python + multiprocessor switch swap

底下 example 利用 multiprocessor 來實現 switch swap. 當然也可以考慮用 stackless 的方式, 把 task 加載到 scheduler manager 來減少 acquire 的次數, 達到 atomic thread 更加的 independent http://www.stackless.com/

from multiprocessing import Process
import time

class Switcher(object):
    """ Switch(swap) the data stored sequence
    -0 for store in seq0, run in seq1
    -1 for store in seq1, run in seq0
    """

    def __init__(self):
     self._seq0 = []
     self._seq1 = []
     self._mode = 0

    def switch(self):
     """ switch mode """
 self._mode = 1 if self._mode == 0 else 0

    def getStoreSeq(self):
 seq = self._seq0[:] if self._mode == 0 else self._seq1[:]
 return seq

    def getRunSeq(self):
 seq = self._seq1[:] if self._mode == 0 else self._seq0[:]
 print "run switcher.seq0 %s" %(self._seq0)
     print "run switcher.seq1 %s" %(self._seq1)
     return seq

    def setStoreSeq(self,pat=[]):
 if self._mode == 0:
     self._seq0 = pat[:]
 else:
     self._seq1 = pat[:]
 print "store switcher.seq0 %s" %(self._seq0)
 print "store switcher.seq1 %s" %(self._seq1)

    def setRunSeq(self,pat=[]):
 if self._mode == 1:
     self._seq0 = pat[:]
 else:
     self._seq1 = pat[:]

    def clear(self):
 del self._seq0[:]
 del self._seq1[:]


def test(switcher):
    """ test """
    switcher.setStoreSeq([1,2,3])
    switcher.switch()
    assert(switcher.getRunSeq()==[1,2,3])
    switcher.setStoreSeq([4,5,6])
    switcher.switch()
    switcher.clear()


def sample_run(switcher):
    """ avg switcher.getRunSeq() """
    try:
     seq = switcher.getRunSeq()
     print "avg %.2f, %s" %(sum(seq)/len(seq), seq)
    except ZeroDivisionError:
     print "Error %s" %(seq)


def patten_gen(switcher,sel=0):
    """ random patten gen """
    if sel ==0:
     switcher.setStoreSeq([i for i in range(10)])
    else:
     switcher.setStoreSeq([i for i in range(10,20,1)])


def pre_load_status(switcher):
    """ pre load status """

    print "pre_load_status"
    p0 = Process(target=patten_gen, args=(switcher,0))
    p0.start()
    p0.join()

    print switcher._seq0
    print switcher._seq1


def switch_status(switcher):
    switcher.switch()


def pipe_load_status(switcher,sel=0):
    """ pipe load status """

    print "pipe_load_status"
    p0 = Process(target=patten_gen, args=(switcher,sel))
    p1 = Process(target=sample_run, args=(switcher,))
    p0.start()
    p1.start()
    p0.join()
    p1.join()


def end_load_status(switcher):
    """ end load status """

    print "end_load_status"
    p1 = Process(target=sample_run, args=(switcher,))
    p1.start()
    p1.join()


def main():

    switcher = Switcher()
    test(switcher)


    for i in range(5):
 if i == 0:
     pre_load_status(switcher)
     switch_status(switcher)
 elif i in [1,2,3]:
     pipe_load_status(switcher, i%2)
     switch_status(switcher)
 else:
     end_load_status(switcher)
     switch_status(switcher)

if __name__ == "__main__":
    main()