from twisted.python.threadpool import ThreadPool
from twisted.internet import threads

class Pool:
    """wrapper class to handles a twisted threadpool"""
    def __init__(self,name,maxthreads):
        """
        :param string name: name of the threadpool
        :param integer maxthreads: how many thread a allowed at maximum
        """
        self.maxthreads = maxthreads
        self.pool =  ThreadPool(minthreads=1, maxthreads=maxthreads, name=name)
        self.reactor = None

    def start(self, reactor):
        """stats the pool and adds the pool.stop function to the stop procedure.
        
        :param reactor: a valid twisted reactor
        """
        self.pool.start()
        self.reactor = reactor
        self.reactor.addSystemEventTrigger('before', 'shutdown', self.pool.stop)

    def run(self,f,*args,**kwargs):
        """run a function in Twisted's thread pool"""
        return threads.deferToThreadPool(self.reactor, self.pool, f, *args, **kwargs)

taskPool = Pool('task',5)
"""taskpool to handle sending data"""

dbPool = Pool('database',5)
"""pool to handle database connection via sqlalchemy""" 

pools=[taskPool,dbPool]
"""all available pools"""

def startPool(reactor):
    '''run start function for all items in :attr:`pools`'''
    for pool in pools:
        pool.start(reactor)

__all__=["Pool", "startPool", "dbPool", "taskPool", "pools"]