view tests/test-parents.t @ 16120:47ee41fcf42b

largefiles: optimize update speed by only updating changed largefiles

Historically, during 'hg update', every largefile in the working copy was
hashed (which is a very expensive operation on big files) and any
largefiles that did not have a hash that matched their standin were
updated.

This patch optimizes 'hg update' by keeping track of what standins have
changed between the old and new revisions, and only updating the largefiles
that have changed.  This saves a lot of time by avoiding the unecessary
calculation of a list of sha1 hashes for big files.

With this patch, the time 'hg update' takes to complete is a function of
how many largefiles need to be updated and what their size is.

Performance tests on a repository with about 80 largefiles ranging from
a few MB to about 97 MB are shown below.  The tests show how long it takes
to run 'hg update' with no changes actually being updated.

Mercurial 2.1 release:

$ time hg update
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
getting changed largefiles
0 largefiles updated, 0 removed

real    0m10.045s
user    0m9.367s
sys    0m0.674s

With this patch:

$ time hg update
0 files updated, 0 files merged, 0 files removed, 0 files unresolved

real    0m0.965s
user    0m0.845s
sys    0m0.115s

The same repsoitory, without the largefiles extension enabled:

$ time hg update
0 files updated, 0 files merged, 0 files removed, 0 files unresolved

real    0m0.799s
user    0m0.684s
sys    0m0.111s

So before the patch, 'hg update' with no changes was approximately 9.25s
slower with largefiles enabled.  With this patch, it is approximately 0.165s
slower.

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
  [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