Mercurial > cpython-lru_cache-weakref

annotate Lib/statcache.py @ 38664:7619216bbc19 2.4

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Bug #1502728: Correctly link against librt library on HP-UX. (backport from rev. 46743)
author Georg Brandl <georg@python.org>
date Thu, 08 Jun 2006 12:54:16 +0000
parents 65cf478950ff
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
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1 """Maintain a cache of stat() information on files.
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2
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3 There are functions to reset the cache or to selectively remove items.
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4 """
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6 import warnings
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7 warnings.warn("The statcache module is obsolete. Use os.stat() instead.",
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8 DeprecationWarning)
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9 del warnings
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10
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11 import os as _os
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12 from stat import *
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13
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14 __all__ = ["stat","reset","forget","forget_prefix","forget_dir",
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15 "forget_except_prefix","isdir"]
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16
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17 # The cache. Keys are pathnames, values are os.stat outcomes.
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18 # Remember that multiple threads may be calling this! So, e.g., that
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19 # path in cache returns 1 doesn't mean the cache will still contain
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20 # path on the next line. Code defensively.
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21
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22 cache = {}
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23
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24 def stat(path):
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25 """Stat a file, possibly out of the cache."""
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26 ret = cache.get(path, None)
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27 if ret is None:
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28 cache[path] = ret = _os.stat(path)
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29 return ret
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30
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31 def reset():
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32 """Clear the cache."""
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33 cache.clear()
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34
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35 # For thread saftey, always use forget() internally too.
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36 def forget(path):
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37 """Remove a given item from the cache, if it exists."""
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38 try:
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39 del cache[path]
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40 except KeyError:
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41 pass
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42
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43 def forget_prefix(prefix):
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44 """Remove all pathnames with a given prefix."""
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45 for path in cache.keys():
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46 if path.startswith(prefix):
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47 forget(path)
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48
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49 def forget_dir(prefix):
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50 """Forget a directory and all entries except for entries in subdirs."""
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51
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52 # Remove trailing separator, if any. This is tricky to do in a
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53 # x-platform way. For example, Windows accepts both / and \ as
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54 # separators, and if there's nothing *but* a separator we want to
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55 # preserve that this is the root. Only os.path has the platform
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56 # knowledge we need.
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57 from os.path import split, join
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58 prefix = split(join(prefix, "xxx"))[0]
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59 forget(prefix)
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60 for path in cache.keys():
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61 # First check that the path at least starts with the prefix, so
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62 # that when it doesn't we can avoid paying for split().
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63 if path.startswith(prefix) and split(path)[0] == prefix:
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64 forget(path)
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66 def forget_except_prefix(prefix):
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67 """Remove all pathnames except with a given prefix.
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68
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69 Normally used with prefix = '/' after a chdir().
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70 """
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71
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72 for path in cache.keys():
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73 if not path.startswith(prefix):
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74 forget(path)
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76 def isdir(path):
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77 """Return True if directory, else False."""
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78 try:
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79 st = stat(path)
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80 except _os.error:
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81 return False
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82 return S_ISDIR(st.st_mode)