tests/test-narrow-clone-stream.t

copies: filter out copies from non-existent source later in _chain()

_changesetforwardcopies() repeatedly calls _chain(). That is very
expensive because _chain() does lookups in the manifest. I hope to
split up the function in two parts: 1) simple chaining, not
considering end points, and 2) filter out files that don't exist in
the end points (and ping-pong copies/renames).

This patches gets us closer to that by moving the check for
non-existent source later in the function. Now there are no more
checks for "src" and "dst" in the first loop; all the filtering of
invalid copies is done in the second loop. The code also looks much
more consistent now.

No measureable impact on `hg debugpathcopies 4.0 4.8`. That shouldn't
be surprising since the only case we're doing more checks now is in
case of chained copies/renames, which are quire rare in practice.

Differential Revision: https://phab.mercurial-scm.org/D6277

#testcases tree flat-fncache flat-nofncache

Tests narrow stream clones

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

#if tree
  $ cat << EOF >> $HGRCPATH
  > [experimental]
  > treemanifest = 1
  > EOF
#endif

#if flat-nofncache
  $ cat << EOF >> $HGRCPATH
  > [format]
  > usefncache = 0
  > EOF
#endif

Server setup

  $ hg init master
  $ cd master
  $ mkdir dir
  $ mkdir dir/src
  $ cd dir/src
  $ for x in `$TESTDIR/seq.py 20`; do echo $x > "F$x"; hg add "F$x"; hg commit -m "Commit src $x"; done

  $ cd ..
  $ mkdir tests
  $ cd tests
  $ for x in `$TESTDIR/seq.py 20`; do echo $x > "F$x"; hg add "F$x"; hg commit -m "Commit src $x"; done
  $ cd ../../..

Trying to stream clone when the server does not support it

  $ hg clone --narrow ssh://user@dummy/master narrow --noupdate --include "dir/src/F10" --stream
  streaming all changes
  remote: abort: server does not support narrow stream clones
  abort: pull failed on remote
  [255]

Enable stream clone on the server

  $ echo "[experimental]" >> master/.hg/hgrc
  $ echo "server.stream-narrow-clones=True" >> master/.hg/hgrc

Cloning a specific file when stream clone is supported

  $ hg clone --narrow ssh://user@dummy/master narrow --noupdate --include "dir/src/F10" --stream
  streaming all changes
  * files to transfer, * KB of data (glob)
  transferred * KB in * seconds (* */sec) (glob)

  $ cd narrow
  $ ls
  $ hg tracked
  I path:dir/src/F10

Making sure we have the correct set of requirements

  $ cat .hg/requires
  dotencode (tree flat-fncache !)
  fncache (tree flat-fncache !)
  generaldelta
  narrowhg-experimental
  revlogv1
  sparserevlog
  store
  treemanifest (tree !)

Making sure store has the required files

  $ ls .hg/store/
  00changelog.i
  00manifest.i
  data (tree flat-fncache !)
  fncache (tree flat-fncache !)
  meta (tree !)
  narrowspec
  undo
  undo.backupfiles
  undo.narrowspec
  undo.phaseroots

Checking that repository has all the required data and not broken

  $ hg verify
  checking changesets
  checking manifests
  checking directory manifests (tree !)
  crosschecking files in changesets and manifests
  checking files
  checked 40 changesets with 1 changes to 1 files