Delegate dynamicBeans for external plugins

When dynamicbeans are defined by an external plugin on commands from a
different plugin, instantiate the dynamic bean with a delegating
classloader which uses the command's classloader as the parent and
resolves resources via the dynamicbean's classloader.  Also instantiate
the dynamicbeans using the injector from the command.

Change-Id: If2cff8235a9680eb64c58b77f2d482c5896baf0f

gerrit-httpd/src/main/java/com/google/gerrit/httpd/restapi/ParameterParser.java

@@ -36,6 +36,7 @@ import com.google.gson.JsonObject;
 import com.google.gson.JsonPrimitive;
 import com.google.gwtexpui.server.CacheHeaders;
 import com.google.inject.Inject;
+import com.google.inject.Injector;
 import java.io.IOException;
 import java.io.StringWriter;
 import java.util.HashSet;
@@ -51,11 +52,16 @@ class ParameterParser {
       ImmutableSet.of("pp", "prettyPrint", "strict", "callback", "alt", "fields");
 
   private final CmdLineParser.Factory parserFactory;
+  private final Injector injector;
   private final DynamicMap<DynamicOptions.DynamicBean> dynamicBeans;
 
   @Inject
-  ParameterParser(CmdLineParser.Factory pf, DynamicMap<DynamicOptions.DynamicBean> dynamicBeans) {
+  ParameterParser(
+      CmdLineParser.Factory pf,
+      Injector injector,
+      DynamicMap<DynamicOptions.DynamicBean> dynamicBeans) {
     this.parserFactory = pf;
+    this.injector = injector;
     this.dynamicBeans = dynamicBeans;
   }
 
@@ -63,7 +69,7 @@ class ParameterParser {
       T param, ListMultimap<String, String> in, HttpServletRequest req, HttpServletResponse res)
       throws IOException {
     CmdLineParser clp = parserFactory.create(param);
-    DynamicOptions pluginOptions = new DynamicOptions(param, dynamicBeans);
+    DynamicOptions pluginOptions = new DynamicOptions(param, injector, dynamicBeans);
     pluginOptions.parseDynamicBeans(clp);
     pluginOptions.setDynamicBeans();
     pluginOptions.onBeanParseStart();

gerrit-server/src/main/java/com/google/gerrit/server/DynamicOptions.java

@@ -15,7 +15,9 @@
 package com.google.gerrit.server;
 
 import com.google.gerrit.extensions.registration.DynamicMap;
+import com.google.gerrit.server.plugins.DelegatingClassLoader;
 import com.google.gerrit.util.cli.CmdLineParser;
+import com.google.inject.Injector;
 import com.google.inject.Provider;
 import java.util.HashMap;
 import java.util.Map;
@@ -80,15 +82,16 @@ public class DynamicOptions {
     void setDynamicBean(String plugin, DynamicBean dynamicBean);
   }
 
-  Object bean;
+  protected Object bean;
-  Map<String, DynamicBean> beansByPlugin;
+  protected Map<String, DynamicBean> beansByPlugin;
+  protected Injector injector;
 
   /**
    * Internal: For Gerrit to include options from DynamicBeans, setup a DynamicMap and instantiate
    * this class so the following methods can be called if desired:
    *
    * <pre>
-   *    DynamicOptions pluginOptions = new DynamicOptions(bean, dynamicBeans);
+   *    DynamicOptions pluginOptions = new DynamicOptions(bean, injector, dynamicBeans);
    *    pluginOptions.parseDynamicBeans(clp);
    *    pluginOptions.setDynamicBeans();
    *    pluginOptions.onBeanParseStart();
@@ -98,18 +101,40 @@ public class DynamicOptions {
    *    pluginOptions.onBeanParseEnd();
    * </pre>
    */
-  public DynamicOptions(Object bean, DynamicMap<DynamicBean> dynamicBeans) {
+  public DynamicOptions(Object bean, Injector injector, DynamicMap<DynamicBean> dynamicBeans) {
     this.bean = bean;
-    beansByPlugin = new HashMap<>();
+    this.injector = injector;
+    beansByPlugin = new HashMap<String, DynamicBean>();
     for (String plugin : dynamicBeans.plugins()) {
       Provider<DynamicBean> provider =
           dynamicBeans.byPlugin(plugin).get(bean.getClass().getCanonicalName());
       if (provider != null) {
-        beansByPlugin.put(plugin, provider.get());
+        beansByPlugin.put(plugin, getDynamicBean(bean, provider.get()));
       }
     }
   }
 
+  public DynamicBean getDynamicBean(Object bean, DynamicBean dynamicBean) {
+    ClassLoader coreCl = getClass().getClassLoader();
+    ClassLoader beanCl = bean.getClass().getClassLoader();
+    if (beanCl != coreCl) { // bean from a plugin?
+      ClassLoader dynamicBeanCl = dynamicBean.getClass().getClassLoader();
+      if (beanCl != dynamicBeanCl) { // in a different plugin?
+        ClassLoader mergedCL = new DelegatingClassLoader(beanCl, dynamicBeanCl);
+        try {
+          return injector
+              .createChildInjector()
+              .getInstance(
+                  (Class<DynamicOptions.DynamicBean>)
+                      mergedCL.loadClass(dynamicBean.getClass().getCanonicalName()));
+        } catch (ClassNotFoundException e) {
+          throw new RuntimeException(e);
+        }
+      }
+    }
+    return dynamicBean;
+  }
+
   public void parseDynamicBeans(CmdLineParser clp) {
     for (Entry<String, DynamicBean> e : beansByPlugin.entrySet()) {
       clp.parseWithPrefix(e.getKey(), e.getValue());

gerrit-server/src/main/java/com/google/gerrit/server/plugins/DelegatingClassLoader.java

@@ -0,0 +1,69 @@
+// Copyright (C) 2016 The Android Open Source Project
+//
+// Licensed 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://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 com.google.gerrit.server.plugins;
+
+import com.google.common.io.ByteStreams;
+
+import java.io.ByteArrayOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.net.URL;
+import java.util.Enumeration;
+
+public class DelegatingClassLoader extends ClassLoader {
+  public ClassLoader target;
+
+  public DelegatingClassLoader(ClassLoader parent, ClassLoader target) {
+    super(parent);
+    this.target = target;
+  }
+
+  public Class<?> findClass(String name) throws ClassNotFoundException {
+    String path = name.replace('.', '/') + ".class";
+    InputStream resource = target.getResourceAsStream(path);
+    if (resource != null) {
+      try {
+        byte[] bytes = ByteStreams.toByteArray(resource);
+        return defineClass(name, bytes, 0, bytes.length);
+      } catch (IOException e) {
+      }
+    }
+    throw new ClassNotFoundException(name);
+  }
+
+  public URL getResource(String name) {
+    URL rtn = getParent().getResource(name);
+    if (rtn == null) {
+      rtn = target.getResource(name);
+    }
+    return rtn;
+  }
+
+  public Enumeration<URL> getResources(String name) throws IOException {
+    Enumeration<URL> rtn = getParent().getResources(name);
+    if (rtn == null) {
+      rtn = target.getResources(name);
+    }
+    return rtn;
+  }
+
+  public InputStream getResourceAsStream(String name) {
+    InputStream rtn = getParent().getResourceAsStream(name);
+    if (rtn == null) {
+      rtn = target.getResourceAsStream(name);
+    }
+    return rtn;
+  }
+}

gerrit-sshd/src/main/java/com/google/gerrit/sshd/BaseCommand.java

@@ -35,6 +35,7 @@ import com.google.gerrit.sshd.SshScope.Context;
 import com.google.gerrit.util.cli.CmdLineParser;
 import com.google.gerrit.util.cli.EndOfOptionsHandler;
 import com.google.inject.Inject;
+import com.google.inject.Injector;
 import java.io.BufferedWriter;
 import java.io.IOException;
 import java.io.InputStream;
@@ -86,13 +87,15 @@ public abstract class BaseCommand implements Command {
 
   @Inject private SshScope.Context context;
 
-  @Inject private DynamicMap<DynamicOptions.DynamicBean> dynamicBeans;
-
   /** Commands declared by a plugin can be scoped by the plugin name. */
   @Inject(optional = true)
   @PluginName
   private String pluginName;
 
+  @Inject private Injector injector;
+
+  @Inject private DynamicMap<DynamicOptions.DynamicBean> dynamicBeans = null;
+
   /** The task, as scheduled on a worker thread. */
   private final AtomicReference<Future<?>> task;
 
@@ -197,7 +200,7 @@ public abstract class BaseCommand implements Command {
    */
   protected void parseCommandLine(Object options) throws UnloggedFailure {
     final CmdLineParser clp = newCmdLineParser(options);
-    DynamicOptions pluginOptions = new DynamicOptions(options, dynamicBeans);
+    DynamicOptions pluginOptions = new DynamicOptions(options, injector, dynamicBeans);
     pluginOptions.parseDynamicBeans(clp);
     pluginOptions.setDynamicBeans();
     pluginOptions.onBeanParseStart();