Merge pull request #215 from basil/JellyClassLoaderTearOff

Migrate from Guava's cache to `ConcurrentHashMap` in `JellyClassLoaderTearOff`

Author: jglick

jelly/src/main/java/org/kohsuke/stapler/jelly/JellyClassLoaderTearOff.java

@@ -23,9 +23,6 @@
 
 package org.kohsuke.stapler.jelly;
 
-import com.google.common.cache.CacheBuilder;
-import com.google.common.cache.CacheLoader;
-import com.google.common.cache.LoadingCache;
 import org.apache.commons.jelly.JellyContext;
 import org.apache.commons.jelly.JellyException;
 import org.apache.commons.jelly.TagLibrary;
@@ -35,6 +32,8 @@
 
 import java.lang.ref.WeakReference;
 import java.net.URL;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ConcurrentMap;
 
 /**
  * {@link MetaClassLoader} tear-off for Jelly support.
@@ -47,7 +46,7 @@ public class JellyClassLoaderTearOff {
     /**
      * See {@link JellyClassTearOff#scripts} for why we use {@link WeakReference} here.
      */
-    private volatile WeakReference<LoadingCache<String,TagLibrary>> taglibs;
+    private volatile WeakReference<ConcurrentMap<String,TagLibrary>> taglibs;
 
     static ExpressionFactory EXPRESSION_FACTORY = new JexlExpressionFactory();
 
@@ -56,16 +55,18 @@ public JellyClassLoaderTearOff(MetaClassLoader owner) {
     }
 
     public TagLibrary getTagLibrary(String nsUri) {
-        LoadingCache<String,TagLibrary> m=null;
+        ConcurrentMap<String,TagLibrary> m=null;
         if(taglibs!=null)
             m = taglibs.get();
         if(m==null) {
-            m = CacheBuilder.newBuilder().build(new CacheLoader<String,TagLibrary>() {
-                public TagLibrary load(String nsUri) {
+            m = new ConcurrentHashMap<>();
+            taglibs = new WeakReference<>(m);
+        }
+        TagLibrary tl = m.computeIfAbsent(nsUri, key -> {
                     if(owner.parent!=null) {
                         // parent first
-                        TagLibrary tl = owner.parent.loadTearOff(JellyClassLoaderTearOff.class).getTagLibrary(nsUri);
-                        if(tl!=null)    return tl;
+                        TagLibrary taglib = owner.parent.loadTearOff(JellyClassLoaderTearOff.class).getTagLibrary(nsUri);
+                        if(taglib!=null)    return taglib;
                     }
 
                     String taglibBasePath = trimHeadSlash(nsUri);
@@ -90,12 +91,7 @@ public TagLibrary load(String nsUri) {
                         return new StaplerTagLibrary();
 
                     return NO_SUCH_TAGLIBRARY;    // "not found" is also cached.
-                }
-            });
-            taglibs = new WeakReference<LoadingCache<String,TagLibrary>>(m);
-        }
-
-        TagLibrary tl = m.getUnchecked(nsUri);
+        });
         if (tl==NO_SUCH_TAGLIBRARY)     return null;
         return tl;
     }