Makes it so a node can only the root of one connection at a time

This resulted in needing to make structural changes. For example, if
connection 2 has a root of A, and A has the children B and C then if A
is assigned to another connection (by way of the owner calling Embed
again), then connection 2 is told A has been deleted and B and C are
removed as children of A.

Because this does structural changes the server change id is advanced.

BUG=389339
TEST=covered by unit tests
R=ben@chromium.org

Review URL: https://codereview.chromium.org/397803003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@283663 0039d316-1c4b-4281-b951-d872f2087c98

mojo/services/public/cpp/view_manager/lib/view_manager_client_impl.cc

@@ -478,6 +478,7 @@ class EmbedTransaction : public ViewManagerTransaction {
  private:
   // Overridden from ViewManagerTransaction:
   virtual void DoCommit() OVERRIDE {
+    GetAndAdvanceNextServerChangeId();
     service()->Embed(url_, node_id_, ActionCompletedCallback());
   }
   virtual void DoActionCompleted(bool success) OVERRIDE {

mojo/services/public/interfaces/view_manager/view_manager.mojom

@@ -127,12 +127,20 @@ interface ViewManagerService {
   SetFocus(uint32 node_id) => (bool success);
 
   // Embeds the app for |url| in the specified node. More specifically this
-  // creates a new connection to the specified url, expecting to get an
+  // creates a new connection to the specified url, expecting to get a
   // ViewManagerClient and configures it with the root node |node|. Fails
   // if |node| was not created by this connection.
+  //
   // If a particular client invokes Embed() multiple times with the same url,
   // the connection is reused. When this happens the ViewManagerClient is
   // notified of the additional roots by way of OnRootAdded().
+  //
+  // A node may only be a root of one connection at a time. Subsequent calls to
+  // Embed() for the same node result in the node being removed from the
+  // current connection. The current connection is told this by way of
+  // OnNodeDeleted().
+  //
+  // This advances the server change id.
   Embed(string url, uint32 node_id) => (bool success);
 
   // TODO(sky): move these to a separate interface when FIFO works.

mojo/services/view_manager/root_node_manager.cc

@@ -33,6 +33,10 @@ RootNodeManager::ScopedChange::~ScopedChange() {
   root_->FinishChange();
 }
 
+void RootNodeManager::ScopedChange::SendServerChangeIdAdvanced() {
+  root_->SendServerChangeIdAdvanced();
+}
+
 RootNodeManager::Context::Context() {
   // Pass in false as native viewport creates the PlatformEventSource.
   aura::Env::CreateInstance(false);
@@ -141,6 +145,16 @@ ViewManagerServiceImpl* RootNodeManager::GetConnectionByCreator(
   return NULL;
 }
 
+ViewManagerServiceImpl* RootNodeManager::GetConnectionWithRoot(
+    const NodeId& id) {
+  for (ConnectionMap::const_iterator i = connection_map_.begin();
+       i != connection_map_.end(); ++i) {
+    if (i->second->HasRoot(id))
+      return i->second;
+  }
+  return NULL;
+}
+
 void RootNodeManager::DispatchViewInputEventToWindowManager(
     const View* view,
     const ui::Event* event) {
@@ -236,6 +250,15 @@ void RootNodeManager::FinishChange() {
   current_change_ = NULL;
 }
 
+void RootNodeManager::SendServerChangeIdAdvanced() {
+  CHECK(current_change_);
+  for (ConnectionMap::iterator i = connection_map_.begin();
+       i != connection_map_.end(); ++i) {
+    if (!DidConnectionMessageClient(i->first))
+      i->second->client()->OnServerChangeIdAdvanced(next_server_change_id_ + 1);
+  }
+}
+
 ViewManagerServiceImpl* RootNodeManager::EmbedImpl(
     const ConnectionSpecificId creator_id,
     const String& url,
@@ -261,6 +284,7 @@ ViewManagerServiceImpl* RootNodeManager::EmbedImpl(
                                  root_id);
   BindToPipe(connection, pipe.handle0.Pass());
   connections_created_by_connect_.insert(connection);
+  OnConnectionMessagedClient(connection->id());
   return connection;
 }
 

mojo/services/view_manager/root_node_manager.h

@@ -69,6 +69,10 @@ class MOJO_VIEW_MANAGER_EXPORT RootNodeManager
       return message_ids_.count(connection_id) > 0;
     }
 
+    // Sends OnServerChangeIdAdvanced() to all connections that have not yet
+    // been messaged.
+    void SendServerChangeIdAdvanced();
+
    private:
     RootNodeManager* root_;
     const ConnectionSpecificId connection_id_;
@@ -133,6 +137,9 @@ class MOJO_VIEW_MANAGER_EXPORT RootNodeManager
       ConnectionSpecificId creator_id,
       const std::string& url) const;
 
+  // Returns the ViewManagerServiceImpl that has |id| as a root.
+  ViewManagerServiceImpl* GetConnectionWithRoot(const NodeId& id);
+
   void DispatchViewInputEventToWindowManager(const View* view,
                                              const ui::Event* event);
 
@@ -178,6 +185,9 @@ class MOJO_VIEW_MANAGER_EXPORT RootNodeManager
   // Balances a call to PrepareForChange().
   void FinishChange();
 
+  // See description in ScopedChange.
+  void SendServerChangeIdAdvanced();
+
   // Returns true if the specified connection originated the current change.
   bool IsChangeSource(ConnectionSpecificId connection_id) const {
     return current_change_ && current_change_->connection_id() == connection_id;

mojo/services/view_manager/view_manager_service_impl.cc

@@ -86,6 +86,10 @@ const View* ViewManagerServiceImpl::GetView(const ViewId& id) const {
   return root_node_manager_->GetView(id);
 }
 
+bool ViewManagerServiceImpl::HasRoot(const NodeId& id) const {
+  return roots_.find(NodeIdToTransportId(id)) != roots_.end();
+}
+
 void ViewManagerServiceImpl::OnViewManagerServiceImplDestroyed(
     ConnectionSpecificId id) {
   if (creator_id_ == id)
@@ -119,7 +123,7 @@ void ViewManagerServiceImpl::ProcessNodeHierarchyChanged(
     if (node->id().connection_id != id_ && !IsNodeDescendantOfRoots(node)) {
       // Node was a descendant of roots and is no longer, treat it as though the
       // node was deleted.
-      RemoveFromKnown(node);
+      RemoveFromKnown(node, NULL);
       client()->OnNodeDeleted(NodeIdToTransportId(node->id()),
                               server_change_id);
       root_node_manager_->OnConnectionMessagedClient(id_);
@@ -407,21 +411,24 @@ void ViewManagerServiceImpl::GetUnknownNodesFrom(
     GetUnknownNodesFrom(children[i], nodes);
 }
 
-void ViewManagerServiceImpl::RemoveFromKnown(const Node* node) {
-  if (node->id().connection_id == id_)
+void ViewManagerServiceImpl::RemoveFromKnown(const Node* node,
+                                             std::vector<Node*>* local_nodes) {
+  if (node->id().connection_id == id_) {
+    if (local_nodes)
+      local_nodes->push_back(GetNode(node->id()));
     return;
+  }
   known_nodes_.erase(NodeIdToTransportId(node->id()));
   std::vector<const Node*> children = node->GetChildren();
   for (size_t i = 0; i < children.size(); ++i)
-    RemoveFromKnown(children[i]);
+    RemoveFromKnown(children[i], local_nodes);
 }
 
-bool ViewManagerServiceImpl::AddRoot(Id transport_node_id) {
-  if (roots_.count(transport_node_id) > 0)
-    return false;
+void ViewManagerServiceImpl::AddRoot(const NodeId& node_id) {
+  const Id transport_node_id(NodeIdToTransportId(node_id));
+  CHECK(roots_.count(transport_node_id) == 0);
 
   std::vector<const Node*> to_send;
-  const NodeId node_id(NodeIdFromTransportId(transport_node_id));
   CHECK_EQ(creator_id_, node_id.connection_id);
   roots_.insert(transport_node_id);
   Node* node = GetNode(node_id);
@@ -435,7 +442,31 @@ bool ViewManagerServiceImpl::AddRoot(Id transport_node_id) {
   }
 
   client()->OnRootAdded(NodesToNodeDatas(to_send));
-  return true;
+  root_node_manager_->OnConnectionMessagedClient(id_);
+}
+
+void ViewManagerServiceImpl::RemoveRoot(const NodeId& node_id) {
+  const Id transport_node_id(NodeIdToTransportId(node_id));
+  CHECK(roots_.count(transport_node_id) > 0);
+
+  roots_.erase(transport_node_id);
+  if (roots_.empty())
+    roots_.insert(NodeIdToTransportId(InvalidNodeId()));
+
+  // No need to do anything if we created the node.
+  if (node_id.connection_id == id_)
+    return;
+
+  client()->OnNodeDeleted(transport_node_id,
+                          root_node_manager_->next_server_change_id());
+  root_node_manager_->OnConnectionMessagedClient(id_);
+
+  // This connection no longer knows about the node. Unparent any nodes that
+  // were parented to nodes in the root.
+  std::vector<Node*> local_nodes;
+  RemoveFromKnown(GetNode(node_id), &local_nodes);
+  for (size_t i = 0; i < local_nodes.size(); ++i)
+    local_nodes[i]->GetParent()->Remove(local_nodes[i]);
 }
 
 bool ViewManagerServiceImpl::IsNodeDescendantOfRoots(const Node* node) const {
@@ -737,13 +768,30 @@ void ViewManagerServiceImpl::Embed(const String& url,
                                    const Callback<void(bool)>& callback) {
   bool success = CanEmbed(transport_node_id);
   if (success) {
-    // We may already have this connection, if so reuse it.
-    ViewManagerServiceImpl* existing_connection =
+    // Only allow a node to be the root for one connection.
+    const NodeId node_id(NodeIdFromTransportId(transport_node_id));
+    ViewManagerServiceImpl* connection_by_url =
         root_node_manager_->GetConnectionByCreator(id_, url.To<std::string>());
-    if (existing_connection)
-      success = existing_connection->AddRoot(transport_node_id);
-    else
-      root_node_manager_->Embed(id_, url, transport_node_id);
+    ViewManagerServiceImpl* connection_with_node_as_root =
+        root_node_manager_->GetConnectionWithRoot(node_id);
+    if ((connection_by_url != connection_with_node_as_root ||
+         (!connection_by_url && !connection_with_node_as_root)) &&
+        (!connection_by_url || !connection_by_url->HasRoot(node_id))) {
+      RootNodeManager::ScopedChange change(
+          this, root_node_manager_,
+          RootNodeManager::CHANGE_TYPE_ADVANCE_SERVER_CHANGE_ID, true);
+      // Never message the originating connection.
+      root_node_manager_->OnConnectionMessagedClient(id_);
+      if (connection_with_node_as_root)
+        connection_with_node_as_root->RemoveRoot(node_id);
+      if (connection_by_url)
+        connection_by_url->AddRoot(node_id);
+      else
+        root_node_manager_->Embed(id_, url, transport_node_id);
+      change.SendServerChangeIdAdvanced();
+    } else {
+      success = false;
+    }
   }
   callback.Run(success);
 }

mojo/services/view_manager/view_manager_service_impl.h

@@ -68,6 +68,9 @@ class MOJO_VIEW_MANAGER_EXPORT ViewManagerServiceImpl
   }
   const View* GetView(const ViewId& id) const;
 
+  // Returns true if this has |id| as a root.
+  bool HasRoot(const NodeId& id) const;
+
   // Invoked when a connection is destroyed.
   void OnViewManagerServiceImplDestroyed(ConnectionSpecificId id);
 
@@ -141,13 +144,16 @@ class MOJO_VIEW_MANAGER_EXPORT ViewManagerServiceImpl
   void GetUnknownNodesFrom(const Node* node, std::vector<const Node*>* nodes);
 
   // Removes |node| and all its descendants from |known_nodes_|. This does not
-  // recurse through nodes that were created by this connection.
-  void RemoveFromKnown(const Node* node);
+  // recurse through nodes that were created by this connection. All nodes owned
+  // by this connection are added to |local_nodes|.
+  void RemoveFromKnown(const Node* node, std::vector<Node*>* local_nodes);
+
+  // Adds |node_id| to the set of roots this connection knows about. The caller
+  // should have verified |node_id| is not among the roots of this connection.
+  void AddRoot(const NodeId& node_id);
 
-  // Adds |transport_node_id| to the set of roots this connection knows about.
-  // Returns true if |transport_node_id| was not already a root for this
-  // connection.
-  bool AddRoot(Id transport_node_id);
+  // Removes |node_id| from the set of roots this connection knows about.
+  void RemoveRoot(const NodeId& node_id);
 
   // Returns true if |node| is a non-null and a descendant of |roots_| (or
   // |roots_| is empty).