Add extension point to register JGit PreUploadHooks

Very similar to the PostReceiveHook change that Saša made in
I0212eab6e4867819ebe7ecc7fc5532c26bb82282, it is conceivable that
a plugin may want to attach a PreUploadHook, such as for displaying
messages to a user.

Change-Id: If8e8f4e0b3774e4360048b7d3719d10f66719c78

gerrit-httpd/src/main/java/com/google/gerrit/httpd/GitOverHttpServlet.java

@@ -51,6 +51,8 @@ import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.Repository;
 import org.eclipse.jgit.transport.PostReceiveHook;
 import org.eclipse.jgit.transport.PostReceiveHookChain;
+import org.eclipse.jgit.transport.PreUploadHook;
+import org.eclipse.jgit.transport.PreUploadHookChain;
 import org.eclipse.jgit.transport.ReceivePack;
 import org.eclipse.jgit.transport.UploadPack;
 import org.eclipse.jgit.transport.resolver.ReceivePackFactory;
@@ -188,15 +190,20 @@ public class GitOverHttpServlet extends GitServlet {
 
   static class UploadFactory implements UploadPackFactory<HttpServletRequest> {
     private final TransferConfig config;
+    private DynamicSet<PreUploadHook> preUploadHooks;
 
     @Inject
-    UploadFactory(TransferConfig tc) {
+    UploadFactory(TransferConfig tc,
+        DynamicSet<PreUploadHook> preUploadHooks) {
       this.config = tc;
+      this.preUploadHooks = preUploadHooks;
     }
 
     @Override
     public UploadPack create(HttpServletRequest req, Repository repo) {
       UploadPack up = new UploadPack(repo);
+      up.setPreUploadHook(PreUploadHookChain.newChain(
+          Lists.newArrayList(preUploadHooks)));
       up.setPackConfig(config.getPackConfig());
       up.setTimeout(config.getTimeout());
       return up;

gerrit-server/src/main/java/com/google/gerrit/server/config/GerritGlobalModule.java

@@ -131,6 +131,7 @@ import com.google.inject.internal.UniqueAnnotations;
 
 import org.apache.velocity.runtime.RuntimeInstance;
 import org.eclipse.jgit.transport.PostReceiveHook;
+import org.eclipse.jgit.transport.PreUploadHook;
 
 import java.util.List;
 import java.util.Set;
@@ -250,6 +251,7 @@ public class GerritGlobalModule extends FactoryModule {
     DynamicSet.setOf(binder(), CacheRemovalListener.class);
     DynamicMap.mapOf(binder(), CapabilityDefinition.class);
     DynamicSet.setOf(binder(), GitReferenceUpdatedListener.class);
+    DynamicSet.setOf(binder(), PreUploadHook.class);;
     DynamicSet.setOf(binder(), ReceivePackInitializer.class);
     DynamicSet.setOf(binder(), PostReceiveHook.class);
     DynamicSet.setOf(binder(), NewProjectCreatedListener.class);

gerrit-sshd/src/main/java/com/google/gerrit/sshd/commands/Upload.java

@@ -14,6 +14,8 @@
 
 package com.google.gerrit.sshd.commands;
 
+import com.google.common.collect.Lists;
+import com.google.gerrit.extensions.registration.DynamicSet;
 import com.google.gerrit.reviewdb.server.ReviewDb;
 import com.google.gerrit.server.git.ChangeCache;
 import com.google.gerrit.server.git.TagCache;
@@ -23,6 +25,8 @@ import com.google.gerrit.sshd.AbstractGitCommand;
 import com.google.inject.Inject;
 import com.google.inject.Provider;
 
+import org.eclipse.jgit.transport.PreUploadHook;
+import org.eclipse.jgit.transport.PreUploadHookChain;
 import org.eclipse.jgit.transport.UploadPack;
 
 import java.io.IOException;
@@ -41,6 +45,9 @@ final class Upload extends AbstractGitCommand {
   @Inject
   private ChangeCache changeCache;
 
+  @Inject
+  private DynamicSet<PreUploadHook> preUploadHooks;
+
   @Override
   protected void runImpl() throws IOException, Failure {
     if (!projectControl.canRunUploadPack()) {
@@ -48,6 +55,8 @@ final class Upload extends AbstractGitCommand {
     }
 
     final UploadPack up = new UploadPack(repo);
+    up.setPreUploadHook(PreUploadHookChain.newChain(
+        Lists.newArrayList(preUploadHooks)));
     if (!projectControl.allRefsAreVisible()) {
       up.setAdvertiseRefsHook(new VisibleRefFilter(tagCache, changeCache, repo,
           projectControl, db.get(), true));