use ClassLoaderLeakPreventor to reduce ClassLoaderLeaks of plugins

scm-webapp/src/test/java/sonia/scm/boot/ClassLoaderLifeCycleTest.java

@@ -0,0 +1,112 @@
+package sonia.scm.boot;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+import se.jiderhamn.classloader.leak.prevention.ClassLoaderLeakPreventor;
+import se.jiderhamn.classloader.leak.prevention.ClassLoaderLeakPreventorFactory;
+
+import java.io.Closeable;
+import java.io.IOException;
+import java.net.URL;
+import java.net.URLClassLoader;
+import java.util.List;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.Mockito.*;
+
+@ExtendWith(MockitoExtension.class)
+class ClassLoaderLifeCycleTest {
+
+  @Mock
+  private ClassLoaderLeakPreventorFactory classLoaderLeakPreventorFactory;
+
+  @Mock
+  private ClassLoaderLeakPreventor classLoaderLeakPreventor;
+
+  @Test
+  void shouldThrowIllegalStateExceptionWithoutInit() {
+    ClassLoaderLifeCycle lifeCycle = ClassLoaderLifeCycle.create();
+    assertThrows(IllegalStateException.class, lifeCycle::getBootstrapClassLoader);
+  }
+
+  @Test
+  void shouldThrowIllegalStateExceptionAfterShutdown() {
+    ClassLoaderLifeCycle lifeCycle = createMockedLifeCycle();
+    lifeCycle.init();
+
+    lifeCycle.shutdown();
+    assertThrows(IllegalStateException.class, lifeCycle::getBootstrapClassLoader);
+  }
+
+  @Test
+  void shouldCreateBootstrapClassLoaderOnInit() {
+    ClassLoaderLifeCycle lifeCycle = ClassLoaderLifeCycle.create();
+    lifeCycle.init();
+
+    assertThat(lifeCycle.getBootstrapClassLoader()).isNotNull();
+  }
+
+  @Test
+  void shouldCallTheLeakPreventor() {
+    ClassLoaderLifeCycle lifeCycle = createMockedLifeCycle();
+
+    lifeCycle.init();
+    verify(classLoaderLeakPreventor, times(2)).runPreClassLoaderInitiators();
+
+    lifeCycle.createChildFirstPluginClassLoader(new URL[0], null, "a");
+    lifeCycle.createPluginClassLoader(new URL[0], null, "b");
+    verify(classLoaderLeakPreventor, times(4)).runPreClassLoaderInitiators();
+
+    lifeCycle.shutdown();
+    verify(classLoaderLeakPreventor, times(4)).runCleanUps();
+  }
+
+  @Test
+  void shouldCloseCloseableClassLoaders() throws IOException {
+    // we use URLClassLoader, because we must be sure that the classloader is closable
+    URLClassLoader webappClassLoader = spy(new URLClassLoader(new URL[0], Thread.currentThread().getContextClassLoader()));
+
+    ClassLoaderLifeCycle lifeCycle = createMockedLifeCycle(webappClassLoader);
+    lifeCycle.setClassLoaderAppendListener(c -> spy(c));
+    lifeCycle.init();
+
+    ClassLoader pluginA = lifeCycle.createChildFirstPluginClassLoader(new URL[0], null, "a");
+    ClassLoader pluginB = lifeCycle.createPluginClassLoader(new URL[0], null, "b");
+
+    lifeCycle.shutdown();
+
+    closed(pluginB);
+    closed(pluginA);
+
+    neverClosed(webappClassLoader);
+  }
+
+  private void neverClosed(Object object) throws IOException {
+    Closeable closeable = closeable(object);
+    verify(closeable, never()).close();
+  }
+
+  private void closed(Object object) throws IOException {
+    Closeable closeable = closeable(object);
+    verify(closeable).close();
+  }
+
+  private Closeable closeable(Object object) {
+    assertThat(object).isInstanceOf(Closeable.class);
+    return (Closeable) object;
+  }
+
+  private ClassLoaderLifeCycle createMockedLifeCycle() {
+    return createMockedLifeCycle(Thread.currentThread().getContextClassLoader());
+  }
+
+  private ClassLoaderLifeCycle createMockedLifeCycle(ClassLoader classLoader) {
+    when(classLoaderLeakPreventorFactory.newLeakPreventor(any(ClassLoader.class))).thenReturn(classLoaderLeakPreventor);
+    return new ClassLoaderLifeCycle(classLoader, classLoaderLeakPreventorFactory);
+  }
+
+}

scm-webapp/src/test/java/sonia/scm/plugin/PluginProcessorTest.java

@@ -42,6 +42,7 @@ import org.junit.Before;
 import org.junit.Rule;
 import org.junit.Test;
 import org.junit.rules.TemporaryFolder;
+import sonia.scm.boot.ClassLoaderLifeCycle;
 
 import static org.hamcrest.Matchers.*;
 
@@ -288,7 +289,7 @@ public class PluginProcessorTest
   public void setUp() throws IOException
   {
     pluginDirectory = temp.newFolder();
-    processor = new PluginProcessor(pluginDirectory.toPath());
+    processor = new PluginProcessor(ClassLoaderLifeCycle.create(), pluginDirectory.toPath());
   }
 
   //~--- methods --------------------------------------------------------------