452 lines
19 KiB
Python
452 lines
19 KiB
Python
from config import config
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import contextlib
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from dataclasses import dataclass
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import errno
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import json
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import logging
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from pathlib import Path
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from port_discovery import PortDiscovery
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import random
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import socket
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import struct
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import threading
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import time
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from typing import Any, Dict
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from models import MCPResponse
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# Configure logging using settings from config
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logging.basicConfig(
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level=getattr(logging, config.log_level),
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format=config.log_format
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)
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logger = logging.getLogger("mcp-for-unity-server")
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# Module-level lock to guard global connection initialization
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_connection_lock = threading.Lock()
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# Maximum allowed framed payload size (64 MiB)
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FRAMED_MAX = 64 * 1024 * 1024
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@dataclass
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class UnityConnection:
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"""Manages the socket connection to the Unity Editor."""
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host: str = config.unity_host
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port: int = None # Will be set dynamically
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sock: socket.socket = None # Socket for Unity communication
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use_framing: bool = False # Negotiated per-connection
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def __post_init__(self):
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"""Set port from discovery if not explicitly provided"""
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if self.port is None:
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self.port = PortDiscovery.discover_unity_port()
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self._io_lock = threading.Lock()
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self._conn_lock = threading.Lock()
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def connect(self) -> bool:
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"""Establish a connection to the Unity Editor."""
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if self.sock:
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return True
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with self._conn_lock:
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if self.sock:
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return True
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try:
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# Bounded connect to avoid indefinite blocking
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connect_timeout = float(
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getattr(config, "connect_timeout", getattr(config, "connection_timeout", 1.0)))
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self.sock = socket.create_connection(
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(self.host, self.port), connect_timeout)
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# Disable Nagle's algorithm to reduce small RPC latency
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with contextlib.suppress(Exception):
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self.sock.setsockopt(
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socket.IPPROTO_TCP, socket.TCP_NODELAY, 1)
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logger.debug(f"Connected to Unity at {self.host}:{self.port}")
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# Strict handshake: require FRAMING=1
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try:
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require_framing = getattr(config, "require_framing", True)
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timeout = float(getattr(config, "handshake_timeout", 1.0))
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self.sock.settimeout(timeout)
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buf = bytearray()
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deadline = time.monotonic() + timeout
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while time.monotonic() < deadline and len(buf) < 512:
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try:
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chunk = self.sock.recv(256)
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if not chunk:
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break
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buf.extend(chunk)
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if b"\n" in buf:
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break
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except socket.timeout:
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break
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text = bytes(buf).decode('ascii', errors='ignore').strip()
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if 'FRAMING=1' in text:
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self.use_framing = True
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logger.debug(
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'MCP for Unity handshake received: FRAMING=1 (strict)')
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else:
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if require_framing:
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# Best-effort plain-text advisory for legacy peers
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with contextlib.suppress(Exception):
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self.sock.sendall(
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b'MCP for Unity requires FRAMING=1\n')
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raise ConnectionError(
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f'MCP for Unity requires FRAMING=1, got: {text!r}')
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else:
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self.use_framing = False
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logger.warning(
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'MCP for Unity handshake missing FRAMING=1; proceeding in legacy mode by configuration')
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finally:
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self.sock.settimeout(config.connection_timeout)
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return True
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except Exception as e:
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logger.error(f"Failed to connect to Unity: {str(e)}")
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try:
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if self.sock:
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self.sock.close()
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except Exception:
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pass
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self.sock = None
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return False
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def disconnect(self):
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"""Close the connection to the Unity Editor."""
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if self.sock:
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try:
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self.sock.close()
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except Exception as e:
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logger.error(f"Error disconnecting from Unity: {str(e)}")
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finally:
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self.sock = None
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def _read_exact(self, sock: socket.socket, count: int) -> bytes:
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data = bytearray()
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while len(data) < count:
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chunk = sock.recv(count - len(data))
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if not chunk:
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raise ConnectionError(
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"Connection closed before reading expected bytes")
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data.extend(chunk)
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return bytes(data)
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def receive_full_response(self, sock, buffer_size=config.buffer_size) -> bytes:
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"""Receive a complete response from Unity, handling chunked data."""
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if self.use_framing:
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try:
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# Consume heartbeats, but do not hang indefinitely if only zero-length frames arrive
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heartbeat_count = 0
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deadline = time.monotonic() + getattr(config, 'framed_receive_timeout', 2.0)
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while True:
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header = self._read_exact(sock, 8)
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payload_len = struct.unpack('>Q', header)[0]
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if payload_len == 0:
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# Heartbeat/no-op frame: consume and continue waiting for a data frame
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logger.debug("Received heartbeat frame (length=0)")
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heartbeat_count += 1
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if heartbeat_count >= getattr(config, 'max_heartbeat_frames', 16) or time.monotonic() > deadline:
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# Treat as empty successful response to match C# server behavior
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logger.debug(
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"Heartbeat threshold reached; returning empty response")
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return b""
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continue
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if payload_len > FRAMED_MAX:
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raise ValueError(
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f"Invalid framed length: {payload_len}")
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payload = self._read_exact(sock, payload_len)
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logger.debug(
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f"Received framed response ({len(payload)} bytes)")
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return payload
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except socket.timeout as e:
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logger.warning("Socket timeout during framed receive")
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raise TimeoutError("Timeout receiving Unity response") from e
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except Exception as e:
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logger.error(f"Error during framed receive: {str(e)}")
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raise
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chunks = []
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# Respect the socket's currently configured timeout
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try:
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while True:
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chunk = sock.recv(buffer_size)
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if not chunk:
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if not chunks:
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raise Exception(
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"Connection closed before receiving data")
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break
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chunks.append(chunk)
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# Process the data received so far
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data = b''.join(chunks)
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decoded_data = data.decode('utf-8')
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# Check if we've received a complete response
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try:
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# Special case for ping-pong
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if decoded_data.strip().startswith('{"status":"success","result":{"message":"pong"'):
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logger.debug("Received ping response")
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return data
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# Handle escaped quotes in the content
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if '"content":' in decoded_data:
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# Find the content field and its value
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content_start = decoded_data.find('"content":') + 9
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content_end = decoded_data.rfind('"', content_start)
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if content_end > content_start:
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# Replace escaped quotes in content with regular quotes
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content = decoded_data[content_start:content_end]
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content = content.replace('\\"', '"')
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decoded_data = decoded_data[:content_start] + \
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content + decoded_data[content_end:]
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# Validate JSON format
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json.loads(decoded_data)
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# If we get here, we have valid JSON
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logger.info(
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f"Received complete response ({len(data)} bytes)")
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return data
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except json.JSONDecodeError:
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# We haven't received a complete valid JSON response yet
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continue
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except Exception as e:
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logger.warning(
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f"Error processing response chunk: {str(e)}")
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# Continue reading more chunks as this might not be the complete response
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continue
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except socket.timeout:
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logger.warning("Socket timeout during receive")
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raise Exception("Timeout receiving Unity response")
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except Exception as e:
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logger.error(f"Error during receive: {str(e)}")
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raise
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def send_command(self, command_type: str, params: Dict[str, Any] = None) -> Dict[str, Any]:
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"""Send a command with retry/backoff and port rediscovery. Pings only when requested."""
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# Defensive guard: catch empty/placeholder invocations early
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if not command_type:
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raise ValueError("MCP call missing command_type")
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if params is None:
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return MCPResponse(success=False, error="MCP call received with no parameters (client placeholder?)")
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attempts = max(config.max_retries, 5)
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base_backoff = max(0.5, config.retry_delay)
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def read_status_file() -> dict | None:
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try:
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status_files = sorted(Path.home().joinpath(
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'.unity-mcp').glob('unity-mcp-status-*.json'), key=lambda p: p.stat().st_mtime, reverse=True)
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if not status_files:
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return None
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latest = status_files[0]
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with latest.open('r') as f:
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return json.load(f)
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except Exception:
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return None
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last_short_timeout = None
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# Preflight: if Unity reports reloading, return a structured hint so clients can retry politely
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try:
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status = read_status_file()
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if status and (status.get('reloading') or status.get('reason') == 'reloading'):
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return MCPResponse(
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success=False,
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error="Unity domain reload in progress, please try again shortly",
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data={"state": "reloading", "retry_after_ms": int(
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config.reload_retry_ms)}
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)
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except Exception:
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pass
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for attempt in range(attempts + 1):
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try:
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# Ensure connected (handshake occurs within connect())
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if not self.sock and not self.connect():
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raise Exception("Could not connect to Unity")
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# Build payload
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if command_type == 'ping':
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payload = b'ping'
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else:
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command = {"type": command_type, "params": params or {}}
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payload = json.dumps(
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command, ensure_ascii=False).encode('utf-8')
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# Send/receive are serialized to protect the shared socket
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with self._io_lock:
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mode = 'framed' if self.use_framing else 'legacy'
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with contextlib.suppress(Exception):
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logger.debug(
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"send %d bytes; mode=%s; head=%s",
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len(payload),
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mode,
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(payload[:32]).decode('utf-8', 'ignore'),
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)
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if self.use_framing:
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header = struct.pack('>Q', len(payload))
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self.sock.sendall(header)
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self.sock.sendall(payload)
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else:
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self.sock.sendall(payload)
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# During retry bursts use a short receive timeout and ensure restoration
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restore_timeout = None
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if attempt > 0 and last_short_timeout is None:
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restore_timeout = self.sock.gettimeout()
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self.sock.settimeout(1.0)
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try:
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response_data = self.receive_full_response(self.sock)
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with contextlib.suppress(Exception):
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logger.debug("recv %d bytes; mode=%s",
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len(response_data), mode)
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finally:
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if restore_timeout is not None:
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self.sock.settimeout(restore_timeout)
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last_short_timeout = None
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# Parse
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if command_type == 'ping':
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resp = json.loads(response_data.decode('utf-8'))
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if resp.get('status') == 'success' and resp.get('result', {}).get('message') == 'pong':
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return {"message": "pong"}
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raise Exception("Ping unsuccessful")
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resp = json.loads(response_data.decode('utf-8'))
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if resp.get('status') == 'error':
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err = resp.get('error') or resp.get(
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'message', 'Unknown Unity error')
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raise Exception(err)
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return resp.get('result', {})
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except Exception as e:
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logger.warning(
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f"Unity communication attempt {attempt+1} failed: {e}")
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try:
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if self.sock:
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self.sock.close()
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finally:
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self.sock = None
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# Re-discover port each time
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try:
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new_port = PortDiscovery.discover_unity_port()
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if new_port != self.port:
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logger.info(
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f"Unity port changed {self.port} -> {new_port}")
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self.port = new_port
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except Exception as de:
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logger.debug(f"Port discovery failed: {de}")
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if attempt < attempts:
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# Heartbeat-aware, jittered backoff
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status = read_status_file()
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# Base exponential backoff
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backoff = base_backoff * (2 ** attempt)
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# Decorrelated jitter multiplier
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jitter = random.uniform(0.1, 0.3)
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# Fast‑retry for transient socket failures
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fast_error = isinstance(
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e, (ConnectionRefusedError, ConnectionResetError, TimeoutError))
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if not fast_error:
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try:
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err_no = getattr(e, 'errno', None)
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fast_error = err_no in (
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errno.ECONNREFUSED, errno.ECONNRESET, errno.ETIMEDOUT)
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except Exception:
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pass
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# Cap backoff depending on state
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if status and status.get('reloading'):
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cap = 0.8
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elif fast_error:
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cap = 0.25
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else:
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cap = 3.0
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sleep_s = min(cap, jitter * (2 ** attempt))
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time.sleep(sleep_s)
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continue
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raise
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# Global Unity connection
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_unity_connection = None
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def get_unity_connection() -> UnityConnection:
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"""Retrieve or establish a persistent Unity connection.
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Note: Do NOT ping on every retrieval to avoid connection storms. Rely on
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send_command() exceptions to detect broken sockets and reconnect there.
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"""
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global _unity_connection
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if _unity_connection is not None:
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return _unity_connection
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# Double-checked locking to avoid concurrent socket creation
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with _connection_lock:
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if _unity_connection is not None:
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return _unity_connection
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logger.info("Creating new Unity connection")
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_unity_connection = UnityConnection()
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if not _unity_connection.connect():
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_unity_connection = None
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raise ConnectionError(
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"Could not connect to Unity. Ensure the Unity Editor and MCP Bridge are running.")
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logger.info("Connected to Unity on startup")
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return _unity_connection
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# -----------------------------
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# Centralized retry helpers
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# -----------------------------
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def _is_reloading_response(resp: dict) -> bool:
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"""Return True if the Unity response indicates the editor is reloading."""
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if not isinstance(resp, dict):
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return False
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if resp.get("state") == "reloading":
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return True
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message_text = (resp.get("message") or resp.get("error") or "").lower()
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return "reload" in message_text
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def send_command_with_retry(command_type: str, params: Dict[str, Any], *, max_retries: int | None = None, retry_ms: int | None = None) -> Dict[str, Any]:
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"""Send a command via the shared connection, waiting politely through Unity reloads.
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Uses config.reload_retry_ms and config.reload_max_retries by default. Preserves the
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structured failure if retries are exhausted.
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"""
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conn = get_unity_connection()
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if max_retries is None:
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max_retries = getattr(config, "reload_max_retries", 40)
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if retry_ms is None:
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retry_ms = getattr(config, "reload_retry_ms", 250)
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response = conn.send_command(command_type, params)
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retries = 0
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while _is_reloading_response(response) and retries < max_retries:
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delay_ms = int(response.get("retry_after_ms", retry_ms)
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) if isinstance(response, dict) else retry_ms
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time.sleep(max(0.0, delay_ms / 1000.0))
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retries += 1
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response = conn.send_command(command_type, params)
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return response
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async def async_send_command_with_retry(command_type: str, params: dict[str, Any], *, loop=None, max_retries: int | None = None, retry_ms: int | None = None) -> dict[str, Any] | MCPResponse:
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"""Async wrapper that runs the blocking retry helper in a thread pool."""
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try:
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import asyncio # local import to avoid mandatory asyncio dependency for sync callers
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if loop is None:
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loop = asyncio.get_running_loop()
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return await loop.run_in_executor(
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None,
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lambda: send_command_with_retry(
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command_type, params, max_retries=max_retries, retry_ms=retry_ms),
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)
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except Exception as e:
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return MCPResponse(success=False, error=str(e))
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