utils.py

   1 import os
   2 import time
   3 import sys
   4 import errno
   5
   6 def safe_write(fn, contents):
   7         bak = ''
   8         if os.path.exists(fn):
   9                 bak = fn + '.bak'
  10                 if os.path.exists(bak): os.unlink(bak)
  11                 os.rename(fn, bak)
  12         try:
  13                 with open(fn, 'w') as h:
  14                         h.write(contents)
  15         except:
  16                 os.rename(bak, fn)
  17                 return False
  18         if bak != '':
  19                 os.unlink(bak)
  20         return True
  21
  22 def retry_write(fn, contents):
  23         while 1:
  24                 try:
  25                         with open(fn, 'w') as h: h.write(contents)
  26                         break
  27                 except IOError as e:
  28                         if e.errno == errno.ENOSPC:
  29                                 sys.stderr.write('disk full, retrying in 10s\n')
  30                                 time.sleep(10)
  31                         else:
  32                                 raise e
  33
  34 def retry_makedirs(fn):
  35         while 1:
  36                 try:
  37                         os.makedirs(fn)
  38                         break
  39                 except OSError as e:
  40                         if e.errno == errno.ENOSPC:
  41                                 sys.stderr.write('makedir: disk full, retrying in 10s\n')
  42                                 time.sleep(10)
  43                         else:
  44                                 raise e
  45
  46 if __name__ == "__main__":
  47         try: data = open('test.dat', 'r').read()
  48         except: data = ''
  49         print safe_write('test.dat', data + ('A'*128))