perf(function_call): skip DeepSeek V3 regex scans until the JSON fence closes

lightllm/server/function_call_parser.py

@@ -1107,11 +1107,16 @@ def parse_streaming_increment(self, new_text: str, tools: List[Tool]) -> Streami
 
         calls: list[ToolCallItem] = []
         try:
-            partial_match = re.search(
-                pattern=r"<｜tool▁call▁begin｜>(.*)<｜tool▁sep｜>(.*)\n```json\n(.*)\n```.*",
-                string=current_text,
-                flags=re.DOTALL,
-            )
+            # The pattern needs a closing ``` fence after ```json, so skip the scan until then.
+            partial_match = None
+            json_header = "\n```json\n"
+            header_at = current_text.find(json_header)
+            if header_at != -1 and current_text.find("\n```", header_at + len(json_header)) != -1:
+                partial_match = re.search(
+                    pattern=r"<｜tool▁call▁begin｜>(.*)<｜tool▁sep｜>(.*)\n```json\n(.*)\n```.*",
+                    string=current_text,
+                    flags=re.DOTALL,
+                )
             if partial_match:
                 func_name = partial_match.group(2).strip()
                 func_args_raw = partial_match.group(3).strip()

unit_tests/server/test_deepseek_tool_parser_stream.py

@@ -82,6 +82,53 @@ def test_dsml_emits_buffered_invoke_on_next_delta():
     assert json.loads(arguments[1]) == {"location": "Paris"}
 
 
+def _v3_call(name, payload):
+    return "<｜tool▁call▁begin｜>function<｜tool▁sep｜>" + name + "\n```json\n" + payload + "\n```<｜tool▁call▁end｜>"
+
+
+def test_deepseekv3_streams_long_arguments_in_small_deltas():
+    arguments = {"content": "print(1)\n" * 500}
+    payload = json.dumps(arguments)
+    call = _v3_call("write_file", payload)
+    deltas = ["<｜tool▁calls▁begin｜>"] + [call[i : i + 4] for i in range(0, len(call), 4)]
+
+    parser = FunctionCallParser(TOOLS, "deepseekv3")
+    names, streamed = _stream(parser, deltas)
+
+    assert names == ["write_file"]
+    assert json.loads(streamed[0]) == arguments
+
+
+def test_deepseekv3_holds_arguments_until_the_json_fence_closes():
+    payload = json.dumps({"content": "x" * 200})
+    head = "<｜tool▁calls▁begin｜><｜tool▁call▁begin｜>function<｜tool▁sep｜>write_file\n```json\n"
+    parser = FunctionCallParser(TOOLS, "deepseekv3")
+    names, streamed = _stream(parser, [head] + [payload[i : i + 4] for i in range(0, len(payload), 4)])
+    assert names == []
+    assert streamed == {}
+
+    # The closing fence is split across deltas. The name is emitted on the delta that
+    # completes it, and the arguments follow on the next delta, same as one regex search.
+    names, streamed = _stream(parser, ["\n", "``", "`<｜tool▁call▁end｜>", "<｜tool▁calls▁end｜>"])
+    assert names == ["write_file"]
+    assert json.loads(streamed[0]) == {"content": "x" * 200}
+
+
+def test_deepseekv3_keeps_a_fence_inside_the_argument():
+    content = "line1\n```\nline2\n```python\ncode"
+    payload = json.dumps({"content": content})
+    text = "<｜tool▁calls▁begin｜>" + _v3_call("write_file", payload)
+    deltas = [text[: len("<｜tool▁calls▁begin｜>")]] + [
+        text[i : i + 4] for i in range(len("<｜tool▁calls▁begin｜>"), len(text), 4)
+    ]
+
+    parser = FunctionCallParser(TOOLS, "deepseekv3")
+    names, streamed = _stream(parser, deltas)
+
+    assert names == ["write_file"]
+    assert json.loads(streamed[0]) == {"content": content}
+
+
 def test_deepseekv31_streams_long_arguments_in_small_deltas():
     arguments = {"content": "print(1)\n" * 500}
     payload = json.dumps(arguments)