Skip to main content

A python implementation of the three Reader-Writer problems.

Project description

Reader Writer Lock

A python implementation of the three Reader-Writer problems.

repo status Active Build Status Coverage Status BugTracker

Python Version Pypi Version

Code size in bytes License

Downloads Downloads Downloads pyReaderWriterLock_repo_star

Not only does it implement the reader-writer problems, it is also compliant with the python lock interface which among others include support for timeout.

For reading about the theory behind the reader-writer problems refer to Wikipedia.

Installation

Install the python package readerwriterlock

python3 -m pip install -U readerwriterlock

Usage

  1. Choose a rwlock class base on your access priority need and feature need which is going to be use by the threads:
Priority +Speed +Downgradable*
Reader priority (aka First readers-writers problem) RWLockRead RWLockReadD
Writer priority (aka Second readers-writers problem) RWLockWrite RWLockWriteD
Fair priority (aka Third readers-writers problem) RWLockFair RWLockFairD

* Downgradable feature allows the locks to be atomically downgraded from being locked in write-mode to locked in read-mode

ⓘ Downgradable classes come with a theoretical ~20% negative effect on performance for acquiring and releasing locks.

  1. Instantiate an instance of the chosen RWLock class:
from readerwriterlock import rwlock
a = rwlock.RWLockFairD()
  1. Generate read locks and write locks using the following methods:
      a_reader_lock = a.gen_rlock()

      a_writer_lock = a.gen_wlock()
  1. Use the generated read/write locks to protect section in your code:

Pythonic usage example

with a.gen_rlock():
  #Read stuff

with a.gen_wlock():
  #Write stuff

Use case (Timeout) example

b = a.gen_wlock()
if b.acquire(blocking=True, timeout=5):
  try:
    #Do stuff
  finally:
    b.release()

Use case (Downgrade) example

b = a.gen_wlock()
if b.acquire():
    try:
        #Read/Write stuff
        b = b.downgrade()
        #Read stuff
    finally:
        b.release()

Live example

Refer to the file test_rwlock.py which has above 90% line coverage of rwlock.py.

The tests can be initiated by doing

make check.test.coverage

Contact

Project details


Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Files for readerwriterlock, version 1.0.7
Filename, size File type Python version Upload date Hashes
Filename, size readerwriterlock-1.0.7-py3-none-any.whl (7.2 kB) File type Wheel Python version py3 Upload date Hashes View
Filename, size readerwriterlock-1.0.7.tar.gz (14.0 kB) File type Source Python version None Upload date Hashes View

Supported by

Pingdom Pingdom Monitoring Google Google Object Storage and Download Analytics Sentry Sentry Error logging AWS AWS Cloud computing DataDog DataDog Monitoring Fastly Fastly CDN DigiCert DigiCert EV certificate StatusPage StatusPage Status page