Stamina recovery mecanism inside Redis TTLs

.gitignore

env

README.md

A what you want point recovery system inside a TTL storage

Requirements

• virtualenv
• a Redis server up and running on your machine, default port (6379).

Test it

$ git clone https://gist.github.com/4987023.git
$ cd 4987023
$ virtualenv env
$ . env/bin/activate
$ pip install redis
$ ./env/bin/python player.py
Player bob just created
Player bob (stamina=100)

Let's decrease its stamina
Player bob (stamina=90)

And wait for 1 second
have a look to the stamina
Player bob (stamina=91)

and again, wait for 2 seconds

And now the stamina is
Player bob (stamina=93)

A stamina recovery mecanism inside redis TTL... fun :)

player.py

import redis
import time


conf = {
    'host': 'localhost',
    'port': 6379
}

pool = redis.ConnectionPool(host=conf['host'], port=conf['port'])
redis = redis.Redis(connection_pool=pool)


class Player(object):

    MAX_STAMINA = 100
    RECOVERY_TIME = 1

    def __init__(self, name):
        self.name = name
        self.stamina = Player.MAX_STAMINA

    def _get_redis_key(self):
        return 'player:%s:stamina' % self.name

    def get_stamina(self):
        ttl = redis.ttl(self._get_redis_key())
        return Player.MAX_STAMINA if ttl is None\
            else int(Player.MAX_STAMINA - (float(ttl) / Player.RECOVERY_TIME))

    def set_stamina(self, value):
        key = self._get_redis_key()

        with redis.pipeline(transaction=True) as pipe:

            pipe.multi()
            pipe.set(key, value)
            ttl = int(Player.RECOVERY_TIME * (Player.MAX_STAMINA - value))

            if ttl > 0:
                pipe.expire(key, ttl)
            pipe.execute()

        return self

    stamina = property(get_stamina, set_stamina)

    def __repr__(self):
        return 'Player %s (stamina=%d)' % (self.name, self.stamina)


if __name__ == '__main__':
    player1 = Player('bob')
    print 'Player bob just created'
    print player1

    # decrease the stamina
    player1.stamina = Player.MAX_STAMINA - 10
    print '\nLet\'s decrease its stamina'
    print player1

    print '\nAnd wait for 1 second'
    time.sleep(1)
    print 'have a look to the stamina'
    print player1

    print '\nand again, wait for 2 seconds'
    time.sleep(2)
    print '\nAnd now the stamina is'
    print player1

    print '\nA stamina recovery mecanism inside redis TTL... fun :)\n'