view tests/test-mq-qqueue.t @ 32558:aa91085cadf3

transaction: delete callbacks after use

Before this change, localrepository instances that performed multiple
transactions would leak transaction objects. This could occur when
running `hg convert`. When running `hg convert`, the leak would be
~90 MB per 10,000 changesets as measured with the Mercurial repo itself.

The leak I tracked down involved the "validate" closure from
localrepository.transaction(). It appeared to be keeping a
reference to the original transaction via __closure__. __del__
semantics and a circular reference involving the repo object
may have also come into play.

Attempting to refactor the "validate" closure proved to be
difficult because the "tr" reference in that closure may
reference an object that isn't created until transaction.__init__
is called. And the "validate" closure is passed as an argument to
transaction.__init__. Plus there is a giant warning comment in
"validate" about how hacky it is. I did not want to venture into
the dragon den.

Anyway, we've had problems with transactions causing leaks before.
The solution then (14e683d6b273) is the same as the solution in this
patch: drop references to callbacks after they are called. This
not only breaks cycles in core Mercurial but can help break cycles
in extensions that accidentally introduce them.

While I only tracked down a leak due to self.validator, since this is
the 2nd time I've tracked down leaks due to transaction callbacks I
figure enough is enough and we should prevent the class of leak from
occurring regardless of the variable. That's why all callback variables
are now nuked.

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

  $ hg init foo
  $ cd foo
  $ echo a > a
  $ hg ci -qAm a

Default queue:

  $ hg qqueue
  patches (active)

  $ echo b > a
  $ hg qnew -fgDU somestuff

Applied patches in default queue:

  $ hg qap
  somestuff

Try to change patch (create succeeds, switch fails):

  $ hg qqueue foo --create
  abort: new queue created, but cannot make active as patches are applied
  [255]

  $ hg qqueue
  foo
  patches (active)

Empty default queue:

  $ hg qpop
  popping somestuff
  patch queue now empty

Switch queue:

  $ hg qqueue foo
  $ hg qqueue
  foo (active)
  patches

List queues, quiet:

  $ hg qqueue --quiet
  foo
  patches

Fail creating queue with already existing name:

  $ hg qqueue --create foo
  abort: queue "foo" already exists
  [255]

  $ hg qqueue
  foo (active)
  patches

Create new queue for rename:

  $ hg qqueue --create bar

  $ hg qqueue
  bar (active)
  foo
  patches

Rename queue, same name:

  $ hg qqueue --rename bar
  abort: can't rename "bar" to its current name
  [255]

Rename queue to existing:

  $ hg qqueue --rename foo
  abort: queue "foo" already exists
  [255]

Rename queue:

  $ hg qqueue --rename buz

  $ hg qqueue
  buz (active)
  foo
  patches

Switch back to previous queue:

  $ hg qqueue foo
  $ hg qqueue --delete buz

  $ hg qqueue
  foo (active)
  patches

Create queue for purge:

  $ hg qqueue --create purge-me

  $ hg qqueue
  foo
  patches
  purge-me (active)

Create patch for purge:

  $ hg qnew patch-purge-me

  $ ls -1d .hg/patches-purge-me 2>/dev/null || true
  .hg/patches-purge-me

  $ hg qpop -a
  popping patch-purge-me
  patch queue now empty

Purge queue:

  $ hg qqueue foo
  $ hg qqueue --purge purge-me

  $ hg qqueue
  foo (active)
  patches

  $ ls -1d .hg/patches-purge-me 2>/dev/null || true

Unapplied patches:

  $ hg qun
  $ echo c > a
  $ hg qnew -fgDU otherstuff

Fail switching back:

  $ hg qqueue patches
  abort: new queue created, but cannot make active as patches are applied
  [255]

Fail deleting current:

  $ hg qqueue foo --delete
  abort: cannot delete currently active queue
  [255]

Switch back and delete foo:

  $ hg qpop -a
  popping otherstuff
  patch queue now empty

  $ hg qqueue patches
  $ hg qqueue foo --delete
  $ hg qqueue
  patches (active)

Tricky cases:

  $ hg qqueue store --create
  $ hg qnew journal

  $ hg qqueue
  patches
  store (active)

  $ hg qpop -a
  popping journal
  patch queue now empty

  $ hg qqueue patches
  $ hg qun
  somestuff

Invalid names:

  $ hg qqueue test/../../bar --create
  abort: invalid queue name, may not contain the characters ":\/."
  [255]

  $ hg qqueue . --create
  abort: invalid queue name, may not contain the characters ":\/."
  [255]

  $ cd ..