python:处理变量锁定的优雅方法？

Question

我的代码看起来像这样:

def startSearching(self):
    self.searchingLock.acquire()
    searching = self.searching
    if self.searching:
        self.searchingLock.release()
        self.logger.error("Already searching!")
        return False

    self.searching = True
    self.searchingLock.release()

    #some more init code, then start the thread which
    #constantly checks self.searching to determine when to stop

虽然有点丑。大量的获取和释放。这看起来更漂亮:

def startSearching(self):
    with self.searchingLock:
        if self.searching:
            self.logger.error("Already searching!")
            return False

        self.searching = True

    #some more init code, then start the thread which
    #constantly checks self.searching to determine when to stop

但这会使锁保持的时间比绝对必要的时间长，特别是如果 self.logger.error 需要一段时间(就像它写入磁盘一样，它会这样做)。在尽可能少地持有锁和拥有更漂亮的代码之间是否有中间立场？

Answer 1

也许你需要像这样分离这个逻辑:

def initSearch(self):
    with self.searchingLock:
        if self.searching : raise SearchingError('AlreadySearching')
        self.searching = True
def startSearching(self):
    try: self.initSearch()
    except SearchingError as error :
        self.logger.error(error.message)
        return False
    #some more init code, then start the thread which
    #constantly checks self.searching to determine when to stop

另外，您告诉您的 searchingLock 自动释放它的原因。