Guido van Rossum | c636014 | 1990-10-13 19:23:40 +0000 | [diff] [blame] | 1 | # Module 'statcache' |
| 2 | # |
| 3 | # Maintain a cache of file stats. |
| 4 | # There are functions to reset the cache or to selectively remove items. |
| 5 | |
Guido van Rossum | 25d7caf | 1992-03-31 19:04:48 +0000 | [diff] [blame^] | 6 | import os |
Guido van Rossum | 40d9304 | 1990-10-21 16:17:34 +0000 | [diff] [blame] | 7 | from stat import * |
Guido van Rossum | c636014 | 1990-10-13 19:23:40 +0000 | [diff] [blame] | 8 | |
| 9 | # The cache. |
Guido van Rossum | 25d7caf | 1992-03-31 19:04:48 +0000 | [diff] [blame^] | 10 | # Keys are pathnames, values are `os.stat' outcomes. |
Guido van Rossum | c636014 | 1990-10-13 19:23:40 +0000 | [diff] [blame] | 11 | # |
| 12 | cache = {} |
| 13 | |
| 14 | |
| 15 | # Stat a file, possibly out of the cache. |
| 16 | # |
| 17 | def stat(path): |
Guido van Rossum | 40d9304 | 1990-10-21 16:17:34 +0000 | [diff] [blame] | 18 | if cache.has_key(path): |
Guido van Rossum | c636014 | 1990-10-13 19:23:40 +0000 | [diff] [blame] | 19 | return cache[path] |
Guido van Rossum | 25d7caf | 1992-03-31 19:04:48 +0000 | [diff] [blame^] | 20 | cache[path] = ret = os.stat(path) |
Guido van Rossum | c636014 | 1990-10-13 19:23:40 +0000 | [diff] [blame] | 21 | return ret |
| 22 | |
| 23 | |
| 24 | # Reset the cache completely. |
| 25 | # Hack: to reset a global variable, we import this module. |
| 26 | # |
| 27 | def reset(): |
| 28 | import statcache |
| 29 | # Check that we really imported the same module |
| 30 | if cache is not statcache.cache: |
| 31 | raise 'sorry, statcache identity crisis' |
| 32 | statcache.cache = {} |
| 33 | |
| 34 | |
| 35 | # Remove a given item from the cache, if it exists. |
| 36 | # |
| 37 | def forget(path): |
Guido van Rossum | 40d9304 | 1990-10-21 16:17:34 +0000 | [diff] [blame] | 38 | if cache.has_key(path): |
Guido van Rossum | c636014 | 1990-10-13 19:23:40 +0000 | [diff] [blame] | 39 | del cache[path] |
Guido van Rossum | c636014 | 1990-10-13 19:23:40 +0000 | [diff] [blame] | 40 | |
| 41 | |
| 42 | # Remove all pathnames with a given prefix. |
| 43 | # |
| 44 | def forget_prefix(prefix): |
| 45 | n = len(prefix) |
| 46 | for path in cache.keys(): |
Guido van Rossum | bdfcfcc | 1992-01-01 19:35:13 +0000 | [diff] [blame] | 47 | if path[:n] == prefix: |
Guido van Rossum | c636014 | 1990-10-13 19:23:40 +0000 | [diff] [blame] | 48 | del cache[path] |
| 49 | |
| 50 | |
| 51 | # Forget about a directory and all entries in it, but not about |
| 52 | # entries in subdirectories. |
| 53 | # |
| 54 | def forget_dir(prefix): |
Guido van Rossum | bdfcfcc | 1992-01-01 19:35:13 +0000 | [diff] [blame] | 55 | if prefix[-1:] == '/' and prefix <> '/': |
Guido van Rossum | c636014 | 1990-10-13 19:23:40 +0000 | [diff] [blame] | 56 | prefix = prefix[:-1] |
| 57 | forget(prefix) |
| 58 | if prefix[-1:] <> '/': |
| 59 | prefix = prefix + '/' |
| 60 | n = len(prefix) |
| 61 | for path in cache.keys(): |
Guido van Rossum | bdfcfcc | 1992-01-01 19:35:13 +0000 | [diff] [blame] | 62 | if path[:n] == prefix: |
Guido van Rossum | c636014 | 1990-10-13 19:23:40 +0000 | [diff] [blame] | 63 | rest = path[n:] |
Guido van Rossum | bdfcfcc | 1992-01-01 19:35:13 +0000 | [diff] [blame] | 64 | if rest[-1:] == '/': rest = rest[:-1] |
Guido van Rossum | c636014 | 1990-10-13 19:23:40 +0000 | [diff] [blame] | 65 | if '/' not in rest: |
| 66 | del cache[path] |
| 67 | |
| 68 | |
| 69 | # Remove all pathnames except with a given prefix. |
| 70 | # Normally used with prefix = '/' after a chdir(). |
| 71 | # |
| 72 | def forget_except_prefix(prefix): |
| 73 | n = len(prefix) |
| 74 | for path in cache.keys(): |
| 75 | if path[:n] <> prefix: |
| 76 | del cache[path] |
| 77 | |
| 78 | |
| 79 | # Check for directory. |
| 80 | # |
| 81 | def isdir(path): |
| 82 | try: |
Guido van Rossum | 40d9304 | 1990-10-21 16:17:34 +0000 | [diff] [blame] | 83 | st = stat(path) |
Guido van Rossum | 25d7caf | 1992-03-31 19:04:48 +0000 | [diff] [blame^] | 84 | except os.error: |
Guido van Rossum | c636014 | 1990-10-13 19:23:40 +0000 | [diff] [blame] | 85 | return 0 |
Guido van Rossum | 40d9304 | 1990-10-21 16:17:34 +0000 | [diff] [blame] | 86 | return S_ISDIR(st[ST_MODE]) |