binding/mdsal-binding-dom-codec/src/main/java/org/opendaylight/mdsal/binding/dom/codec/loader/RootCodecClassLoader.java

   1 /*
   2  * Copyright (c) 2019 PANTHEON.tech, s.r.o. and others.  All rights reserved.
   3  *
   4  * This program and the accompanying materials are made available under the
   5  * terms of the Eclipse Public License v1.0 which accompanies this distribution,
   6  * and is available at http://www.eclipse.org/legal/epl-v10.html
   7  */
   8 package org.opendaylight.mdsal.binding.dom.codec.loader;
   9
  10 import static com.google.common.base.Verify.verify;
  11
  12 import com.google.common.collect.ImmutableMap;
  13 import com.google.common.collect.ImmutableMap.Builder;
  14 import java.security.AccessController;
  15 import java.security.PrivilegedAction;
  16 import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
  17 import org.slf4j.Logger;
  18 import org.slf4j.LoggerFactory;
  19
  20 // A root codec classloader, binding only whatever is available StaticClassPool
  21 final class RootCodecClassLoader extends CodecClassLoader {
  22     private static final Logger LOG = LoggerFactory.getLogger(RootCodecClassLoader.class);
  23
  24     static {
  25         verify(registerAsParallelCapable());
  26     }
  27
  28     @SuppressWarnings("rawtypes")
  29     private static final AtomicReferenceFieldUpdater<RootCodecClassLoader, ImmutableMap> LOADERS_UPDATER =
  30             AtomicReferenceFieldUpdater.newUpdater(RootCodecClassLoader.class, ImmutableMap.class, "loaders");
  31
  32     private volatile ImmutableMap<ClassLoader, CodecClassLoader> loaders = ImmutableMap.of();
  33
  34     RootCodecClassLoader() {
  35         super();
  36     }
  37
  38     @Override
  39     CodecClassLoader findClassLoader(final Class<?> bindingClass) {
  40         final ClassLoader target = bindingClass.getClassLoader();
  41         if (target == null) {
  42             // No class loader associated ... well, let's use root then
  43             return this;
  44         }
  45
  46         // Cache for update
  47         ImmutableMap<ClassLoader, CodecClassLoader> local = loaders;
  48         final CodecClassLoader known = local.get(target);
  49         if (known != null) {
  50             return known;
  51         }
  52
  53         // Alright, we need to determine if the class is accessible through our hierarchy (in which case we use
  54         // ourselves) or we need to create a new Leaf.
  55         final CodecClassLoader found;
  56         if (!isOurClass(bindingClass)) {
  57             StaticClassPool.verifyStaticLinkage(target);
  58             found = AccessController.doPrivileged(
  59                 (PrivilegedAction<CodecClassLoader>)() -> new LeafCodecClassLoader(this, target));
  60         } else {
  61             found = this;
  62         }
  63
  64         // Now make sure we cache this result
  65         while (true) {
  66             final Builder<ClassLoader, CodecClassLoader> builder = ImmutableMap.builderWithExpectedSize(
  67                 local.size() + 1);
  68             builder.putAll(local);
  69             builder.put(target, found);
  70
  71             if (LOADERS_UPDATER.compareAndSet(this, local, builder.build())) {
  72                 return found;
  73             }
  74
  75             local = loaders;
  76             final CodecClassLoader recheck = local.get(target);
  77             if (recheck != null) {
  78                 return recheck;
  79             }
  80         }
  81     }
  82
  83     private boolean isOurClass(final Class<?> bindingClass) {
  84         final Class<?> ourClass;
  85         try {
  86             ourClass = loadClass(bindingClass.getName(), false);
  87         } catch (ClassNotFoundException e) {
  88             LOG.debug("Failed to load {}", bindingClass, e);
  89             return false;
  90         }
  91         return bindingClass.equals(ourClass);
  92     }
  93 }