bundle2: implement consume() API on unbundlepart
We want bundle parts to not be seekable by default. That means
eliminating the generic seek() method.
A common pattern in bundle2.py is to seek to the end of the part
data. This is mainly used by the part iteration code to ensure
the underlying stream is advanced to the next bundle part.
In this commit, we establish a dedicated API for consuming a
bundle2 part data. We switch users of seek() to it.
The old implementation of seek(0, os.SEEK_END) would effectively
call self.read(). The new implementation calls self.read(32768)
in a loop. The old implementation would therefore assemble a
buffer to hold all remaining data being seeked over. For seeking
over large bundle parts, this would involve a large allocation and
a lot of overhead to collect intermediate data! This overhead can
be seen in the results for `hg perfbundleread`:
! bundle2 iterparts()
! wall 10.891305 comb 10.820000 user 7.990000 sys 2.830000 (best of 3)
! wall 8.070791 comb 8.060000 user 7.180000 sys 0.880000 (best of 3)
! bundle2 part seek()
! wall 12.991478 comb 10.390000 user 7.720000 sys 2.670000 (best of 3)
! wall 10.370142 comb 10.350000 user 7.430000 sys 2.920000 (best of 3)
Of course, skipping over large payload data isn't likely very common.
So I doubt the performance wins will be observed in the wild.
Differential Revision: https://phab.mercurial-scm.org/D1388
This test doesn't yet work due to the way fsmonitor is integrated with test runner
$ exit 80
test sparse interaction with other extensions
$ hg init myrepo
$ cd myrepo
$ cat > .hg/hgrc <<EOF
> [extensions]
> sparse=
> strip=
> EOF
Test fsmonitor integration (if available)
TODO: make fully isolated integration test a'la https://github.com/facebook/watchman/blob/master/tests/integration/WatchmanInstance.py
(this one is using the systemwide watchman instance)
$ touch .watchmanconfig
$ echo "ignoredir1/" >> .hgignore
$ hg commit -Am ignoredir1
adding .hgignore
$ echo "ignoredir2/" >> .hgignore
$ hg commit -m ignoredir2
$ hg sparse --reset
$ hg sparse -I ignoredir1 -I ignoredir2 -I dir1
$ mkdir ignoredir1 ignoredir2 dir1
$ touch ignoredir1/file ignoredir2/file dir1/file
Run status twice to compensate for a condition in fsmonitor where it will check
ignored files the second time it runs, regardless of previous state (ask @sid0)
$ hg status --config extensions.fsmonitor=
? dir1/file
$ hg status --config extensions.fsmonitor=
? dir1/file
Test that fsmonitor ignore hash check updates when .hgignore changes
$ hg up -q ".^"
$ hg status --config extensions.fsmonitor=
? dir1/file
? ignoredir2/file