MessagePack for Python 使用教程

MessagePack for Python 使用教程

msgpack-python MessagePack serializer implementation for Python msgpack.org[Python] msgpack-python 项目地址: https://gitcode.com/gh_mirrors/ms/msgpack-python

1. 项目介绍

MessagePack 是一种高效的二进制序列化格式,类似于 JSON,但它更快且更小。MessagePack for Python 是 MessagePack 的 Python 实现,提供了 CPython 绑定,用于读取和写入 MessagePack 数据。

该项目的主要特点包括:

  • 高效性:比 JSON 更快,数据更小。
  • 多语言支持:可以在多种编程语言之间交换数据。
  • 灵活性:支持自定义数据类型的序列化和反序列化。

2. 项目快速启动

安装

首先,使用 pip 安装 msgpack-python

pip install msgpack

基本使用

以下是一个简单的示例,展示如何使用 msgpack 进行数据的打包和解包:

import msgpack

# 打包数据
data = [1, 2, 3]
packed_data = msgpack.packb(data)
print(f"Packed data: {packed_data}")

# 解包数据
unpacked_data = msgpack.unpackb(packed_data)
print(f"Unpacked data: {unpacked_data}")

流式解包

msgpack 还支持流式解包,适用于处理大量数据:

import msgpack
from io import BytesIO

buf = BytesIO()
for i in range(100):
    buf.write(msgpack.packb(i))

buf.seek(0)
unpacker = msgpack.Unpacker(buf)
for unpacked in unpacker:
    print(unpacked)

3. 应用案例和最佳实践

应用案例

  1. 网络通信:在网络通信中,使用 MessagePack 可以显著减少数据传输的大小,提高通信效率。
  2. 日志记录:在日志记录中,使用 MessagePack 可以减少日志文件的大小,便于存储和传输。
  3. 缓存系统:在缓存系统中,使用 MessagePack 可以提高数据的读写速度。

最佳实践

  1. 自定义数据类型:通过 defaultobject_hook 参数,可以实现自定义数据类型的序列化和反序列化。
  2. 性能优化:在处理大量数据时,可以使用 use_list=False 来提高解包性能。
  3. 安全性:在处理不可信数据时,使用 max_buffer_sizestrict_map_key 参数来提高安全性。

4. 典型生态项目

  1. Redis:Redis 是一个高性能的键值存储系统,支持多种数据类型的存储和操作。MessagePack 可以作为 Redis 的序列化格式,提高数据存储和传输的效率。
  2. Kafka:Kafka 是一个分布式流处理平台,支持高吞吐量的数据流处理。MessagePack 可以作为 Kafka 的消息序列化格式,提高数据传输的效率。
  3. Elasticsearch:Elasticsearch 是一个分布式搜索和分析引擎,支持海量数据的存储和查询。MessagePack 可以作为 Elasticsearch 的数据序列化格式,提高数据存储和查询的效率。

通过以上内容,您可以快速上手并深入了解 MessagePack for Python 的使用和应用场景。

msgpack-python MessagePack serializer implementation for Python msgpack.org[Python] msgpack-python 项目地址: https://gitcode.com/gh_mirrors/ms/msgpack-python

创作声明:本文部分内容由AI辅助生成(AIGC),仅供参考

======================= MessagePack for Python ======================= :author: INADA Naoki :version: 0.4.1 :date: 2014-02-17 .. image:: https://secure.travis-ci.org/msgpack/msgpack-python.png :target: https://travis-ci.org/#!/msgpack/msgpack-python What's this ------------ `MessagePack <http://msgpack.org/>`_ is a fast, compact binary serialization format, suitable for similar data to JSON. This package provides CPython bindings for reading and writing MessagePack data. Install --------- You can use ``pip`` or ``easy_install`` to install msgpack:: $ easy_install msgpack-python or $ pip install msgpack-python PyPy ^^^^^ msgpack-python provides pure python implementation. PyPy can use this. Windows ^^^^^^^ When you can't use binary distribution, you need to install Visual Studio or Windows SDK on Windows. (NOTE: Visual C++ Express 2010 doesn't support amd64. Windows SDK is recommanded way to build amd64 msgpack without any fee.) Without extension, using pure python implementation on CPython runs slowly. Notes ----- Note for msgpack 2.0 support ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ msgpack 2.0 adds two types: *bin* and *ext*. *raw* was bytes or string type like Python 2's ``str``. To distinguish string and bytes, msgpack 2.0 adds *bin*. It is non-string binary like Python 3's ``bytes``. To use *bin* type for packing ``bytes``, pass ``use_bin_type=True`` to packer argument. >>> import msgpack >>> packed = msgpack.packb([b'spam', u'egg'], use_bin_type=True) >>> msgpack.unpackb(packed, encoding='utf-8') ['spam', u'egg'] You shoud use it carefully. When you use ``use_bin_type=True``, packed binary can be unpacked by unpackers supporting msgpack-2.0. To use *ext* type, pass ``msgpack.ExtType`` object to packer. >>> import msgpack >>> packed = msgpack.packb(msgpack.ExtType(42, b'xyzzy')) >>> msgpack.unpackb(packed) ExtType(code=42, data='xyzzy') You can use it with ``default`` and ``ext_hook``. See below. Note for msgpack 0.2.x users ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ The msgpack 0.3 have some incompatible changes. The default value of ``use_list`` keyword argument is ``True`` from 0.3. You should pass the argument explicitly for backward compatibility. `Unpacker.unpack()` and some unpack methods now raises `OutOfData` instead of `StopIteration`. `StopIteration` is used for iterator protocol only. How to use ----------- One-shot pack & unpack ^^^^^^^^^^^^^^^^^^^^^^ Use ``packb`` for packing and ``unpackb`` for unpacking. msgpack provides ``dumps`` and ``loads`` as alias for compatibility with ``json`` and ``pickle``. ``pack`` and ``dump`` packs to file-like object. ``unpack`` and ``load`` unpacks from file-like object. :: >>> import msgpack >>> msgpack.packb([1, 2, 3]) '\x93\x01\x02\x03' >>> msgpack.unpackb(_) [1, 2, 3] ``unpack`` unpacks msgpack's array to Python's list, but can unpack to tuple:: >>> msgpack.unpackb(b'\x93\x01\x02\x03', use_list=False) (1, 2, 3) You should always pass the ``use_list`` keyword argument. See performance issues relating to use_list_ below. Read the docstring for other options. Streaming unpacking ^^^^^^^^^^^^^^^^^^^ ``Unpacker`` is a "streaming unpacker". It unpacks multiple objects from one stream (or from bytes provided through its ``feed`` method). :: import msgpack from io import BytesIO buf = BytesIO() for i in range(100): buf.write(msgpack.packb(range(i))) buf.seek(0) unpacker = msgpack.Unpacker(buf) for unpacked in unpacker: print unpacked Packing/unpacking of custom data type ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ It is also possible to pack/unpack custom data types. Here is an example for ``datetime.datetime``. :: import datetime import msgpack useful_dict = { "id": 1, "created": datetime.datetime.now(), } def decode_datetime(obj): if b'__datetime__' in obj: obj = datetime.datetime.strptime(obj["as_str"], "%Y%m%dT%H:%M:%S.%f") return obj def encode_datetime(obj): if isinstance(obj, datetime.datetime): return {'__datetime__': True, 'as_str': obj.strftime("%Y%m%dT%H:%M:%S.%f")} return obj packed_dict = msgpack.packb(useful_dict, default=encode_datetime) this_dict_again = msgpack.unpackb(packed_dict, object_hook=decode_datetime) ``Unpacker``'s ``object_hook`` callback receives a dict; the ``object_pairs_hook`` callback may instead be used to receive a list of key-value pairs. Extended types ^^^^^^^^^^^^^^^ It is also possible to pack/unpack custom data types using the msgpack 2.0 feature. >>> import msgpack >>> import array >>> def default(obj): ... if isinstance(obj, array.array) and obj.typecode == 'd': ... return msgpack.ExtType(42, obj.tostring()) ... raise TypeError("Unknown type: %r" % (obj,)) ... >>> def ext_hook(code, data): ... if code == 42: ... a = array.array('d') ... a.fromstring(data) ... return a ... return ExtType(code, data) ... >>> data = array.array('d', [1.2, 3.4]) >>> packed = msgpack.packb(data, default=default) >>> unpacked = msgpack.unpackb(packed, ext_hook=ext_hook) >>> data == unpacked True Advanced unpacking control ^^^^^^^^^^^^^^^^^^^^^^^^^^ As an alternative to iteration, ``Unpacker`` objects provide ``unpack``, ``skip``, ``read_array_header`` and ``read_map_header`` methods. The former two read an entire message from the stream, respectively deserialising and returning the result, or ignoring it. The latter two methods return the number of elements in the upcoming container, so that each element in an array, or key-value pair in a map, can be unpacked or skipped individually. Each of these methods may optionally write the packed data it reads to a callback function: :: from io import BytesIO def distribute(unpacker, get_worker): nelems = unpacker.read_map_header() for i in range(nelems): # Select a worker for the given key key = unpacker.unpack() worker = get_worker(key) # Send the value as a packed message to worker bytestream = BytesIO() unpacker.skip(bytestream.write) worker.send(bytestream.getvalue()) Note about performance ------------------------ GC ^^ CPython's GC starts when growing allocated object. This means unpacking may cause useless GC. You can use ``gc.disable()`` when unpacking large message. `use_list` option ^^^^^^^^^^^^^^^^^^ List is the default sequence type of Python. But tuple is lighter than list. You can use ``use_list=False`` while unpacking when performance is important. Python's dict can't use list as key and MessagePack allows array for key of mapping. ``use_list=False`` allows unpacking such message. Another way to unpacking such object is using ``object_pairs_hook``. Test ---- MessagePack uses `pytest` for testing. Run test with following command: $ py.test .. vim: filetype=rst
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