InstanceLoader: ConcurrentModificationException if find() is called a…

…synchronously
aditosoftware · Apr 21, 2017 · d9568bf · d9568bf
1 parent 6b5667f
commit d9568bf
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Showing 2 changed files with 24 additions and 3 deletions.
diff --git a/pom.xml b/pom.xml
@@ -6,7 +6,7 @@
 
   <groupId>de.adito.picoservice</groupId>
   <artifactId>picoservice</artifactId>
-  <version>1.1.0</version>
+  <version>1.1.1</version>
 
   <name>${project.groupId}:${project.artifactId}</name>
   <description>A minimalist registry for java services using serviceloader</description>

diff --git a/src/main/java/de/adito/picoservice/InstanceLoader.java b/src/main/java/de/adito/picoservice/InstanceLoader.java
@@ -28,14 +28,15 @@ IPicoRegistry load()
     return new IPicoRegistry()
     {
       private final ServiceLoader<IPicoRegistration> serviceLoader = ServiceLoader.load(IPicoRegistration.class);
+      private final Collection<IPicoRegistration> loadedServices = _loadServices();
 
       @Nonnull
       @Override
       public <C, A extends Annotation> Map<Class<? extends C>, A> find(@Nonnull Class<C> pSearchedType,
                                                                        @Nonnull Class<A> pAnnotationClass)
       {
         Map<Class<? extends C>, A> map = new HashMap<>();
-        for (IPicoRegistration registration : serviceLoader)
+        for (IPicoRegistration registration : loadedServices)
         {
           Class<?> annotatedClass = registration.getAnnotatedClass();
           if (pSearchedType.isAssignableFrom(annotatedClass))
@@ -55,7 +56,7 @@ public <T, C> Stream<T> find(@Nonnull Class<C> pSearchedType,
                                    @Nonnull Function<Class<? extends C>, T> pResolverFunction)
       {
         Stream.Builder<T> streamBuilder = Stream.builder();
-        for (IPicoRegistration registration : serviceLoader)
+        for (IPicoRegistration registration : loadedServices)
         {
           Class<?> annotatedClass = registration.getAnnotatedClass();
           if (pSearchedType.isAssignableFrom(annotatedClass))
@@ -69,6 +70,26 @@ public <T, C> Stream<T> find(@Nonnull Class<C> pSearchedType,
         return streamBuilder.build();
       }
 
+      /**
+       * We have to load all of our PicoServices into a separate collection, because
+       * the Java-ServiceLoader throws a ConcurrentModificationException if >1 iterators
+       * are iterated at the same time.
+       * Reloading of cached Registrations is currently not supported yet.
+       *
+       * @see <a href="https://anydoby.com/jblog/en/java/2128">https://anydoby.com/jblog/en/java/2128</a>
+       * @see <a href="https://issues.apache.org/jira/browse/SIS-193">https://issues.apache.org/jira/browse/SIS-193</a>
+       */
+      @Nonnull
+      private Collection<IPicoRegistration> _loadServices()
+      {
+        synchronized (serviceLoader)
+        {
+          HashSet<IPicoRegistration> foundServices = new HashSet<>();
+          for (IPicoRegistration registration : serviceLoader)
+            foundServices.add(registration);
+          return Collections.unmodifiableSet(foundServices);
+        }
+      }
     };
   }
 }