tests/test-cache-abuse.t

templatekw: add new-style template expansion to {manifest}

The goal is to allow us to easily access to nested data. The dot operator
will be introduced later so we can write '{p1.files}' instead of
'{revset("p1()") % "{files}"}' for example.

In the example above, 'p1' needs to carry a mapping dict along with its
string representation. If it were a list or a dict, it could be wrapped
semi-transparently with the _hybrid class, but for non-list/dict types,
it would be difficult to proxy all necessary functions to underlying value
type because several core operations may conflict with the ones of the
underlying value:

 - hash(value) should be different from hash(wrapped(value)), which means
   dict[wrapped(value)] would be invalid
 - 'value == wrapped(value)' would be false, breaks 'ifcontains'
 - len(wrapped(value)) may be either len(value) or len(iter(wrapped(value)))

So the wrapper has no proxy functions and its scope designed to be minimal.
It's unwrapped at eval*() functions so we don't have to care for a wrapped
object unless it's really needed:

  # most template functions just call evalfuncarg()
  unwrapped_value = evalfuncarg(context, mapping, args[n])
  # if wrapped value is needed, use evalrawexp()
  maybe_wrapped_value = evalrawexp(context, mapping, args[n])

Another idea was to wrap every template variable with a tagging class, but
which seemed uneasy without a static type checker.

This patch updates {manifest} to a mappable as an example.

Enable obsolete markers

  $ cat >> $HGRCPATH << EOF
  > [experimental]
  > stabilization=createmarkers
  > [phases]
  > publish=False
  > EOF

Build a repo with some cacheable bits:

  $ hg init a
  $ cd a

  $ echo a > a
  $ hg ci -qAm0
  $ hg tag t1
  $ hg book -i bk1

  $ hg branch -q b2
  $ hg ci -Am1
  $ hg tag t2

  $ echo dumb > dumb
  $ hg ci -qAmdumb
  $ hg debugobsolete b1174d11b69e63cb0c5726621a43c859f0858d7f
  obsoleted 1 changesets

  $ hg phase -pr t1
  $ hg phase -fsr t2

Make a helper function to check cache damage invariants:

- command output shouldn't change
- cache should be present after first use
- corruption/repair should be silent (no exceptions or warnings)
- cache should survive deletion, overwrite, and append
- unreadable / unwriteable caches should be ignored
- cache should be rebuilt after corruption

  $ damage() {
  >  CMD=$1
  >  CACHE=.hg/cache/$2
  >  CLEAN=$3
  >  hg $CMD > before
  >  test -f $CACHE || echo "not present"
  >  echo bad > $CACHE
  >  test -z "$CLEAN" || $CLEAN
  >  hg $CMD > after
  >  "$RUNTESTDIR/pdiff" before after || echo "*** overwrite corruption"
  >  echo corruption >> $CACHE
  >  test -z "$CLEAN" || $CLEAN
  >  hg $CMD > after
  >  "$RUNTESTDIR/pdiff" before after || echo "*** append corruption"
  >  rm $CACHE
  >  mkdir $CACHE
  >  test -z "$CLEAN" || $CLEAN
  >  hg $CMD > after
  >  "$RUNTESTDIR/pdiff" before after || echo "*** read-only corruption"
  >  test -d $CACHE || echo "*** directory clobbered"
  >  rmdir $CACHE
  >  test -z "$CLEAN" || $CLEAN
  >  hg $CMD > after
  >  "$RUNTESTDIR/pdiff" before after || echo "*** missing corruption"
  >  test -f $CACHE || echo "not rebuilt"
  > }

Beat up tags caches:

  $ damage "tags --hidden" tags2
  $ damage tags tags2-visible
  $ damage "tag -f t3" hgtagsfnodes1

Beat up branch caches:

  $ damage branches branch2-base "rm .hg/cache/branch2-[vs]*"
  $ damage branches branch2-served "rm .hg/cache/branch2-[bv]*"
  $ damage branches branch2-visible
  $ damage "log -r branch(.)" rbc-names-v1
  $ damage "log -r branch(default)" rbc-names-v1
  $ damage "log -r branch(b2)" rbc-revs-v1

We currently can't detect an rbc cache with unknown names:

  $ damage "log -qr branch(b2)" rbc-names-v1
  --- before	* (glob)
  +++ after	* (glob)
  @@ -1,8 +?,0 @@ (glob)
  -2:5fb7d38b9dc4
  -3:60b597ffdafa
  -4:b1174d11b69e
  -5:6354685872c0
  -6:5ebc725f1bef
  -7:7b76eec2f273
  -8:ef3428d9d644
  -9:ba7a936bc03c
  *** append corruption