Python synchronization helpers.

synchronization.py

import threading


def threadify(func):
    "A decorator to run a function asynchronously"
    def run(*fargs, **fkwargs):
        threading.Thread(target=func, args=fargs, kwargs=fkwargs).start()
    return run


class Barrier:
    "Synchronization barrier"

    def __init__(self, numthreads):
        self.lock = threading.Lock()
        self.numthreads = numthreads
        self.sem = threading.Semaphore(0)
        self.sem2 = threading.Semaphore(self.numthreads)
        self.count = 0

    def sync(self):
        self.sem2.acquire()
        with self.lock:
            self.count += 1
            if self.count == self.numthreads:
                self.sem.release()

        self.sem.acquire()
        with self.lock:
            self.count -= 1
            if self.count != 0:
                self.sem.release()
            else:
                for x in range(self.numthreads):
                    self.sem2.release()


class Semaphore2:
    "Semaphore that takes negative init value and can release value > 1"
    def __init__(self, value):
        self.value = value
        self.sem = threading.Semaphore(value if value >= 0 else 0)
        self.lock = threading.Lock()

    def acquire(self):
        self.sem.acquire()

    def release(self, value=1):
        with self.lock:
            if self.value < 0:
                self.value += value
            if self.value >= 0:
                for i in range(value):
                    self.sem.release()