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
$ cat >> $HGRCPATH << EOF
> [diff]
> git=1
> [extensions]
> absorb=
> EOF
$ sedi() { # workaround check-code
> pattern="$1"
> shift
> for i in "$@"; do
> sed "$pattern" "$i" > "$i".tmp
> mv "$i".tmp "$i"
> done
> }
rename a to b, then b to a
$ hg init repo1
$ cd repo1
$ echo 1 > a
$ hg ci -A a -m 1
$ hg mv a b
$ echo 2 >> b
$ hg ci -m 2
$ hg mv b a
$ echo 3 >> a
$ hg ci -m 3
$ hg annotate -ncf a
0 eff892de26ec a: 1
1 bf56e1f4f857 b: 2
2 0b888b00216c a: 3
$ sedi 's/$/a/' a
$ hg absorb -apq
showing changes for a
@@ -0,3 +0,3 @@
eff892d -1
bf56e1f -2
0b888b0 -3
eff892d +1a
bf56e1f +2a
0b888b0 +3a
3 changesets affected
0b888b0 3
bf56e1f 2
eff892d 1
$ hg status
$ hg annotate -ncf a
0 5d1c5620e6f2 a: 1a
1 9a14ffe67ae9 b: 2a
2 9191d121a268 a: 3a
when the first changeset is public
$ hg phase --public -r 0
$ sedi 's/a/A/' a
$ hg absorb -apq
showing changes for a
@@ -0,3 +0,3 @@
-1a
9a14ffe -2a
9191d12 -3a
+1A
9a14ffe +2A
9191d12 +3A
2 changesets affected
9191d12 3
9a14ffe 2
$ hg diff
diff --git a/a b/a
--- a/a
+++ b/a
@@ -1,3 +1,3 @@
-1a
+1A
2A
3A
copy a to b
$ cd ..
$ hg init repo2
$ cd repo2
$ echo 1 > a
$ hg ci -A a -m 1
$ hg cp a b
$ echo 2 >> b
$ hg ci -m 2
$ hg log -T '{rev}:{node|short} {desc}\n'
1:17b72129ab68 2
0:eff892de26ec 1
$ sedi 's/$/a/' a
$ sedi 's/$/b/' b
$ hg absorb -apq
showing changes for a
@@ -0,1 +0,1 @@
eff892d -1
eff892d +1a
showing changes for b
@@ -0,2 +0,2 @@
-1
17b7212 -2
+1b
17b7212 +2b
2 changesets affected
17b7212 2
eff892d 1
$ hg diff
diff --git a/b b/b
--- a/b
+++ b/b
@@ -1,2 +1,2 @@
-1
+1b
2b
copy b to a
$ cd ..
$ hg init repo3
$ cd repo3
$ echo 1 > b
$ hg ci -A b -m 1
$ hg cp b a
$ echo 2 >> a
$ hg ci -m 2
$ hg log -T '{rev}:{node|short} {desc}\n'
1:e62c256d8b24 2
0:55105f940d5c 1
$ sedi 's/$/a/' a
$ sedi 's/$/a/' b
$ hg absorb -apq
showing changes for a
@@ -0,2 +0,2 @@
-1
e62c256 -2
+1a
e62c256 +2a
showing changes for b
@@ -0,1 +0,1 @@
55105f9 -1
55105f9 +1a
2 changesets affected
e62c256 2
55105f9 1
$ hg diff
diff --git a/a b/a
--- a/a
+++ b/a
@@ -1,2 +1,2 @@
-1
+1a
2a
"move" b to both a and c, follow a - sorted alphabetically
$ cd ..
$ hg init repo4
$ cd repo4
$ echo 1 > b
$ hg ci -A b -m 1
$ hg cp b a
$ hg cp b c
$ hg rm b
$ echo 2 >> a
$ echo 3 >> c
$ hg commit -m cp
$ hg log -T '{rev}:{node|short} {desc}\n'
1:366daad8e679 cp
0:55105f940d5c 1
$ sedi 's/$/a/' a
$ sedi 's/$/c/' c
$ hg absorb -apq
showing changes for a
@@ -0,2 +0,2 @@
55105f9 -1
366daad -2
55105f9 +1a
366daad +2a
showing changes for c
@@ -0,2 +0,2 @@
-1
366daad -3
+1c
366daad +3c
2 changesets affected
366daad cp
55105f9 1
$ hg log -G -p -T '{rev}:{node|short} {desc}\n'
@ 1:70606019f91b cp
| diff --git a/b b/a
| rename from b
| rename to a
| --- a/b
| +++ b/a
| @@ -1,1 +1,2 @@
| 1a
| +2a
| diff --git a/b b/c
| copy from b
| copy to c
| --- a/b
| +++ b/c
| @@ -1,1 +1,2 @@
| -1a
| +1
| +3c
|
o 0:bfb67c3539c1 1
diff --git a/b b/b
new file mode 100644
--- /dev/null
+++ b/b
@@ -0,0 +1,1 @@
+1a
run absorb again would apply the change to c
$ hg absorb -apq
showing changes for c
@@ -0,1 +0,1 @@
7060601 -1
7060601 +1c
1 changesets affected
7060601 cp
$ hg log -G -p -T '{rev}:{node|short} {desc}\n'
@ 1:8bd536cce368 cp
| diff --git a/b b/a
| rename from b
| rename to a
| --- a/b
| +++ b/a
| @@ -1,1 +1,2 @@
| 1a
| +2a
| diff --git a/b b/c
| copy from b
| copy to c
| --- a/b
| +++ b/c
| @@ -1,1 +1,2 @@
| -1a
| +1c
| +3c
|
o 0:bfb67c3539c1 1
diff --git a/b b/b
new file mode 100644
--- /dev/null
+++ b/b
@@ -0,0 +1,1 @@
+1a
"move" b to a, c and d, follow d if a gets renamed to e, and c is deleted
$ cd ..
$ hg init repo5
$ cd repo5
$ echo 1 > b
$ hg ci -A b -m 1
$ hg cp b a
$ hg cp b c
$ hg cp b d
$ hg rm b
$ echo 2 >> a
$ echo 3 >> c
$ echo 4 >> d
$ hg commit -m cp
$ hg mv a e
$ hg rm c
$ hg commit -m mv
$ hg log -T '{rev}:{node|short} {desc}\n'
2:49911557c471 mv
1:7bc3d43ede83 cp
0:55105f940d5c 1
$ sedi 's/$/e/' e
$ sedi 's/$/d/' d
$ hg absorb -apq
showing changes for d
@@ -0,2 +0,2 @@
55105f9 -1
7bc3d43 -4
55105f9 +1d
7bc3d43 +4d
showing changes for e
@@ -0,2 +0,2 @@
-1
7bc3d43 -2
+1e
7bc3d43 +2e
2 changesets affected
7bc3d43 cp
55105f9 1
$ hg diff
diff --git a/e b/e
--- a/e
+++ b/e
@@ -1,2 +1,2 @@
-1
+1e
2e
$ hg log -G -p -T '{rev}:{node|short} {desc}\n'
@ 2:34be9b0c786e mv
| diff --git a/c b/c
| deleted file mode 100644
| --- a/c
| +++ /dev/null
| @@ -1,2 +0,0 @@
| -1
| -3
| diff --git a/a b/e
| rename from a
| rename to e
|
o 1:13e56db5948d cp
| diff --git a/b b/a
| rename from b
| rename to a
| --- a/b
| +++ b/a
| @@ -1,1 +1,2 @@
| -1d
| +1
| +2e
| diff --git a/b b/c
| copy from b
| copy to c
| --- a/b
| +++ b/c
| @@ -1,1 +1,2 @@
| -1d
| +1
| +3
| diff --git a/b b/d
| copy from b
| copy to d
| --- a/b
| +++ b/d
| @@ -1,1 +1,2 @@
| 1d
| +4d
|
o 0:0037613a5dc6 1
diff --git a/b b/b
new file mode 100644
--- /dev/null
+++ b/b
@@ -0,0 +1,1 @@
+1d