Simple context manager to wrap django utilities in pg_advisory locks

pg_advisory_xact_lock.py

from django.db import connection, transaction
from contextlib import contextmanager


@contextmanager
def pg_advisory_xact_lock(*keys):
    """
    Acquire an exclusive database lock against an arbitrary string key
    """
    string_key = '.'.join(keys)
    lock_key = sha1(string_key).digest().__hash__()
    lockstring = 'SELECT pg_advisory_xact_lock({0});'.format(lock_key)

    transaction.set_autocommit(False)
    try:
        connection.cursor().execute(lockstring)
        yield
    finally:
        transaction.commit()
        transaction.set_autocommit(True)

WARNING in case anyone stumbles upon this nine+ years later, don't use as-is without rolling your own hashing mechanism: __hash__() isn't stable so you'll end up getting different locks for the same keys.