oslo.limit example usage

example.py

from oslo_limit import limit

LIMIT_ENFORCER = limit.Enforcer()


def create_foobar(self, context, foobar):

    # check if project is over the limit prior to creating the resource
    claim = 1
    resource_name = 'foobars'
    usage_callback = self._list_foobars_for_project
    LIMIT_ENFORCER.enforce(
        resource_name, claim, context.project_id, usage_callback
    )

    # execute business logic, or whatever the thing is that increments project
    # usage of a resource
    driver.create_foobar(foobar)

    # make sure we're still within the project limit and avoid race conditions
    # where another thread or process put us at the limit before we exit the
    # API
    try:
        LIMIT_ENFORCER.verify(
            resource_name, claim, context.project_id, usage_callback
        )
    except limit.UsageExceededLimitException():
        driver.rollback(foobar)
        raise