pulsar/functions/serde.py

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# -*- encoding: utf-8 -*-

# Licensed to the Apache Software Foundation (ASF) under one
# or more contributor license agreements.  See the NOTICE file
# distributed with this work for additional information
# regarding copyright ownership.  The ASF licenses this file
# to you under the Apache License, Version 2.0 (the
# "License"); you may not use this file except in compliance
# with the License.  You may obtain a copy of the License at
#
#   http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
# KIND, either express or implied.  See the License for the
# specific language governing permissions and limitations
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#
"""
SerDe defines the interface for serialization/deserialization.

Every time a message is read from pulsar topic, the serde is invoked to
serialize the bytes into an object before invoking the process method.
Anytime a python object needs to be written back to pulsar, it is
serialized into bytes before writing.
"""
import pickle
from abc import abstractmethod


class SerDe(object):
    """Interface for Serialization/Deserialization"""

    @abstractmethod
    def serialize(self, input):
        """Serialize input message into bytes"""
        pass

    @abstractmethod
    def deserialize(self, input_bytes):
        """Serialize input_bytes into an object"""
        pass


class PickleSerDe(SerDe):
    """Pickle based serializer"""

    def serialize(self, input):
        return pickle.dumps(input)

    def deserialize(self, input_bytes):
        return pickle.loads(input_bytes)


class IdentitySerDe(SerDe):
    """Simple Serde that just conversion to string and back"""

    def __init__(self):
        self._types = [int, float, complex, str]

    def serialize(self, input):
        if type(input) in self._types:
            return str(input).encode('utf-8')
        if type(input) == bytes:
            return input
        raise TypeError("IdentitySerde cannot serialize object of type %s" % type(input))

    def deserialize(self, input_bytes):
        for typ in self._types:
            try:
                return typ(input_bytes.decode('utf-8'))
            except:
                pass
        return input_bytes