3x performance improvement for serialization (#700)

* 3x performance improvement for serialization

Instead of re-inspecting the type metadata everytime an object is serialized,
create a single serialization function for each type and just call it when an instance is serialized

* pre-compute uatype array serializers

* Make VariantTypeCustom instances valid cache keys

VariantTypeCustom instances can be used as cache keys for serialization functions

asyncua/ua/ua_binary.py

@@ -2,12 +2,13 @@
 Binary protocol specific functions and constants
 """
 
+import functools
 import struct
 import logging
+from typing import Any, Callable
 import uuid
 from enum import IntEnum, Enum, IntFlag
-from dataclasses import is_dataclass, fields
-
+from dataclasses import is_dataclass, fields, Field
 from asyncua import ua
 from .uaerrors import UaError
 from ..common.utils import Buffer
@@ -168,18 +169,23 @@ class Primitives(Primitives1):
     Guid = _Guid()
 
 
-def pack_uatype(vtype, value):
+@functools.lru_cache(maxsize=None)
+def create_uatype_serializer(vtype):
     if hasattr(Primitives, vtype.name):
-        return getattr(Primitives, vtype.name).pack(value)
+        return getattr(Primitives, vtype.name).pack
     if vtype.value > 25:
-        return Primitives.Bytes.pack(value)
+        return Primitives.Bytes.pack
     if vtype == ua.VariantType.ExtensionObject:
-        return extensionobject_to_binary(value)
+        return extensionobject_to_binary
     if vtype in (ua.VariantType.NodeId, ua.VariantType.ExpandedNodeId):
-        return nodeid_to_binary(value)
+        return nodeid_to_binary
     if vtype == ua.VariantType.Variant:
-        return variant_to_binary(value)
-    return struct_to_binary(value)
+        return variant_to_binary
+    return struct_to_binary
+
+
+def pack_uatype(vtype, value):
+    return create_uatype_serializer(vtype)(value)
 
 
 def unpack_uatype(vtype, data):
@@ -200,16 +206,23 @@ def unpack_uatype(vtype, data):
     raise UaError(f'Cannot unpack unknown variant type {vtype}')
 
 
-def pack_uatype_array(vtype, array):
+@functools.lru_cache(maxsize=None)
+def create_uatype_array_serializer(vtype):
     if hasattr(Primitives1, vtype.name):
         data_type = getattr(Primitives1, vtype.name)
-        return data_type.pack_array(array)
+        return data_type.pack_array
+    serializer = create_uatype_serializer(vtype)
+
+    def serialize(array):
         if array is None:
             return b'\xff\xff\xff\xff'
-    length = len(array)
-    b = [pack_uatype(vtype, val) for val in array]
-    b.insert(0, Primitives.Int32.pack(length))
-    return b"".join(b)
+        length = Primitives.Int32.pack(len(array))
+        return length + b"".join(serializer(val) for val in array)
+    return serialize
+
+
+def pack_uatype_array(vtype, array):
+    return create_uatype_array_serializer(vtype)(array)
 
 
 def unpack_uatype_array(vtype, data):
@@ -224,68 +237,104 @@ def unpack_uatype_array(vtype, data):
     return [unpack_uatype(vtype, data) for _ in range(length)]
 
 
-def struct_to_binary(obj):
-    packet = []
-    enc_count = 0
-    enc = 0
-    for field in fields(obj):
-        if type_is_union(field.type):
-            if getattr(obj, field.name) is not None:
-                enc = enc | 1 << enc_count
-            enc_count += 1
-
-    for field in fields(obj):
+def field_serializer(field: Field) -> Callable[[Any], bytes]:
+    is_optional = type_is_union(field.type)
     uatype = field.type
-        if field.name == "Encoding":
-            packet.append(Primitives.Byte.pack(enc))
-            continue
-        val = getattr(obj, field.name)
-        if type_is_union(uatype):
+    if is_optional:
         uatype = type_from_union(uatype)
     if type_is_list(uatype):
-            packet.append(list_to_binary(type_from_list(uatype), val))
+        return create_list_serializer(type_from_list(uatype))
     else:
-            if val is None and type_is_union(field.type):
-                pass
+        serializer = create_type_serializer(uatype)
+        if is_optional:
+            return lambda val: b'' if val is None else serializer(val)
         else:
-                packet.append(to_binary(uatype, val))
-    return b''.join(packet)
+            return serializer
 
 
-def to_binary(uatype, val):
-    """
-    Pack a python object to binary given a type hint
-    """
+@functools.lru_cache(maxsize=None)
+def create_dataclass_serializer(dataclazz):
+    """Given a dataclass, return a function that serializes instances of this dataclass"""
+    data_fields = fields(dataclazz)
+    union_fields_encodings = [  # Name and binary encoding of optional fields
+        (field.name, 1 << enc_count)
+        for enc_count, field
+        in enumerate(filter(lambda f: type_is_union(f.type), data_fields))
+    ]
+
+    def serialize_encoding(obj):
+        enc = 0
+        for name, enc_val in union_fields_encodings:
+            if obj.__dict__[name] is not None:
+                enc |= enc_val
+        return Primitives.Byte.pack(enc)
+
+    encoding_functions = [(f.name, field_serializer(f)) for f in data_fields]
+
+    def serialize(obj):
+        return b''.join(
+            serialize_encoding(obj) if name == 'Encoding'
+            else serializer(obj.__dict__[name])
+            for name, serializer in encoding_functions
+        )
+
+    return serialize
+
+
+def struct_to_binary(obj):
+    serializer = create_dataclass_serializer(obj.__class__)
+    return serializer(obj)
+
+
+@functools.lru_cache(maxsize=None)
+def create_type_serializer(uatype):
+    """Create a binary serialization function for the given UA type"""
     if type_is_list(uatype):
-        return list_to_binary(type_from_list(uatype), val)
+        return create_list_serializer(type_from_list(uatype))
     if hasattr(Primitives, uatype.__name__):
-        return getattr(Primitives, uatype.__name__).pack(val)
+        return getattr(Primitives, uatype.__name__).pack
     if issubclass(uatype, Enum):
-        if isinstance(val, (IntEnum, Enum, IntFlag)):
-            return Primitives.Int32.pack(val.value)
-        return Primitives.Int32.pack(val)
+        return lambda val: \
+            Primitives.Int32.pack(val.value) if isinstance(val, (IntEnum, Enum, IntFlag)) \
+            else Primitives.Int32.pack(val)
     if hasattr(ua.VariantType, uatype.__name__):
         vtype = getattr(ua.VariantType, uatype.__name__)
-        return pack_uatype(vtype, val)
-    if isinstance(val, ua.NodeId):
-        return nodeid_to_binary(val)
-    if isinstance(val, ua.Variant):
-        return variant_to_binary(val)
-    if is_dataclass(val):
-        return struct_to_binary(val)
-    raise UaError(f'No known way to pack {val} of type {uatype} to ua binary')
+        return create_uatype_serializer(vtype)
+    if issubclass(uatype, ua.NodeId):
+        return nodeid_to_binary
+    if issubclass(uatype, ua.Variant):
+        return variant_to_binary
+    if is_dataclass(uatype):
+        return create_dataclass_serializer(uatype)
+    raise UaError(f'No known way to pack value of type {uatype} to ua binary')
 
 
-def list_to_binary(uatype, val):
-    if val is None:
-        return Primitives.Int32.pack(-1)
+def to_binary(uatype, val):
+    return create_type_serializer(uatype)(val)
+
+
+@functools.lru_cache(maxsize=None)
+def create_list_serializer(uatype) -> Callable[[Any], bytes]:
+    """
+    Given a type, return a function that takes a list of instances
+    of that type and serializes it.
+    """
     if hasattr(Primitives1, uatype.__name__):
         data_type = getattr(Primitives1, uatype.__name__)
-        return data_type.pack_array(val)
+        return data_type.pack_array
+    type_serializer = create_type_serializer(uatype)
+    none_val = Primitives.Int32.pack(-1)
+
+    def serialize(val):
+        if val is None:
+            return none_val
         data_size = Primitives.Int32.pack(len(val))
-    pack = [to_binary(uatype, el) for el in val]
-    pack.insert(0, data_size)
-    return b''.join(pack)
+        return data_size + b''.join(type_serializer(el) for el in val)
+    return serialize
+
+
+def list_to_binary(uatype, val):
+    return create_list_serializer(uatype)(val)
 
 
 def nodeid_to_binary(nodeid):

asyncua/ua/uatypes.py

@@ -758,7 +758,7 @@ class VariantTypeCustom:
     """
     Looks like sometime we get variant with other values than those
     defined in VariantType.
-    FIXME: We should not need this class, as far as I iunderstand the spec
+    FIXME: We should not need this class, as far as I understand the spec
     variants can only be of VariantType
     """
 
@@ -776,7 +776,10 @@ class VariantTypeCustom:
     __repr__ = __str__
 
     def __eq__(self, other):
-        return self.value == other.value
+        return isinstance(other, type(self)) and self.value == other.value
+    
+    def __hash__(self) -> int:
+        return self.value.__hash__()
 
 
 @dataclass(frozen=True)