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https://github.com/appnexus/pyrobuf

A Cython alternative to Google's Python Protobuf library
https://github.com/appnexus/pyrobuf

Last synced: 13 days ago
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A Cython alternative to Google's Python Protobuf library

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README 

        
# Pyrobuf Library



### Introduction



Pyrobuf is an alternative to Google's Python Protobuf library.



It generates lightning-fast Cython code that's 2-4x faster than Google's Python

Protobuf library using their C++ backend and 20-40x faster than Google's pure-python

implementation.



What's more, Pyrobuf is self-contained and easy to install.



### Requirements



Pyrobuf requires Cython, and Jinja2. If you want to contribute to pyrobuf you

may also want to install pytest.



Pyrobuf *does not* require protoc.



Pyrobuf has been tested with Python 2.7 and Python 3.5.



Pyrobuf appears to be working on OSX, Linux and Windows (for the latter getting

Cython to work properly is the trickiest bit especially if you are still using

2.7).



### Contributing



People use protobuf in many different ways. Pyrobuf handles the use cases of

AppNexus and other contributors, but is not yet a 100% drop-in replacement to

what protoc would generate.



You can help make it so!



Fork and clone the repository, then run:



    $ python setup.py develop



It will generate the platform specific `pyrobuf_list` then compile

the `pyrobuf_list` and `pyrobuf_util` modules.



### Unit Testing



You can run the test suite (a work in progress) using py.test directly:



    $ py.test



Or using the `test` command (which installs pytest if not already available):



    $ python setup.py test



Either method will automatically build all the protobuf message specs in

`tests/proto` and point the `PYTHONPATH` to the built messages before running

the tests.



Re-running the `develop` or `test` commands will automatically re-build the

`pyrobuf_list` and `pyrobuf_util` modules if necessary.



The `clean` command does the house keeping for you:



    $ python setup.py clean



If you find that pyrobuf does not work for one of your proto files, add a minimal

proto file to `tests/proto` that breaks before submitting a pull request.



Pull requests including a breaking test are gold!



Improving testing is in the cards.



### Installation



You may very well be able to just use pyrobuf as is... just pip it!



    $ pip install pyrobuf



Should do the trick!



To check, you may want to make sure the following command does not raise an

exception:



    $ python -c "import pyrobuf_list"



If it does raise an exception try:



    $ pip install pyrobuf -v -v -v --upgrade --force --no-cache



### Compiling



When you `pip install pyrobuf` you get the pyrobuf CLI tool ...:



    $ pyrobuf --help

    usage: pyrobuf [-h] [--out-dir OUT_DIR] [--build-dir BUILD_DIR] [--install] source



    a Cython based protobuf compiler



    positional arguments:

      source                filename.proto or directory containing proto files



    optional arguments:

      -h, --help            show this help message and exit

      --out-dir OUT_DIR     cythonize output directory [default: out]

      --build-dir BUILD_DIR

                            C compiler build directory [default: build]

      --install             install the extension [default: False]

      --package             the name of the package to install to



If you do not want to have to deal with setuptools entry\_points idiosyncrasies

you can also do:



    $ python -m pyrobuf --help



### Use



Suppose you have installed `test_message.proto` which contains a spec for the

message `Test`. In Python, you can import your new message class by running:



    from test_message_proto import Test



With the message class imported, we can create a new message:



    test = Test()



Now that we have instantiated a message `test`, we can fill individual fields:



    >>> test.field = 5

    >>> test.req_field = 2

    >>> test.string_field = "hello!"

    >>> test.list_fieldx.append(12)

    >>> test.test_ref.field2 = 3.14



And access those same fields:



    >>> test.string_field

    'hello!'



Once we have at least filled out any "required" fields, we can serialize to a

byte array:



    bytearray(b'\x10\x05\x1a\x06hello! \x0c2\t\x19\x1f\x85\xebQ\xb8\x1e\t@P\x02')



We can also deserialize a protobuf message to our message instance:



    >>> test.ParseFromString('\x10\x05\x1a\x06hello! \x0c2\t\x19\x1f\x85\xebQ\xb8\x1e\t@P\x02')

    25



Note that the `ParseFromString` method returns the number of bytes consumed.



In addition to serializing and deserializing to and from protobuf messages,

Pyrobuf also allows us to serialize and deserialize to and from JSON and native

Python dictionaries:



    >>> test.SerializeToJson()

    '{"field": 5, "req_field": 2, "list_fieldx": [12], "string_field": "hello!", "test_ref": {"field2": 3.14}}'



    >>> test.ParseFromJson('{"field": 5, "req_field": 2, "list_fieldx": [12], "string_field": "hello!", "test_ref": {"field2": 3.14}}')



    >>> test.SerializeToDict()

    {'field': 5,

     'list_fieldx': [12],

     'req_field': 2,

     'string_field': 'hello!',

     'test_ref': {'field2': 3.14}}



Finally, the `pyrobuf_util` module contains functions for encoding and decoding integers.



    >>> import pyrobuf_util

    >>> pyrobuf_util.to_varint(2**16-1)

    bytearray(b'\xff\xff\x03')

    >>> pyrobuf_util.from_varint(b'\xff\xff\x03', offset=0)

    (65535L, 3)

    >>> pyrobuf_util.to_signed_varint(-2**16)

    bytearray(b'\xff\xff\x07')

    >>> pyrobuf_util.from_signed_varint(b'\xff\xff\x07', offset=0)

    (-65536L, 3)



The `from_varint` and `from_signed_varint` functions return both the decoded integer and

the offset of the first byte after the encoded integer in the source data.



### Packaging



If you are compiling multiple messages or a directory of messages and don't want them

all to be built to their own separate package but instead want a single namespace

containing all your messages, you can specify a package name:



    pyrobuf /path/to/proto/specs --install --package=my_messages



Then you can import your message classes from the `my_messages` pakcage:



    >>> from my_messages import MyMessage1, MyMessage2



### Distributing a Python Package with Pyrobuf Modules



Suppose you have a Python package called 'sample' arranged on disk as follows:



    sample/

        proto/

            my_message.proto

        sample/

            __init__.py

        setup.py



Pyrobuf adds a new setup keyword `pyrobuf_modules` which can be used to specify either

individual protobuf files or folders containing protobuf files. For example, the `setup.py`

file could look like this:



from setuptools import setup, find_packages



    setup(

        name="sample",

        version="0.1",

        packages=find_packages(),

        description="A sample package",

        install_requires=['pyrobuf'],

        setup_requires=['pyrobuf'],

        pyrobuf_modules="proto"

    )



In addition to the package "sample", setuptools will also build a package named

"sample\_proto" which will contain the compiled Protobuf messages.



Once installed this sample package can be used as follows:



    >>> from sample_proto import MyMessage

    >>> my_message = MyMessage()



### Performance



On my development machine (Ubuntu 14.04), Pyrobuf is roughly 2.0x as fast as

Google's library for message serialization and 2.3x as fast for message

deserialization when using the C++ backend for Google's library:



    > python tests/perf_test.py

    Google took 1.649168 seconds to serialize

    Pyrobuf took 0.825525 seconds to serialize

    Google took 1.113041 seconds to deserialize

    Pyrobuf took 0.466113 seconds to deserialize



When not using the C++ backend, Pyrobuf is roughly 25x as fast for serialization

and 55x as fast for deserialization:



    Google took 20.215662 seconds to serialize

    Pyrobuf took 0.819555 seconds to serialize

    Google took 24.990137 seconds to deserialize

    Pyrobuf took 0.455732 seconds to deserialize



### Differences from the Google library



If pyrobuf is missing a feature from protoc that you need, let us know! We are

trying to make it as easy as possible for you to help make pyrobuf better.



For the most part, Pyrobuf should be a drag-and-drop replacement for the Google

protobuf library. There are a few differences, though. First, Pyrobuf does not

currently implement the `ListFields`, `WhichOneOf`, `HasExtension`,

`ClearExtension` and `ByteSize` methods.



Second, Pyrobuf simply assumes that the schema being used for a given message

is the same on the send and receive ends, so changing the type of a field on

one end without changing it on the other may cause bugs; adding or removing

fields will not break anything.