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cache decorator

/ Published in: Python
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  1. import cPickle,hashlib,tempfile,os,time,types
  2.  
  3. def cache(nbsec=0,path=None,islog=False):
  4.     """ cache (decorator) tout retour de methode en pickable
  5.         - nbsec : (opt) nb secondes du cache (si =0 unlimited)
  6.         - path : (opt) chemin pour stocker le pickle (sinon temp dir)
  7.         - islog: (opt) affiche un log clair des manips
  8.     """
  9.     def _f2(*args,**kwargs):
  10.         mname = _f2.fct.__name__
  11.         def log(msg): print "*** CACHE %s (%ds): " % (mname,nbsec),msg
  12.         file=os.path.join(path or tempfile.gettempdir(),
  13.             "zcache_%s_%s.pickle" % (mname,hashlib.md5(str(args)+str(kwargs)).hexdigest())
  14.         )
  15.         if os.path.isfile(file):
  16.             if nbsec>0:
  17.                 ftime = os.stat(file).st_mtime
  18.                 ntime = time.time()
  19.                 isLoad = ftime + nbsec > ntime
  20.                 if isLoad:
  21.                     if islog: log("use cache : %s renew in %ds" % (file,nbsec - (ntime - ftime)) )
  22.                 else:
  23.                     if islog: log("cache has expired since %d sec" % (ntime - ftime))
  24.             else:
  25.                 isLoad = True
  26.                 if islog: log("use cache : %s (no expiration time)" % (file,) )
  27.             if isLoad:
  28.                 return cPickle.load(open(file,"rb"))
  29.         else:
  30.             if islog: log("no cache file")
  31.  
  32.         val = _f2.fct(*args, **kwargs)
  33.         if islog: log("create %s"%file)
  34.         fid=open(file,"wb")
  35.         cPickle.dump(val,fid)
  36.         fid.close()
  37.         return val
  38.  
  39.     if type(nbsec) == types.FunctionType:   # to be able to work without decorator params
  40.         _f2.fct, nbsec= nbsec , 0
  41.         return _f2
  42.     else:
  43.         def _f1(func):
  44.             _f2.fct = func
  45.             return _f2
  46.         return _f1

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