changing-files: rework the way we store changed files in side-data
We need to store new data so this is a good opportunity to rework this fully.
1) We directly store the list of affected file in the side data:
* This avoid having to fetch and parse the `files` list in the revision in
addition to the sidedata. Making the data more self sufficient.
* This work around situation where that `files` field contains wrong
information, and open the way to other bug fixing (eg:
issue6219)
* The format (fixed initial index, sorted files) allow for fast lookup of
filename within the structure.
* This unify the storage of affected files and copies sources and destination,
limiting the number filename stored redundantly.
* This prepare for the fact we should drop the `files` as soon as we do any
change affecting the revision schema.
* This rely on compression to avoid a significant increase of the changelog.d.
More testing on this will be done before we freeze the final format.
2) We can store additional data:
* The new "merged" field,
* A future "salvaged" set recording files that might have been deleted but have
were still present in the final result.
Differential Revision: https://phab.mercurial-scm.org/D9090
$ hg init a
$ cd a
$ hg diff inexistent1 inexistent2
inexistent1: * (glob)
inexistent2: * (glob)
$ echo bar > foo
$ hg add foo
$ hg ci -m 'add foo'
$ echo foobar > foo
$ hg ci -m 'change foo'
$ hg --quiet diff -r 0 -r 1
diff -r a99fb63adac3 -r 9b8568d3af2f foo
--- a/foo Thu Jan 01 00:00:00 1970 +0000
+++ b/foo Thu Jan 01 00:00:00 1970 +0000
@@ -1,1 +1,1 @@
-bar
+foobar
$ hg diff -r 0 -r 1
diff -r a99fb63adac3 -r 9b8568d3af2f foo
--- a/foo Thu Jan 01 00:00:00 1970 +0000
+++ b/foo Thu Jan 01 00:00:00 1970 +0000
@@ -1,1 +1,1 @@
-bar
+foobar
$ hg --verbose diff -r 0 -r 1
diff -r a99fb63adac3 -r 9b8568d3af2f foo
--- a/foo Thu Jan 01 00:00:00 1970 +0000
+++ b/foo Thu Jan 01 00:00:00 1970 +0000
@@ -1,1 +1,1 @@
-bar
+foobar
$ hg --debug diff -r 0 -r 1
diff -r a99fb63adac3f31816a22f665bc3b7a7655b30f4 -r 9b8568d3af2f1749445eef03aede868a6f39f210 foo
--- a/foo Thu Jan 01 00:00:00 1970 +0000
+++ b/foo Thu Jan 01 00:00:00 1970 +0000
@@ -1,1 +1,1 @@
-bar
+foobar
$ cd ..