branchcache: skip entries that are topological heads in the on disk file
In the majority of cases, topological heads are also branch heads. We have
efficient way to get the topological heads and efficient way to retrieve
their branch information. So there is little value in putting them in the branch
cache file explicitly. On the contrary, writing them explicitly tend to create
very large cache file that are inefficient to read and update.
So the branch cache v3 format is no longer including them. This changeset focus
on the format aspect and have no focus on the performance aspect. We will cover
that later.
#require no-windows
$ . "$TESTDIR/remotefilelog-library.sh"
$ hg init master
$ cd master
$ cat >> .hg/hgrc <<EOF
> [remotefilelog]
> server=True
> EOF
$ echo x > x
$ hg commit -qAm x
$ echo y > y
$ rm x
$ hg commit -qAm DxAy
$ echo yy > y
$ hg commit -qAm y
$ cd ..
$ hgcloneshallow ssh://user@dummy/master shallow -q
1 files fetched over 1 fetches - (1 misses, 0.00% hit ratio) over *s (glob)
# Set the prefetchdays config to zero so that all commits are prefetched
# no matter what their creation date is.
$ cd shallow
$ cat >> .hg/hgrc <<EOF
> [remotefilelog]
> prefetchdays=0
> EOF
$ cd ..
# Prefetch all data and repack
$ cd shallow
$ cat >> .hg/hgrc <<EOF
> [remotefilelog]
> bgprefetchrevs=all()
> EOF
$ hg prefetch
2 files fetched over 1 fetches - (2 misses, 0.00% hit ratio) over *s (glob)
$ hg repack
$ find $CACHEDIR | sort | grep -E ".datapack|.histpack"
$TESTTMP/hgcache/master/packs/7bcd2d90b99395ca43172a0dd24e18860b2902f9.histpack
$TESTTMP/hgcache/master/packs/dc8f8fdc76690ce27791ce9f53a18da379e50d37.datapack
# Ensure that all file versions were prefetched
$ hg debugdatapack `ls -ct $TESTTMP/hgcache/master/packs/*.datapack | head -n 1`
$TESTTMP/hgcache/master/packs/dc8f8fdc76690ce27791ce9f53a18da379e50d37:
x:
Node Delta Base Delta Length Blob Size
1406e7411862 000000000000 2 2
Total: 2 2 (0.0% bigger)
y:
Node Delta Base Delta Length Blob Size
50dbc4572b8e 000000000000 3 3
076f5e2225b3 50dbc4572b8e 14 2
Total: 17 5 (240.0% bigger)
# Test garbage collection during repack
$ cat >> .hg/hgrc <<EOF
> [remotefilelog]
> bgprefetchrevs=tip
> gcrepack=True
> nodettl=86400
> EOF
$ hg repack
$ find $CACHEDIR | sort | grep -E ".datapack|.histpack"
$TESTTMP/hgcache/master/packs/7bcd2d90b99395ca43172a0dd24e18860b2902f9.histpack
$TESTTMP/hgcache/master/packs/a4e1d094ec2aee8a08a4d6d95a13c634cc7d7394.datapack
# Ensure that file 'x' was garbage collected. It should be GCed because it is not in the keepset
# and is old (commit date is 0.0 in tests). Ensure that file 'y' is present as it is in the keepset.
$ hg debugdatapack `ls -ct $TESTTMP/hgcache/master/packs/*.datapack | head -n 1`
$TESTTMP/hgcache/master/packs/a4e1d094ec2aee8a08a4d6d95a13c634cc7d7394:
y:
Node Delta Base Delta Length Blob Size
50dbc4572b8e 000000000000 3 3
Total: 3 3 (0.0% bigger)
# Prefetch all data again and repack for later garbage collection
$ cat >> .hg/hgrc <<EOF
> [remotefilelog]
> bgprefetchrevs=all()
> EOF
$ hg prefetch
2 files fetched over 1 fetches - (2 misses, 0.00% hit ratio) over *s (glob)
$ hg repack
$ find $CACHEDIR | sort | grep -E ".datapack|.histpack"
$TESTTMP/hgcache/master/packs/7bcd2d90b99395ca43172a0dd24e18860b2902f9.histpack
$TESTTMP/hgcache/master/packs/dc8f8fdc76690ce27791ce9f53a18da379e50d37.datapack
# Ensure that all file versions were prefetched
$ hg debugdatapack `ls -ct $TESTTMP/hgcache/master/packs/*.datapack | head -n 1`
$TESTTMP/hgcache/master/packs/dc8f8fdc76690ce27791ce9f53a18da379e50d37:
x:
Node Delta Base Delta Length Blob Size
1406e7411862 000000000000 2 2
Total: 2 2 (0.0% bigger)
y:
Node Delta Base Delta Length Blob Size
50dbc4572b8e 000000000000 3 3
076f5e2225b3 50dbc4572b8e 14 2
Total: 17 5 (240.0% bigger)
# Test garbage collection during repack. Ensure that new files are not removed even though they are not in the keepset
# For the purposes of the test the TTL of a file is set to current time + 100 seconds. i.e. all commits in tests have
# a date of 1970 and therefore to prevent garbage collection we have to set nodettl to be farther from 1970 than we are now.
$ cat >> .hg/hgrc <<EOF
> [remotefilelog]
> bgprefetchrevs=
> nodettl=$(($(date +%s) + 100))
> EOF
$ hg repack
$ find $CACHEDIR | sort | grep -E ".datapack|.histpack"
$TESTTMP/hgcache/master/packs/7bcd2d90b99395ca43172a0dd24e18860b2902f9.histpack
$TESTTMP/hgcache/master/packs/dc8f8fdc76690ce27791ce9f53a18da379e50d37.datapack
# Ensure that all file versions were prefetched
$ hg debugdatapack `ls -ct $TESTTMP/hgcache/master/packs/*.datapack | head -n 1`
$TESTTMP/hgcache/master/packs/dc8f8fdc76690ce27791ce9f53a18da379e50d37:
x:
Node Delta Base Delta Length Blob Size
1406e7411862 000000000000 2 2
Total: 2 2 (0.0% bigger)
y:
Node Delta Base Delta Length Blob Size
50dbc4572b8e 000000000000 3 3
076f5e2225b3 50dbc4572b8e 14 2
Total: 17 5 (240.0% bigger)