Noparallel.py

import gevent
import time


class Noparallel(object):  # Only allow function running once in same time

    def __init__(self, blocking=True):
        self.threads = {}
        self.blocking = blocking  # Blocking: Acts like normal function else thread returned

    def __call__(self, func):
        def wrapper(*args, **kwargs):
            key = (func, tuple(args), str(kwargs))  # Unique key for function including parameters
            if key in self.threads:  # Thread already running (if using blocking mode)
                thread = self.threads[key]
                if self.blocking:
                    thread.join()  # Blocking until its finished
                    return thread.value  # Return the value
                else:  # No blocking
                    if thread.ready():  # Its finished, create a new
                        thread = gevent.spawn(func, *args, **kwargs)
                        self.threads[key] = thread
                        return thread
                    else:  # Still running
                        return thread
            else:  # Thread not running
                thread = gevent.spawn(func, *args, **kwargs)  # Spawning new thread
                thread.link(lambda thread: self.cleanup(key, thread))
                self.threads[key] = thread
                if self.blocking:  # Wait for finish
                    thread.join()
                    ret = thread.value
                    return ret
                else:  # No blocking just return the thread
                    return thread
        wrapper.func_name = func.func_name

        return wrapper

    # Cleanup finished threads
    def cleanup(self, key, thread):
        if key in self.threads:
            del(self.threads[key])


if __name__ == "__main__":
    class Test():

        @Noparallel()
        def count(self, num=5):
            for i in range(num):
                print self, i
                time.sleep(1)
            return "%s return:%s" % (self, i)

    class TestNoblock():

        @Noparallel(blocking=False)
        def count(self, num=5):
            for i in range(num):
                print self, i
                time.sleep(1)
            return "%s return:%s" % (self, i)

    def testBlocking():
        test = Test()
        test2 = Test()
        print "Counting..."
        print "Creating class1/thread1"
        thread1 = gevent.spawn(test.count)
        print "Creating class1/thread2 (ignored)"
        thread2 = gevent.spawn(test.count)
        print "Creating class2/thread3"
        thread3 = gevent.spawn(test2.count)

        print "Joining class1/thread1"
        thread1.join()
        print "Joining class1/thread2"
        thread2.join()
        print "Joining class2/thread3"
        thread3.join()

        print "Creating class1/thread4 (its finished, allowed again)"
        thread4 = gevent.spawn(test.count)
        print "Joining thread4"
        thread4.join()

        print thread1.value, thread2.value, thread3.value, thread4.value
        print "Done."

    def testNoblocking():
        test = TestNoblock()
        test2 = TestNoblock()
        print "Creating class1/thread1"
        thread1 = test.count()
        print "Creating class1/thread2 (ignored)"
        thread2 = test.count()
        print "Creating class2/thread3"
        thread3 = test2.count()
        print "Joining class1/thread1"
        thread1.join()
        print "Joining class1/thread2"
        thread2.join()
        print "Joining class2/thread3"
        thread3.join()

        print "Creating class1/thread4 (its finished, allowed again)"
        thread4 = test.count()
        print "Joining thread4"
        thread4.join()

        print thread1.value, thread2.value, thread3.value, thread4.value
        print "Done."

    def testBenchmark():
        import time

        def printThreadNum():
            import gc
            from greenlet import greenlet
            objs = [obj for obj in gc.get_objects() if isinstance(obj, greenlet)]
            print "Greenlets: %s" % len(objs)

        printThreadNum()
        test = TestNoblock()
        s = time.time()
        for i in range(3):
            gevent.spawn(test.count, i + 1)
        print "Created in %.3fs" % (time.time() - s)
        printThreadNum()
        time.sleep(5)
    from gevent import monkey
    monkey.patch_all()

    testBenchmark()
    print "Testing blocking mode..."
    testBlocking()
    print "Testing noblocking mode..."
    testNoblocking()