Support branch creation via REST

A new branch can be created by PUT on
'/projects/<project-name>/branches/<ref>.

The WebUI was adapted to use this new REST endpoint to create branches.
The old RPC for creating a branch in ProjectAdminService was deleted.

Change-Id: Id94bc4737eedde383507c7c567b3b6b102b105c5

Documentation/rest-api-projects.txt

@@ -560,6 +560,44 @@ describes the branch.
   }
 ----
 
+[[create-branch]]
+Create Branch
+~~~~~~~~~~~~~
+[verse]
+'PUT /projects/link:#project-name[\{project-name\}]/branches/link:#branch-id[\{branch-id\}]'
+
+Creates a new branch.
+
+In the request body additional data for the branch can be provided as
+link:#branch-input[BranchInput].
+
+.Request
+----
+  PUT /projects/MyProject/branches/stable HTTP/1.0
+  Content-Type: application/json;charset=UTF-8
+
+  {
+    "revision": "76016386a0d8ecc7b6be212424978bb45959d668"
+  }
+----
+
+As response a link:#branch-info[BranchInfo] entity is returned that
+describes the created branch.
+
+.Response
+----
+  HTTP/1.1 201 Created
+  Content-Disposition: attachment
+  Content-Type: application/json;charset=UTF-8
+
+  )]}'
+  {
+    "ref": "refs/heads/stable",
+    "revision": "76016386a0d8ecc7b6be212424978bb45959d668",
+    "can_delete": true
+  }
+----
+
 [[child-project-endpoints]]
 Child Project Endpoints
 -----------------------
@@ -968,6 +1006,24 @@ The `BranchInfo` entity contains information about a branch.
 Whether the calling user can delete this branch.
 |=========================
 
+[[branch-input]]
+BranchInput
+~~~~~~~~~~~
+The `BranchInput` entity contains information for the creation of
+a new branch.
+
+[options="header",width="50%",cols="1,^2,4"]
+|=======================
+|Field Name||Description
+|`ref`     |optional|
+The name of the branch. The prefix `refs/heads/` can be
+omitted. +
+If set, must match the branch ID in the URL.
+|`revision`|optional|
+The base revision of the new branch. +
+If not set, `HEAD` will be used as base revision.
+|=======================
+
 [[dashboard-info]]
 DashboardInfo
 ~~~~~~~~~~~~~

gerrit-common/src/main/java/com/google/gerrit/common/data/ProjectAdminService.java

@@ -56,11 +56,6 @@ public interface ProjectAdminService extends RemoteJsonService {
   void listBranches(Project.NameKey projectName,
       AsyncCallback<ListBranchesResult> callback);
 
-  @Audit
-  @SignInRequired
-  void addBranch(Project.NameKey projectName, String branchName,
-      String startingRevision, AsyncCallback<AddBranchResult> callback);
-
   @Audit
   @SignInRequired
   void deleteBranch(Project.NameKey projectName, Set<Branch.NameKey> ids,

gerrit-gwtui/src/main/java/com/google/gerrit/client/admin/ProjectBranchesScreen.java

@@ -19,12 +19,13 @@ import com.google.gerrit.client.ConfirmationDialog;
 import com.google.gerrit.client.ErrorDialog;
 import com.google.gerrit.client.Gerrit;
 import com.google.gerrit.client.GitwebLink;
+import com.google.gerrit.client.projects.BranchInfo;
+import com.google.gerrit.client.projects.ProjectApi;
 import com.google.gerrit.client.rpc.GerritCallback;
 import com.google.gerrit.client.rpc.ScreenLoadCallback;
 import com.google.gerrit.client.ui.BranchLink;
 import com.google.gerrit.client.ui.FancyFlexTable;
 import com.google.gerrit.client.ui.HintTextBox;
-import com.google.gerrit.common.data.AddBranchResult;
 import com.google.gerrit.common.data.ListBranchesResult;
 import com.google.gerrit.reviewdb.client.Branch;
 import com.google.gerrit.reviewdb.client.Change;
@@ -185,62 +186,29 @@ public class ProjectBranchesScreen extends ProjectScreen {
     }
 
     addBranch.setEnabled(false);
-    Util.PROJECT_SVC.addBranch(getProjectKey(), branchName, rev,
-        new GerritCallback<AddBranchResult>() {
-          public void onSuccess(final AddBranchResult result) {
-            addBranch.setEnabled(true);
-            if (!result.hasError()) {
-              nameTxtBox.setText("");
-              irevTxtBox.setText("");
-              display(result.getListBranchesResult().getBranches());
-            } else {
-              final AddBranchResult.Error error = result.getError();
-              final String msg;
-              switch (error.getType()) {
-                case INVALID_NAME:
-                  selectAllAndFocus(nameTxtBox);
-                  msg = Gerrit.M.invalidBranchName(branchName);
-                  break;
-
-                case INVALID_REVISION:
-                  selectAllAndFocus(irevTxtBox);
-                  msg = Gerrit.M.invalidRevision(rev);
-                  break;
-
-                case BRANCH_CREATION_NOT_ALLOWED_UNDER_REFNAME_PREFIX:
-                  selectAllAndFocus(nameTxtBox);
-                  msg =
-                      Gerrit.M.branchCreationNotAllowedUnderRefnamePrefix(error
-                          .getRefname());
-                  break;
-
-                case BRANCH_ALREADY_EXISTS:
-                  selectAllAndFocus(nameTxtBox);
-                  msg = Gerrit.M.branchAlreadyExists(error.getRefname());
-                  break;
-
-                case BRANCH_CREATION_CONFLICT:
-                  selectAllAndFocus(nameTxtBox);
-                  msg =
-                      Gerrit.M.branchCreationConflict(branchName,
-                          error.getRefname());
-                  break;
-
-                default:
-                  msg =
-                      Gerrit.M.branchCreationFailed(branchName,
-                          error.toString());
-              }
-              new ErrorDialog(msg).center();
-            }
-          }
-
+    ProjectApi.createBranch(getProjectKey(), branchName, rev,
+        new GerritCallback<BranchInfo>() {
           @Override
-          public void onFailure(final Throwable caught) {
+          public void onSuccess(BranchInfo result) {
             addBranch.setEnabled(true);
-            super.onFailure(caught);
+            nameTxtBox.setText("");
+            irevTxtBox.setText("");
+            Util.PROJECT_SVC.listBranches(getProjectKey(),
+                new GerritCallback<ListBranchesResult>() {
+                  @Override
+                  public void onSuccess(ListBranchesResult result) {
+                    display(result.getBranches());
+                  }
+                });
           }
-        });
+
+      @Override
+      public void onFailure(Throwable caught) {
+        addBranch.setEnabled(true);
+        selectAllAndFocus(nameTxtBox);
+        new ErrorDialog(caught.getMessage()).center();
+      }
+    });
   }
 
   private static void selectAllAndFocus(final TextBox textBox) {

gerrit-gwtui/src/main/java/com/google/gerrit/client/projects/BranchInfo.java

@@ -0,0 +1,26 @@
+// 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.client.projects;
+
+import com.google.gwt.core.client.JavaScriptObject;
+
+public class BranchInfo extends JavaScriptObject {
+  public final native String ref() /*-{ return this.ref; }-*/;
+  public final native String revision() /*-{ return this.revision; }-*/;
+  public final native boolean canDelete() /*-{ return this['can_delete'] ? true : false; }-*/;
+
+  protected BranchInfo() {
+  }
+}

gerrit-gwtui/src/main/java/com/google/gerrit/client/projects/ProjectApi.java

@@ -33,6 +33,15 @@ public class ProjectApi {
         .put(input, asyncCallback);
   }
 
+  /** Create a new branch */
+  public static void createBranch(Project.NameKey projectName, String ref,
+      String revision, AsyncCallback<BranchInfo> asyncCallback) {
+    BranchInput input = BranchInput.create();
+    input.setRevision(revision);
+    new RestApi("/projects/").id(projectName.get()).view("branches").id(ref)
+        .ifNoneMatch().put(input, asyncCallback);
+  }
+
   static RestApi config(Project.NameKey name) {
     return new RestApi("/projects/").id(name.get()).view("config");
   }
@@ -53,4 +62,15 @@ public class ProjectApi {
 
     final native void setCreateEmptyCommit(boolean cc) /*-{ if(cc)this.create_empty_commit=cc; }-*/;
   }
+
+  private static class BranchInput extends JavaScriptObject {
+    static BranchInput create() {
+      return (BranchInput) createObject();
+    }
+
+    protected BranchInput() {
+    }
+
+    final native void setRevision(String r) /*-{ if(r)this.revision=r; }-*/;
+  }
 }

gerrit-httpd/src/main/java/com/google/gerrit/httpd/rpc/project/ProjectAdminServiceImpl.java

@@ -15,7 +15,6 @@
 package com.google.gerrit.httpd.rpc.project;
 
 import com.google.gerrit.common.data.AccessSection;
-import com.google.gerrit.common.data.AddBranchResult;
 import com.google.gerrit.common.data.ListBranchesResult;
 import com.google.gerrit.common.data.ProjectAccess;
 import com.google.gerrit.common.data.ProjectAdminService;
@@ -32,7 +31,6 @@ import java.util.List;
 import java.util.Set;
 
 class ProjectAdminServiceImpl implements ProjectAdminService {
-  private final AddBranch.Factory addBranchFactory;
   private final ChangeProjectAccess.Factory changeProjectAccessFactory;
   private final ReviewProjectAccess.Factory reviewProjectAccessFactory;
   private final ChangeProjectSettings.Factory changeProjectSettingsFactory;
@@ -43,8 +41,7 @@ class ProjectAdminServiceImpl implements ProjectAdminService {
   private final ProjectDetailFactory.Factory projectDetailFactory;
 
   @Inject
-  ProjectAdminServiceImpl(final AddBranch.Factory addBranchFactory,
-      final ChangeProjectAccess.Factory changeProjectAccessFactory,
+  ProjectAdminServiceImpl(final ChangeProjectAccess.Factory changeProjectAccessFactory,
       final ReviewProjectAccess.Factory reviewProjectAccessFactory,
       final ChangeProjectSettings.Factory changeProjectSettingsFactory,
       final DeleteBranches.Factory deleteBranchesFactory,
@@ -52,7 +49,6 @@ class ProjectAdminServiceImpl implements ProjectAdminService {
       final VisibleProjectDetails.Factory visibleProjectDetailsFactory,
       final ProjectAccessFactory.Factory projectAccessFactory,
       final ProjectDetailFactory.Factory projectDetailFactory) {
-    this.addBranchFactory = addBranchFactory;
     this.changeProjectAccessFactory = changeProjectAccessFactory;
     this.reviewProjectAccessFactory = reviewProjectAccessFactory;
     this.changeProjectSettingsFactory = changeProjectSettingsFactory;
@@ -119,12 +115,4 @@ class ProjectAdminServiceImpl implements ProjectAdminService {
       final AsyncCallback<Set<Branch.NameKey>> callback) {
     deleteBranchesFactory.create(projectName, toRemove).to(callback);
   }
-
-  @Override
-  public void addBranch(final Project.NameKey projectName,
-      final String branchName, final String startingRevision,
-      final AsyncCallback<AddBranchResult> callback) {
-    addBranchFactory.create(projectName, branchName, startingRevision).to(
-        callback);
-  }
 }

gerrit-httpd/src/main/java/com/google/gerrit/httpd/rpc/project/ProjectModule.java

@@ -28,7 +28,6 @@ public class ProjectModule extends RpcServletModule {
     install(new FactoryModule() {
       @Override
       protected void configure() {
-        factory(AddBranch.Factory.class);
         factory(ChangeProjectAccess.Factory.class);
         factory(ReviewProjectAccess.Factory.class);
         factory(ChangeProjectSettings.Factory.class);

gerrit-server/src/main/java/com/google/gerrit/server/project/BranchesCollection.java

@@ -15,6 +15,7 @@
 package com.google.gerrit.server.project;
 
 import com.google.gerrit.extensions.registration.DynamicMap;
+import com.google.gerrit.extensions.restapi.AcceptsCreate;
 import com.google.gerrit.extensions.restapi.ChildCollection;
 import com.google.gerrit.extensions.restapi.IdString;
 import com.google.gerrit.extensions.restapi.ResourceNotFoundException;
@@ -29,15 +30,18 @@ import java.io.IOException;
 import java.util.List;
 
 public class BranchesCollection implements
-    ChildCollection<ProjectResource, BranchResource> {
+    ChildCollection<ProjectResource, BranchResource>,
+    AcceptsCreate<ProjectResource> {
   private final DynamicMap<RestView<BranchResource>> views;
   private final Provider<ListBranches> list;
+  private final CreateBranch.Factory createBranchFactory;
 
   @Inject
   BranchesCollection(DynamicMap<RestView<BranchResource>> views,
-      Provider<ListBranches> list) {
+      Provider<ListBranches> list, CreateBranch.Factory createBranchFactory) {
     this.views = views;
     this.list = list;
+    this.createBranchFactory = createBranchFactory;
   }
 
   @Override
@@ -66,4 +70,10 @@ public class BranchesCollection implements
   public DynamicMap<RestView<BranchResource>> views() {
     return views;
   }
+
+  @SuppressWarnings("unchecked")
+  @Override
+  public CreateBranch create(ProjectResource parent, IdString name) {
+    return createBranchFactory.create(name.get());
+  }
 }

gerrit-server/src/main/java/com/google/gerrit/server/project/CreateBranch.java

@@ -1,4 +1,4 @@
-// Copyright (C) 2009 The Android Open Source Project
+// 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.
@@ -12,26 +12,28 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-package com.google.gerrit.httpd.rpc.project;
+package com.google.gerrit.server.project;
 
 import com.google.gerrit.common.ChangeHooks;
-import com.google.gerrit.common.data.AddBranchResult;
 import com.google.gerrit.common.errors.InvalidRevisionException;
-import com.google.gerrit.httpd.rpc.Handler;
+import com.google.gerrit.extensions.restapi.BadRequestException;
+import com.google.gerrit.extensions.restapi.DefaultInput;
+import com.google.gerrit.extensions.restapi.ResourceConflictException;
+import com.google.gerrit.extensions.restapi.RestModifyView;
 import com.google.gerrit.reviewdb.client.Branch;
 import com.google.gerrit.reviewdb.client.Project;
 import com.google.gerrit.server.IdentifiedUser;
 import com.google.gerrit.server.extensions.events.GitReferenceUpdated;
 import com.google.gerrit.server.git.GitRepositoryManager;
-import com.google.gerrit.server.project.NoSuchProjectException;
-import com.google.gerrit.server.project.ProjectControl;
-import com.google.gerrit.server.project.RefControl;
+import com.google.gerrit.server.project.CreateBranch.Input;
+import com.google.gerrit.server.project.ListBranches.BranchInfo;
 import com.google.gerrit.server.util.MagicBranch;
 import com.google.inject.Inject;
 import com.google.inject.assistedinject.Assisted;
 
 import org.eclipse.jgit.errors.IncorrectObjectTypeException;
 import org.eclipse.jgit.errors.MissingObjectException;
+import org.eclipse.jgit.errors.RevisionSyntaxException;
 import org.eclipse.jgit.lib.Constants;
 import org.eclipse.jgit.lib.ObjectId;
 import org.eclipse.jgit.lib.Ref;
@@ -45,101 +47,92 @@ import org.slf4j.LoggerFactory;
 
 import java.io.IOException;
 
-class AddBranch extends Handler<AddBranchResult> {
-  private static final Logger log = LoggerFactory.getLogger(AddBranch.class);
+public class CreateBranch implements RestModifyView<ProjectResource, Input> {
+  private static final Logger log = LoggerFactory.getLogger(CreateBranch.class);
 
-  interface Factory {
-    AddBranch create(@Assisted Project.NameKey projectName,
-        @Assisted("branchName") String branchName,
-        @Assisted("startingRevision") String startingRevision);
+  static class Input {
+    String ref;
+
+    @DefaultInput
+    String revision;
+  }
+
+  static interface Factory {
+    CreateBranch create(String ref);
   }
 
-  private final ProjectControl.Factory projectControlFactory;
-  private final ListBranches.Factory listBranchesFactory;
   private final IdentifiedUser identifiedUser;
   private final GitRepositoryManager repoManager;
   private final GitReferenceUpdated referenceUpdated;
   private final ChangeHooks hooks;
-
-  private final Project.NameKey projectName;
-  private final String branchName;
-  private final String startingRevision;
+  private String ref;
 
   @Inject
-  AddBranch(final ProjectControl.Factory projectControlFactory,
-      final ListBranches.Factory listBranchesFactory,
-      final IdentifiedUser identifiedUser,
-      final GitRepositoryManager repoManager,
-      GitReferenceUpdated referenceUpdated,
-      final ChangeHooks hooks,
-
-      @Assisted Project.NameKey projectName,
-      @Assisted("branchName") String branchName,
-      @Assisted("startingRevision") String startingRevision) {
-    this.projectControlFactory = projectControlFactory;
-    this.listBranchesFactory = listBranchesFactory;
+  CreateBranch(IdentifiedUser identifiedUser, GitRepositoryManager repoManager,
+      GitReferenceUpdated referenceUpdated, ChangeHooks hooks,
+      @Assisted String ref) {
     this.identifiedUser = identifiedUser;
     this.repoManager = repoManager;
     this.referenceUpdated = referenceUpdated;
     this.hooks = hooks;
-
-    this.projectName = projectName;
-    this.branchName = branchName;
-    this.startingRevision = startingRevision;
+    this.ref = ref;
   }
 
   @Override
-  public AddBranchResult call() throws NoSuchProjectException, IOException {
-    final ProjectControl projectControl =
-        projectControlFactory.controlFor(projectName);
-
-    String refname = branchName;
-    while (refname.startsWith("/")) {
-      refname = refname.substring(1);
+  public BranchInfo apply(ProjectResource rsrc, Input input)
+      throws BadRequestException, ResourceConflictException, IOException {
+    if (input == null) {
+      input = new Input();
     }
-    if (!refname.startsWith(Constants.R_REFS)) {
-      refname = Constants.R_HEADS + refname;
+    if (input.ref != null && !ref.equals(input.ref)) {
+      throw new BadRequestException("ref must match URL");
     }
-    if (!Repository.isValidRefName(refname)) {
-      return new AddBranchResult(new AddBranchResult.Error(
-          AddBranchResult.Error.Type.INVALID_NAME, refname));
+    if (input.revision == null) {
+      input.revision = Constants.HEAD;
     }
-    if (MagicBranch.isMagicBranch(refname)) {
-      return new AddBranchResult(
-          new AddBranchResult.Error(
-              AddBranchResult.Error.Type.BRANCH_CREATION_NOT_ALLOWED_UNDER_REFNAME_PREFIX,
-              MagicBranch.getMagicRefNamePrefix(refname)));
+    while (ref.startsWith("/")) {
+      ref = ref.substring(1);
+    }
+    if (!ref.startsWith(Constants.R_REFS)) {
+      ref = Constants.R_HEADS + ref;
+    }
+    if (!Repository.isValidRefName(ref)) {
+      throw new BadRequestException("invalid branch name \"" + ref + "\"");
+    }
+    if (MagicBranch.isMagicBranch(ref)) {
+      throw new BadRequestException("not allowed to create branches under \""
+          + MagicBranch.getMagicRefNamePrefix(ref) + "\"");
     }
 
-    final Branch.NameKey name = new Branch.NameKey(projectName, refname);
-    final RefControl refControl = projectControl.controlForRef(name);
-    final Repository repo = repoManager.openRepository(projectName);
+    final Branch.NameKey name = new Branch.NameKey(rsrc.getNameKey(), ref);
+    final RefControl refControl = rsrc.getControl().controlForRef(name);
+    final Repository repo = repoManager.openRepository(rsrc.getNameKey());
     try {
-      final ObjectId revid = parseStartingRevision(repo);
+      final ObjectId revid = parseBaseRevision(repo, rsrc.getNameKey(), input.revision);
       final RevWalk rw = verifyConnected(repo, revid);
       RevObject object = rw.parseAny(revid);
 
-      if (refname.startsWith(Constants.R_HEADS)) {
+      if (ref.startsWith(Constants.R_HEADS)) {
         // Ensure that what we start the branch from is a commit. If we
         // were given a tag, deference to the commit instead.
         //
         try {
           object = rw.parseCommit(object);
         } catch (IncorrectObjectTypeException notCommit) {
-          throw new IllegalStateException(startingRevision + " not a commit");
+          throw new BadRequestException("\"" + input.revision + "\" not a commit");
         }
       }
 
       if (!refControl.canCreate(rw, object)) {
-        throw new IllegalStateException("Cannot create " + refname);
+        throw new IllegalStateException("Cannot create \"" + ref + "\"");
       }
 
       try {
-        final RefUpdate u = repo.updateRef(refname);
+        final RefUpdate u = repo.updateRef(ref);
         u.setExpectedOldObjectId(ObjectId.zeroId());
         u.setNewObjectId(object.copy());
         u.setRefLogIdent(identifiedUser.newRefLogIdent());
-        u.setRefLogMessage("created via web from " + startingRevision, false);
+        u.setRefLogMessage("created via REST from " + input.revision, false);
         final RefUpdate.Result result = u.update(rw);
         switch (result) {
           case FAST_FORWARD:
@@ -149,15 +142,16 @@ class AddBranch extends Handler<AddBranchResult> {
             hooks.doRefUpdatedHook(name, u, identifiedUser.getAccount());
             break;
           case LOCK_FAILURE:
-            if (repo.getRef(refname) != null) {
-              return new AddBranchResult(new AddBranchResult.Error(
-                  AddBranchResult.Error.Type.BRANCH_ALREADY_EXISTS, refname));
+            if (repo.getRef(ref) != null) {
+              throw new ResourceConflictException("branch \"" + ref
+                  + "\" already exists");
             }
-            String refPrefix = getRefPrefix(refname);
+            String refPrefix = getRefPrefix(ref);
             while (!Constants.R_HEADS.equals(refPrefix)) {
               if (repo.getRef(refPrefix) != null) {
-                return new AddBranchResult(new AddBranchResult.Error(
-                    AddBranchResult.Error.Type.BRANCH_CREATION_CONFLICT, refPrefix));
+                throw new ResourceConflictException("Cannot create branch \""
+                    + ref + "\" since it conflicts with branch \"" + refPrefix
+                    + "\".");
               }
               refPrefix = getRefPrefix(refPrefix);
             }
@@ -165,18 +159,21 @@ class AddBranch extends Handler<AddBranchResult> {
             throw new IOException(result.name());
           }
         }
+
+        BranchInfo b = new BranchInfo();
+        b.ref = ref;
+        b.revision = revid.getName();
+        b.setCanDelete(refControl.canDelete());
+        return b;
       } catch (IOException err) {
-        log.error("Cannot create branch " + name, err);
+        log.error("Cannot create branch \"" + name + "\"", err);
         throw err;
       }
     } catch (InvalidRevisionException e) {
-      return new AddBranchResult(new AddBranchResult.Error(
-          AddBranchResult.Error.Type.INVALID_REVISION));
+      throw new BadRequestException("invalid revision \"" + input.revision + "\"");
     } finally {
       repo.close();
     }
-
-    return new AddBranchResult(listBranchesFactory.create(projectName).call());
   }
 
   private static String getRefPrefix(final String refName) {
@@ -187,17 +184,21 @@ class AddBranch extends Handler<AddBranchResult> {
     return Constants.R_HEADS;
   }
 
-  private ObjectId parseStartingRevision(final Repository repo)
+  private ObjectId parseBaseRevision(Repository repo,
+      Project.NameKey projectName, String baseRevision)
       throws InvalidRevisionException {
     try {
-      final ObjectId revid = repo.resolve(startingRevision);
+      final ObjectId revid = repo.resolve(baseRevision);
       if (revid == null) {
         throw new InvalidRevisionException();
       }
       return revid;
     } catch (IOException err) {
-      log.error("Cannot resolve \"" + startingRevision + "\" in project \""
-          + projectName + "\"", err);
+      log.error("Cannot resolve \"" + baseRevision + "\" in project \""
+          + projectName.get() + "\"", err);
+      throw new InvalidRevisionException();
+    } catch (RevisionSyntaxException err) {
+      log.error("Invalid revision syntax \"" + baseRevision + "\"", err);
       throw new InvalidRevisionException();
     }
   }

gerrit-server/src/main/java/com/google/gerrit/server/project/Module.java

@@ -53,7 +53,9 @@ public class Module extends RestApiModule {
     post(PROJECT_KIND, "gc").to(GarbageCollect.class);
 
     child(PROJECT_KIND, "branches").to(BranchesCollection.class);
+    put(BRANCH_KIND).to(PutBranch.class);
     get(BRANCH_KIND).to(GetBranch.class);
+    install(new FactoryModuleBuilder().build(CreateBranch.Factory.class));
 
     child(PROJECT_KIND, "dashboards").to(DashboardsCollection.class);
     get(DASHBOARD_KIND).to(GetDashboard.class);

gerrit-server/src/main/java/com/google/gerrit/server/project/PutBranch.java

@@ -0,0 +1,29 @@
+// 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.server.project;
+
+import com.google.gerrit.extensions.restapi.ResourceConflictException;
+import com.google.gerrit.extensions.restapi.RestModifyView;
+import com.google.gerrit.server.project.CreateBranch.Input;
+
+public class PutBranch implements RestModifyView<BranchResource, Input> {
+
+  @Override
+  public Object apply(BranchResource rsrc, Input input)
+      throws ResourceConflictException {
+    throw new ResourceConflictException("Branch \"" + rsrc.getBranchInfo().ref
+        + "\" already exists");
+  }
+}