Output token usage

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

rerank.py

@@ -67,6 +67,7 @@ class ReRank(NNOperator):
                 texts[idx].append(text.strip())
 
         tokenized = self.tokenizer(*texts, padding=True, truncation='longest_first', return_tensors="pt", max_length=self.max_length)
+        token_count = torch.count_nonzero(tokenized['input_ids'])
 
         logits = self.model(**tokenized)
         scores = self.post_proc(logits)
@@ -78,7 +79,7 @@ class ReRank(NNOperator):
         else:
             re_docs = [docs[i] for i in re_ids if scores[i] >= self._threshold]
             re_scores = [scores[i] for i in re_ids if scores[i] >= self._threshold]
-        return re_docs, re_scores
+        return re_docs, re_scores, token_count
 
 
     def post_proc(self, logits):