bundle2: inline changegroup.readexactly()
Profiling reveals this loop is pretty tight. Literally any
function call elimination can make a big difference.
This commit inlines the relatively trivial changegroup.readexactly()
method inside the loop.
The results with `hg perfbundleread` on a bundle of the Firefox repo
speak for themselves:
! read(8k)
! wall 0.679730 comb 0.680000 user 0.140000 sys 0.540000 (best of 15)
! read(16k)
! wall 0.577228 comb 0.570000 user 0.080000 sys 0.490000 (best of 17)
! read(32k)
! wall 0.516060 comb 0.520000 user 0.040000 sys 0.480000 (best of 20)
! read(128k)
! wall 0.496378 comb 0.490000 user 0.010000 sys 0.480000 (best of 20)
! bundle2 iterparts()
! wall 3.460903 comb 3.460000 user 2.760000 sys 0.700000 (best of 3)
! wall 3.056811 comb 3.050000 user 2.340000 sys 0.710000 (best of 4)
! bundle2 iterparts() seekable
! wall 4.312722 comb 4.310000 user 3.480000 sys 0.830000 (best of 3)
! wall 4.007676 comb 4.000000 user 3.170000 sys 0.830000 (best of 3)
! bundle2 part seek()
! wall 6.754764 comb 6.740000 user 3.970000 sys 2.770000 (best of 3)
! wall 6.267110 comb 6.250000 user 3.480000 sys 2.770000 (best of 3)
! bundle2 part read(8k)
! wall 3.668004 comb 3.660000 user 2.960000 sys 0.700000 (best of 3)
! wall 3.404164 comb 3.400000 user 2.650000 sys 0.750000 (best of 3)
! bundle2 part read(16k)
! wall 3.489196 comb 3.480000 user 2.750000 sys 0.730000 (best of 3)
! wall 3.197972 comb 3.200000 user 2.490000 sys 0.710000 (best of 4)
! bundle2 part read(32k)
! wall 3.388569 comb 3.380000 user 2.640000 sys 0.740000 (best of 3)
! wall 3.060557 comb 3.060000 user 2.340000 sys 0.720000 (best of 4)
! bundle2 part read(128k)
! wall 3.276415 comb 3.270000 user 2.560000 sys 0.710000 (best of 4)
! wall 2.952209 comb 2.950000 user 2.230000 sys 0.720000 (best of 4)
Differential Revision: https://phab.mercurial-scm.org/D1392
--- a/mercurial/bundle2.py Mon Nov 13 22:05:54 2017 -0800
+++ b/mercurial/bundle2.py Mon Nov 13 21:48:35 2017 -0800
@@ -1198,13 +1198,21 @@
headersize = struct.calcsize(_fpayloadsize)
readexactly = changegroup.readexactly
+ read = fh.read
chunksize = _unpack(_fpayloadsize, readexactly(fh, headersize))[0]
indebug(ui, 'payload chunk size: %i' % chunksize)
+ # changegroup.readexactly() is inlined below for performance.
while chunksize:
if chunksize >= 0:
- yield readexactly(fh, chunksize)
+ s = read(chunksize)
+ if len(s) < chunksize:
+ raise error.Abort(_('stream ended unexpectedly '
+ ' (got %d bytes, expected %d)') %
+ (len(s), chunksize))
+
+ yield s
elif chunksize == flaginterrupt:
# Interrupt "signal" detected. The regular stream is interrupted
# and a bundle2 part follows. Consume it.
@@ -1213,7 +1221,13 @@
raise error.BundleValueError(
'negative payload chunk size: %s' % chunksize)
- chunksize = _unpack(_fpayloadsize, readexactly(fh, headersize))[0]
+ s = read(headersize)
+ if len(s) < headersize:
+ raise error.Abort(_('stream ended unexpectedly '
+ ' (got %d bytes, expected %d)') %
+ (len(s), chunksize))
+
+ chunksize = _unpack(_fpayloadsize, s)[0]
# indebug() inlined for performance.
if dolog: