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.
Test encode/decode filters
$ hg init repo
$ cd repo
$ cat > .hg/hgrc <<EOF
> [encode]
> not.gz = tr [:lower:] [:upper:]
> *.gz = gzip -d
> [decode]
> not.gz = tr [:upper:] [:lower:]
> *.gz = gzip
> EOF
$ echo "this is a test" | gzip > a.gz
$ echo "this is a test" > not.gz
$ hg add *
$ hg ci -m "test"
no changes
$ hg status
$ touch *
no changes
$ hg status
check contents in repo are encoded
$ hg debugdata a.gz 0
this is a test
$ hg debugdata not.gz 0
THIS IS A TEST
check committed content was decoded
$ gunzip < a.gz
this is a test
$ cat not.gz
this is a test
$ rm *
$ hg co -C
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
check decoding of our new working dir copy
$ gunzip < a.gz
this is a test
$ cat not.gz
this is a test
check hg cat operation
$ hg cat a.gz
this is a test
$ hg cat --decode a.gz | gunzip
this is a test
$ mkdir subdir
$ cd subdir
$ hg -R .. cat ../a.gz
this is a test
$ hg -R .. cat --decode ../a.gz | gunzip
this is a test
$ cd ..
check tempfile filter
$ hg cat a.gz --decode --config 'decode.*.gz=tempfile:gzip -c INFILE > OUTFILE' | gunzip
this is a test
$ hg cat a.gz --decode --config 'decode.*.gz=tempfile:sh -c "exit 1"'
abort: command '*' failed: exited with status 1 (glob)
[255]
$ cd ..