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waf/waflib/extras/lru_cache.py
Thomas Nagy b283f54c08 docs
2011-10-14 20:22:09 +02:00

99 lines
2.4 KiB
Python

#! /usr/bin/env python
# encoding: utf-8
# Thomas Nagy 2011
import os, shutil, re
from waflib import Options, Build, Logs
"""
Apply a least recently used policy to the Waf cache.
For performance reasons, it is called after the build is complete.
We assume that the the folders are written atomically
Do export WAFCACHE=/tmp/foo_xyz where xyz represents the cache size in bytes
If missing, the default cache size will be set to 10GB
"""
re_num = re.compile('[a-zA-Z_-]+(\d+)')
CACHESIZE = 10*1024*1024*1024 # in bytes
CLEANRATIO = 0.8
DIRSIZE = 4096
def compile(self):
if Options.cache_global and not Options.options.nocache:
try:
os.makedirs(Options.cache_global)
except:
pass
try:
self.raw_compile()
finally:
if Options.cache_global and not Options.options.nocache:
self.sweep()
def sweep(self):
global CACHESIZE
CACHEDIR = Options.cache_global
# get the cache max size from the WAFCACHE filename
re_num = re.compile('[a-zA-Z_]+(\d+)')
val = re_num.sub('\\1', os.path.basename(Options.cache_global))
try:
CACHESIZE = int(val)
except:
pass
# map folder names to timestamps
flist = {}
for x in os.listdir(CACHEDIR):
j = os.path.join(CACHEDIR, x)
if os.path.isdir(j) and len(x) == 64: # dir names are md5 hexdigests
flist[x] = [os.stat(j).st_mtime, 0]
for (x, v) in flist.items():
cnt = DIRSIZE # each entry takes 4kB
d = os.path.join(CACHEDIR, x)
for k in os.listdir(d):
cnt += os.stat(os.path.join(d, k)).st_size
flist[x][1] = cnt
total = sum([x[1] for x in flist.values()])
Logs.debug('lru: Cache size is %r' % total)
if total >= CACHESIZE:
Logs.debug('lru: Trimming the cache since %r > %r' % (total, CACHESIZE))
# make a list to sort the folders by timestamp
lst = [(p, v[0], v[1]) for (p, v) in flist.items()]
lst.sort(key=lambda x: x[1]) # sort by timestamp
lst.reverse()
while total >= CACHESIZE * CLEANRATIO:
(k, t, s) = lst.pop()
p = os.path.join(CACHEDIR, k)
v = p + '.del'
try:
os.rename(p, v)
except:
# someone already did it
pass
else:
try:
shutil.rmtree(v)
except:
# this should not happen, but who knows?
Logs.warn('If you ever see this message, report it (%r)' % v)
total -= s
del flist[k]
Logs.debug('lru: Total at the end %r' % total)
Build.BuildContext.raw_compile = Build.BuildContext.compile
Build.BuildContext.compile = compile
Build.BuildContext.sweep = sweep