[#374] Improve initialize_offsets calling in Python serialization

Author: mikir

compiler/extensions/python/runtime/src/zserio/serialization.py

@@ -8,7 +8,7 @@
 from zserio.bitbuffer import BitBuffer
 from zserio.bitreader import BitStreamReader
 
-def serialize(obj: typing.Any) -> BitBuffer:
+def serialize(obj: typing.Any, *, call_initialize_offsets = True) -> BitBuffer:
     """
     Serializes generated object to the bit buffer.
 
@@ -28,13 +28,12 @@ def serialize(obj: typing.Any) -> BitBuffer:
         bitbuffer = zserio.serialize(obj)
 
     :param obj: Generated object to serialize.
+    :param call_initialize_offsets: True to call initialize_offsets() method on generated object.
     :returns: Bit buffer which represents generated object in binary format.
     :raises PythonRuntimeException: Throws in case of any error during serialization.
     """
 
-    writer = BitStreamWriter()
-    obj.initialize_offsets(writer.bitposition)
-    obj.write(writer)
+    writer = _serialize(obj, call_initialize_offsets)
 
     return BitBuffer(writer.byte_array, writer.bitposition)
 
@@ -62,7 +61,7 @@ def deserialize(obj_class: typing.Type[typing.Any], bitbuffer: BitBuffer, *args)
 
     return obj_class.from_reader(reader, *args)
 
-def serialize_to_bytes(obj: typing.Any) -> bytes:
+def serialize_to_bytes(obj: typing.Any, *, call_initialize_offsets = True) -> bytes:
     """
     Serializes generated object to the byte buffer.
 
@@ -84,11 +83,12 @@ def serialize_to_bytes(obj: typing.Any) -> bytes:
         buffer = zserio.serialize_to_bytes(obj)
 
     :param obj: Generated object to serialize.
+    :param call_initialize_offsets: True to call initialize_offsets() method on generated object.
     :returns: Bytes which represents generated object in binary format.
     :raises PythonRuntimeException: Throws in case of any error during serialization.
     """
 
-    bitbuffer = serialize(obj)
+    bitbuffer = serialize(obj, call_initialize_offsets = call_initialize_offsets)
 
     return bitbuffer.buffer
 
@@ -120,7 +120,7 @@ def deserialize_bytes(obj_class: typing.Type[typing.Any], buffer: bytes, *args)
 
     return deserialize(obj_class, bitbuffer, *args)
 
-def serialize_to_file(obj: typing.Any, filename: str) -> None:
+def serialize_to_file(obj: typing.Any, filename: str, *, call_initialize_offsets = True) -> None:
     """
     Serializes generated object to the file.
 
@@ -138,13 +138,12 @@ def serialize_to_file(obj: typing.Any, filename: str) -> None:
         buffer = zserio.serialize_to_file(obj, "file_name.bin")
 
     :param obj: Generated object to serialize.
+    :param call_initialize_offsets: True to call initialize_offsets() method on generated object.
     :param filename: File to write.
     :raises PythonRuntimeException: Throws in case of any error during serialization.
     """
 
-    writer = BitStreamWriter()
-    obj.initialize_offsets(writer.bitposition)
-    obj.write(writer)
+    writer = _serialize(obj, call_initialize_offsets)
     writer.to_file(filename)
 
 def deserialize_from_file(obj_class: typing.Type[typing.Any], filename: str, *args) -> typing.Any:
@@ -171,3 +170,11 @@ def deserialize_from_file(obj_class: typing.Type[typing.Any], filename: str, *ar
     reader = BitStreamReader.from_file(filename)
 
     return obj_class.from_reader(reader, *args)
+
+def _serialize(obj: typing.Any, call_initialize_offsets: bool) -> BitStreamWriter:
+    writer = BitStreamWriter()
+    if call_initialize_offsets:
+        obj.initialize_offsets(writer.bitposition)
+    obj.write(writer)
+
+    return writer

compiler/extensions/python/runtime/tests/test_serialization.py

@@ -21,6 +21,9 @@ def from_reader(cls, reader, parameter):
     def get_value(self):
         return self._value
 
+    def offsets_initalized(self):
+        return self._offsets_initialized
+
     @staticmethod
     def bitsizeof(_bitposition = 0):
         return 31 # to make an unaligned type
@@ -33,19 +36,23 @@ def read(self, reader):
         self._value = reader.read_bits(self.bitsizeof(0))
 
     def write(self, writer):
-        # don't write anything if offsets are not initialized to force test failure
-        if self._offsets_initialized:
-            writer.write_bits(self._value, self.bitsizeof(0))
+        writer.write_bits(self._value, self.bitsizeof(0))
 
 class SerializationTest(unittest.TestCase):
 
     def test_serialize(self):
         dummy_object = DummyObject(0xAB, 0xDEAD)
         bitbuffer = serialize(dummy_object)
+        self.assertTrue(dummy_object.offsets_initalized())
         expected_bitsize = 31
         self.assertEqual(expected_bitsize, bitbuffer.bitsize)
         self.assertEqual(b'\x00\x01\xBD\x5A', bitbuffer.buffer)
 
+    def test_serialize_skip_offsets(self):
+        dummy_object = DummyObject(0xAB, 0xDEAD)
+        serialize(dummy_object, call_initialize_offsets = False)
+        self.assertFalse(dummy_object.offsets_initalized())
+
     def test_deserialize(self):
         bitbuffer = BitBuffer(b'\x00\x01\xBD\x5A', 31)
         dummy_object = deserialize(DummyObject, bitbuffer, 0xAB)
@@ -58,10 +65,16 @@ def test_deserialize(self):
     def test_serialize_to_bytes(self):
         dummy_object = DummyObject(0xAB, 0xDEAD)
         buffer = serialize_to_bytes(dummy_object)
+        self.assertTrue(dummy_object.offsets_initalized())
         expected_bitsize = 31
         self.assertEqual((expected_bitsize + 7) // 8, len(buffer))
         self.assertEqual(b'\x00\x01\xBD\x5A', buffer)
 
+    def test_serialize_to_bytes_skip_offsets(self):
+        dummy_object = DummyObject(0xAB, 0xDEAD)
+        serialize_to_bytes(dummy_object, call_initialize_offsets = False)
+        self.assertFalse(dummy_object.offsets_initalized())
+
     def test_deserialize_bytes(self):
         buffer = b'\x00\x01\xBD\x5A'
         dummy_object = deserialize_bytes(DummyObject, buffer, 0xAB)
@@ -71,5 +84,12 @@ def test_to_file_from_file(self):
         dummy_object = DummyObject(0xAB, 0xDEAD)
         filename = "SerializationTest.bin"
         serialize_to_file(dummy_object, filename)
+        self.assertTrue(dummy_object.offsets_initalized())
         read_dummy_object = deserialize_from_file(DummyObject, filename, 0xAB)
         self.assertEqual(dummy_object.get_value(), read_dummy_object.get_value())
+
+    def test_to_file_from_file_skip_offsets(self):
+        dummy_object = DummyObject(0xAB, 0xDEAD)
+        filename = "SerializationTest.bin"
+        serialize_to_file(dummy_object, filename, call_initialize_offsets = False)
+        self.assertFalse(dummy_object.offsets_initalized())