# HG changeset patch
# User Martin Geisler <mg@lazybytes.net>
# Date 1241468092 -7200
# Node ID 7f27e69dd27f2ab6d17c8a5b0589faa8840467c6
# Parent  908c5906091bf9a229be085a5752fc8b3604b78e
util: stop overwriting sha1, overwrite _fastsha1 instead

Some modules (like revlog) would import util.sha1 as _sha1. This
defeats the purpose of having util.sha1 overwrite itself with a faster
version -- revlog would end up always calling the slow version. By
always delegating to util._fastsha1 we avoid this at the cost of an
extra (but unconditional) indirection.

diff -r 908c5906091b -r 7f27e69dd27f mercurial/util.py
--- a/mercurial/util.py	Mon May 04 21:30:39 2009 +0200
+++ b/mercurial/util.py	Mon May 04 22:14:52 2009 +0200
@@ -21,13 +21,18 @@
 # Python compatibility
 
 def sha1(s):
+    return _fastsha1(s)
+
+def _fastsha1(s):
+    # This function will import sha1 from hashlib or sha (whichever is
+    # available) and overwrite itself with it on the first call.
+    # Subsequent calls will go directly to the imported function.
     try:
-        import hashlib
-        _sha1 = hashlib.sha1
+        from hashlib import sha1 as _sha1
     except ImportError:
         from sha import sha as _sha1
-    global sha1
-    sha1 = _sha1
+    global _fastsha1
+    _fastsha1 = _sha1
     return _sha1(s)
 
 import subprocess