streamclone: define first iteration of version 2 of stream format
(This patch is based on a first draft from Gregory Szorc, with deeper rework)
Version 1 of the stream clone format was invented many years ago and suffers
from a few deficiencies:
1) Filenames are stored in store-encoded (on filesystem) form rather than in
their internal form. This makes future compatibility with new store
filename encodings more difficult.
2) File entry "headers" consist of a newline of the file name followed by the
string file size. Converting strings to integers is avoidable overhead. We
can't store filenames with newlines (manifests have this limitation as
well, so it isn't a major concern). But the big concern here is the
necessity for readline(). Scanning for newlines means reading ahead and
that means extra buffer allocations and slicing (in Python) and this makes
performance suffer.
3) Filenames aren't compressed optimally. Filenames should be compressed well
since there is a lot of repeated data. However, since they are scattered
all over the stream (with revlog data in between), they typically fall
outside the window size of the compressor and don't compress.
4) It can only exchange stored based content, being able to exchange caches
too would be nice.
5) It is limited to a stream-based protocol and isn't suitable for an on-disk
format for general repository reading because the offset of individual file
entries requires scanning the entire file to find file records.
As part of enabling streaming clones to work in bundle2, #2 proved to have a
significant negative impact on performance. Since bundle2 provides the
opportunity to start fresh, Gregory Szorc figured he would take the
opportunity to invent a new streaming clone data format.
The new format devised in this series addresses #1, #2, and #4. It punts on #3
because it was complex without yielding a significant gain and on #5 because
devising a new store format that "packs" multiple revlogs into a single
"packed revlog" is massive scope bloat. However, this v2 format might be
suitable for streaming into a "packed revlog" with minimal processing. If it
works, great. If not, we can always invent stream format when it is needed.
This patch only introduces the bases of the format. We'll get it usable through
bundle2 first, then we'll extend the format in future patches to bring it to its
full potential (especially #4).
Criss cross merging
$ hg init criss-cross
$ cd criss-cross
$ echo '0 base' > f1
$ echo '0 base' > f2
$ hg ci -Aqm '0 base'
$ echo '1 first change' > f1
$ hg ci -m '1 first change f1'
$ hg up -qr0
$ echo '2 first change' > f2
$ mkdir d1
$ echo '0 base' > d1/f3
$ echo '0 base' > d1/f4
$ hg add -q d1
$ hg ci -qm '2 first change f2'
$ hg merge -qr 1
$ hg rm d1/f3
$ hg mv -q d1 d2
$ hg ci -m '3 merge'
$ hg up -qr2
$ hg merge -qr1
$ hg ci -qm '4 merge'
$ echo '5 second change' > f1
$ hg ci -m '5 second change f1'
$ hg up -r3
2 files updated, 0 files merged, 2 files removed, 0 files unresolved
$ echo '6 second change' > f2
$ hg ci -m '6 second change f2'
$ hg log -G
@ changeset: 6:6373bbfdae1d
| tag: tip
| parent: 3:c202c8af058d
| user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: 6 second change f2
|
| o changeset: 5:e673248094b1
| | user: test
| | date: Thu Jan 01 00:00:00 1970 +0000
| | summary: 5 second change f1
| |
| o changeset: 4:177f58377c06
| |\ parent: 2:d1d156401c1b
| | | parent: 1:0f6b37dbe527
| | | user: test
| | | date: Thu Jan 01 00:00:00 1970 +0000
| | | summary: 4 merge
| | |
o---+ changeset: 3:c202c8af058d
| | | parent: 2:d1d156401c1b
|/ / parent: 1:0f6b37dbe527
| | user: test
| | date: Thu Jan 01 00:00:00 1970 +0000
| | summary: 3 merge
| |
| o changeset: 2:d1d156401c1b
| | parent: 0:40494bf2444c
| | user: test
| | date: Thu Jan 01 00:00:00 1970 +0000
| | summary: 2 first change f2
| |
o | changeset: 1:0f6b37dbe527
|/ user: test
| date: Thu Jan 01 00:00:00 1970 +0000
| summary: 1 first change f1
|
o changeset: 0:40494bf2444c
user: test
date: Thu Jan 01 00:00:00 1970 +0000
summary: 0 base
$ hg merge -v --debug --tool internal:dump 5 --config merge.preferancestor='!'
note: using 0f6b37dbe527 as ancestor of 6373bbfdae1d and e673248094b1
alternatively, use --config merge.preferancestor=d1d156401c1b
searching for copies back to rev 3
unmatched files in local:
d2/f4
unmatched files in other:
d1/f3
d1/f4
all copies found (* = to merge, ! = divergent, % = renamed and deleted):
src: 'd1/f4' -> dst: 'd2/f4'
checking for directory renames
discovered dir src: 'd1/' -> dst: 'd2/'
pending file src: 'd1/f3' -> dst: 'd2/f3'
pending file src: 'd1/f4' -> dst: 'd2/f4'
resolving manifests
branchmerge: True, force: False, partial: False
ancestor: 0f6b37dbe527, local: 6373bbfdae1d+, remote: e673248094b1
preserving d2/f4 for resolve of d2/f4
preserving f2 for resolve of f2
f1: remote is newer -> g
getting f1
d2/f3: local directory rename - get from d1/f3 -> dg
getting d1/f3 to d2/f3
d2/f4: local directory rename, both created -> m (premerge)
f2: versions differ -> m (premerge)
picked tool ':dump' for f2 (binary False symlink False changedelete False)
merging f2
my f2@6373bbfdae1d+ other f2@e673248094b1 ancestor f2@0f6b37dbe527
f2: versions differ -> m (merge)
picked tool ':dump' for f2 (binary False symlink False changedelete False)
my f2@6373bbfdae1d+ other f2@e673248094b1 ancestor f2@0f6b37dbe527
3 files updated, 0 files merged, 0 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon
[1]
$ f --dump --recurse *
d2: directory with 2 files
d2/f3:
>>>
0 base
<<<
d2/f4:
>>>
0 base
<<<
f1:
>>>
5 second change
<<<
f2:
>>>
6 second change
<<<
f2.base:
>>>
0 base
<<<
f2.local:
>>>
6 second change
<<<
f2.orig:
>>>
6 second change
<<<
f2.other:
>>>
2 first change
<<<
$ hg up -qC .
$ hg merge -v --tool internal:dump 5 --config merge.preferancestor="null 40663881 3b08d"
note: using 0f6b37dbe527 as ancestor of 6373bbfdae1d and e673248094b1
alternatively, use --config merge.preferancestor=d1d156401c1b
resolving manifests
getting f1
getting d1/f3 to d2/f3
merging f2
3 files updated, 0 files merged, 0 files removed, 1 files unresolved
use 'hg resolve' to retry unresolved file merges or 'hg merge --abort' to abandon
[1]
Redo merge with merge.preferancestor="*" to enable bid merge
$ rm f*
$ hg up -qC .
$ hg merge -v --debug --tool internal:dump 5 --config merge.preferancestor="*"
note: merging 6373bbfdae1d+ and e673248094b1 using bids from ancestors 0f6b37dbe527 and d1d156401c1b
calculating bids for ancestor 0f6b37dbe527
searching for copies back to rev 3
unmatched files in local:
d2/f4
unmatched files in other:
d1/f3
d1/f4
all copies found (* = to merge, ! = divergent, % = renamed and deleted):
src: 'd1/f4' -> dst: 'd2/f4'
checking for directory renames
discovered dir src: 'd1/' -> dst: 'd2/'
pending file src: 'd1/f3' -> dst: 'd2/f3'
pending file src: 'd1/f4' -> dst: 'd2/f4'
resolving manifests
branchmerge: True, force: False, partial: False
ancestor: 0f6b37dbe527, local: 6373bbfdae1d+, remote: e673248094b1
d2/f3: local directory rename - get from d1/f3 -> dg
d2/f4: local directory rename, both created -> m
f1: remote is newer -> g
f2: versions differ -> m
calculating bids for ancestor d1d156401c1b
searching for copies back to rev 3
unmatched files in local:
d2/f4
all copies found (* = to merge, ! = divergent, % = renamed and deleted):
src: 'd1/f4' -> dst: 'd2/f4'
checking for directory renames
discovered dir src: 'd1/' -> dst: 'd2/'
resolving manifests
branchmerge: True, force: False, partial: False
ancestor: d1d156401c1b, local: 6373bbfdae1d+, remote: e673248094b1
f1: versions differ -> m
f2: remote unchanged -> k
auction for merging merge bids
d2/f3: consensus for dg
d2/f4: consensus for m
f1: picking 'get' action
f2: picking 'keep' action
end of auction
preserving d2/f4 for resolve of d2/f4
f1: remote is newer -> g
getting f1
f2: remote unchanged -> k
d2/f3: local directory rename - get from d1/f3 -> dg
getting d1/f3 to d2/f3
d2/f4: local directory rename, both created -> m (premerge)
3 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ f --dump --recurse *
d2: directory with 2 files
d2/f3:
>>>
0 base
<<<
d2/f4:
>>>
0 base
<<<
f1:
>>>
5 second change
<<<
f2:
>>>
6 second change
<<<
The other way around:
$ hg up -C -r5
4 files updated, 0 files merged, 1 files removed, 0 files unresolved
$ hg merge -v --debug --config merge.preferancestor="*"
note: merging e673248094b1+ and 6373bbfdae1d using bids from ancestors 0f6b37dbe527 and d1d156401c1b
calculating bids for ancestor 0f6b37dbe527
searching for copies back to rev 3
unmatched files in local:
d1/f3
d1/f4
unmatched files in other:
d2/f4
all copies found (* = to merge, ! = divergent, % = renamed and deleted):
src: 'd1/f4' -> dst: 'd2/f4'
checking for directory renames
discovered dir src: 'd1/' -> dst: 'd2/'
pending file src: 'd1/f3' -> dst: 'd2/f3'
pending file src: 'd1/f4' -> dst: 'd2/f4'
resolving manifests
branchmerge: True, force: False, partial: False
ancestor: 0f6b37dbe527, local: e673248094b1+, remote: 6373bbfdae1d
d2/f3: remote directory rename - move from d1/f3 -> dm
d2/f4: remote directory rename, both created -> m
f1: remote unchanged -> k
f2: versions differ -> m
calculating bids for ancestor d1d156401c1b
searching for copies back to rev 3
unmatched files in other:
d2/f4
all copies found (* = to merge, ! = divergent, % = renamed and deleted):
src: 'd1/f4' -> dst: 'd2/f4'
checking for directory renames
discovered dir src: 'd1/' -> dst: 'd2/'
resolving manifests
branchmerge: True, force: False, partial: False
ancestor: d1d156401c1b, local: e673248094b1+, remote: 6373bbfdae1d
d1/f3: other deleted -> r
d1/f4: other deleted -> r
d2/f4: remote created -> g
f1: versions differ -> m
f2: remote is newer -> g
auction for merging merge bids
d1/f3: consensus for r
d1/f4: consensus for r
d2/f3: consensus for dm
d2/f4: picking 'get' action
f1: picking 'keep' action
f2: picking 'get' action
end of auction
d1/f3: other deleted -> r
removing d1/f3
d1/f4: other deleted -> r
removing d1/f4
d2/f4: remote created -> g
getting d2/f4
f2: remote is newer -> g
getting f2
f1: remote unchanged -> k
2 files updated, 0 files merged, 2 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ f --dump --recurse *
d2: directory with 2 files
d2/f3:
>>>
0 base
<<<
d2/f4:
>>>
0 base
<<<
f1:
>>>
5 second change
<<<
f2:
>>>
6 second change
<<<
Verify how the output looks and and how verbose it is:
$ hg up -qC
$ hg merge
2 files updated, 0 files merged, 2 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg up -qC tip
$ hg merge -v
note: merging 6373bbfdae1d+ and e673248094b1 using bids from ancestors 0f6b37dbe527 and d1d156401c1b
calculating bids for ancestor 0f6b37dbe527
resolving manifests
calculating bids for ancestor d1d156401c1b
resolving manifests
auction for merging merge bids
d2/f3: consensus for dg
d2/f4: consensus for m
f1: picking 'get' action
f2: picking 'keep' action
end of auction
getting f1
getting d1/f3 to d2/f3
3 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ hg up -qC
$ hg merge -v --debug --config merge.preferancestor="*"
note: merging 6373bbfdae1d+ and e673248094b1 using bids from ancestors 0f6b37dbe527 and d1d156401c1b
calculating bids for ancestor 0f6b37dbe527
searching for copies back to rev 3
unmatched files in local:
d2/f4
unmatched files in other:
d1/f3
d1/f4
all copies found (* = to merge, ! = divergent, % = renamed and deleted):
src: 'd1/f4' -> dst: 'd2/f4'
checking for directory renames
discovered dir src: 'd1/' -> dst: 'd2/'
pending file src: 'd1/f3' -> dst: 'd2/f3'
pending file src: 'd1/f4' -> dst: 'd2/f4'
resolving manifests
branchmerge: True, force: False, partial: False
ancestor: 0f6b37dbe527, local: 6373bbfdae1d+, remote: e673248094b1
d2/f3: local directory rename - get from d1/f3 -> dg
d2/f4: local directory rename, both created -> m
f1: remote is newer -> g
f2: versions differ -> m
calculating bids for ancestor d1d156401c1b
searching for copies back to rev 3
unmatched files in local:
d2/f4
all copies found (* = to merge, ! = divergent, % = renamed and deleted):
src: 'd1/f4' -> dst: 'd2/f4'
checking for directory renames
discovered dir src: 'd1/' -> dst: 'd2/'
resolving manifests
branchmerge: True, force: False, partial: False
ancestor: d1d156401c1b, local: 6373bbfdae1d+, remote: e673248094b1
f1: versions differ -> m
f2: remote unchanged -> k
auction for merging merge bids
d2/f3: consensus for dg
d2/f4: consensus for m
f1: picking 'get' action
f2: picking 'keep' action
end of auction
preserving d2/f4 for resolve of d2/f4
f1: remote is newer -> g
getting f1
f2: remote unchanged -> k
d2/f3: local directory rename - get from d1/f3 -> dg
getting d1/f3 to d2/f3
d2/f4: local directory rename, both created -> m (premerge)
3 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ cd ..
http://stackoverflow.com/questions/9350005/how-do-i-specify-a-merge-base-to-use-in-a-hg-merge/9430810
$ hg init ancestor-merging
$ cd ancestor-merging
$ echo a > x
$ hg commit -A -m a x
$ hg update -q 0
$ echo b >> x
$ hg commit -m b
$ hg update -q 0
$ echo c >> x
$ hg commit -qm c
$ hg update -q 1
$ hg merge -q --tool internal:local 2
$ echo c >> x
$ hg commit -m bc
$ hg update -q 2
$ hg merge -q --tool internal:local 1
$ echo b >> x
$ hg commit -qm cb
$ hg merge --config merge.preferancestor='!'
note: using 70008a2163f6 as ancestor of 0d355fdef312 and 4b8b546a3eef
alternatively, use --config merge.preferancestor=b211bbc6eb3c
merging x
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ cat x
a
c
b
c
$ hg up -qC .
$ hg merge --config merge.preferancestor=b211bbc6eb3c
note: using b211bbc6eb3c as ancestor of 0d355fdef312 and 4b8b546a3eef
alternatively, use --config merge.preferancestor=70008a2163f6
merging x
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ cat x
a
b
c
b
$ hg up -qC .
$ hg merge -v --config merge.preferancestor="*"
note: merging 0d355fdef312+ and 4b8b546a3eef using bids from ancestors 70008a2163f6 and b211bbc6eb3c
calculating bids for ancestor 70008a2163f6
resolving manifests
calculating bids for ancestor b211bbc6eb3c
resolving manifests
auction for merging merge bids
x: multiple bids for merge action:
versions differ -> m
versions differ -> m
x: ambiguous merge - picked m action
end of auction
merging x
0 files updated, 1 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ cat x
a
c
b
c
Verify that the old context ancestor works with / despite preferancestor:
$ hg log -r 'ancestor(head())' --config merge.preferancestor=1 -T '{rev}\n'
1
$ hg log -r 'ancestor(head())' --config merge.preferancestor=2 -T '{rev}\n'
2
$ hg log -r 'ancestor(head())' --config merge.preferancestor=3 -T '{rev}\n'
1
$ hg log -r 'ancestor(head())' --config merge.preferancestor='1337 * - 2' -T '{rev}\n'
2
$ cd ..