_CLASS_LOADER) {
+      if ((contextClassLoader != null) && (contextClassLoader != DEFAULT_CLASS_LOADER)) {
         URL resource = contextClassLoader.getResource(name);
         if (resource != null) {
           return resource;
@@ -223,7 +225,9 @@ public Class<?> loadClass(String name) throws ClassNotFoundException {
       }
 
       ClassLoader parentClassLoader = getParent();
-      if (parentClassLoader != null && parentClassLoader != contextClassLoader && parentClassLoader != classClassLoader) {
+      if ((parentClassLoader != null)
+          && (parentClassLoader != classClassLoader)
+          && (parentClassLoader != contextClassLoader)) {
         return parentClassLoader.getResource(name);
       }
 
@@ -245,7 +249,9 @@ public Enumeration<URL> getResources(String name) throws IOException {
       }
 
       ClassLoader parentClassLoader = getParent();
-      if (parentClassLoader != null && parentClassLoader != contextClassLoader && parentClassLoader != classClassLoader) {
+      if ((parentClassLoader != null)
+          && (parentClassLoader != classClassLoader)
+          && (parentClassLoader != contextClassLoader)) {
         resources.addAll(Collections.list(parentClassLoader.getResources(name)));
       }