# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#    http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
# implied.
# See the License for the specific language governing permissions and
# limitations under the License.

r"""
Zaqar backed by Redis.

Redis?
------

Redis is sometimes called a "data structure store" because it makes common
data structures like hashes, lists, and sets available in shared, in-memory
storage. Zaqar chose redis because it has strong consistency and its Lua
scripting allows for semi-complex transactions to be built atop the primitives
it provides.

Supported Features
------------------

- FIFO
- Claims
- High Throughput[1]_
- At-least-once Delivery

.. [1] This depends on the backing Redis store performance. For more
information, see `Redis' benchmarks <http://redis.io/topics/benchmarks>`_.

Redis is only a storage driver, and can't be used as the sole backend for a
Zaqar deployment.

Unsupported Features
--------------------

- Durability[2]_

.. [2] As an in-memory store, Redis doesn't support the durability guarantees
       the MongoDB or SQLAlchemy backends do.

Redis is not supported as the backend for the Management Store, which means
either MongoDB or SQLAlchemy are required in addition to Redis for a working
deployment.


"""