442524 workaround jvm crash when changed jar files are reloaded

Change-Id: Id8c1ea8afb90099761726b2b930423bd29409646
Signed-off-by: Igor Fedorenko <igor@ifedorenko.com>

4 files changed, 73 insertions, 0 deletions

diff --git a/org.eclipse.m2e.core/src/org/eclipse/m2e/core/internal/MavenPluginActivator.java b/org.eclipse.m2e.core/src/org/eclipse/m2e/core/internal/MavenPluginActivator.java
index 82207689..84b0615f 100644
--- a/org.eclipse.m2e.core/src/org/eclipse/m2e/core/internal/MavenPluginActivator.java
+++ b/org.eclipse.m2e.core/src/org/eclipse/m2e/core/internal/MavenPluginActivator.java
@@ -166,6 +166,8 @@ public class MavenPluginActivator extends Plugin {
       new Throwable().printStackTrace();
     }
 
+    URLConnectionCaches.disable();
+
     this.bundleContext = context;
 
     try {
diff --git a/org.eclipse.m2e.core/src/org/eclipse/m2e/core/internal/URLConnectionCaches.java b/org.eclipse.m2e.core/src/org/eclipse/m2e/core/internal/URLConnectionCaches.java
new file mode 100644
index 00000000..633125cc
--- /dev/null
+++ b/org.eclipse.m2e.core/src/org/eclipse/m2e/core/internal/URLConnectionCaches.java
@@ -0,0 +1,62 @@
+/*******************************************************************************
+ * Copyright (c) 2014 Takari, Inc.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *      Takari, Inc. - initial API and implementation
+ *******************************************************************************/
+
+package org.eclipse.m2e.core.internal;
+
+import java.net.URLConnection;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+
+/**
+ * Workaround for JDK bug http://bugs.java.com/view_bug.do?bug_id=6207022
+ * 
+ * @since 1.6
+ * @see https://bugs.eclipse.org/bugs/show_bug.cgi?id=442524
+ * @see http://bugs.java.com/view_bug.do?bug_id=6207022
+ */
+public final class URLConnectionCaches {
+
+  private static final Logger log = LoggerFactory.getLogger(URLConnectionCaches.class);
+
+  private static final URLConnection conn = new URLConnection(null) {
+    public void connect() {
+    }
+  };
+
+  private URLConnectionCaches() {
+  }
+
+  /**
+   * Disables caching of URLConnections by default.
+   * <p>
+   * According to JDK bug 6207022, JVM caches opened jar files, which results in JVM crashes or other unpredictable
+   * results if the jar are closed, overwritten and reopened.
+   * <p>
+   * This workaround disables URLConnection caching for all protocols, not just jar files, which may result in
+   * performance problems for other URLConnection clients. There is also no way to guarantee that other code does not
+   * reenable caching of URLConnections.
+   * <p>
+   * Longer term solution is likely two fold. First, always create unique copies of jar files passed to Maven class
+   * realms. Second, use {@link URLConnection#setUseCaches(boolean)} to false for all jar files opened by Maven and
+   * Sisu. Both require significant effort, however.
+   */
+  public static void disable() {
+    conn.setDefaultUseCaches(false);
+  }
+
+  public static void assertDisabled() {
+    if(conn.getDefaultUseCaches()) {
+      log.error("Unexpected URLConnection defaultUseCaches enabled");
+    }
+  }
+}
diff --git a/org.eclipse.m2e.core/src/org/eclipse/m2e/core/internal/builder/MavenBuilderImpl.java b/org.eclipse.m2e.core/src/org/eclipse/m2e/core/internal/builder/MavenBuilderImpl.java
index ff7339cf..eee6de1b 100644
--- a/org.eclipse.m2e.core/src/org/eclipse/m2e/core/internal/builder/MavenBuilderImpl.java
+++ b/org.eclipse.m2e.core/src/org/eclipse/m2e/core/internal/builder/MavenBuilderImpl.java
@@ -46,6 +46,7 @@ import org.apache.maven.project.MavenProject;
 import org.eclipse.m2e.core.internal.ExtensionReader;
 import org.eclipse.m2e.core.internal.IMavenConstants;
 import org.eclipse.m2e.core.internal.MavenPluginActivator;
+import org.eclipse.m2e.core.internal.URLConnectionCaches;
 import org.eclipse.m2e.core.internal.builder.BuildResultCollector.Message;
 import org.eclipse.m2e.core.internal.builder.IIncrementalBuildFramework.BuildContext;
 import org.eclipse.m2e.core.internal.builder.plexusbuildapi.AbstractEclipseBuildContext;
@@ -93,6 +94,10 @@ public class MavenBuilderImpl {
   public Set<IProject> build(MavenSession session, IMavenProjectFacade projectFacade, int kind,
       Map<String, String> args, Map<MojoExecutionKey, List<AbstractBuildParticipant>> participants,
       IProgressMonitor monitor) throws CoreException {
+
+    // 442524 safety guard
+    URLConnectionCaches.assertDisabled();
+
     Collection<BuildDebugHook> debugHooks = MavenBuilder.getDebugHooks();
 
     Set<IProject> dependencies = new HashSet<IProject>();
diff --git a/org.eclipse.m2e.core/src/org/eclipse/m2e/core/internal/project/registry/ProjectRegistryManager.java b/org.eclipse.m2e.core/src/org/eclipse/m2e/core/internal/project/registry/ProjectRegistryManager.java
index 493d1348..874e85ce 100644
--- a/org.eclipse.m2e.core/src/org/eclipse/m2e/core/internal/project/registry/ProjectRegistryManager.java
+++ b/org.eclipse.m2e.core/src/org/eclipse/m2e/core/internal/project/registry/ProjectRegistryManager.java
@@ -81,6 +81,7 @@ import org.eclipse.m2e.core.embedder.IMavenExecutionContext;
 import org.eclipse.m2e.core.internal.ExtensionReader;
 import org.eclipse.m2e.core.internal.IMavenConstants;
 import org.eclipse.m2e.core.internal.Messages;
+import org.eclipse.m2e.core.internal.URLConnectionCaches;
 import org.eclipse.m2e.core.internal.builder.MavenBuilder;
 import org.eclipse.m2e.core.internal.embedder.MavenExecutionContext;
 import org.eclipse.m2e.core.internal.embedder.MavenImpl;
@@ -309,6 +310,9 @@ public class ProjectRegistryManager {
       throws CoreException {
     log.debug("Refreshing: {}", pomFiles); //$NON-NLS-1$
 
+    // 442524 safety guard
+    URLConnectionCaches.assertDisabled();
+
     final DependencyResolutionContext context = new DependencyResolutionContext(pomFiles);
 
     // safety net -- do not force refresh of the same installed/resolved artifact more than once