Lib/dircache.py

   1 """Read and cache directory listings.
   2
   3 The listdir() routine returns a sorted list of the files in a directory,
   4 using a cache to avoid reading the directory more often than necessary.
   5 The annotate() routine appends slashes to directories."""
   6
   7 import os
   8
   9 __all__ = ["listdir", "opendir", "annotate", "reset"]
  10
  11 cache = {}
  12
  13 def reset():
  14     """Reset the cache completely."""
  15     global cache
  16     cache = {}
  17
  18 def listdir(path):
  19     """List directory contents, using cache."""
  20     try:
  21         cached_mtime, list = cache[path]
  22         del cache[path]
  23     except KeyError:
  24         cached_mtime, list = -1, []
  25     try:
  26         mtime = os.stat(path)[8]
  27     except os.error:
  28         return []
  29     if mtime != cached_mtime:
  30         try:
  31             list = os.listdir(path)
  32         except os.error:
  33             return []
  34         list.sort()
  35     cache[path] = mtime, list
  36     return list
  37
  38 opendir = listdir # XXX backward compatibility
  39
  40 def annotate(head, list):
  41     """Add '/' suffixes to directories."""
  42     for i in range(len(list)):
  43         if os.path.isdir(os.path.join(head, list[i])):
  44             list[i] = list[i] + '/'