Enable plugins on init to read/edit the All-Projects project.config

Some plugins may store their configuration in the project.config file
of the All-Projects project. The configuration may depend on user
input during the plugin initalization. Plugins are now able to write
configuration parameters into the All-Projects project.config during
an InitStep.

E.g. plugins may provide functionality which should be
enabled/disabled per project, which is reflected by an 'enabled'
parameter in project.config:

  [plugin "myPlugin"]
    enabled = true

If this parameter is not set, the value should be inherited from the
parent project. Having the possibility to edit the All-Projects
project.config on init the user can decide during the plugin
initialization if the functionality should by default be
enabled/disabled for all projects.

Change-Id: I8e240858e0778469c0d511ff380865f317448e15
Signed-off-by: Edwin Kempin <edwin.kempin@sap.com>

Documentation/dev-plugins.txt

@@ -280,6 +280,41 @@ and accessing / changing configuration settings using Section.Factory.
 In addition to the standard Gerrit init injections, plugins receive
 the @PluginName String injection containing their own plugin name.
 
+During their initialization plugins may get access to the
+`project.config` file of the `All-Projects` project and they are able
+to store configuration parameters in it. For this a plugin `InitStep`
+can get `com.google.gerrit.pgm.init.AllProjectsConfig` injected:
+
+[source,java]
+----
+  public class MyInitStep implements InitStep {
+    private final String pluginName;
+    private final ConsoleUI ui;
+    private final AllProjectsConfig allProjectsConfig;
+
+    public MyInitStep(@PluginName String pluginName, ConsoleUI ui,
+        AllProjectsConfig allProjectsConfig) {
+      this.pluginName = pluginName;
+      this.ui = ui;
+      this.allProjectsConfig = allProjectsConfig;
+    }
+
+    @Override
+    public void run() throws Exception {
+      ui.message("\n");
+      ui.header(pluginName + " Integration");
+      boolean enabled = ui.yesno(true, "By default enabled for all projects");
+      Config cfg = allProjectsConfig.load();
+      if (enabled) {
+        cfg.setBoolean("plugin", pluginName, "enabled", enabled);
+      } else {
+        cfg.unset("plugin", pluginName, "enabled");
+      }
+      allProjectsConfig.save(pluginName, "Initialize " + pluginName + " Integration");
+    }
+  }
+----
+
 Bear in mind that the Plugin's InitStep class will be loaded but
 the standard Gerrit runtime environment is not available and the plugin's
 own Guice modules were not initialized.

gerrit-pgm/BUCK

@@ -1,13 +1,15 @@
 SRCS = 'src/main/java/com/google/gerrit/pgm/'
 
 INIT_API_SRCS = [SRCS + n for n in [
+  'init/AllProjectsConfig.java',
+  'init/AllProjectsNameOnInitProvider.java',
+  'util/ConsoleUI.java',
+  'util/Die.java',
   'init/InitFlags.java',
   'init/InitStep.java',
   'init/InitStep.java',
   'init/InstallPlugins.java',
   'init/Section.java',
-  'util/ConsoleUI.java',
-  'util/Die.java',
 ]]
 
 java_library(
@@ -16,6 +18,7 @@ java_library(
   deps = [
     '//gerrit-common:server',
     '//gerrit-server:server',
+    '//lib:guava',
     '//lib/guice:guice',
     '//lib/guice:guice-assistedinject',
     '//lib/jgit:jgit',

gerrit-pgm/src/main/java/com/google/gerrit/pgm/init/AllProjectsConfig.java

@@ -0,0 +1,153 @@
+// Copyright (C) 2013 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.pgm.init;
+
+import com.google.gerrit.server.config.SitePaths;
+import com.google.gerrit.server.git.GitRepositoryManager;
+import com.google.gerrit.server.git.ProjectConfig;
+import com.google.gerrit.server.git.VersionedMetaData;
+import com.google.inject.Inject;
+
+import org.eclipse.jgit.errors.ConfigInvalidException;
+import org.eclipse.jgit.internal.storage.file.FileRepository;
+import org.eclipse.jgit.lib.CommitBuilder;
+import org.eclipse.jgit.lib.Config;
+import org.eclipse.jgit.lib.ObjectId;
+import org.eclipse.jgit.lib.PersonIdent;
+import org.eclipse.jgit.lib.RefUpdate;
+import org.eclipse.jgit.lib.Repository;
+import org.eclipse.jgit.lib.RepositoryCache.FileKey;
+import org.eclipse.jgit.revwalk.RevTree;
+import org.eclipse.jgit.revwalk.RevWalk;
+import org.eclipse.jgit.util.FS;
+
+import java.io.File;
+import java.io.IOException;
+
+public class AllProjectsConfig extends VersionedMetaData {
+  private final String project;
+  private final File path;
+
+  private Config cfg;
+  private ObjectId revision;
+
+  @Inject
+  AllProjectsConfig(AllProjectsNameOnInitProvider allProjects, SitePaths site,
+      Section.Factory sections) {
+    project = allProjects.get();
+    File basePath = site.resolve(sections.get("gerrit", null).get("basePath"));
+    if (basePath == null) {
+      throw new IllegalStateException("gerrit.basePath must be configured");
+    }
+    path = FileKey.resolve(new File(basePath, project), FS.DETECTED);
+    if (path == null) {
+      throw new IllegalStateException(project + " project not found");
+    }
+  }
+
+  @Override
+  protected String getRefName() {
+    return GitRepositoryManager.REF_CONFIG;
+  }
+
+  public Config load() throws IOException, ConfigInvalidException {
+    Repository repo = new FileRepository(path);
+    try {
+      load(repo);
+    } finally {
+      repo.close();
+    }
+    return cfg;
+  }
+
+  @Override
+  protected void onLoad() throws IOException, ConfigInvalidException {
+    cfg = readConfig(ProjectConfig.PROJECT_CONFIG);
+    revision = getRevision();
+  }
+
+  @Override
+  protected void onSave(CommitBuilder commit) throws IOException,
+      ConfigInvalidException {
+    throw new UnsupportedOperationException();
+  }
+
+  public void save(String pluginName, String message) throws IOException {
+    Repository repo = new FileRepository(path);
+    try {
+      inserter = repo.newObjectInserter();
+      reader = repo.newObjectReader();
+      try {
+        RevWalk rw = new RevWalk(reader);
+        try {
+          RevTree srcTree = revision != null ? rw.parseTree(revision) : null;
+          newTree = readTree(srcTree);
+          saveConfig(ProjectConfig.PROJECT_CONFIG, cfg);
+          ObjectId res = newTree.writeTree(inserter);
+          if (res.equals(srcTree)) {
+            // If there are no changes to the content, don't create the commit.
+            return;
+          }
+
+          PersonIdent ident = new PersonIdent(pluginName, pluginName + "@gerrit");
+          String msg = "Update from plugin " + pluginName + ": " + message;
+          CommitBuilder commit = new CommitBuilder();
+          commit.setAuthor(ident);
+          commit.setCommitter(ident);
+          commit.setMessage(msg);
+          commit.setTreeId(res);
+          if (revision != null) {
+            commit.addParentId(revision);
+          }
+          ObjectId newRevision = inserter.insert(commit);
+          updateRef(repo, ident, newRevision, "commit: " + msg);
+          revision = newRevision;
+        } finally {
+          rw.release();
+        }
+      } finally {
+        if (inserter != null) {
+          inserter.release();
+          inserter = null;
+        }
+        if (reader != null) {
+          reader.release();
+          reader = null;
+        }
+      }
+    } finally {
+      repo.close();
+    }
+  }
+
+  private void updateRef(Repository repo, PersonIdent ident,
+      ObjectId newRevision, String refLogMsg) throws IOException {
+    RefUpdate ru = repo.updateRef(getRefName());
+    ru.setRefLogIdent(ident);
+    ru.setNewObjectId(newRevision);
+    ru.setExpectedOldObjectId(revision);
+    ru.setRefLogMessage(refLogMsg, false);
+    RefUpdate.Result r = ru.update();
+    switch(r) {
+      case FAST_FORWARD:
+      case NEW:
+      case NO_CHANGE:
+        break;
+      default:
+        throw new IOException("Failed to update " + getRefName() + " of "
+            + project + ": " + r.name());
+    }
+  }
+}

gerrit-pgm/src/main/java/com/google/gerrit/pgm/init/AllProjectsNameOnInitProvider.java

@@ -0,0 +1,36 @@
+// Copyright (C) 2013 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.pgm.init;
+
+import com.google.common.base.Objects;
+import com.google.common.base.Strings;
+import com.google.gerrit.server.config.AllProjectsNameProvider;
+import com.google.inject.Inject;
+import com.google.inject.Provider;
+
+public class AllProjectsNameOnInitProvider implements Provider<String> {
+  private final String name;
+
+  @Inject
+  AllProjectsNameOnInitProvider(Section.Factory sections) {
+    String n = sections.get("gerrit", null).get("allProjects");
+    name = Objects.firstNonNull(
+        Strings.emptyToNull(n), AllProjectsNameProvider.DEFAULT);
+  }
+
+  public String get() {
+    return name;
+  }
+}

gerrit-server/src/main/java/com/google/gerrit/server/git/ProjectConfig.java

@@ -80,7 +80,7 @@ public class ProjectConfig extends VersionedMetaData {
   private static final String KEY_LINK = "link";
   private static final String KEY_ENABLED = "enabled";
 
-  private static final String PROJECT_CONFIG = "project.config";
+  public static final String PROJECT_CONFIG = "project.config";
   private static final String GROUP_LIST = "groups";
 
   private static final String PROJECT = "project";

gerrit-server/src/main/java/com/google/gerrit/server/git/VersionedMetaData.java

@@ -54,9 +54,9 @@ import java.io.IOException;
  */
 public abstract class VersionedMetaData {
   private RevCommit revision;
-  private ObjectReader reader;
+  protected ObjectReader reader;
-  private ObjectInserter inserter;
+  protected ObjectInserter inserter;
-  private DirCache newTree;
+  protected DirCache newTree;
 
   /** @return name of the reference storing this configuration. */
   protected abstract String getRefName();
@@ -319,7 +319,7 @@ public abstract class VersionedMetaData {
     };
   }
 
-  private DirCache readTree(RevTree tree) throws IOException,
+  protected DirCache readTree(RevTree tree) throws IOException,
       MissingObjectException, IncorrectObjectTypeException {
     DirCache dc = DirCache.newInCore();
     if (tree != null) {