tests/test-inotify-debuginotify.t

revset: optimize missing ancestor expressions

A missing ancestor expression is any expression of the form (::x - ::y) or
equivalent. Such expressions are remarkably common, and so far have involved
multiple walks down the DAG, followed by a set difference operation.

With this patch, such expressions will be transformed into uses of the fast
algorithm at ancestor.missingancestor.

For a repository with over 600,000 revisions, perfrevset for '::tip - ::-10000'
returns:

Before: ! wall 3.999575 comb 4.000000 user 3.910000 sys 0.090000 (best of 3)
After:  ! wall 0.132423 comb 0.130000 user 0.130000 sys 0.000000 (best of 75)

  $ "$TESTDIR/hghave" inotify || exit 80
  $ hg init
  $ echo "[extensions]" >> $HGRCPATH
  $ echo "inotify=" >> $HGRCPATH

inserve

  $ hg inserve -d --pid-file=hg.pid
  $ cat hg.pid >> "$DAEMON_PIDS"

let the daemon finish its stuff

  $ sleep 1

empty

  $ hg debuginotify
  directories being watched:
    /
    .hg/
  $ mkdir a
  $ sleep 1

only 'a

  $ hg debuginotify
  directories being watched:
    /
    .hg/
    a/
  $ rmdir a
  $ sleep 1

empty again

  $ hg debuginotify
  directories being watched:
    /
    .hg/
  $ "$TESTDIR/killdaemons.py" hg.pid