view tests/test-debugbuilddag.t @ 42743:8c9a6adec67a

rust-discovery: using the children cache in add_missing

The DAG range computation often needs to get back to very old
revisions, and turns out to be disproportionately long, given
that the end goal is to remove the descendents of the given
missing revisons from the undecided set.

The fast iteration capabilities available in the Rust case make
it possible to avoid the DAG range entirely, at the cost of
precomputing the children cache, and to simply iterate on
children of the given missing revisions.

This is a case where staying on the same side of the interface
between the two languages has clear benefits.

On discoveries with initial undecided sets
small enough to bypass sampling entirely, the total cost of
computing the children cache and the subsequent iteration
becomes better than the Python + C counterpart, which relies on
reachableroots2.

For example, on a repo with more than one million revisions with
an initial undecided set of 11 elements, we get these figures:

Rust version with simple iteration
  addcommons: 57.287us
  first undecided computation: 184.278334ms
  first children cache computation: 131.056us
  addmissings iteration: 42.766us
  first addinfo total: 185.24 ms

Python + C version
  first addcommons: 0.29 ms
  addcommons 0.21 ms
  first undecided computation 191.35 ms
  addmissings 45.75 ms
  first addinfo total: 237.77 ms

On discoveries with large undecided sets, the initial price paid
makes the first addinfo slower than the Python + C version,
but that's more than compensated by the gain in sampling and
subsequent iterations.
Here's an extreme example with an undecided set of a million revisions:

Rust version:
  first undecided computation: 293.842629ms
  first children cache computation: 407.911297ms
  addmissings iteration: 34.312869ms
  first addinfo total: 776.02 ms
  taking initial sample
  query 2: sampling time: 1318.38 ms
  query 2; still undecided: 1005013, sample size is: 200
  addmissings: 143.062us

Python + C version:
  first undecided computation 298.13 ms
  addmissings 80.13 ms
  first addinfo total: 399.62 ms
  taking initial sample
  query 2: sampling time: 3957.23 ms
  query 2; still undecided: 1005013, sample size is: 200
  addmissings 52.88 ms

Differential Revision: https://phab.mercurial-scm.org/D6428

plain

  $ hg init
  $ hg debugbuilddag '+2:f +3:p2 @temp <f+4 @default /p2 +2' \
  > --config extensions.progress= --config progress.assume-tty=1 \
  > --config progress.delay=0 --config progress.refresh=0 \
  > --config progress.format=topic,bar,number \
  > --config progress.width=60
  \r (no-eol) (esc)
  building [                                          ]  0/12\r (no-eol) (esc)
  building [                                          ]  0/12\r (no-eol) (esc)
  building [==>                                       ]  1/12\r (no-eol) (esc)
  building [==>                                       ]  1/12\r (no-eol) (esc)
  building [======>                                   ]  2/12\r (no-eol) (esc)
  building [=========>                                ]  3/12\r (no-eol) (esc)
  building [=============>                            ]  4/12\r (no-eol) (esc)
  building [=============>                            ]  4/12\r (no-eol) (esc)
  building [=============>                            ]  4/12\r (no-eol) (esc)
  building [================>                         ]  5/12\r (no-eol) (esc)
  building [====================>                     ]  6/12\r (no-eol) (esc)
  building [=======================>                  ]  7/12\r (no-eol) (esc)
  building [===========================>              ]  8/12\r (no-eol) (esc)
  building [===========================>              ]  8/12\r (no-eol) (esc)
  building [==============================>           ]  9/12\r (no-eol) (esc)
  building [==================================>       ] 10/12\r (no-eol) (esc)
  building [=====================================>    ] 11/12\r (no-eol) (esc)
                                                              \r (no-eol) (esc)

tags
  $ cat .hg/localtags
  66f7d451a68b85ed82ff5fcc254daf50c74144bd f
  bebd167eb94d257ace0e814aeb98e6972ed2970d p2
dag
  $ hg debugdag -t -b
  +2:f
  +3:p2
  @temp*f+3
  @default*/p2+2:tip
tip
  $ hg id
  000000000000
glog
  $ hg log -G --template '{rev}: {desc} [{branches}] @ {date}\n'
  o  11: r11 [] @ 11.00
  |
  o  10: r10 [] @ 10.00
  |
  o    9: r9 [] @ 9.00
  |\
  | o  8: r8 [temp] @ 8.00
  | |
  | o  7: r7 [temp] @ 7.00
  | |
  | o  6: r6 [temp] @ 6.00
  | |
  | o  5: r5 [temp] @ 5.00
  | |
  o |  4: r4 [] @ 4.00
  | |
  o |  3: r3 [] @ 3.00
  | |
  o |  2: r2 [] @ 2.00
  |/
  o  1: r1 [] @ 1.00
  |
  o  0: r0 [] @ 0.00
  

overwritten files, starting on a non-default branch

  $ rm -r .hg
  $ hg init
  $ hg debugbuilddag '@start.@default.:f +3:p2 @temp <f+4 @default /p2 +2' -q -o
tags
  $ cat .hg/localtags
  f778700ebd50fcf282b23a4446bd155da6453eb6 f
  bbccf169769006e2490efd2a02f11c3d38d462bd p2
dag
  $ hg debugdag -t -b
  @start+1
  @default+1:f
  +3:p2
  @temp*f+3
  @default*/p2+2:tip
tip
  $ hg id
  000000000000
glog
  $ hg log -G --template '{rev}: {desc} [{branches}] @ {date}\n'
  o  11: r11 [] @ 11.00
  |
  o  10: r10 [] @ 10.00
  |
  o    9: r9 [] @ 9.00
  |\
  | o  8: r8 [temp] @ 8.00
  | |
  | o  7: r7 [temp] @ 7.00
  | |
  | o  6: r6 [temp] @ 6.00
  | |
  | o  5: r5 [temp] @ 5.00
  | |
  o |  4: r4 [] @ 4.00
  | |
  o |  3: r3 [] @ 3.00
  | |
  o |  2: r2 [] @ 2.00
  |/
  o  1: r1 [] @ 1.00
  |
  o  0: r0 [start] @ 0.00
  
glog of
  $ hg log -G --template '{rev}: {desc} [{branches}]\n' of
  o  11: r11 []
  |
  o  10: r10 []
  |
  o    9: r9 []
  |\
  | o  8: r8 [temp]
  | |
  | o  7: r7 [temp]
  | |
  | o  6: r6 [temp]
  | |
  | o  5: r5 [temp]
  | |
  o |  4: r4 []
  | |
  o |  3: r3 []
  | |
  o |  2: r2 []
  |/
  o  1: r1 []
  |
  o  0: r0 [start]
  
tags
  $ hg tags -v
  tip                               11:9ffe238a67a2
  p2                                 4:bbccf1697690 local
  f                                  1:f778700ebd50 local
cat of
  $ hg cat of --rev tip
  r11


new and mergeable files

  $ rm -r .hg
  $ hg init
  $ hg debugbuilddag '+2:f +3:p2 @temp <f+4 @default /p2 +2' -q -mn
dag
  $ hg debugdag -t -b
  +2:f
  +3:p2
  @temp*f+3
  @default*/p2+2:tip
tip
  $ hg id
  000000000000
glog
  $ hg log -G --template '{rev}: {desc} [{branches}] @ {date}\n'
  o  11: r11 [] @ 11.00
  |
  o  10: r10 [] @ 10.00
  |
  o    9: r9 [] @ 9.00
  |\
  | o  8: r8 [temp] @ 8.00
  | |
  | o  7: r7 [temp] @ 7.00
  | |
  | o  6: r6 [temp] @ 6.00
  | |
  | o  5: r5 [temp] @ 5.00
  | |
  o |  4: r4 [] @ 4.00
  | |
  o |  3: r3 [] @ 3.00
  | |
  o |  2: r2 [] @ 2.00
  |/
  o  1: r1 [] @ 1.00
  |
  o  0: r0 [] @ 0.00
  
glog mf
  $ hg log -G --template '{rev}: {desc} [{branches}]\n' mf
  o  11: r11 []
  |
  o  10: r10 []
  |
  o    9: r9 []
  |\
  | o  8: r8 [temp]
  | |
  | o  7: r7 [temp]
  | |
  | o  6: r6 [temp]
  | |
  | o  5: r5 [temp]
  | |
  o |  4: r4 []
  | |
  o |  3: r3 []
  | |
  o |  2: r2 []
  |/
  o  1: r1 []
  |
  o  0: r0 []
  

man r4
  $ hg manifest -r4
  mf
  nf0
  nf1
  nf2
  nf3
  nf4
cat r4 mf
  $ hg cat -r4 mf
  0 r0
  1
  2 r1
  3
  4 r2
  5
  6 r3
  7
  8 r4
  9
  10
  11
  12
  13
  14
  15
  16
  17
  18
  19
  20
  21
  22
  23
man r8
  $ hg manifest -r8
  mf
  nf0
  nf1
  nf5
  nf6
  nf7
  nf8
cat r8 mf
  $ hg cat -r8 mf
  0 r0
  1
  2 r1
  3
  4
  5
  6
  7
  8
  9
  10 r5
  11
  12 r6
  13
  14 r7
  15
  16 r8
  17
  18
  19
  20
  21
  22
  23
man
  $ hg manifest --rev tip
  mf
  nf0
  nf1
  nf10
  nf11
  nf2
  nf3
  nf4
  nf5
  nf6
  nf7
  nf8
  nf9
cat mf
  $ hg cat mf --rev tip
  0 r0
  1
  2 r1
  3
  4 r2
  5
  6 r3
  7
  8 r4
  9
  10 r5
  11
  12 r6
  13
  14 r7
  15
  16 r8
  17
  18 r9
  19
  20 r10
  21
  22 r11
  23