documentation: add some internals documentation about bid merge
This is an important algorithm that was only documented on the wiki so far.
Some update to the algorithm (and associated doc) is to expected in the future
since the bid merge algorithm is bug-ridden when it comes to file deletion comes
to play.
Differential Revision: https://phab.mercurial-scm.org/D8711
#testcases extra sidedata
#if extra
$ cat >> $HGRCPATH << EOF
> [experimental]
> copies.write-to=changeset-only
> copies.read-from=changeset-only
> [alias]
> changesetcopies = log -r . -T 'files: {files}
> {extras % "{ifcontains("files", key, "{key}: {value}\n")}"}
> {extras % "{ifcontains("copies", key, "{key}: {value}\n")}"}'
> EOF
#endif
#if sidedata
$ cat >> $HGRCPATH << EOF
> [format]
> exp-use-copies-side-data-changeset = yes
> EOF
#endif
$ cat >> $HGRCPATH << EOF
> [alias]
> showcopies = log -r . -T '{file_copies % "{source} -> {name}\n"}'
> [extensions]
> rebase =
> split =
> EOF
Check that copies are recorded correctly
$ hg init repo
$ cd repo
#if sidedata
$ hg debugformat -v
format-variant repo config default
fncache: yes yes yes
dotencode: yes yes yes
generaldelta: yes yes yes
sparserevlog: yes yes yes
sidedata: yes yes no
persistent-nodemap: no no no
copies-sdc: yes yes no
plain-cl-delta: yes yes yes
compression: zlib zlib zlib
compression-level: default default default
#else
$ hg debugformat -v
format-variant repo config default
fncache: yes yes yes
dotencode: yes yes yes
generaldelta: yes yes yes
sparserevlog: yes yes yes
sidedata: no no no
persistent-nodemap: no no no
copies-sdc: no no no
plain-cl-delta: yes yes yes
compression: zlib zlib zlib
compression-level: default default default
#endif
$ echo a > a
$ hg add a
$ hg ci -m initial
$ hg cp a b
$ hg cp a c
$ hg cp a d
$ hg ci -m 'copy a to b, c, and d'
#if extra
$ hg changesetcopies
files: b c d
filesadded: 0
1
2
p1copies: 0\x00a (esc)
1\x00a (esc)
2\x00a (esc)
#else
$ hg debugsidedata -c -v -- -1
2 sidedata entries
entry-0010 size 11
'0\x00a\n1\x00a\n2\x00a'
entry-0012 size 5
'0\n1\n2'
#endif
$ hg showcopies
a -> b
a -> c
a -> d
#if extra
$ hg showcopies --config experimental.copies.read-from=compatibility
a -> b
a -> c
a -> d
$ hg showcopies --config experimental.copies.read-from=filelog-only
#endif
Check that renames are recorded correctly
$ hg mv b b2
$ hg ci -m 'rename b to b2'
#if extra
$ hg changesetcopies
files: b b2
filesadded: 1
filesremoved: 0
p1copies: 1\x00b (esc)
#else
$ hg debugsidedata -c -v -- -1
3 sidedata entries
entry-0010 size 3
'1\x00b'
entry-0012 size 1
'1'
entry-0013 size 1
'0'
#endif
$ hg showcopies
b -> b2
Rename onto existing file. This should get recorded in the changeset files list and in the extras,
even though there is no filelog entry.
$ hg cp b2 c --force
$ hg st --copies
M c
b2
#if extra
$ hg debugindex c
rev linkrev nodeid p1 p2
0 1 b789fdd96dc2 000000000000 000000000000
#else
$ hg debugindex c
rev linkrev nodeid p1 p2
0 1 37d9b5d994ea 000000000000 000000000000
#endif
$ hg ci -m 'move b onto d'
#if extra
$ hg changesetcopies
files: c
p1copies: 0\x00b2 (esc)
#else
$ hg debugsidedata -c -v -- -1
1 sidedata entries
entry-0010 size 4
'0\x00b2'
#endif
$ hg showcopies
b2 -> c
#if extra
$ hg debugindex c
rev linkrev nodeid p1 p2
0 1 b789fdd96dc2 000000000000 000000000000
#else
$ hg debugindex c
rev linkrev nodeid p1 p2
0 1 37d9b5d994ea 000000000000 000000000000
1 3 029625640347 000000000000 000000000000
#endif
Create a merge commit with copying done during merge.
$ hg co 0
0 files updated, 0 files merged, 3 files removed, 0 files unresolved
$ hg cp a e
$ hg cp a f
$ hg ci -m 'copy a to e and f'
created new head
$ hg merge 3
3 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
File 'a' exists on both sides, so 'g' could be recorded as being from p1 or p2, but we currently
always record it as being from p1
$ hg cp a g
File 'd' exists only in p2, so 'h' should be from p2
$ hg cp d h
File 'f' exists only in p1, so 'i' should be from p1
$ hg cp f i
$ hg ci -m 'merge'
#if extra
$ hg changesetcopies
files: g h i
filesadded: 0
1
2
p1copies: 0\x00a (esc)
2\x00f (esc)
p2copies: 1\x00d (esc)
#else
$ hg debugsidedata -c -v -- -1
3 sidedata entries
entry-0010 size 7
'0\x00a\n2\x00f'
entry-0011 size 3
'1\x00d'
entry-0012 size 5
'0\n1\n2'
#endif
$ hg showcopies
a -> g
d -> h
f -> i
Test writing to both changeset and filelog
$ hg cp a j
#if extra
$ hg ci -m 'copy a to j' --config experimental.copies.write-to=compatibility
$ hg changesetcopies
files: j
filesadded: 0
filesremoved:
p1copies: 0\x00a (esc)
p2copies:
#else
$ hg ci -m 'copy a to j'
$ hg debugsidedata -c -v -- -1
2 sidedata entries
entry-0010 size 3
'0\x00a'
entry-0012 size 1
'0'
#endif
$ hg debugdata j 0
\x01 (esc)
copy: a
copyrev: b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3
\x01 (esc)
a
$ hg showcopies
a -> j
$ hg showcopies --config experimental.copies.read-from=compatibility
a -> j
$ hg showcopies --config experimental.copies.read-from=filelog-only
a -> j
Existing copy information in the changeset gets removed on amend and writing
copy information on to the filelog
#if extra
$ hg ci --amend -m 'copy a to j, v2' \
> --config experimental.copies.write-to=filelog-only
saved backup bundle to $TESTTMP/repo/.hg/strip-backup/*-*-amend.hg (glob)
$ hg changesetcopies
files: j
#else
$ hg ci --amend -m 'copy a to j, v2'
saved backup bundle to $TESTTMP/repo/.hg/strip-backup/*-*-amend.hg (glob)
$ hg debugsidedata -c -v -- -1
2 sidedata entries
entry-0010 size 3
'0\x00a'
entry-0012 size 1
'0'
#endif
$ hg showcopies --config experimental.copies.read-from=filelog-only
a -> j
The entries should be written to extras even if they're empty (so the client
won't have to fall back to reading from filelogs)
$ echo x >> j
#if extra
$ hg ci -m 'modify j' --config experimental.copies.write-to=compatibility
$ hg changesetcopies
files: j
filesadded:
filesremoved:
p1copies:
p2copies:
#else
$ hg ci -m 'modify j'
$ hg debugsidedata -c -v -- -1
#endif
Test writing only to filelog
$ hg cp a k
#if extra
$ hg ci -m 'copy a to k' --config experimental.copies.write-to=filelog-only
$ hg changesetcopies
files: k
#else
$ hg ci -m 'copy a to k'
$ hg debugsidedata -c -v -- -1
2 sidedata entries
entry-0010 size 3
'0\x00a'
entry-0012 size 1
'0'
#endif
$ hg debugdata k 0
\x01 (esc)
copy: a
copyrev: b789fdd96dc2f3bd229c1dd8eedf0fc60e2b68e3
\x01 (esc)
a
#if extra
$ hg showcopies
$ hg showcopies --config experimental.copies.read-from=compatibility
a -> k
$ hg showcopies --config experimental.copies.read-from=filelog-only
a -> k
#else
$ hg showcopies
a -> k
#endif
$ cd ..
Test rebasing a commit with copy information
$ hg init rebase-rename
$ cd rebase-rename
$ echo a > a
$ hg ci -Aqm 'add a'
$ echo a2 > a
$ hg ci -m 'modify a'
$ hg co -q 0
$ hg mv a b
$ hg ci -qm 'rename a to b'
$ hg rebase -d 1 --config rebase.experimental.inmemory=yes
rebasing 2:* "rename a to b" (tip) (glob)
merging a and b to b
saved backup bundle to $TESTTMP/rebase-rename/.hg/strip-backup/*-*-rebase.hg (glob)
$ hg st --change . --copies
A b
a
R a
$ cd ..
Test splitting a commit
$ hg init split
$ cd split
$ echo a > a
$ echo b > b
$ hg ci -Aqm 'add a and b'
$ echo a2 > a
$ hg mv b c
$ hg ci -m 'modify a, move b to c'
$ hg --config ui.interactive=yes split <<EOF
> y
> y
> n
> y
> EOF
diff --git a/a b/a
1 hunks, 1 lines changed
examine changes to 'a'?
(enter ? for help) [Ynesfdaq?] y
@@ -1,1 +1,1 @@
-a
+a2
record this change to 'a'?
(enter ? for help) [Ynesfdaq?] y
diff --git a/b b/c
rename from b
rename to c
examine changes to 'b' and 'c'?
(enter ? for help) [Ynesfdaq?] n
created new head
diff --git a/b b/c
rename from b
rename to c
examine changes to 'b' and 'c'?
(enter ? for help) [Ynesfdaq?] y
saved backup bundle to $TESTTMP/split/.hg/strip-backup/*-*-split.hg (glob)
$ cd ..
Test committing half a rename
$ hg init partial
$ cd partial
$ echo a > a
$ hg ci -Aqm 'add a'
$ hg mv a b
$ hg ci -m 'remove a' a
#if sidedata
Test upgrading/downgrading to sidedata storage
==============================================
downgrading (keeping some sidedata)
$ hg debugformat -v
format-variant repo config default
fncache: yes yes yes
dotencode: yes yes yes
generaldelta: yes yes yes
sparserevlog: yes yes yes
sidedata: yes yes no
persistent-nodemap: no no no
copies-sdc: yes yes no
plain-cl-delta: yes yes yes
compression: zlib zlib zlib
compression-level: default default default
$ hg debugsidedata -c -- 0
1 sidedata entries
entry-0012 size 1
$ hg debugsidedata -c -- 1
1 sidedata entries
entry-0013 size 1
$ hg debugsidedata -m -- 0
$ cat << EOF > .hg/hgrc
> [format]
> exp-use-side-data = yes
> exp-use-copies-side-data-changeset = no
> EOF
$ hg debugupgraderepo --run --quiet --no-backup > /dev/null
$ hg debugformat -v
format-variant repo config default
fncache: yes yes yes
dotencode: yes yes yes
generaldelta: yes yes yes
sparserevlog: yes yes yes
sidedata: yes yes no
persistent-nodemap: no no no
copies-sdc: no no no
plain-cl-delta: yes yes yes
compression: zlib zlib zlib
compression-level: default default default
$ hg debugsidedata -c -- 0
$ hg debugsidedata -c -- 1
$ hg debugsidedata -m -- 0
upgrading
$ cat << EOF > .hg/hgrc
> [format]
> exp-use-copies-side-data-changeset = yes
> EOF
$ hg debugupgraderepo --run --quiet --no-backup > /dev/null
$ hg debugformat -v
format-variant repo config default
fncache: yes yes yes
dotencode: yes yes yes
generaldelta: yes yes yes
sparserevlog: yes yes yes
sidedata: yes yes no
persistent-nodemap: no no no
copies-sdc: yes yes no
plain-cl-delta: yes yes yes
compression: zlib zlib zlib
compression-level: default default default
$ hg debugsidedata -c -- 0
1 sidedata entries
entry-0012 size 1
$ hg debugsidedata -c -- 1
1 sidedata entries
entry-0013 size 1
$ hg debugsidedata -m -- 0
#endif
$ cd ..