[Feature] Update llama2 (#372)

opencompass/models/llama2.py

@@ -59,12 +59,18 @@ class Llama2(BaseModel):
         self.tokenizer = Tokenizer(tokenizer_path)
 
     def generate(self, inputs: List[str], max_out_len: int) -> List[str]:
-        out = self.generator.text_completion(
-            inputs,
-            temperature=0,
+        prompt_tokens = []
+        for input in inputs:
+            tokens = self.tokenizer.encode(input, True, False)
+            num_token = min(self.model.params.max_seq_len, len(tokens))
+            prompt_tokens.append(tokens[-num_token:])
+        generation_tokens, _ = self.generator.generate(
+            prompt_tokens=prompt_tokens,
             max_gen_len=max_out_len,
+            temperature=0,
         )
-        return [i['generation'] for i in out]
+        results = [self.tokenizer.decode(t) for t in generation_tokens]
+        return results
 
     def get_ppl(self,
                 inputs: List[str],
@@ -183,7 +189,7 @@ class Llama2Chat(BaseModel):
             )
             return [r['generation']['content'] for r in results]
         except AssertionError:
-            self.warning('Batched data max token limit exceeded, '
+            self.logger.warning('Batched data max token limit exceeded, '
                                 'try to run one by one...')
 
         results = []