hother-cancelable 0.5.0

A comprehensive async cancellation system for Python streams

Cancelable

A comprehensive, production-ready async cancellation system for Python 3.12+ using anyio.

Table of Contents

• Features
• Installation
• Quick Start
• Integrations
• Documentation
• Development
• Contributing
• License

Features

• Multiple Cancellation Sources: Timeout, manual tokens, OS signals, and custom conditions
• Composable Design: Combine multiple cancellation sources easily
• Stream Processing: Built-in support for cancelable async iterators
• Operation Tracking: Full lifecycle tracking with status and progress reporting
• Library Integrations: Ready-to-use FastAPI integration for request cancellation
• Type Safe: Full type hints and runtime validation with Pydantic
• Production Ready: Comprehensive error handling, logging, and performance optimized

Installation

Core Installation

The core library includes only essential dependencies (anyio and pydantic):

uv add hother-cancelable

Optional Extras

Cancelable provides optional extras for various integrations and use cases:

Available Extras

Extra	Dependencies	Purpose
fastapi	fastapi	FastAPI middleware for request cancellation
examples	google-genai, pynput, psutil	Run example scripts and demonstrations

Installing with Extras

FastAPI integration:

uv add "hother-cancelable[fastapi]"

Examples:

uv add "hother-cancelable[examples]"

All extras:

uv add "hother-cancelable[fastapi,examples]"

Quick Start

Basic Usage

from hother.cancelable import Cancelable

# Timeout-based cancellation
async with Cancelable.with_timeout(30.0) as cancel:
    result = await long_running_operation()

# Manual cancellation with token
from hother.cancelable import CancellationToken

token = CancellationToken()

async with Cancelable.with_token(token) as cancel:
    # In another task/thread: await token.cancel()
    result = await interruptible_operation()

Stream Processing

# Cancelable stream processing
async with Cancelable.with_timeout(60.0) as cancel:
    async for item in cancel.stream(data_source(), report_interval=100):
        await process_item(item)

Function Decorators

from hother.cancelable import cancelable

@cancelable(timeout=30.0, register_globally=True)
async def process_data(data: list, cancelable: Cancelable = None):
    for i, item in enumerate(data):
        await cancelable.report_progress(f"Processing item {i+1}/{len(data)}")
        await process_item(item)

Integrations

Cancelable provides seamless integration with FastAPI. See the integrations documentation for detailed guides and examples.

• FastAPI: Add cancellation middleware to FastAPI applications with automatic request-scoped cancellation

Documentation

To build and serve the documentation locally:

1. Install the documentation dependencies:

uv sync --group doc
source .venv/bin/activate

2. Serve the documentation:

mkdocs serve

Development

Dependency Groups

Cancelable uses dependency groups for development and documentation:

Group	Purpose	Key Dependencies
dev	Development tools	pytest, ruff, basedpyright, twine, git-cliff
doc	Documentation building	mkdocs, mkdocs-material, mike

Installation

Basic development setup:

uv sync --group dev
source .venv/bin/activate
lefthook install

This creates a virtual environment, installs all development dependencies, and installs the library in editable mode. It also sets up Lefthook git hooks.

Full development setup with extras:

Some tests and examples require optional extras. To run the full test suite:

# Install dev tools + all extras
uv sync --group dev --all-extras

Selective installation:

# Install with specific extras
uv sync --group dev --extra fastapi --extra examples

# Install documentation tools
uv sync --group doc

Quick Reference

Available extras:

• fastapi - FastAPI middleware
• examples - Example scripts

Available groups:

• dev - Development tools (pytest, ruff, basedpyright, etc.)
• doc - Documentation tools (mkdocs, mkdocs-material, etc.)

Git Hooks with Lefthook

This project uses Lefthook for managing git hooks. Hooks are automatically installed when you run make install-dev.

To run hooks manually:

# Run all pre-commit hooks
lefthook run pre-commit

Tests

Run core tests (without integration extras):

uv run pytest

Integration tests that require optional dependencies (fastapi) will be automatically skipped if the extras are not installed.

Run all tests including integrations:

# First install all extras
uv sync --all-extras

# Then run tests
uv run pytest

Run specific test categories:

# Run only unit tests
uv run pytest tests/unit

# Run only integration tests (requires extras)
uv run pytest tests/integration

Coverage

uv run pytest --cov=hother.cancelable

Building the package

uv build

Release process

This project uses Git tags for versioning with automatic semantic versioning based on conventional commits. Version numbers are automatically derived from Git tags using hatch-vcs.

Quick Release Commands

# Check current version
hatch version

# Create development release (v1.0.0 → v1.0.1-dev1)
hatch release dev

# Create release candidate (v1.0.1-dev1 → v1.0.1rc1)
hatch release rc

# Create final release (v1.0.1rc1 → v1.0.1)
hatch release final

Release from Specific Commit

You can optionally specify a commit SHA to create a release from:

# Release from a specific commit
hatch release dev abc123
hatch release rc def456
hatch release final 789xyz

The SHA must be:

• Reachable from HEAD (on current branch history)
• Not already included in a previous release

How it Works

• Development releases (dev): Increments patch version and adds -dev suffix
• Release candidates (rc): Removes -dev and adds rc suffix
• Final releases (final): Uses git-cliff to analyze commits and automatically bumps major/minor/patch based on conventional commits

The release process:

1. Analyzes commit history (for final releases)
2. Calculates the next version number
3. Creates and pushes the git tag
4. GitHub Actions automatically builds and publishes the release

Manual Tagging (Advanced)

If needed, you can still create tags manually:

# Manual tag creation
git tag -a v1.2.3 -m "Release v1.2.3"
git push origin v1.2.3

Changelog Management

This project uses git-cliff to automatically generate changelogs from conventional commits.

# Generate/update CHANGELOG.md
make changelog

# Preview unreleased changes
make changelog-unreleased

# Get changelog for latest tag (used in releases)
make changelog-tag

The changelog is automatically updated and included in GitHub releases when you push a version tag.

Generate the licenses:

uv run pip-licenses --from=mixed --order count -f md --output-file licenses.md
uv run pip-licenses --from=mixed --order count -f csv --output-file licenses.csv

Build the new documentation:

uv run mike deploy --push --update-aliases <version> latest
uv run mike set-default latest
uv run mike list

Checking the documentation locally

uv run mike serve

Development practices

Branching & Pull-Requests

Each git branch should have the format <tag>/item_<id> with eventually a descriptive suffix.

We us a Squash & Merge approach.

Conventional Commits

We use Conventional Commits.

Format: <type>(<scope>): <subject>

<scope> is optional

Example

feat: add hat wobble
^--^  ^------------^
|     |
|     +-> Summary in present tense.
|
+-------> Type: chore, docs, feat, fix, refactor, style, or test.

More Examples:

• feat: (new feature for the user, not a new feature for build script)
• fix: (bug fix for the user, not a fix to a build script)
• docs: (changes to the documentation)
• style: (formatting, missing semi colons, etc; no production code change)
• refactor: (refactoring production code, eg. renaming a variable)
• test: (adding missing tests, refactoring tests; no production code change)
• chore: (updating grunt tasks etc; no production code change)
• build: (changes in the build system)
• ci: (changes in the CI/CD and deployment pipelines)
• perf: (significant performance improvement)
• revert: (revert a previous change)

Contributing

We welcome contributions! Please see our Contributing Guide for details on how to get started.

License

This project is licensed under the MIT License - see the LICENSE file for details.