view tests/test-narrow-clone-non-narrow-server.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

Test attempting a narrow clone against a server that doesn't support narrowhg.

  $ . "$TESTDIR/narrow-library.sh"

  $ hg init master
  $ cd master

  $ for x in `$TESTDIR/seq.py 10`; do
  >   echo $x > "f$x"
  >   hg add "f$x"
  >   hg commit -m "Add $x"
  > done

  $ hg serve -a localhost -p $HGPORT1 --config extensions.narrow=! -d \
  >    --pid-file=hg.pid
  $ cat hg.pid >> "$DAEMON_PIDS"
  $ hg serve -a localhost -p $HGPORT2 -d --pid-file=hg.pid
  $ cat hg.pid >> "$DAEMON_PIDS"

Verify that narrow is advertised in the bundle2 capabilities:

  $ cat >> unquote.py <<EOF
  > from __future__ import print_function
  > import sys
  > if sys.version[0] == '3':
  >     import urllib.parse as up
  >     unquote = up.unquote_plus
  > else:
  >     import urllib
  >     unquote = urllib.unquote_plus
  > print(unquote(list(sys.stdin)[1]))
  > EOF
  $ echo hello | hg -R . serve --stdio | \
  >   "$PYTHON" unquote.py | tr ' ' '\n' | grep narrow
  exp-narrow-1

  $ cd ..

  $ hg clone --narrow --include f1 http://localhost:$HGPORT1/ narrowclone
  requesting all changes
  abort: server does not support narrow clones
  [255]

Make a narrow clone (via HGPORT2), then try to narrow and widen
into it (from HGPORT1) to prove that narrowing is fine and widening fails
gracefully:
  $ hg clone -r 0 --narrow --include f1 http://localhost:$HGPORT2/ narrowclone
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  new changesets * (glob)
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd narrowclone
  $ hg tracked --addexclude f2 http://localhost:$HGPORT1/
  comparing with http://localhost:$HGPORT1/
  searching for changes
  looking for local changes to affected paths

  $ hg tracked --addinclude f1 http://localhost:$HGPORT1/
  nothing to widen or narrow

  $ hg tracked --addinclude f9 http://localhost:$HGPORT1/
  comparing with http://localhost:$HGPORT1/
  abort: server does not support narrow clones
  [255]