tests/test-revlog-mmapindex.t

revsymbol: stop delegating to repo.__getitem__ for unhandled symbols (API)

The only remaining cases where we were delegating unhandled symbols to
repo.__getitem__ should now be when the symbol could not be found. In
that case we just delegated to repo.__getitem__ for the error
message. Let's just copy the error message instead.

If there were any cases where we got e.g. a binary nodeid or an
integer revnum into revsymbol() (e.g. via repo.lookup()), we'd now
start raising an exception instead. That is why this is marked (API).

This affects one test case, but the new behavior seems better to me. I
can't tell if the old behavior was desired or if the test was just
there to document how it happened to work.

Differential Revision: https://phab.mercurial-scm.org/D3196

create verbosemmap.py
  $ cat << EOF > verbosemmap.py
  > # extension to make util.mmapread verbose
  > 
  > from __future__ import absolute_import
  > 
  > from mercurial import (
  >     extensions,
  >     pycompat,
  >     util,
  > )
  > 
  > def extsetup(ui):
  >     def mmapread(orig, fp):
  >         ui.write(b"mmapping %s\n" % pycompat.bytestr(fp.name))
  >         ui.flush()
  >         return orig(fp)
  > 
  >     extensions.wrapfunction(util, 'mmapread', mmapread)
  > EOF

setting up base repo
  $ hg init a
  $ cd a
  $ touch a
  $ hg add a
  $ hg commit -qm base
  $ for i in `$TESTDIR/seq.py 1 100` ; do
  > echo $i > a
  > hg commit -qm $i
  > done

set up verbosemmap extension
  $ cat << EOF >> $HGRCPATH
  > [extensions]
  > verbosemmap=$TESTTMP/verbosemmap.py
  > EOF

mmap index which is now more than 4k long
  $ hg log -l 5 -T '{rev}\n' --config experimental.mmapindexthreshold=4k
  mmapping $TESTTMP/a/.hg/store/00changelog.i
  100
  99
  98
  97
  96

do not mmap index which is still less than 32k
  $ hg log -l 5 -T '{rev}\n' --config experimental.mmapindexthreshold=32k
  100
  99
  98
  97
  96

  $ cd ..