feat: speed up unmarshalling headers (#347)

src/dbus_fast/_private/unmarshaller.pxd

@@ -22,7 +22,18 @@ cdef unsigned int HEADER_SIGNATURE_SIZE
 cdef unsigned int LITTLE_ENDIAN
 cdef unsigned int BIG_ENDIAN
 cdef unsigned int PROTOCOL_VERSION
+
+
+cdef unsigned int HEADER_PATH_IDX
+cdef unsigned int HEADER_INTERFACE_IDX
+cdef unsigned int HEADER_MEMBER_IDX
+cdef unsigned int HEADER_ERROR_NAME_IDX
+cdef unsigned int HEADER_REPLY_SERIAL_IDX
+cdef unsigned int HEADER_DESTINATION_IDX
+cdef unsigned int HEADER_SENDER_IDX
+cdef unsigned int HEADER_SIGNATURE_IDX
 cdef unsigned int HEADER_UNIX_FDS_IDX
+
 cdef cython.list HEADER_IDX_TO_ARG_NAME
 
 cdef str UINT32_CAST
@@ -95,6 +106,8 @@ cdef unsigned int TOKEN_LEFT_PAREN_AS_INT
 cdef object MARSHALL_STREAM_END_ERROR
 cdef object DEFAULT_BUFFER_SIZE
 
+cdef list _EMPTY_HEADERS
+
 cdef cython.uint EAGAIN
 cdef cython.uint EWOULDBLOCK
 
@@ -222,9 +235,10 @@ cdef class Unmarshaller:
 
     @cython.locals(
         body=cython.list,
-        header_fields=cython.dict,
+        header_fields=cython.list,
         token_as_int=cython.uint,
         signature=cython.str,
+        message=Message
     )
     cdef _read_body(self)
 
@@ -237,5 +251,6 @@ cdef class Unmarshaller:
         o=cython.ulong,
         token_as_int=cython.uint,
         signature_len=cython.uint,
+        headers=cython.list
     )
-    cdef cython.dict _header_fields(self, unsigned int header_length)
+    cdef cython.list _header_fields(self, unsigned int header_length)

src/dbus_fast/_private/unmarshaller.py

@@ -134,8 +134,18 @@
     "signature",
     "unix_fds",
 ]
+HEADER_PATH_IDX = HEADER_IDX_TO_ARG_NAME.index("path")
+HEADER_INTERFACE_IDX = HEADER_IDX_TO_ARG_NAME.index("interface")
+HEADER_MEMBER_IDX = HEADER_IDX_TO_ARG_NAME.index("member")
+HEADER_ERROR_NAME_IDX = HEADER_IDX_TO_ARG_NAME.index("error_name")
+HEADER_REPLY_SERIAL_IDX = HEADER_IDX_TO_ARG_NAME.index("reply_serial")
+HEADER_DESTINATION_IDX = HEADER_IDX_TO_ARG_NAME.index("destination")
+HEADER_SENDER_IDX = HEADER_IDX_TO_ARG_NAME.index("sender")
+HEADER_SIGNATURE_IDX = HEADER_IDX_TO_ARG_NAME.index("signature")
 HEADER_UNIX_FDS_IDX = HEADER_IDX_TO_ARG_NAME.index("unix_fds")
 
+_EMPTY_HEADERS = [None] * len(HEADER_IDX_TO_ARG_NAME)
+
 _SignatureType = SignatureType
 _int = int
 
@@ -596,12 +606,12 @@ def read_array(self, type_: _SignatureType) -> Iterable[Any]:
             result_list.append(reader(self, child_type))
         return result_list
 
-    def _header_fields(self, header_length: _int) -> dict[str, Any]:
+    def _header_fields(self, header_length: _int) -> list[Any]:
         """Header fields are always a(yv)."""
         beginning_pos = self._pos
-        headers = {}
         buf = self._buf
         readers = self._readers
+        headers = _EMPTY_HEADERS.copy()
         while self._pos - beginning_pos < header_length:
             # Now read the y (byte) of struct (yv)
             self._pos += (-self._pos & 7) + 1  # align 8 + 1 for 'y' byte
@@ -616,18 +626,19 @@ def _header_fields(self, header_length: _int) -> dict[str, Any]:
                 continue
             token_as_int = buf[o]
             # Now that we have the token we can read the variant value
-            key = HEADER_IDX_TO_ARG_NAME[field_0]
             # Strings and signatures are the most common types
             # so we inline them for performance
             if token_as_int == TOKEN_O_AS_INT or token_as_int == TOKEN_S_AS_INT:
-                headers[key] = self._read_string_unpack()
+                headers[field_0] = self._read_string_unpack()
             elif token_as_int == TOKEN_G_AS_INT:
-                headers[key] = self._read_signature()
+                headers[field_0] = self._read_signature()
             else:
                 token = buf[o : o + signature_len].decode()
                 # There shouldn't be any other types in the header
                 # but just in case, we'll read it using the slow path
-                headers[key] = readers[token](self, get_signature_tree(token).types[0])
+                headers[field_0] = readers[token](
+                    self, get_signature_tree(token).types[0]
+                )
         return headers
 
     def _read_header(self) -> None:
@@ -694,7 +705,7 @@ def _read_body(self) -> None:
         self._pos = HEADER_ARRAY_OF_STRUCT_SIGNATURE_POSITION
         header_fields = self._header_fields(self._header_len)
         self._pos += -self._pos & 7  # align 8
-        signature = header_fields.pop("signature", "")
+        signature = header_fields[HEADER_SIGNATURE_IDX]
         if not self._body_len:
             tree = SIGNATURE_TREE_EMPTY
             body: list[Any] = []
@@ -749,7 +760,13 @@ def _read_body(self) -> None:
             # The D-Bus implementation already validates the message,
             # so we don't need to do it again.
             validate=False,
-            **header_fields,
+            destination=header_fields[HEADER_DESTINATION_IDX],
+            path=header_fields[HEADER_PATH_IDX],
+            interface=header_fields[HEADER_INTERFACE_IDX],
+            member=header_fields[HEADER_MEMBER_IDX],
+            reply_serial=header_fields[HEADER_REPLY_SERIAL_IDX],
+            error_name=header_fields[HEADER_ERROR_NAME_IDX],
+            sender=header_fields[HEADER_SENDER_IDX],
         )
         self._read_complete = True
 

src/dbus_fast/message.py

@@ -107,12 +107,12 @@ def __init__(
         message_type: MessageType = MESSAGE_TYPE_METHOD_CALL,
         flags: Union[MessageFlag, int] = MESSAGE_FLAG_NONE,
         error_name: Optional[Union[str, ErrorType]] = None,
-        reply_serial: int = 0,
+        reply_serial: Optional[int] = None,
         sender: Optional[str] = None,
         unix_fds: list[int] = [],
         signature: Optional[Union[SignatureTree, str]] = None,
         body: list[Any] = [],
-        serial: int = 0,
+        serial: Optional[int] = None,
         validate: bool = True,
     ) -> None:
         self.destination = destination