discovery-helper: use reflink copy if available
A reflink copy will copy the files "as usual" but keep using the same data block
underneath. This is only supported by "copy on write" file system like btrfs or
zfs.
This will achieve similar performance that the existing hardlink clone that
Mercurial performs with the same initial space saving. However, it will behave
better on revlogs start being touch by strip. Instead of duplicating all data in
the touched revlogs, only the block actually affected by the strip will be
duplicated. This save a lot of space when building many variants of large
repositories.
The --reflink=always flag make sure the `cp` call fails if reflink copies are
not supported. Falling back to local clone.
#require sqlite
$ cat >> $HGRCPATH <<EOF
> [extensions]
> sqlitestore =
> EOF
New repo should not use SQLite by default
$ hg init empty-no-sqlite
$ cat empty-no-sqlite/.hg/requires
dotencode
fncache
generaldelta
revlogv1
sparserevlog
store
storage.new-repo-backend=sqlite is recognized
$ hg --config storage.new-repo-backend=sqlite init empty-sqlite
$ cat empty-sqlite/.hg/requires
dotencode
exp-sqlite-001
exp-sqlite-comp-001=zstd (zstd !)
exp-sqlite-comp-001=$BUNDLE2_COMPRESSIONS$ (no-zstd !)
fncache
generaldelta
revlogv1
sparserevlog
store
$ cat >> $HGRCPATH << EOF
> [storage]
> new-repo-backend = sqlite
> EOF
Can force compression to zlib
$ hg --config storage.sqlite.compression=zlib init empty-zlib
$ cat empty-zlib/.hg/requires
dotencode
exp-sqlite-001
exp-sqlite-comp-001=$BUNDLE2_COMPRESSIONS$
fncache
generaldelta
revlogv1
sparserevlog
store
Can force compression to none
$ hg --config storage.sqlite.compression=none init empty-none
$ cat empty-none/.hg/requires
dotencode
exp-sqlite-001
exp-sqlite-comp-001=none
fncache
generaldelta
revlogv1
sparserevlog
store
Can make a local commit
$ hg init local-commit
$ cd local-commit
$ echo 0 > foo
$ hg commit -A -m initial
adding foo
That results in a row being inserted into various tables
$ sqlite3 .hg/store/db.sqlite -init /dev/null << EOF
> SELECT * FROM filepath;
> EOF
1|foo
$ sqlite3 .hg/store/db.sqlite -init /dev/null << EOF
> SELECT * FROM fileindex;
> EOF
1|1|0|-1|-1|0|0|1||6/\xef(L\xe2\xca\x02\xae\xcc\x8d\xe6\xd5\xe8\xa1\xc3\xaf\x05V\xfe (esc)
$ sqlite3 .hg/store/db.sqlite -init /dev/null << EOF
> SELECT * FROM delta;
> EOF
1|1| \xd2\xaf\x8d\xd2"\x01\xdd\x8dH\xe5\xdc\xfc\xae\xd2\x81\xff\x94"\xc7|0 (esc)
Tracking multiple files works
$ echo 1 > bar
$ hg commit -A -m 'add bar'
adding bar
$ sqlite3 .hg/store/db.sqlite -init /dev/null << EOF
> SELECT * FROM filedata ORDER BY id ASC;
> EOF
1|1|foo|0|6/\xef(L\xe2\xca\x02\xae\xcc\x8d\xe6\xd5\xe8\xa1\xc3\xaf\x05V\xfe|-1|-1|0|0|1| (esc)
2|2|bar|0|\xb8\xe0/d3s\x80!\xa0e\xf9Au\xc7\xcd#\xdb_\x05\xbe|-1|-1|1|0|2| (esc)
Multiple revisions of a file works
$ echo a >> foo
$ hg commit -m 'modify foo'
$ sqlite3 .hg/store/db.sqlite -init /dev/null << EOF
> SELECT * FROM filedata ORDER BY id ASC;
> EOF
1|1|foo|0|6/\xef(L\xe2\xca\x02\xae\xcc\x8d\xe6\xd5\xe8\xa1\xc3\xaf\x05V\xfe|-1|-1|0|0|1| (esc)
2|2|bar|0|\xb8\xe0/d3s\x80!\xa0e\xf9Au\xc7\xcd#\xdb_\x05\xbe|-1|-1|1|0|2| (esc)
3|1|foo|1|\xdd\xb3V\xcd\xde1p@\xf7\x8e\x90\xb8*\x8b,\xe9\x0e\xd6j+|0|-1|2|0|3|1 (esc)
$ cd ..