view tests/test-patch.t @ 38732:be4984261611

merge: mark file gets as not thread safe (issue5933)

In default installs, this has the effect of disabling the thread-based
worker on Windows when manifesting files in the working directory. My
measurements have shown that with revlog-based repositories, Mercurial
spends a lot of CPU time in revlog code resolving file data. This ends
up incurring a lot of context switching across threads and slows down
`hg update` operations when going from an empty working directory to
the tip of the repo.

On mozilla-unified (246,351 files) on an i7-6700K (4+4 CPUs):

before: 487s wall
after:  360s wall (equivalent to worker.enabled=false)
cpus=2: 379s wall

Even with only 2 threads, the thread pool is still slower.

The introduction of the thread-based worker (02b36e860e0b) states that
it resulted in a "~50%" speedup for `hg sparse --enable-profile` and
`hg sparse --disable-profile`. This disagrees with my measurement
above. I theorize a few reasons for this:

1) Removal of files from the working directory is I/O - not CPU - bound
   and should benefit from a thread pool (unless I/O is insanely fast
   and the GIL release is near instantaneous). So tests like `hg sparse
   --enable-profile` may exercise deletion throughput and aren't good
   benchmarks for worker tasks that are CPU heavy.
2) The patch was authored by someone at Facebook. The results were
   likely measured against a repository using remotefilelog. And I
   believe that revision retrieval during working directory updates with
   remotefilelog will often use a remote store, thus being I/O and not
   CPU bound. This probably resulted in an overstated performance gain.

Since there appears to be a need to enable the thread-based worker with
some stores, I've made the flagging of file gets as thread safe
configurable. I've made it experimental because I don't want to formalize
a boolean flag for this option and because this attribute is best
captured against the store implementation. But we don't have a proper
store API for this yet. I'd rather cross this bridge later.

It is possible there are revlog-based repositories that do benefit from
a thread-based worker. I didn't do very comprehensive testing. If there
are, we may want to devise a more proper algorithm for whether to use
the thread-based worker, including possibly config options to limit the
number of threads to use. But until I see evidence that justifies
complexity, simplicity wins.

Differential Revision: https://phab.mercurial-scm.org/D3963

  $ cat > patchtool.py <<EOF
  > from __future__ import absolute_import, print_function
  > import sys
  > print('Using custom patch')
  > if '--binary' in sys.argv:
  >     print('--binary found !')
  > EOF

  $ echo "[ui]" >> $HGRCPATH
  $ echo "patch=$PYTHON ../patchtool.py" >> $HGRCPATH

  $ hg init a
  $ cd a
  $ echo a > a
  $ hg commit -Ama -d '1 0'
  adding a
  $ echo b >> a
  $ hg commit -Amb -d '2 0'
  $ cd ..

This test checks that:
 - custom patch commands with arguments actually work
 - patch code does not try to add weird arguments like
 --binary when custom patch commands are used. For instance
 --binary is added by default under win32.

check custom patch options are honored

  $ hg --cwd a export -o ../a.diff tip
  $ hg clone -r 0 a b
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  new changesets 8580ff50825a
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ hg --cwd b import -v ../a.diff
  applying ../a.diff
  Using custom patch
  applied to working directory

Issue2417: hg import with # comments in description

Prepare source repo and patch:

  $ rm $HGRCPATH
  $ hg init c
  $ cd c
  $ printf "a\rc" > a
  $ hg ci -A -m 0 a -d '0 0'
  $ printf "a\rb\rc" > a
  $ cat << eof > log
  > first line which can't start with '# '
  > # second line is a comment but that shouldn't be a problem.
  > A patch marker like this was more problematic even after d7452292f9d3:
  > # HG changeset patch
  > # User lines looks like this - but it _is_ just a comment
  > eof
  $ hg ci -l log -d '0 0'
  $ hg export -o p 1
  $ cd ..

Clone and apply patch:

  $ hg clone -r 0 c d
  adding changesets
  adding manifests
  adding file changes
  added 1 changesets with 1 changes to 1 files
  new changesets 7fadb901d403
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cd d
  $ hg import ../c/p
  applying ../c/p
  $ hg log -v -r 1
  changeset:   1:cd0bde79c428
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  files:       a
  description:
  first line which can't start with '# '
  # second line is a comment but that shouldn't be a problem.
  A patch marker like this was more problematic even after d7452292f9d3:
  # HG changeset patch
  # User lines looks like this - but it _is_ just a comment
  
  

Error exit (issue4746)

  $ cat >> exit1.py <<EOF
  > import sys
  > sys.exit(1)
  > EOF

  $ hg import ../c/p --config ui.patch="\"$PYTHON\" \"`pwd`/exit1.py\""
  applying ../c/p
  abort: patch command failed: exited with status 1
  [255]

  $ cd ..