[hotfix] Extract PluginManager interface

flink-core/src/main/java/org/apache/flink/core/plugin/DefaultPluginManager.java

@@ -0,0 +1,84 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http:https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.flink.core.plugin;
+
+import org.apache.flink.annotation.Internal;
+import org.apache.flink.annotation.VisibleForTesting;
+
+import org.apache.flink.shaded.guava18.com.google.common.collect.Iterators;
+
+import javax.annotation.concurrent.ThreadSafe;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.Iterator;
+
+/**
+ * Default implementation of {@link PluginManager}.
+ */
+@Internal
+@ThreadSafe
+public class DefaultPluginManager implements PluginManager {
+
+ /** Parent-classloader to all classloader that are used for plugin loading. We expect that this is thread-safe. */
+ private final ClassLoader parentClassLoader;
+
+ /** A collection of descriptions of all plugins known to this plugin manager. */
+ private final Collection<PluginDescriptor> pluginDescriptors;
+
+ /** List of patterns for classes that should always be resolved from the parent ClassLoader. */
+ private final String[] alwaysParentFirstPatterns;
+
+ @VisibleForTesting
+ DefaultPluginManager() {
+ parentClassLoader = null;
+ pluginDescriptors = null;
+ alwaysParentFirstPatterns = null;
+ }
+
+ public DefaultPluginManager(Collection<PluginDescriptor> pluginDescriptors, String[] alwaysParentFirstPatterns) {
+ this(pluginDescriptors, DefaultPluginManager.class.getClassLoader(), alwaysParentFirstPatterns);
+ }
+
+ public DefaultPluginManager(Collection<PluginDescriptor> pluginDescriptors, ClassLoader parentClassLoader, String[] alwaysParentFirstPatterns) {
+ this.pluginDescriptors = pluginDescriptors;
+ this.parentClassLoader = parentClassLoader;
+ this.alwaysParentFirstPatterns = alwaysParentFirstPatterns;
+ }
+
+ @Override
+ public <P> Iterator<P> load(Class<P> service) {
+ ArrayList<Iterator<P>> combinedIterators = new ArrayList<>(pluginDescriptors.size());
+ for (PluginDescriptor pluginDescriptor : pluginDescriptors) {
+ PluginLoader pluginLoader = PluginLoader.create(pluginDescriptor, parentClassLoader, alwaysParentFirstPatterns);
+ combinedIterators.add(pluginLoader.load(service));
+ }
+ return Iterators.concat(combinedIterators.iterator());
+ }
+
+ @Override
+ public String toString() {
+ return "PluginManager{" +
+ "parentClassLoader=" + parentClassLoader +
+ ", pluginDescriptors=" + pluginDescriptors +
+ ", alwaysParentFirstPatterns=" + Arrays.toString(alwaysParentFirstPatterns) +
+ '}';
+ }
+}

flink-core/src/main/java/org/apache/flink/core/plugin/PluginManager.java

@@ -18,42 +18,13 @@
 
 package org.apache.flink.core.plugin;
 
-import org.apache.flink.annotation.Internal;
-
-import org.apache.flink.shaded.guava18.com.google.common.collect.Iterators;
-
-import javax.annotation.concurrent.ThreadSafe;
-
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.Collection;
 import java.util.Iterator;
 
 /**
- * Manager class and entry-point for the plugin mechanism in Flink.
+ * PluginManager is responsible for managing cluster plugins which are loaded using separate class loaders so that their dependencies
+ * don't interfere with Flink's dependencies.
  */
-@Internal
-@ThreadSafe
-public class PluginManager {
-
- /** Parent-classloader to all classloader that are used for plugin loading. We expect that this is thread-safe. */
- private final ClassLoader parentClassLoader;
-
- /** A collection of descriptions of all plugins known to this plugin manager. */
- private final Collection<PluginDescriptor> pluginDescriptors;
-
- /** List of patterns for classes that should always be resolved from the parent ClassLoader. */
- private final String[] alwaysParentFirstPatterns;
-
- public PluginManager(Collection<PluginDescriptor> pluginDescriptors, String[] alwaysParentFirstPatterns) {
- this(pluginDescriptors, PluginManager.class.getClassLoader(), alwaysParentFirstPatterns);
- }
-
- public PluginManager(Collection<PluginDescriptor> pluginDescriptors, ClassLoader parentClassLoader, String[] alwaysParentFirstPatterns) {
- this.pluginDescriptors = pluginDescriptors;
- this.parentClassLoader = parentClassLoader;
- this.alwaysParentFirstPatterns = alwaysParentFirstPatterns;
- }
+public interface PluginManager {
 
  /**
  * Returns in iterator over all available implementations of the given service interface (SPI) in all the plugins
@@ -63,21 +34,5 @@ public PluginManager(Collection<PluginDescriptor> pluginDescriptors, ClassLoader
  * @param <P> Type of the requested plugin service.
  * @return Iterator over all implementations of the given service that could be loaded from all known plugins.
  */
- public <P> Iterator<P> load(Class<P> service) {
- ArrayList<Iterator<P>> combinedIterators = new ArrayList<>(pluginDescriptors.size());
- for (PluginDescriptor pluginDescriptor : pluginDescriptors) {
- PluginLoader pluginLoader = PluginLoader.create(pluginDescriptor, parentClassLoader, alwaysParentFirstPatterns);
- combinedIterators.add(pluginLoader.load(service));
- }
- return Iterators.concat(combinedIterators.iterator());
- }
-
- @Override
- public String toString() {
- return "PluginManager{" +
- "parentClassLoader=" + parentClassLoader +
- ", pluginDescriptors=" + pluginDescriptors +
- ", alwaysParentFirstPatterns=" + Arrays.toString(alwaysParentFirstPatterns) +
- '}';
- }
+ <P> Iterator<P> load(Class<P> service);
 }

flink-core/src/main/java/org/apache/flink/core/plugin/PluginUtils.java

@@ -43,13 +43,13 @@ private static PluginManager createPluginManagerFromRootFolder(PluginConfig plug
  try {
  Collection<PluginDescriptor> pluginDescriptors =
  new DirectoryBasedPluginFinder(pluginConfig.getPluginsPath().get()).findPlugins();
- return new PluginManager(pluginDescriptors, pluginConfig.getAlwaysParentFirstPatterns());
+ return new DefaultPluginManager(pluginDescriptors, pluginConfig.getAlwaysParentFirstPatterns());
  } catch (IOException e) {
  throw new FlinkRuntimeException("Exception when trying to initialize plugin system.", e);
  }
  }
  else {
- return new PluginManager(Collections.emptyList(), pluginConfig.getAlwaysParentFirstPatterns());
+ return new DefaultPluginManager(Collections.emptyList(), pluginConfig.getAlwaysParentFirstPatterns());
  }
  }
 }

flink-tests/src/test/java/org/apache/flink/test/plugin/PluginManagerTest.java → flink-tests/src/test/java/org/apache/flink/test/plugin/DefaultPluginManagerTest.java

@@ -18,6 +18,7 @@
 
 package org.apache.flink.test.plugin;
 
+import org.apache.flink.core.plugin.DefaultPluginManager;
 import org.apache.flink.core.plugin.DirectoryBasedPluginFinder;
 import org.apache.flink.core.plugin.PluginDescriptor;
 import org.apache.flink.core.plugin.PluginFinder;
@@ -43,9 +44,9 @@
 import java.util.Set;
 
 /**
- * Test for {@link PluginManager}.
+ * Test for {@link DefaultPluginManager}.
  */
-public class PluginManagerTest extends PluginTestBase {
+public class DefaultPluginManagerTest extends PluginTestBase {
 
  @Rule
  public TemporaryFolder temporaryFolder = new TemporaryFolder();
@@ -84,7 +85,7 @@ public void setup() throws Exception {
  public void testPluginLoading() {
 
  String[] parentPatterns = { TestSpi.class.getName(), OtherTestSpi.class.getName() };
- final PluginManager pluginManager = new PluginManager(descriptors, PARENT_CLASS_LOADER, parentPatterns);
+ final PluginManager pluginManager = new DefaultPluginManager(descriptors, PARENT_CLASS_LOADER, parentPatterns);
  final List<TestSpi> serviceImplList = Lists.newArrayList(pluginManager.load(TestSpi.class));
  Assert.assertEquals(2, serviceImplList.size());