Python package for reference counting native pointers

Overview

refcount

license status Documentation Status master: Build status - master testing: Build status - devel

Reference counted native handles

This package is primarily for managing resources in native libraries, written for instance in C++, from Python. While it boils down to "simply" maintaining a set of counters, it is deceptively complicated to do so properly and not end up with memory leaks or crashes. This package offers structured options for reliably managing external native resources. Surprisingly I could not locate an existing package doing just what I needed. Other use cases requiring reference counting, aside from native library resources, may benefit from reusing and extending classes in refcount.

refcount from version 0.7 includes classes using cffi. Other low-level interoperability mechanisms may well be added in the future.

License

MIT (see License.txt)

Documentation

Hosted at pyrefcount.readthedocs.io

Source code

The code repository is on GitHub.

Installation

pip install refcount

From source:

pip install -r requirements.txt
python setup.py install

Sample use

The following example is based on one of the unit tests.

Say we have a C++ library with objects and a C API:

#define TEST_DOG_PTR  testnative::dog*
#define TEST_OWNER_PTR  testnative::owner*
#define TEST_COUNTED_PTR  testnative::reference_counter*

testnative::dog* create_dog();
testnative::owner* create_owner(testnative::dog* d);
void say_walk(testnative::owner* owner);
void release(testnative::reference_counter* obj);
// etc.

From the outside of the library the API is exported with opaque pointers void* (C structs pointers and native C99 types could be handled too).

void* create_dog();
void* create_owner(void* d);
void say_walk(void* owner);
void release(void* obj);
// etc.

Starting with the end in mind, from Python we want an API hiding the low level details close to the C API, in particular avoiding managing native memory via release C API calls, piggybacking the python GC instead.

dog = Dog()
owner = DogOwner(dog)
owner.say_walk()
print(dog.position)
dog = None # the "native dog" is still alive though, as the owner incremented the ref count
owner = None

This is doable with refcount and the cffi package. One possible design is:

ut_ffi = cffi.FFI()

ut_ffi.cdef('extern void* create_dog();')
ut_ffi.cdef('extern void* create_owner( void* d);')
ut_ffi.cdef('extern void say_walk( void* owner);')
ut_ffi.cdef('extern void release( void* obj);')
# etc.

ut_dll = ut_ffi.dlopen('c:/path/to/test_native_library.dll', 1) # Lazy loading

class CustomCffiNativeHandle(CffiNativeHandle):
    def __init__(self, pointer, prior_ref_count = 0):
        super(CustomCffiNativeHandle, self).__init__(pointer, type_id='', prior_ref_count = prior_ref_count)

    def _release_handle(self) -> bool:
        ut_dll.release(self.get_handle())
        return True

class Dog(CustomCffiNativeHandle):
    def __init__(self, pointer = None):
        if pointer is None:
            pointer = ut_dll.create_dog()
        super(Dog, self).__init__(pointer)
    # etc.

class DogOwner(CustomCffiNativeHandle):

    def __init__(self, dog):
        super(DogOwner, self).__init__(None)
        self._set_handle(ut_dll.create_owner(dog.get_handle()))
        self.dog = dog
        self.dog.add_ref() # Do note this important reference increment

    def say_walk(self):
        ut_dll.say_walk(self.get_handle())

    def _release_handle(self) -> bool:
        super(DogOwner, self)._release_handle()
        # super(DogOwner, self)._release_handle()
        self.dog.release()
        return True

Related work

Ancestry, acknowledgements

This python package refcount actually spawned from prior work for interoperability between C++, R and .NET (R.NET)

refcount features using cffi were also significantly informed by Kevin Plastow's work while he was at the Australian Bureau of Meteorology; this contribution is gratefully acknowledged.

In you have native interop needs you may also want to look at:

Other python packages

refcount was created in part because no existing prior (Python) work could quite fit the need. There are however packages that may better address your particular need:

You might also like...
A test repository to build a python package and publish the package to Artifact Registry using GCB

A test repository to build a python package and publish the package to Artifact Registry using GCB. Then have the package be a dependency in a GCF function.

PSP (Python Starter Package) is meant for those who want to start coding in python but are new to the coding scene.

Python Starter Package PSP (Python Starter Package) is meant for those who want to start coding in python, but are new to the coding scene. We include

PyPIContents is an application that generates a Module Index from the Python Package Index (PyPI) and also from various versions of the Python Standard Library.

PyPIContents is an application that generates a Module Index from the Python Package Index (PyPI) and also from various versions of the Python Standar

Example python package with pybind11 cpp extension

Developing C++ extension in Python using pybind11 This is a summary of the commands used in the tutorial.

qecsim is a Python 3 package for simulating quantum error correction using stabilizer codes.

qecsim qecsim is a Python 3 package for simulating quantum error correction using stabilizer codes.

A command-line utility that creates projects from cookiecutters (project templates), e.g. Python package projects, VueJS projects.
A command-line utility that creates projects from cookiecutters (project templates), e.g. Python package projects, VueJS projects.

Cookiecutter A command-line utility that creates projects from cookiecutters (project templates), e.g. creating a Python package project from a Python

A toy repo illustrating a minimal installable Python package

MyToy: a minimal Python package This repository contains a minimal, toy Python package with a few files as illustration for students of how to lay out

Python package that mirrors the original Nodejs ReplAPI-It.

Python-ReplAPI-It Python package that mirrors the original Nodejs ReplAPI-It. Contributing First fork the repo: $ git clone https://github.com/ReplAPI

This project recreates the R-based RCy3 Cytoscape Automation library as a Python package.

Python library for calling Cytoscape Automation via CyREST

Comments
  • Roadmap for reference counting around pybind11

    Roadmap for reference counting around pybind11

    opened by jmp75 1
  • CFFI wrappers helper functions for use in codegen

    CFFI wrappers helper functions for use in codegen

    Basically, need to write the equivalent of wrapping functions in an the R package cinterop. While a cinterop Python package will be warranted, the refcount wrapping/unwrapping helper functions should probably live in refcount.

    enhancement 
    opened by jmp75 1
  • Bump certifi from 2022.6.15 to 2022.12.7

    Bump certifi from 2022.6.15 to 2022.12.7

    Bumps certifi from 2022.6.15 to 2022.12.7.

    Commits

    Dependabot compatibility score

    Dependabot will resolve any conflicts with this PR as long as you don't alter it yourself. You can also trigger a rebase manually by commenting @dependabot rebase.


    Dependabot commands and options

    You can trigger Dependabot actions by commenting on this PR:

    • @dependabot rebase will rebase this PR
    • @dependabot recreate will recreate this PR, overwriting any edits that have been made to it
    • @dependabot merge will merge this PR after your CI passes on it
    • @dependabot squash and merge will squash and merge this PR after your CI passes on it
    • @dependabot cancel merge will cancel a previously requested merge and block automerging
    • @dependabot reopen will reopen this PR if it is closed
    • @dependabot close will close this PR and stop Dependabot recreating it. You can achieve the same result by closing it manually
    • @dependabot ignore this major version will close this PR and stop Dependabot creating any more for this major version (unless you reopen the PR or upgrade to it yourself)
    • @dependabot ignore this minor version will close this PR and stop Dependabot creating any more for this minor version (unless you reopen the PR or upgrade to it yourself)
    • @dependabot ignore this dependency will close this PR and stop Dependabot creating any more for this dependency (unless you reopen the PR or upgrade to it yourself)
    • @dependabot use these labels will set the current labels as the default for future PRs for this repo and language
    • @dependabot use these reviewers will set the current reviewers as the default for future PRs for this repo and language
    • @dependabot use these assignees will set the current assignees as the default for future PRs for this repo and language
    • @dependabot use this milestone will set the current milestone as the default for future PRs for this repo and language

    You can disable automated security fix PRs for this repo from the Security Alerts page.

    dependencies 
    opened by dependabot[bot] 0
Releases(v1.1.0)
  • v1.1.0(Aug 19, 2022)

    Main changes

    • Expand some features to cater for macos
    • Tidy up and reengineer some of the legacy functions in the platform utilities putils to facilitate library loading. Minor breaking changes, but probably for no-one but the author in effect.
    Source code(tar.gz)
    Source code(zip)
  • v1.0.0(Aug 13, 2022)

    Main changes

    • Improve documentation, and use the mkdocs-material theme
    • mkdocs.yml changes. Enable dark/light modes from mkdocs-material
    • Improved type hints, and add static type checks (mypy)
    • Improve unit tests and add unit test code coverage reporting
    • Manage the package using poetry; phase out setuptools.
    • Apply some of the approaches in https://py-pkgs.org.
    • Restore appveyor CI to a working state
    Source code(tar.gz)
    Source code(zip)
  • 0.9.3(Aug 13, 2022)

Owner
CSIRO Hydroinformatics
CSIRO - hydroinformatics repositories
CSIRO Hydroinformatics
Click2call for asterisk with python

Click2call para Asterisk com Python Este projeto disponibiliza uma API construíd

Benedito Marques 1 Jan 17, 2022
A small C compiler written in Python for learning purposes

A small C compiler written in Python. Generates x64 Intel-format assembly, which is then assembled and linked by nasm and ld.

Scattered Thoughts 3 Oct 22, 2021
The official Repository wherein newbies into Open Source can Contribute during the Hacktoberfest 2021

Hacktoberfest 2021 Get Started With your first Contrinution/Pull Request : Fork/Copy the repo by clicking the right most button on top of the page. Go

HacOkars 25 Aug 20, 2022
A simple hash system.

PBH-Hash-System A simple hash system. Usage You could use it like this: from pbh import pbh print(pbh("Hey", True)) Output: 2feae2471698cfcdcbd6b98ca

Karim 3 Mar 24, 2022
Programmatic interface to Synapse services for Python

A Python client for Sage Bionetworks' Synapse, a collaborative, open-source research platform that allows teams to share data, track analyses, and collaborate

Sage Bionetworks 54 Dec 23, 2022
Architecture example simulator

SCADA architecture Example of a SCADA-like console application, used to serve as a minimal example of a standard architecture of an IIoT system. Insta

1 Nov 06, 2021
A simple flashcard app built as a final project for a databases class.

CS2300 Final Project - Flashcard app 'FlashStudy' Tech stack Backend Python (Language) Django (Web framework) SQLite (Database) Frontend HTML/CSS/Java

Christopher Spencer 2 Feb 03, 2022
Код файнтюнинга оригинального CLIP на русский язык

О чем репозиторий В этом репозитории представлен способ файтюнить оригинальный CLIP на новый язык Почему модель не видит женщину и откуда на картинке

Valentina Biryukova 7 Feb 06, 2022
A command line interface tool converting starknet warp transpiled outputs into readable cairo contracts.

warp-to-cairo warp-to-cairo is a simple tool converting starknet warp outputs (NethermindEth/warp) outputs into readable cairo contracts. The warp out

Michael K 5 Jun 10, 2022
A telegram bot which programed to countdown.

countdown-vi this is a telegram bot which programed to countdown. usage well, first you should specify a exact interval. there is 5 column, very first

Arya Shabane 3 Feb 15, 2022
A python API act as Control Center to control your Clevo Laptop via wmi on windows.

ClevoPyControlCenter A python API act as Control Center to control your Clevo Laptop via wmi on windows. Usage # pip3 install pymi from clevo_wmi impo

3 Sep 19, 2022
Compress .dds file in ggpk to boost fps. This is a python rewrite of PoeTexureResizer.

PoeBooster Compress .dds file in ggpk to boost fps. This is a python rewrite of PoeTexureResizer. Setup Install ImageMagick-7.1.0. Download and unzip

3 Sep 30, 2022
Pre-crisis Risk Management for Personal Finance

Антикризисный риск-менеджмент личных финансов Риск-менеджмент личных финансов условиях санкций и/или финансового кризиса: делаем сегодня все, чтобы за

Dmitry Petukhov 593 Jan 09, 2023
A working roblox account generator it doesnt bypass the capcha stuff cuz these didnt showed up in my test runs

A working roblox account generator (state 11.5.2021) it doesnt bypass the capcha stuff cuz these didnt showed up in my test runs

TerrificTable 22 Jan 03, 2023
Python plugin/extra to load data files from an external source (such as AWS S3) to a local directory

Data Loader Plugin - Python Table of Content (ToC) Data Loader Plugin - Python Table of Content (ToC) Overview References Python module Python virtual

Cloud Helpers 2 Jan 10, 2022
Kivy program for identification & rotation sensing of objects on multi-touch tables.

ObjectViz ObjectViz is a multitouch object detection solution, enabling you to create physical markers out of any reliable multitouch solution. It's e

TangibleDisplay 8 Apr 04, 2022
An early stage integration of Hotwire Turbo with Django

Note: This is not ready for production. APIs likely to change dramatically. Please drop by our Slack channel to discuss!

Hotwire for Django 352 Jan 06, 2023
A python package template that can be adapted for RAP projects

Warning - this repository is a snapshot of a repository internal to NHS Digital. This means that links to videos and some URLs may not work. Repositor

NHS Digital 3 Nov 08, 2022
A simple and convenient build-and-run system for C and C++.

smake Smake is a simple and convenient build-and-run system for C and C++ projects. Why make another build system? CMake and GNU Make are great build

Venkataram Edavamadathil Sivaram 18 Nov 13, 2022
This python module allows to extract data from the RAW-file-format produces by devices from Thermo Fisher Scientific.

fisher_py This Python module allows access to Thermo Orbitrap raw mass spectrometer files. Using this library makes it possible to automate the analys

8 Oct 14, 2022