[Python-checkins] python/dist/src/Lib hmac.py,1.7,1.8

[tim_one at users.sourceforge.net]

Update of /cvsroot/python/python/dist/src/Lib
In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv20234/Lib

Modified Files:
	hmac.py 
Log Message:
Speed HMAC.copy() by installing a secret backdoor argument to
HMAC.__init__().  Adapted from SF patch 895445 "hmac.HMAC.copy() speedup"
by Trevor Perrin, who reported that this approach increased throughput
of his hmac-intensive app by 30%.


Index: hmac.py
===================================================================
RCS file: /cvsroot/python/python/dist/src/Lib/hmac.py,v
retrieving revision 1.7
retrieving revision 1.8
diff -C2 -d -r1.7 -r1.8
*** hmac.py	3 Jun 2002 15:58:31 -0000	1.7
--- hmac.py	20 Mar 2004 20:11:29 -0000	1.8
***************
*** 13,16 ****
--- 13,21 ----
  digest_size = None
  
+ # A unique object passed by HMAC.copy() to the HMAC constructor, in order
+ # that the latter return very quickly.  HMAC("") in contrast is quite
+ # expensive.
+ _secret_backdoor_key = []
+ 
  class HMAC:
      """RFC2104 HMAC class.
***************
*** 26,29 ****
--- 31,38 ----
          digestmod: A module supporting PEP 247. Defaults to the md5 module.
          """
+ 
+         if key is _secret_backdoor_key: # cheap
+             return
+ 
          if digestmod is None:
              import md5
***************
*** 61,66 ****
          An update to this copy won't affect the original object.
          """
!         other = HMAC("")
          other.digestmod = self.digestmod
          other.inner = self.inner.copy()
          other.outer = self.outer.copy()
--- 70,76 ----
          An update to this copy won't affect the original object.
          """
!         other = HMAC(_secret_backdoor_key)
          other.digestmod = self.digestmod
+         other.digest_size = self.digest_size
          other.inner = self.inner.copy()
          other.outer = self.outer.copy()