Support save model with torchscript

Signed-off-by: Jael Gu <mengjia.gu@zilliz.com>

auto_transformers.py

@@ -13,6 +13,9 @@
 # limitations under the License.
 
 import numpy
+import os
+import torch
+from pathlib import Path
 from transformers import AutoTokenizer, AutoModel
 
 from towhee.operator import NNOperator
@@ -40,6 +43,7 @@ class AutoTransformers(NNOperator):
         self.model_name = model_name
         try:
             self.model = AutoModel.from_pretrained(model_name)
+            self.model.eval()
         except Exception as e:
             model_list = get_model_list()
             if model_name not in model_list:
@@ -65,13 +69,29 @@ class AutoTransformers(NNOperator):
             log.error(f'Invalid input for the model: {self.model_name}')
             raise e
         try:
-            features = outs.last_hidden_state.squeeze(0)
+            features = outs['last_hidden_state'].squeeze(0)
         except Exception as e:
             log.error(f'Fail to extract features by model: {self.model_name}')
             raise e
         vec = features.detach().numpy()
         return vec
 
+    def save_model(self, jit: bool = True, destination: str = 'default'):
+        if destination == 'default':
+            path = str(Path(__file__).parent)
+            destination = os.path.join(path, self.model_name + '.pt')
+        inputs = self.tokenizer('[CLS]', return_tensors='pt')
+        inputs = list(inputs.values())
+        if jit:
+            try:
+                traced_model = torch.jit.trace(self.model, inputs, strict=False)
+                torch.jit.save(traced_model, destination)
+            except Exception as e:
+                log.error(f'Fail to save as torchscript: {e}.')
+                raise RuntimeError(f'Fail to save as torchscript: {e}.')
+        else:
+            torch.save(self.model, destination)
+
 
 def get_model_list():
     full_list = [