tests/test-check-config.t

dirstate-tree: Avoid BTreeMap double-lookup when inserting a dirstate entry

The child nodes of a given node in the tree-shaped dirstate are kept in a
`BTreeMap` where keys are file names as strings. Finding or inserting a value
in the map takes `O(log(n))` string comparisons, which adds up when constructing
the tree.

The `entry` API allows finding a "spot" in the map that may or may not be
occupied and then access that value or insert a new one without doing map
lookup again. However the current API is limited in that calling `entry`
requires an owned key (and so a memory allocation), even if it ends up not
being used in the case where the map already has a value with an equal key.

This is still a win, with 4% better end-to-end time for `hg status` measured
here with hyperfine:

```
Benchmark #1: ../hg2/hg status -R $REPO --config=experimental.dirstate-tree.in-memory=1
  Time (mean ± σ):      1.337 s ±  0.018 s    [User: 892.9 ms, System: 437.5 ms]
  Range (min … max):    1.316 s …  1.373 s    10 runs

Benchmark #2: ./hg status -R $REPO --config=experimental.dirstate-tree.in-memory=1
  Time (mean ± σ):      1.291 s ±  0.008 s    [User: 853.4 ms, System: 431.1 ms]
  Range (min … max):    1.283 s …  1.309 s    10 runs

Summary
  './hg status -R $REPO --config=experimental.dirstate-tree.in-memory=1' ran
    1.04 ± 0.02 times faster than '../hg2/hg status -R $REPO --config=experimental.dirstate-tree.in-memory=1'
```

* ./hg is this revision
* ../hg2/hg is its parent
* $REPO is an old snapshot of mozilla-central

Differential Revision: https://phab.mercurial-scm.org/D10550

#require test-repo

  $ . "$TESTDIR/helpers-testrepo.sh"

Sanity check check-config.py

  $ cat > testfile.py << EOF
  > # Good
  > foo = ui.config('ui', 'username')
  > # Missing
  > foo = ui.config('ui', 'doesnotexist')
  > # Missing different type
  > foo = ui.configint('ui', 'missingint')
  > # Missing with default value
  > foo = ui.configbool('ui', 'missingbool1', default=True)
  > foo = ui.configbool('ui', 'missingbool2', False)
  > # Inconsistent values for defaults.
  > foo = ui.configint('ui', 'intdefault', default=1)
  > foo = ui.configint('ui', 'intdefault', default=42)
  > # Can suppress inconsistent value error
  > foo = ui.configint('ui', 'intdefault2', default=1)
  > # inconsistent config: ui.intdefault2
  > foo = ui.configint('ui', 'intdefault2', default=42)
  > EOF

  $ cat > files << EOF
  > mercurial/helptext/config.txt
  > $TESTTMP/testfile.py
  > EOF

  $ cd "$TESTDIR"/..

  $ "$PYTHON" contrib/check-config.py < $TESTTMP/files
  foo = ui.configint('ui', 'intdefault', default=42)
  conflict on ui.intdefault: ('int', '42') != ('int', '1')
  at $TESTTMP/testfile.py:12:
  undocumented: ui.doesnotexist (str)
  undocumented: ui.intdefault (int) [42]
  undocumented: ui.intdefault2 (int) [42]
  undocumented: ui.missingbool1 (bool) [True]
  undocumented: ui.missingbool2 (bool)
  undocumented: ui.missingint (int)

New errors are not allowed. Warnings are strongly discouraged.

  $ testrepohg files "set:(**.py or **.txt) - tests/**" | sed 's|\\|/|g' |
  >   "$PYTHON" contrib/check-config.py