lmdb-simple 0.1.0

LMDB-backed dict-like store

lmdb-simple

Project Overview

This document outlines the implementation and packaging plan for the lmdb-simple Python package, targeting Python 3.9+ and designed to be OS-agnostic. The package will provide a dict-like interface on top of an LMDB disk store, with context-manager support and fork-safe multiprocessing readers (picklable LmdbDict instances).

1. Project Layout

lmdb-simple/
├── LICENSE
├── MANIFEST.in
├── README.md
├── setup.py
└── lmdb_simple/
    ├── __init__.py
    └── core.py

2. Dependencies

• lmdb>=1.0.0 • Python standard library (typing, pathlib, multiprocessing)

3. Core API (lmdb_simple/core.py)

• class LmdbDict[K, V] (implements MutableMapping[K, V] and ContextManager) • __init__(self, path: Union[str, Path], writer: bool = False, **env_kwargs) • Mapping methods: __getitem__, __setitem__, __delitem__, __len__, __iter__ • Views: keys(), values(), items() • Sync/flush: flush() • Close: close() • Context‐manager: __enter__(), __exit__() • Optional transaction(write: bool) context manager for batch writes • Full type hints and docstrings on public methods

5. Packaging (setup.py)

• name="lmdb-simple", version="0.1.0"
• python_requires=">=3.9"
• install_requires=["lmdb>=1.6.2"]
• Read long description from README.md
• Include license, classifiers, and find_packages()
• MANIFEST.in to include README.md and LICENSE

6. Documentation & Examples

• Flesh out README.md (this file) with:
  • Quickstart examples for reader/writer, context managers, and multiprocessing
  • API reference links to docstrings

7. OS‐Agnostic Considerations

• Use pathlib for filesystem paths
• Rely on LMDB’s cross‐platform locking

8. Publishing Workflow

1. Build: python setup.py sdist bdist_wheel
2. Upload: twine upload dist/*
3. Tag & release on GitHub

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With this plan in place, we can now scaffold and implement the package per these outlines.

Quickstart

Install from PyPI:

pip install lmdb-simple

Basic usage:

from lmdb_simple.core import LmdbDict

# Writer mode: open (and create if needed) for writing
with LmdbDict("path/to/db", writer=True, map_size=10_000_000) as db:
    db["foo"] = "bar"                # store strings
    db[b"bytes"] = b"raw bytes"      # store raw bytes
    db[1] = {"nested": [1, 2, 3]}     # store arbitrary Python objects

# Reader mode: open for read-only
with LmdbDict("path/to/db") as db:
    print(db["foo"])                 # "bar"
    print(db[b"bytes"])              # b"raw bytes"
    print(db[1])                       # {"nested": [1, 2, 3]}
    for key, value in db.items():
        print(key, value)

Multiprocessing

from lmdb_simple.core import LmdbDict
from multiprocessing import Pool

TEST_DB_PATH = "path/to/db"

# Create the reader at module level so that each worker process
# will reuse the same LMDB environment when unpickled.
reader = LmdbDict(TEST_DB_PATH)

def reader_worker(key):
    return reader[key]

if __name__ == "__main__":
    keys = [...]

    with Pool(processes=4) as pool:
        for result in pool.imap_unordered(reader_worker, keys):
            print(result)