view tests/test-histedit-bookmark-motion.t @ 17616:9535a0dc41f2

store: implement fncache basic path encoding in C

(This is not yet enabled; it will be turned on in a followup patch.)

The path encoding performed by fncache is complex and (perhaps
surprisingly) slow enough to negatively affect the overall performance
of Mercurial.

For a short path (< 120 bytes), the Python code can be reduced to a fairly
tractable state machine that either determines that nothing needs to be
done in a single pass, or performs the encoding in a second pass.

For longer paths, we avoid the more complicated hashed encoding scheme
for now, and fall back to Python.

Raw performance: I measured in a repo containing 150,000 files in its tip
manifest, with a median path name length of 57 bytes, and 95th percentile
of 96 bytes.

In this repo, the Python code takes 3.1 seconds to encode all path
names, while the hybrid C-and-Python code (called from Python) takes
0.21 seconds, for a speedup of about 14.

Across several other large repositories, I've measured the speedup from
the C code at between 26x and 40x.

For path names above 120 bytes where we must fall back to Python for
hashed encoding, the speedup is about 1.7x.  Thus absolute performance
will depend strongly on the characteristics of a particular repository.

  $ . "$TESTDIR/histedit-helpers.sh"

  $ cat >> $HGRCPATH <<EOF
  > [extensions]
  > graphlog=
  > histedit=
  > EOF

  $ hg init r
  $ cd r

  $ for x in a b c d e f ; do
  >     echo $x > $x
  >     hg add $x
  >     hg ci -m $x
  > done

  $ hg book -r 1 will-move-backwards
  $ hg book -r 2 two
  $ hg book -r 2 also-two
  $ hg book -r 3 three
  $ hg book -r 4 four
  $ hg book -r tip five
  $ hg log --graph
  @  changeset:   5:652413bf663e
  |  bookmark:    five
  |  tag:         tip
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     f
  |
  o  changeset:   4:e860deea161a
  |  bookmark:    four
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     e
  |
  o  changeset:   3:055a42cdd887
  |  bookmark:    three
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     d
  |
  o  changeset:   2:177f92b77385
  |  bookmark:    also-two
  |  bookmark:    two
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     c
  |
  o  changeset:   1:d2ae7f538514
  |  bookmark:    will-move-backwards
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     b
  |
  o  changeset:   0:cb9a9f314b8b
     user:        test
     date:        Thu Jan 01 00:00:00 1970 +0000
     summary:     a
  
  $ HGEDITOR=cat hg histedit 1
  pick d2ae7f538514 1 b
  pick 177f92b77385 2 c
  pick 055a42cdd887 3 d
  pick e860deea161a 4 e
  pick 652413bf663e 5 f
  
  # Edit history between d2ae7f538514 and 652413bf663e
  #
  # Commands:
  #  p, pick = use commit
  #  e, edit = use commit, but stop for amending
  #  f, fold = use commit, but fold into previous commit (combines N and N-1)
  #  d, drop = remove commit from history
  #  m, mess = edit message without changing commit content
  #
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat >> commands.txt <<EOF
  > pick 177f92b77385 2 c
  > drop d2ae7f538514 1 b
  > pick 055a42cdd887 3 d
  > fold e860deea161a 4 e
  > pick 652413bf663e 5 f
  > EOF
  $ hg histedit 1 --commands commands.txt --verbose | grep histedit
  histedit: Should update metadata for the following changes:
  histedit:  055a42cdd887 to ae467701c500
  histedit:     moving bookmarks three
  histedit:  177f92b77385 to d36c0562f908
  histedit:     moving bookmarks also-two, two
  histedit:  652413bf663e to 0efacef7cb48
  histedit:     moving bookmarks five
  histedit:  d2ae7f538514 to cb9a9f314b8b
  histedit:     moving bookmarks will-move-backwards
  histedit:  e860deea161a to ae467701c500
  histedit:     moving bookmarks four
  saved backup bundle to $TESTTMP/r/.hg/strip-backup/d2ae7f538514-backup.hg (glob)
  saved backup bundle to $TESTTMP/r/.hg/strip-backup/34a9919932c1-backup.hg (glob)
  $ hg log --graph
  @  changeset:   3:0efacef7cb48
  |  bookmark:    five
  |  tag:         tip
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     f
  |
  o  changeset:   2:ae467701c500
  |  bookmark:    four
  |  bookmark:    three
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     d
  |
  o  changeset:   1:d36c0562f908
  |  bookmark:    also-two
  |  bookmark:    two
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     c
  |
  o  changeset:   0:cb9a9f314b8b
     bookmark:    will-move-backwards
     user:        test
     date:        Thu Jan 01 00:00:00 1970 +0000
     summary:     a
  
  $ HGEDITOR=cat hg histedit 1
  pick d36c0562f908 1 c
  pick ae467701c500 2 d
  pick 0efacef7cb48 3 f
  
  # Edit history between d36c0562f908 and 0efacef7cb48
  #
  # Commands:
  #  p, pick = use commit
  #  e, edit = use commit, but stop for amending
  #  f, fold = use commit, but fold into previous commit (combines N and N-1)
  #  d, drop = remove commit from history
  #  m, mess = edit message without changing commit content
  #
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat > commands.txt << EOF
  > pick d36c0562f908 1 c
  > pick 0efacef7cb48 3 f
  > pick ae467701c500 2 d
  > EOF
  $ hg histedit 1 --commands commands.txt --verbose | grep histedit
  histedit: Should update metadata for the following changes:
  histedit:  0efacef7cb48 to 1be9c35b4cb2
  histedit:     moving bookmarks five
  histedit:  0efacef7cb48 to 7c044e3e33a9
  histedit:  ae467701c500 to 1be9c35b4cb2
  histedit:     moving bookmarks four, three
  saved backup bundle to $TESTTMP/r/.hg/strip-backup/ae467701c500-backup.hg (glob)

We expect 'five' to stay at tip, since the tipmost bookmark is most
likely the useful signal.

  $ hg log --graph
  @  changeset:   3:1be9c35b4cb2
  |  bookmark:    five
  |  bookmark:    four
  |  bookmark:    three
  |  tag:         tip
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     d
  |
  o  changeset:   2:7c044e3e33a9
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     f
  |
  o  changeset:   1:d36c0562f908
  |  bookmark:    also-two
  |  bookmark:    two
  |  user:        test
  |  date:        Thu Jan 01 00:00:00 1970 +0000
  |  summary:     c
  |
  o  changeset:   0:cb9a9f314b8b
     bookmark:    will-move-backwards
     user:        test
     date:        Thu Jan 01 00:00:00 1970 +0000
     summary:     a