utils: add support for msgspec with stdlib json fallback

Signed-off-by: Eric Callahan <arksine.code@gmail.com>

moonraker/utils/__init__.py

@@ -14,13 +14,13 @@ import sys
 import subprocess
 import asyncio
 import hashlib
-import json
 import shlex
 import re
 import struct
 import socket
 import enum
 from . import source_info
+from . import json_wrapper
 
 # Annotation imports
 from typing import (
@@ -190,7 +190,7 @@ def verify_source(
     if not rfile.exists():
         return None
     try:
-        rinfo = json.loads(rfile.read_text())
+        rinfo = json_wrapper.loads(rfile.read_text())
     except Exception:
         return None
     orig_chksum = rinfo['source_checksum']

moonraker/utils/json_wrapper.py

@@ -0,0 +1,33 @@
+# Wrapper for msgspec with stdlib fallback
+#
+# Copyright (C) 2023 Eric Callahan <arksine.code@gmail.com>
+#
+# This file may be distributed under the terms of the GNU GPLv3 license
+
+from __future__ import annotations
+import os
+import contextlib
+from typing import Any, Union, TYPE_CHECKING
+
+if TYPE_CHECKING:
+    def dumps(obj: Any) -> bytes: ...  # type: ignore
+    def loads(data: Union[str, bytes, bytearray]) -> Any: ...
+
+MSGSPEC_ENABLED = False
+_msgspc_var = os.getenv("MOONRAKER_ENABLE_MSGSPEC", "y").lower()
+if _msgspc_var in ["y", "yes", "true"]:
+    with contextlib.suppress(ImportError):
+        import msgspec
+        from msgspec import DecodeError as JSONDecodeError
+        encoder = msgspec.json.Encoder()
+        decoder = msgspec.json.Decoder()
+        dumps = encoder.encode
+        loads = decoder.decode
+        MSGSPEC_ENABLED = True
+if not MSGSPEC_ENABLED:
+    import json
+    from json import JSONDecodeError  # type: ignore
+    loads = json.loads  # type: ignore
+
+    def dumps(obj) -> bytes:  # type: ignore
+        return json.dumps(obj).encode("utf-8")