protolite 0.1.0

("Lightweight implementation of Google's Protocol Buffers in Python",)

Lightweight implementation of Google’s Protocol Buffers in Python.

In benchmarks, the protolite encoder ran twice as fast as Google’s. Using Python’s timeit module, the same data for both APIs was encoded and decoded 10000 times. The lowest time of three attempts was picked for each:

protobuf:  3.6064529418945312 seconds
protolite: 1.7224960327148438 seconds

If we take the ratio of these two times we see that protolite was about two times faster than its counterpart.

Similarly, using Pypy we get about twice the speed:

protobuf:  0.807873010635376 seconds
protolite: 0.4414529800415039 seconds

The benchmark directory in the github repository contains the files needed to re-run the tests . In addition, you will need the protobuf Python library. Try it on your platform, but, keep your machine as quite as possible so as to not skew the results:

PYTHONPATH=$PYTHONPATH:$(pwd) python benchmark/benchmark.py

Pass the –pypy flag if you want to use Pypy in order to warm up the Pypy JIT compiler and get a more accurate result:

PYTHONPATH=$PYTHONPATH:$(pwd) pypy benchmark/benchmark.py --pypy

You can also make changes to the benchmark/messages.proto file to create your own tests. You’ll need to re-compile the messages.py and messages_pb2.py files in the benchmark directory afterwards by running the make command inside the same directory. Of course, you will need protoc to compile Google’s version.

description

Protocol Buffers (protobuf) is a data interchange format created by Google. protolite is a rewrite of its encoder and file generator specifically created and optimized for Python. The encoder is optimized for speed taking the language’s properties in mind. The generator aims to provide ease-of-use and compatibility with the language. For example, messages are implemented using only dicts. Familiarity with protobuf is required in order to use protolite effectively.

installation

You can download and install protolite from pypi with pip:

pip install python-protolite

Alternatively, you can clone the repository containing the source code from github and install protolite via setuptools:

git clone https://github.com/thelinuxkid/python-protolite.git
cd python-protolite
python setup.py install

usage

generating files

protolite comes with a utility that generates Python files structured for efficiency and readbility. After the installation you will have an executable file called python-protolitec. Its most simple usage takes two positional arguments. The first is a list of the protobuf definition files and the second a directory where to write the Python version of those files:

python-protolitec proto/*.proto python

The output files will retain the same file name as the source; only the extension will be changed. For example, the file proto/messages.proto will produce the file python/messages.py. You can use the --help flag to view the other options offered by python-protolitec.

encoding

Let’s say you have a protobuf file called messages.proto containing:

message User {
    optional uint32 userID = 1;
    enum UserType {
        STANDARD = 0;
        ADMIN = 1;
    }
    optional UserType type = 2;
}

python-protolite will create a Python module messages with a user object which has a decode and an encode method. To encode a message you would do something like:

import messages

msg_enc = {'user_id': 123, 'type': messages.user_type.STANDARD}
data = messages.user.encode(msg_enc)

As you can see, python-protolite changes camel-case variable names to underscore. On the other end, to decode the message you would do something similar:

import messages

msg_dec = messages.user.decode(data)

The variable msg_dec will be equal to msg_enc.

printing

The message objects also contain a pretty print method. Calling message.user.pprint(msg_enc) would produce:

{
    "type": "STANDARD",
    "user_id": 123
}

You can pass the keyword argument stream to pprint to write to a stream different than sys.stdout.

parser

If you download the source code from github you will see a grammar directory at the root level. This directory contains all the files used to create the parser and lexer in protolite.parser, the module used by python-protolitec to parse the protobuf definition files. If you are familiar with Antlr you can edit the proto_lexer.g and proto_parser.g files in this directory to create a new Python parser and/or lexer using the Antlr jar in the same directory:

cd grammar
java -jar antlr-3.1.3.jar -fo . proto_lexer.g
java -jar antlr-3.1.3.jar -fo . proto_parser.g

This will create four files: proto_lexer.py, proto_lexer.tokens, proto_parser.py and proto_parser.tokens. You can leave the *.tokens files where they are but move the *.py files to protolite/parser to use your new parser with python-protolitec. If you want to use a different version of Antlr do so at your own risk. You will likely need the new Antlr version to match the Python runtime version in setup.py.