!7803 remove redundant method root() in tree_adapter.h

Merge pull request !7803 from xiaotianci/fix_redundant_root

mindspore/ccsrc/minddata/dataset/engine/consumers/tree_consumer.cc

@@ -80,20 +80,26 @@ Status ToDevice::Init(std::shared_ptr<api::Dataset> d) {
 Status ToDevice::Send() {
   std::unique_ptr<DataBuffer> db;
   RETURN_IF_NOT_OK(tree_adapter_->Launch());
-  RETURN_IF_NOT_OK(tree_adapter_->root()->GetNextBuffer(&db));
+  std::shared_ptr<DatasetOp> root = std::shared_ptr<DatasetOp>(tree_adapter_->GetRoot());
+  CHECK_FAIL_RETURN_UNEXPECTED(root != nullptr, "Root is a nullptr.");
+  RETURN_IF_NOT_OK(root->GetNextBuffer(&db));
   return Status::OK();
 }
 
 Status ToDevice::Continue() {
   // tree_.root() must be DeviceQueueOp
-  DeviceQueueOp *op = dynamic_cast<DeviceQueueOp *>(tree_adapter_->root().get());
+  std::shared_ptr<DatasetOp> root = std::shared_ptr<DatasetOp>(tree_adapter_->GetRoot());
+  CHECK_FAIL_RETURN_UNEXPECTED(root != nullptr, "Root is a nullptr.");
+  DeviceQueueOp *op = dynamic_cast<DeviceQueueOp *>(root.get());
   CHECK_FAIL_RETURN_UNEXPECTED(op != nullptr, "ContinueSend only supported by DeviceQueueOp");
   op->ContinueSend();
   return Status::OK();
 }
 
 Status ToDevice::Stop() {
-  DeviceQueueOp *op = dynamic_cast<DeviceQueueOp *>(tree_adapter_->root().get());
+  std::shared_ptr<DatasetOp> root = std::shared_ptr<DatasetOp>(tree_adapter_->GetRoot());
+  CHECK_FAIL_RETURN_UNEXPECTED(root != nullptr, "Root is a nullptr.");
+  DeviceQueueOp *op = dynamic_cast<DeviceQueueOp *>(root.get());
   CHECK_FAIL_RETURN_UNEXPECTED(op != nullptr, "StopSend only supported by DeviceQueueOp");
   op->StopSend();
   return Status::OK();

mindspore/ccsrc/minddata/dataset/engine/tree_adapter.cc

@@ -87,5 +87,10 @@ Status TreeAdapter::DFSBuildTree(std::shared_ptr<api::Dataset> ir, std::shared_p
   return Status::OK();
 }
 
+Status TreeAdapter::Launch() const {
+  CHECK_FAIL_RETURN_UNEXPECTED(tree_ != nullptr, "Tree is a nullptr.");
+  return tree_->Launch();
+}
+
 }  // namespace dataset
 }  // namespace mindspore

mindspore/ccsrc/minddata/dataset/engine/tree_adapter.h

@@ -57,9 +57,7 @@ class TreeAdapter {
   // to be able to launch a thread. BuildAndPrepare needs to be called before this function
   TaskGroup *AllTasks() const { return tree_ != nullptr ? tree_->AllTasks() : nullptr; }
 
-  std::shared_ptr<DatasetOp> root() { return tree_->root(); }
-
-  Status Launch() const { return tree_->Launch(); }
+  Status Launch() const;
 
  private:
   // This RECURSIVE function converts IR nodes into DatasetOp in ExecutionTree. IR could build a vector of ops. In