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
$ hg init
Revision 0:
$ echo "unchanged" > unchanged
$ echo "remove me" > remove
$ echo "copy me" > copy
$ echo "move me" > move
$ for i in 1 2 3 4 5 6 7 8 9; do
> echo "merge ok $i" >> zzz1_merge_ok
> done
$ echo "merge bad" > zzz2_merge_bad
$ hg ci -Am "revision 0"
adding copy
adding move
adding remove
adding unchanged
adding zzz1_merge_ok
adding zzz2_merge_bad
Revision 1:
$ hg rm remove
$ hg mv move moved
$ hg cp copy copied
$ echo "added" > added
$ hg add added
$ echo "new first line" > zzz1_merge_ok
$ hg cat zzz1_merge_ok >> zzz1_merge_ok
$ echo "new last line" >> zzz2_merge_bad
$ hg ci -m "revision 1"
Local changes to revision 0:
$ hg co 0
4 files updated, 0 files merged, 3 files removed, 0 files unresolved
$ echo "new last line" >> zzz1_merge_ok
$ echo "another last line" >> zzz2_merge_bad
$ hg diff --nodates | grep "^[+-][^<>]"
--- a/zzz1_merge_ok
+++ b/zzz1_merge_ok
+new last line
--- a/zzz2_merge_bad
+++ b/zzz2_merge_bad
+another last line
$ hg st
M zzz1_merge_ok
M zzz2_merge_bad
Local merge with bad merge tool:
$ HGMERGE=false hg co
merging zzz1_merge_ok
merging zzz2_merge_bad
merging zzz2_merge_bad failed!
3 files updated, 1 files merged, 2 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges
[1]
$ hg resolve -m
(no more unresolved files)
$ hg co 0
merging zzz1_merge_ok
merging zzz2_merge_bad
warning: conflicts while merging zzz2_merge_bad! (edit, then use 'hg resolve --mark')
2 files updated, 1 files merged, 3 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges
[1]
$ hg diff --nodates | grep "^[+-][^<>]"
--- a/zzz1_merge_ok
+++ b/zzz1_merge_ok
+new last line
--- a/zzz2_merge_bad
+++ b/zzz2_merge_bad
+another last line
+=======
$ hg st
M zzz1_merge_ok
M zzz2_merge_bad
? zzz2_merge_bad.orig
Local merge with conflicts:
$ hg resolve -m
(no more unresolved files)
$ hg co
merging zzz1_merge_ok
merging zzz2_merge_bad
warning: conflicts while merging zzz2_merge_bad! (edit, then use 'hg resolve --mark')
3 files updated, 1 files merged, 2 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges
[1]
$ hg resolve -m
(no more unresolved files)
$ hg co 0 --config 'ui.origbackuppath=.hg/origbackups'
merging zzz1_merge_ok
merging zzz2_merge_bad
warning: conflicts while merging zzz2_merge_bad! (edit, then use 'hg resolve --mark')
2 files updated, 1 files merged, 3 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges
[1]
Are orig files from the last commit where we want them?
$ ls .hg/origbackups
zzz2_merge_bad
$ hg diff --nodates | grep "^[+-][^<>]"
--- a/zzz1_merge_ok
+++ b/zzz1_merge_ok
+new last line
--- a/zzz2_merge_bad
+++ b/zzz2_merge_bad
+another last line
+=======
+=======
+new last line
+=======
$ hg st
M zzz1_merge_ok
M zzz2_merge_bad
? zzz2_merge_bad.orig
Local merge without conflicts:
$ hg revert zzz2_merge_bad
$ hg resolve -m
(no more unresolved files)
$ hg co
merging zzz1_merge_ok
4 files updated, 1 files merged, 2 files removed, 0 files unresolved
$ hg diff --nodates | grep "^[+-][^<>]"
--- a/zzz1_merge_ok
+++ b/zzz1_merge_ok
+new last line
$ hg st
M zzz1_merge_ok
? zzz2_merge_bad.orig