flask logger 使用 TimedRotatingFileHandler 报错 PermissionError 另一个程序正在使用此文件

重写 doRollover 方法：
继承 TimedRotatingFileHandler 并重写 doRollover 方法，以确保在文件重命名之前检查目标文件是否存在，如果存在，则不执行重命名操作。这可以避免多进程同时尝试重命名同一个文件的问题。

import os
import time
from logging.handlers import TimedRotatingFileHandler

class CustomTimedRotatingFileHandler(TimedRotatingFileHandler):
    def doRollover(self):
        if self.stream:
            self.stream.close()
            self.stream = None
        currentTime = int(time.time())
        dstNow = time.localtime(currentTime)[-1]
        t = self.rolloverAt - self.interval
        if self.utc:
            timeTuple = time.gmtime(t)
        else:
            timeTuple = time.localtime(t)
            dstThen = timeTuple[-1]
            if dstNow != dstThen:
                if dstNow:
                    pass
                else:
                    pass
        dfn = self.rotation_filename(self.baseFilename + ".")
        if not os.path.exists(dfn):
            self.rotate(self.baseFilename, dfn)
        if self.backupCount > 0:
            for s in self.getFilesToDelete():
                os.remove(s)
        if not self.delay:
            self.stream = self._open()
        newRolloverAt = self.computeRollover(currentTime)
        while newRolloverAt <= currentTime:
            newRolloverAt = newRolloverAt + self.interval
        self.rolloverAt = newRolloverAt