view tests/test-merge-criss-cross.t @ 24735:07200e3332a1

tags: extract .hgtags filenodes cache to a standalone file

Resolution of .hgtags filenodes values has historically been a
performance pain point for large repositories, where reading individual
manifests can take over 100ms. Multiplied by hundreds or even thousands
of heads and resolving .hgtags filenodes becomes a performance issue.

This patch establishes a standalone cache file holding the .hgtags
filenodes for each changeset. After this patch, the .hgtags filenode
for any particular changeset should only have to be computed once
during the lifetime of the repository.

The introduced hgtagsfnodes1 cache file is modeled after the rev branch
cache: the cache is effectively an array of entries consisting of a
changeset fragment and the filenode for a revision. The file grows in
proportion to the length of the repository (24 bytes per changeset) and
is truncated when the repository is stripped. The file is not written
unless tag info is requested and tags have changed since last time.

This patch partially addresses issue4550. Future patches will split the
"tags" cache file into per-filter files and will refactor the cache
format to not capture the .hgtags fnodes, as these are now stored in
the hgtagsfnodes1 cache. This patch is capable of standing alone. We
should not have to wait on the tags cache filter split and format
refactor for this patch to land.

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
  $ hg ci -qm '2 first change f2'

  $ hg merge -qr 1
  $ 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
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ echo '6 second change' > f2
  $ hg ci -m '6 second change f2'

  $ hg log -G
  @  changeset:   6:3b08d01b0ab5
  |  tag:         tip
  |  parent:      3:cf89f02107e5
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     6 second change f2
  |
  | o  changeset:   5:adfe50279922
  | |  user:        test
  | |  date:        Thu Jan 01 00:00:00 1970 +0000
  | |  summary:     5 second change f1
  | |
  | o    changeset:   4:7d3e55501ae6
  | |\   parent:      2:40663881a6dd
  | | |  parent:      1:0f6b37dbe527
  | | |  user:        test
  | | |  date:        Thu Jan 01 00:00:00 1970 +0000
  | | |  summary:     4 merge
  | | |
  o---+  changeset:   3:cf89f02107e5
  | | |  parent:      2:40663881a6dd
  |/ /   parent:      1:0f6b37dbe527
  | |    user:        test
  | |    date:        Thu Jan 01 00:00:00 1970 +0000
  | |    summary:     3 merge
  | |
  | o  changeset:   2:40663881a6dd
  | |  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 3b08d01b0ab5 and adfe50279922
        alternatively, use --config merge.preferancestor=40663881a6dd
    searching for copies back to rev 3
  resolving manifests
   branchmerge: True, force: False, partial: False
   ancestor: 0f6b37dbe527, local: 3b08d01b0ab5+, remote: adfe50279922
   preserving f2 for resolve of f2
   f1: remote is newer -> g
  getting f1
  updating: f1 1/2 files (50.00%)
   f2: versions differ -> m
  updating: f2 2/2 files (100.00%)
  picked tool 'internal:dump' for f2 (binary False symlink False)
  merging f2
  my f2@3b08d01b0ab5+ other f2@adfe50279922 ancestor f2@40494bf2444c
  1 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' to abandon
  [1]

  $ head *
  ==> 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 40663881a6dd as ancestor of 3b08d01b0ab5 and adfe50279922
        alternatively, use --config merge.preferancestor=0f6b37dbe527
  resolving manifests
  merging f1
  0 files updated, 0 files merged, 0 files removed, 1 files unresolved
  use 'hg resolve' to retry unresolved file merges or 'hg update -C .' 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 3b08d01b0ab5+ and adfe50279922 using bids from ancestors 0f6b37dbe527 and 40663881a6dd
  
  calculating bids for ancestor 0f6b37dbe527
    searching for copies back to rev 3
  resolving manifests
   branchmerge: True, force: False, partial: False
   ancestor: 0f6b37dbe527, local: 3b08d01b0ab5+, remote: adfe50279922
   f1: remote is newer -> g
   f2: versions differ -> m
  
  calculating bids for ancestor 40663881a6dd
    searching for copies back to rev 3
  resolving manifests
   branchmerge: True, force: False, partial: False
   ancestor: 40663881a6dd, local: 3b08d01b0ab5+, remote: adfe50279922
   f1: versions differ -> m
   f2: remote unchanged -> k
  
  auction for merging merge bids
   f1: picking 'get' action
   f2: picking 'keep' action
  end of auction
  
   f1: remote is newer -> g
  getting f1
  updating: f1 1/1 files (100.00%)
   f2: remote unchanged -> k
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ head *
  ==> f1 <==
  5 second change
  
  ==> f2 <==
  6 second change


The other way around:

  $ hg up -C -r5
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ hg merge -v --debug --config merge.preferancestor="*"
  note: merging adfe50279922+ and 3b08d01b0ab5 using bids from ancestors 0f6b37dbe527 and 40663881a6dd
  
  calculating bids for ancestor 0f6b37dbe527
    searching for copies back to rev 3
  resolving manifests
   branchmerge: True, force: False, partial: False
   ancestor: 0f6b37dbe527, local: adfe50279922+, remote: 3b08d01b0ab5
   f1: remote unchanged -> k
   f2: versions differ -> m
  
  calculating bids for ancestor 40663881a6dd
    searching for copies back to rev 3
  resolving manifests
   branchmerge: True, force: False, partial: False
   ancestor: 40663881a6dd, local: adfe50279922+, remote: 3b08d01b0ab5
   f1: versions differ -> m
   f2: remote is newer -> g
  
  auction for merging merge bids
   f1: picking 'keep' action
   f2: picking 'get' action
  end of auction
  
   f2: remote is newer -> g
  getting f2
  updating: f2 1/1 files (100.00%)
   f1: remote unchanged -> k
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ head *
  ==> f1 <==
  5 second change
  
  ==> f2 <==
  6 second change

Verify how the output looks and and how verbose it is:

  $ hg up -qC
  $ hg merge
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  (branch merge, don't forget to commit)

  $ hg up -qC
  $ hg merge -v
  note: merging 3b08d01b0ab5+ and adfe50279922 using bids from ancestors 0f6b37dbe527 and 40663881a6dd
  
  calculating bids for ancestor 0f6b37dbe527
  resolving manifests
  
  calculating bids for ancestor 40663881a6dd
  resolving manifests
  
  auction for merging merge bids
   f1: picking 'get' action
   f2: picking 'keep' action
  end of auction
  
  getting f1
  1 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 3b08d01b0ab5+ and adfe50279922 using bids from ancestors 0f6b37dbe527 and 40663881a6dd
  
  calculating bids for ancestor 0f6b37dbe527
    searching for copies back to rev 3
  resolving manifests
   branchmerge: True, force: False, partial: False
   ancestor: 0f6b37dbe527, local: 3b08d01b0ab5+, remote: adfe50279922
   f1: remote is newer -> g
   f2: versions differ -> m
  
  calculating bids for ancestor 40663881a6dd
    searching for copies back to rev 3
  resolving manifests
   branchmerge: True, force: False, partial: False
   ancestor: 40663881a6dd, local: 3b08d01b0ab5+, remote: adfe50279922
   f1: versions differ -> m
   f2: remote unchanged -> k
  
  auction for merging merge bids
   f1: picking 'get' action
   f2: picking 'keep' action
  end of auction
  
   f1: remote is newer -> g
  getting f1
  updating: f1 1/1 files (100.00%)
   f2: remote unchanged -> k
  1 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 ..