view tests/test-share.t @ 46667:93e9f448273c

rhg: Add support for automatic fallback to Python

`rhg` is a command-line application that can do a small subset of what
`hg` can. It is written entirely in Rust, which avoids the cost of starting
a Python interpreter and importing many Python modules.
In a script that runs many `hg` commands, this cost can add up.

However making users decide when to use `rhg` instead of `hg` is
not practical as we want the subset of supported functionality
to grow over time.

Instead we introduce "fallback" behavior where, when `rhg` encounters
something (a sub-command, a repository format, …) that is not implemented
in Rust-only, it does nothing but silently start a subprocess of
Python-based `hg` running the same command.
That way `rhg` becomes a drop-in replacement for `hg` that sometimes
goes faster. Whether Python is used should be an implementation detail
not apparent to users (other than through speed).

A new `fallback` value is added to the previously introduced
`rhg.on-unsupported` configuration key. When in this mode, the new
`rhg.fallback-executable` config is determine what command to use
to run a Python-based `hg`.

The previous `rhg.on-unsupported = abort-silent` configuration was designed
to let a wrapper script call `rhg` and then fall back to `hg` based on the
exit code. This is still available, but having fallback behavior built-in
in rhg might be easier for users instead of leaving that script "as an
exercise for the reader".

Using a subprocess like this is not idea, especially when `rhg` is to be
installed in `$PATH` as `hg`, since the other `hg.py` executable needs
to still be available… somewhere. Eventually this could be replaced
by using PyOxidizer to a have a single executable that embeds a Python
interpreter, but only starts it when needed.

Differential Revision: https://phab.mercurial-scm.org/D10093

#testcases safe normal

#if safe
  $ echo "[format]"         >> $HGRCPATH
  $ echo "use-share-safe = True" >> $HGRCPATH
#endif

  $ echo "[extensions]"      >> $HGRCPATH
  $ echo "share = "          >> $HGRCPATH

prepare repo1

  $ hg init repo1
  $ cd repo1
  $ echo a > a
  $ hg commit -A -m'init'
  adding a

share it

  $ cd ..
  $ hg share repo1 repo2
  updating working directory
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved

share shouldn't have a store dir

  $ cd repo2
  $ test -d .hg/store
  [1]
  $ hg root -Tjson | sed 's|\\\\|\\|g'
  [
   {
    "hgpath": "$TESTTMP/repo2/.hg",
    "reporoot": "$TESTTMP/repo2",
    "storepath": "$TESTTMP/repo1/.hg/store"
   }
  ]

share shouldn't have a full cache dir, original repo should

  $ hg branches
  default                        0:d3873e73d99e
  $ hg tags
  tip                                0:d3873e73d99e
  $ test -d .hg/cache
  [1]
  $ ls -1 .hg/wcache || true
  checkisexec (execbit !)
  checklink (symlink !)
  checklink-target (symlink !)
  manifestfulltextcache (reporevlogstore !)
  $ ls -1 ../repo1/.hg/cache
  branch2-served
  rbc-names-v1
  rbc-revs-v1
  tags2-visible

Cloning a shared repo should pick up the full cache dir on the other hand.

  $ hg clone . ../repo2-clone
  updating to branch default
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ ls -1 ../repo2-clone/.hg/cache
  branch2-base
  branch2-immutable
  branch2-served
  branch2-served.hidden
  branch2-visible
  branch2-visible-hidden
  hgtagsfnodes1
  rbc-names-v1
  rbc-revs-v1
  tags2
  tags2-served
  tags2-visible

Some sed versions appends newline, some don't, and some just fails

  $ cat .hg/sharedpath; echo
  $TESTTMP/repo1/.hg

trailing newline on .hg/sharedpath is ok
  $ hg tip -q
  0:d3873e73d99e
  $ echo '' >> .hg/sharedpath
  $ cat .hg/sharedpath
  $TESTTMP/repo1/.hg
  $ hg tip -q
  0:d3873e73d99e

commit in shared clone

  $ echo a >> a
  $ hg commit -m'change in shared clone'

check original

  $ cd ../repo1
  $ hg log
  changeset:   1:8af4dc49db9e
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     change in shared clone
  
  changeset:   0:d3873e73d99e
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     init
  
  $ hg update
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat a             # should be two lines of "a"
  a
  a

commit in original

  $ echo b > b
  $ hg commit -A -m'another file'
  adding b

check in shared clone

  $ cd ../repo2
  $ hg log
  changeset:   2:c2e0ac586386
  tag:         tip
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     another file
  
  changeset:   1:8af4dc49db9e
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     change in shared clone
  
  changeset:   0:d3873e73d99e
  user:        test
  date:        Thu Jan 01 00:00:00 1970 +0000
  summary:     init
  
  $ hg update
  1 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ cat b             # should exist with one "b"
  b

hg serve shared clone

  $ hg serve -n test -p $HGPORT -d --pid-file=hg.pid
  $ cat hg.pid >> $DAEMON_PIDS
  $ get-with-headers.py localhost:$HGPORT 'raw-file/'
  200 Script output follows
  
  
  -rw-r--r-- 4 a
  -rw-r--r-- 2 b
  
  
Cloning a shared repo via bundle2 results in a non-shared clone

  $ cd ..
  $ hg clone -q --stream --config ui.ssh="\"$PYTHON\" \"$TESTDIR/dummyssh\"" ssh://user@dummy/`pwd`/repo2 cloned-via-bundle2
  $ cat ./cloned-via-bundle2/.hg/requires | grep "shared"
  [1]
  $ hg id --cwd cloned-via-bundle2 -r tip
  c2e0ac586386 tip
  $ cd repo2

test unshare command

  $ hg unshare
  $ test -d .hg/store
  $ test -f .hg/sharedpath
  [1]
  $ grep shared .hg/requires
  [1]
  $ hg unshare
  abort: this is not a shared repo
  [255]

check that a change does not propagate

  $ echo b >> b
  $ hg commit -m'change in unshared'
  $ cd ../repo1
  $ hg id -r tip
  c2e0ac586386 tip

  $ cd ..


non largefiles repos won't enable largefiles

  $ hg share --config extensions.largefiles= repo2 sharedrepo
  The fsmonitor extension is incompatible with the largefiles extension and has been disabled. (fsmonitor !)
  The fsmonitor extension is incompatible with the largefiles extension and has been disabled. (fsmonitor !)
  updating working directory
  2 files updated, 0 files merged, 0 files removed, 0 files unresolved
  $ [ -f sharedrepo/.hg/hgrc ]
  [1]

test shared clones using relative paths work

  $ mkdir thisdir
  $ hg init thisdir/orig
  $ hg share -U thisdir/orig thisdir/abs
  $ hg share -U --relative thisdir/abs thisdir/rel
  $ cat thisdir/rel/.hg/sharedpath
  ../../orig/.hg (no-eol)
  $ grep shared thisdir/*/.hg/requires
  thisdir/abs/.hg/requires:shared
  thisdir/rel/.hg/requires:relshared
  thisdir/rel/.hg/requires:shared

test that relative shared paths aren't relative to $PWD

  $ cd thisdir
  $ hg -R rel root
  $TESTTMP/thisdir/rel
  $ cd ..

now test that relative paths really are relative, survive across
renames and changes of PWD

  $ hg -R thisdir/abs root
  $TESTTMP/thisdir/abs
  $ hg -R thisdir/rel root
  $TESTTMP/thisdir/rel
  $ mv thisdir thatdir
  $ hg -R thatdir/abs root
  abort: .hg/sharedpath points to nonexistent directory $TESTTMP/thisdir/orig/.hg
  [255]
  $ hg -R thatdir/rel root
  $TESTTMP/thatdir/rel

test unshare relshared repo

  $ cd thatdir/rel
  $ hg unshare
  $ test -d .hg/store
  $ test -f .hg/sharedpath
  [1]
  $ grep shared .hg/requires
  [1]
  $ hg unshare
  abort: this is not a shared repo
  [255]
  $ cd ../..

  $ rm -r thatdir

Demonstrate buggy behavior around requirements validation
See comment in localrepo.py:makelocalrepository() for more.

  $ hg init sharenewrequires
  $ hg share sharenewrequires shareoldrequires
  updating working directory
  0 files updated, 0 files merged, 0 files removed, 0 files unresolved

  $ cat >> sharenewrequires/.hg/requires << EOF
  > missing-requirement
  > EOF

We cannot open the repo with the unknown requirement

  $ hg -R sharenewrequires status
  abort: repository requires features unknown to this Mercurial: missing-requirement
  (see https://mercurial-scm.org/wiki/MissingRequirement for more information)
  [255]

BUG: we don't get the same error when opening the shared repo pointing to it

  $ hg -R shareoldrequires status

Explicitly kill daemons to let the test exit on Windows

  $ killdaemons.py

Test sharing a repository which was created with store requirement disable

  $ hg init nostore --config format.usestore=false
  ignoring enabled 'format.use-share-safe' config because it is incompatible with disabled 'format.usestore' config (safe !)
  $ hg share nostore sharednostore
  abort: cannot create shared repository as source was created with 'format.usestore' config disabled
  [255]