rust-nodemap: accounting for dead blocks
By the very append-only nature of the `NodeTree`, inserting
new blocks has the effect of making some of the older ones
useless as they become unreachable.
Therefore some automatic housekeeping will need to be provided.
This is standard procedure in the word of databases, under names
such as "repack" or "vacuum".
The new `masked_readonly_blocks()` will provide callers with
useful information to decide if the nodetree is ripe for
repacking, but all the `NodeTree` can provide is how many
blocks have been masked in the currently mutable part. Analysing
the readonly part would be way too long to do it for each
transaction and defeat the whole purpose of nodemap persistence.
Serializing callers (from the Python layer) will get this figure
before each extraction and maintain an aggregate counter of
unreachable blocks separately.
Note: at this point, the most efficient repacking is just to restart
afresh with a full rescan.
Differential Revision: https://phab.mercurial-scm.org/D8097
Test histedit extension: Merge tools
====================================
Initialization
---------------
$ . "$TESTDIR/histedit-helpers.sh"
$ cat >> $HGRCPATH <<EOF
> [alias]
> logt = log --template '{rev}:{node|short} {desc|firstline}\n'
> [extensions]
> histedit=
> mockmakedate = $TESTDIR/mockmakedate.py
> [ui]
> pre-merge-tool-output-template='pre-merge message for {node}\n'
> EOF
Merge conflict
--------------
$ hg init r
$ cd r
$ echo foo > file
$ hg add file
$ hg ci -m "First" -d "1 0"
$ echo bar > file
$ hg ci -m "Second" -d "2 0"
$ hg logt --graph
@ 1:2aa920f62fb9 Second
|
o 0:7181f42b8fca First
Invert the order of the commits, but fail the merge.
$ hg histedit --config ui.merge=false --commands - 2>&1 <<EOF | fixbundle
> pick 2aa920f62fb9 Second
> pick 7181f42b8fca First
> EOF
merging file
pre-merge message for b90fa2e91a6d11013945a5f684be45b84a8ca6ec
merging file failed!
Fix up the change (pick 7181f42b8fca)
(hg histedit --continue to resume)
$ hg histedit --abort | fixbundle
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
Invert the order of the commits, and pretend the merge succeeded.
$ hg histedit --config ui.merge=true --commands - 2>&1 <<EOF | fixbundle
> pick 2aa920f62fb9 Second
> pick 7181f42b8fca First
> EOF
merging file
pre-merge message for b90fa2e91a6d11013945a5f684be45b84a8ca6ec
7181f42b8fca: skipping changeset (no changes)