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Welcome to libmc

libmc is a fast and lightweight memcached client library for C++/Python/Golang without any other dependencies in runtime. The internal part is written in C++, and the Python wrapper and Golang wrapper are written mainly in Cython and cgo.

The python version of libmc can be considered as a drop in replacement for libmemcached and python-libmemcached.

Update: Golang version of libmc is now in beta, checkout golibmc.

Features

• Server aliases support
• Memory efficient
• TCP I/O multiplexing
• Lazy-connecting

Overview

Internal classes:

               Client
                  | (1:1)
            ConnectionPool
                  | (1:N)
              Connection
           /      | (1:1)   \
BufferReader   Parser   BufferWriter
      | (1:N)
  DataBlock

• Client: top-level API for libmc
• ConnectionPool:
  1. dispatching different keys to different connections according to key route(Consistent hashing)
  2. multiplexing on top of TCP connections
  3. collecting and merging results from TCP connections
• Connection: wrapper for TCP connection to each memcached server. Each Connection has one Parser, one BufferReader, and one BufferWriter.
• BufferReader: buffer helper for receving buffer from memcached server
• BufferWritter: buffer helper for sending buffer to memcached server
• DataBlock: wrapper for each continuous memory space

Internal Details

Dynamic memory allocation and memory-copy are slow, so we tried our best to avoid them.

• Memory Efficiency
  • Pre-allocation in BufferReader
  • Use sendmsg instead of send
  • SmallVector for retrieval results
• Use itoa from rapidjson
• Security concern

Developments

• Memory check
• Profiling
• Benchmark

ALSO SEE

Slide: Reinventing the wheel: libmc