ragflow/mcp_client/mcp_tool_call.py
Yongteng Lei 0eb90e73a5
Feat: add MCP dashboard functionalities list_tools and test_tool (#8505)
### What problem does this PR solve?

Add MCP dashboard functionalities list_tools and test_tool.

### Type of change

- [x] New Feature (non-breaking change which adds functionality)
2025-06-26 13:52:01 +08:00

213 lines
8.7 KiB
Python

import asyncio
import logging
import threading
import weakref
from concurrent.futures import ThreadPoolExecutor
from string import Template
from typing import Any, Literal
from typing_extensions import override
from api.db import MCPServerType
from mcp.client.session import ClientSession
from mcp.client.sse import sse_client
from mcp.client.streamable_http import streamablehttp_client
from mcp.types import CallToolResult, ListToolsResult, TextContent, Tool
from rag.llm.chat_model import ToolCallSession
MCPTaskType = Literal["list_tools", "tool_call"]
MCPTask = tuple[MCPTaskType, dict[str, Any], asyncio.Queue[Any]]
class MCPToolCallSession(ToolCallSession):
_ALL_INSTANCES: weakref.WeakSet["MCPToolCallSession"] = weakref.WeakSet()
def __init__(self, mcp_server: Any, server_variables: dict[str, Any] | None = None) -> None:
self.__class__._ALL_INSTANCES.add(self)
self._mcp_server = mcp_server
self._server_variables = server_variables or {}
self._queue = asyncio.Queue()
self._close = False
self._event_loop = asyncio.new_event_loop()
self._thread_pool = ThreadPoolExecutor(max_workers=1)
self._thread_pool.submit(self._event_loop.run_forever)
asyncio.run_coroutine_threadsafe(self._mcp_server_loop(), self._event_loop)
async def _mcp_server_loop(self) -> None:
url = self._mcp_server.url.strip()
raw_headers: dict[str, str] = self._mcp_server.headers or {}
headers: dict[str, str] = {}
for h, v in raw_headers.items():
nh = Template(h).safe_substitute(self._server_variables)
nv = Template(v).safe_substitute(self._server_variables)
headers[nh] = nv
if self._mcp_server.server_type == MCPServerType.SSE:
# SSE transport
async with sse_client(url, headers) as stream:
async with ClientSession(*stream) as client_session:
try:
await asyncio.wait_for(client_session.initialize(), timeout=5)
logging.info("client_session initialized successfully")
except asyncio.TimeoutError:
logging.error(f"Timeout initializing client_session for server {self._mcp_server.id}")
return
await self._process_mcp_tasks(client_session)
elif self._mcp_server.server_type == MCPServerType.STREAMABLE_HTTP:
# Streamable HTTP transport
async with streamablehttp_client(url, headers) as (read_stream, write_stream, _):
async with ClientSession(read_stream, write_stream) as client_session:
try:
await asyncio.wait_for(client_session.initialize(), timeout=5)
logging.info("client_session initialized successfully")
except asyncio.TimeoutError:
logging.error(f"Timeout initializing client_session for server {self._mcp_server.id}")
return
await asyncio.wait_for(client_session.initialize(), timeout=5)
await self._process_mcp_tasks(client_session)
else:
raise ValueError(f"Unsupported MCP server type {self._mcp_server.server_type} id {self._mcp_server.id}")
async def _process_mcp_tasks(self, client_session: ClientSession) -> None:
while not self._close:
try:
mcp_task, arguments, result_queue = await asyncio.wait_for(self._queue.get(), timeout=1)
except asyncio.TimeoutError:
continue
logging.debug(f"Got MCP task {mcp_task} arguments {arguments}")
r: Any = None
try:
if mcp_task == "list_tools":
r = await client_session.list_tools()
elif mcp_task == "tool_call":
r = await client_session.call_tool(**arguments)
else:
r = ValueError(f"Unknown MCP task {mcp_task}")
except Exception as e:
r = e
await result_queue.put(r)
async def _call_mcp_server(self, task_type: MCPTaskType, timeout: float = 8, **kwargs) -> Any:
results = asyncio.Queue()
await self._queue.put((task_type, kwargs, results))
try:
result: CallToolResult | Exception = await asyncio.wait_for(results.get(), timeout=timeout)
except asyncio.TimeoutError:
raise TimeoutError(f"MCP task '{task_type}' timeout after {timeout}s")
if isinstance(result, Exception):
raise result
return result
async def _call_mcp_tool(self, name: str, arguments: dict[str, Any]) -> str:
result: CallToolResult = await self._call_mcp_server("tool_call", name=name, arguments=arguments)
if result.isError:
return f"MCP server error: {result.content}"
# For now we only support text content
if isinstance(result.content[0], TextContent):
return result.content[0].text
else:
return f"Unsupported content type {type(result.content)}"
async def _get_tools_from_mcp_server(self) -> list[Tool]:
result: ListToolsResult = await self._call_mcp_server("list_tools")
return result.tools
def get_tools(self, timeout: float = 10) -> list[Tool]:
future = asyncio.run_coroutine_threadsafe(self._get_tools_from_mcp_server(), self._event_loop)
try:
return future.result(timeout=timeout)
except TimeoutError:
logging.error(f"Timeout when fetching tools from MCP server: {self._mcp_server.id}")
return []
except Exception:
logging.exception(f"Error fetching tools from MCP server: {self._mcp_server.id}")
return []
@override
def tool_call(self, name: str, arguments: dict[str, Any], timeout: float = 10) -> str:
future = asyncio.run_coroutine_threadsafe(self._call_mcp_tool(name, arguments), self._event_loop)
try:
return future.result(timeout=timeout)
except TimeoutError as te:
logging.error(f"Timeout calling tool '{name}' on MCP server: {self._mcp_server.id}")
return f"Timeout calling tool '{name}': {te}."
except Exception as e:
logging.exception(f"Error calling tool '{name}' on MCP server: {self._mcp_server.id}")
return f"Error calling tool '{name}': {e}."
async def close(self) -> None:
if self._close:
return
self._close = True
self._event_loop.call_soon_threadsafe(self._event_loop.stop)
self._thread_pool.shutdown(wait=True)
self.__class__._ALL_INSTANCES.discard(self)
def close_sync(self, timeout: float = 5) -> None:
if not self._event_loop.is_running():
logging.warning(f"Event loop already stopped for {self._mcp_server.id}")
return
future = asyncio.run_coroutine_threadsafe(self.close(), self._event_loop)
try:
future.result(timeout=timeout)
except TimeoutError:
logging.error(f"Timeout while closing session for server {self._mcp_server.id}")
except Exception:
logging.exception(f"Unexpected error during close_sync for {self._mcp_server.id}")
def close_multiple_mcp_toolcall_sessions(sessions: list[MCPToolCallSession]) -> None:
logging.info(f"Want to clean up {len(sessions)} MCP sessions")
async def _gather_and_stop() -> None:
try:
await asyncio.gather(*[s.close() for s in sessions if s is not None], return_exceptions=True)
finally:
loop.call_soon_threadsafe(loop.stop)
loop = asyncio.new_event_loop()
thread = threading.Thread(target=loop.run_forever, daemon=True)
thread.start()
asyncio.run_coroutine_threadsafe(_gather_and_stop(), loop).result()
thread.join()
logging.info(f"{len(sessions)} MCP sessions has been cleaned up. {len(list(MCPToolCallSession._ALL_INSTANCES))} in global context.")
def shutdown_all_mcp_sessions():
"""Gracefully shutdown all active MCPToolCallSession instances."""
sessions = list(MCPToolCallSession._ALL_INSTANCES)
if not sessions:
logging.info("No MCPToolCallSession instances to close.")
return
logging.info(f"Shutting down {len(sessions)} MCPToolCallSession instances...")
close_multiple_mcp_toolcall_sessions(sessions)
logging.info("All MCPToolCallSession instances have been closed.")
def mcp_tool_metadata_to_openai_tool(mcp_tool: Tool) -> dict[str, Any]:
return {
"type": "function",
"function": {
"name": mcp_tool.name,
"description": mcp_tool.description,
"parameters": mcp_tool.inputSchema,
},
}