- import shutil
- if os.path.exists(self.lock_file):
- raise HandledException('Sorry, lock file!')
- f = open(self.lock_file, 'w+')
- f.close()
-
- # collect modification times of numbered .bak files
- bak_prefix = f'{self.db_file}.bak.'
- backup_dates = []
- i = 0
- bak_as = f'{bak_prefix}{i}'
- while os.path.exists(bak_as):
- mod_time = os.path.getmtime(bak_as)
- backup_dates += [str(datetime.fromtimestamp(mod_time))]
- i += 1
- bak_as = f'{bak_prefix}{i}'
-
- # collect what numbered .bak files to save: the older, the fewer; for each
- # timedelta, keep the newest file that's older
- ages_to_keep = [timedelta(minutes=4**i) for i in range(0, 8)]
- now = datetime.now()
- to_save = []
- for age in ages_to_keep:
- limit = now - age
- for i, date in enumerate(reversed(backup_dates)):
- if datetime.strptime(date, '%Y-%m-%d %H:%M:%S.%f') < limit:
- unreversed_i = len(backup_dates) - i - 1
- if unreversed_i not in to_save:
- to_save += [unreversed_i]
- break
-
- # remove redundant backup files
- j = 0
- for i in to_save:
- if i != j:
- source = f'{bak_prefix}{i}'
- target = f'{bak_prefix}{j}'
- shutil.move(source, target)
- j += 1
- for i in range(j, len(backup_dates)):
- try:
- os.remove(f'{bak_prefix}{i}')
- except FileNotFoundError:
- pass
-
- # put copy of current state at end of bak list
- shutil.copy(self.db_file, f'{bak_prefix}{j}')
- with open(self.db_file, mode) as f:
- f.write(text);
- os.remove(self.lock_file)