view tests/test-convert-baz @ 16120:47ee41fcf42b

largefiles: optimize update speed by only updating changed largefiles

Historically, during 'hg update', every largefile in the working copy was
hashed (which is a very expensive operation on big files) and any
largefiles that did not have a hash that matched their standin were
updated.

This patch optimizes 'hg update' by keeping track of what standins have
changed between the old and new revisions, and only updating the largefiles
that have changed.  This saves a lot of time by avoiding the unecessary
calculation of a list of sha1 hashes for big files.

With this patch, the time 'hg update' takes to complete is a function of
how many largefiles need to be updated and what their size is.

Performance tests on a repository with about 80 largefiles ranging from
a few MB to about 97 MB are shown below.  The tests show how long it takes
to run 'hg update' with no changes actually being updated.

Mercurial 2.1 release:

$ time hg update
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
getting changed largefiles
0 largefiles updated, 0 removed

real    0m10.045s
user    0m9.367s
sys    0m0.674s

With this patch:

$ time hg update
0 files updated, 0 files merged, 0 files removed, 0 files unresolved

real    0m0.965s
user    0m0.845s
sys    0m0.115s

The same repsoitory, without the largefiles extension enabled:

$ time hg update
0 files updated, 0 files merged, 0 files removed, 0 files unresolved

real    0m0.799s
user    0m0.684s
sys    0m0.111s

So before the patch, 'hg update' with no changes was approximately 9.25s
slower with largefiles enabled.  With this patch, it is approximately 0.165s
slower.

#!/bin/sh

"$TESTDIR/hghave" baz || exit 80

baz my-id "mercurial <[e-mail]>"

echo "[extensions]" >> $HGRCPATH
echo "convert=" >> $HGRCPATH
echo 'graphlog =' >> $HGRCPATH

echo % create baz archive
baz make-archive baz@mercurial--convert hg-test-convert-baz

echo % initialize baz repo
mkdir baz-repo
cd baz-repo/
baz init-tree baz@mercurial--convert/baz--test--0
baz import

echo % create initial files
echo 'this is a file' > a
baz add a
mkdir src
baz add src
cd src
dd count=1 if=/dev/zero of=b > /dev/null 2> /dev/null
baz add b
# HACK: hide GNU tar-1.22 "tar: The --preserve option is deprecated, use --preserve-permissions --preserve-order instead"
baz commit -s "added a file, src and src/b (binary)" 2>&1 | grep -v '^tar'

echo % create link file and modify a
ln -s ../a a-link
baz add a-link
echo 'this a modification to a' >> ../a
baz commit -s "added link to a and modify a"

echo % create second link and modify b
ln -s ../a a-link-2
baz add a-link-2
dd count=1 seek=1 if=/dev/zero of=b > /dev/null 2> /dev/null
baz commit -s "added second link and modify b"

echo % b file to link and a-link-2 to regular file
rm -f a-link-2
echo 'this is now a regular file' > a-link-2
ln -sf ../a b
baz commit -s "file to link and link to file test"

echo % move a-link-2 file and src directory
cd ..
baz mv src/a-link-2 c
baz mv src test
baz commit -s "move and rename a-link-2 file and src directory"

echo % move and add the moved file again
echo e > e
baz add e
baz commit -s "add e"
baz mv e f
echo ee > e
baz add e
baz commit -s "move e and recreate it again"
cd ..

echo % converting baz repo to Mercurial
hg convert baz-repo baz-repo-hg

baz register-archive -d baz@mercurial--convert

glog()
{
    hg glog --template '{rev} "{desc|firstline}" files: {files}\n' "$@"
}

echo % show graph log
glog -R baz-repo-hg
hg up -q -R baz-repo-hg
hg -R baz-repo-hg manifest --debug
hg -R baz-repo-hg log -r 5 -r 7 -C --debug | grep copies