# HG changeset patch
# User Boris Feld <boris.feld@octobus.net>
# Date 2018-11-08 14:29:58
# Node ID bfbfd15d65bd862d596af7154ef29f1321b4cfa1
# Parent  a32ccd32982b6b9ed960184e32ed21a78490e721

sparse-revlog: fast-path before computing payload size

In this fast-path case, we do not need to compute the full delta chain
payload. Since it comes with a significant cost, we avoid doing so if
possible.

diff --git a/mercurial/revlogutils/deltas.py b/mercurial/revlogutils/deltas.py
--- a/mercurial/revlogutils/deltas.py
+++ b/mercurial/revlogutils/deltas.py
@@ -257,13 +257,13 @@ def _slicechunktodensity(revlog, revs, t
         return
 
     deltachainspan = segmentspan(revlog, revs)
-    chainpayload = sum(length(r) for r in revs)
 
     if deltachainspan < mingapsize:
         yield revs
         return
 
     readdata = deltachainspan
+    chainpayload = sum(length(r) for r in revs)
 
     if deltachainspan:
         density = chainpayload / float(deltachainspan)