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 parents command
$ hg init repo
$ cd repo
no working directory
$ hg parents
$ echo a > a
$ echo b > b
$ hg ci -Amab -d '0 0'
adding a
adding b
$ echo a >> a
$ hg ci -Ama -d '1 0'
$ echo b >> b
$ hg ci -Amb -d '2 0'
$ echo c > c
$ hg ci -Amc -d '3 0'
adding c
$ hg up -C 1
1 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ echo d > c
$ hg ci -Amc2 -d '4 0'
adding c
created new head
$ hg up -C 3
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg parents
changeset: 3:02d851b7e549
user: test
date: Thu Jan 01 00:00:03 1970 +0000
summary: c
$ hg parents a
changeset: 1:d786049f033a
user: test
date: Thu Jan 01 00:00:01 1970 +0000
summary: a
hg parents c, single revision
$ hg parents c
changeset: 3:02d851b7e549
user: test
date: Thu Jan 01 00:00:03 1970 +0000
summary: c
$ hg parents -r 3 c
abort: 'c' not found in manifest!
[255]
$ hg parents -r 2
changeset: 1:d786049f033a
user: test
date: Thu Jan 01 00:00:01 1970 +0000
summary: a
$ hg parents -r 2 a
changeset: 1:d786049f033a
user: test
date: Thu Jan 01 00:00:01 1970 +0000
summary: a
$ hg parents -r 2 ../a
abort: ../a not under root '$TESTTMP/repo'
[255]
cd dir; hg parents -r 2 ../a
$ mkdir dir
$ cd dir
$ hg parents -r 2 ../a
changeset: 1:d786049f033a
user: test
date: Thu Jan 01 00:00:01 1970 +0000
summary: a
$ hg parents -r 2 path:a
changeset: 1:d786049f033a
user: test
date: Thu Jan 01 00:00:01 1970 +0000
summary: a
$ cd ..
$ hg parents -r 2 glob:a
abort: can only specify an explicit filename
[255]
merge working dir with 2 parents, hg parents c
$ HGMERGE=true hg merge
merging c
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg parents c
changeset: 3:02d851b7e549
user: test
date: Thu Jan 01 00:00:03 1970 +0000
summary: c
changeset: 4:48cee28d4b4e
tag: tip
parent: 1:d786049f033a
user: test
date: Thu Jan 01 00:00:04 1970 +0000
summary: c2
merge working dir with 1 parent, hg parents
$ hg up -C 2
0 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ HGMERGE=true hg merge -r 4
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg parents
changeset: 2:6cfac479f009
user: test
date: Thu Jan 01 00:00:02 1970 +0000
summary: b
changeset: 4:48cee28d4b4e
tag: tip
parent: 1:d786049f033a
user: test
date: Thu Jan 01 00:00:04 1970 +0000
summary: c2
merge working dir with 1 parent, hg parents c
$ hg parents c
changeset: 4:48cee28d4b4e
tag: tip
parent: 1:d786049f033a
user: test
date: Thu Jan 01 00:00:04 1970 +0000
summary: c2
$ cd ..