tests/test-propertycache.py.out

ui: add special-purpose atexit functionality

In spite of its longstanding use, Python's built-in atexit code is
not suitable for Mercurial's purposes, for several reasons:

* Handlers run after application code has finished.

* Because of this, the code that runs handlers swallows exceptions
  (since there's no possible stacktrace to associate errors with).
  If we're lucky, we'll get something spat out to stderr (if stderr
  still works), which of course isn't any use in a big deployment
  where it's important that exceptions get logged and aggregated.

* Mercurial's current atexit handlers make unfortunate assumptions
  about process state (specifically stdio) that, coupled with the
  above problems, make it impossible to deal with certain categories
  of error (try "hg status > /dev/full" on a Linux box).

* In Python 3, the atexit implementation is completely hidden, so
  we can't hijack the platform's atexit code to run handlers at a
  time of our choosing.

As a result, here's a perfectly cromulent atexit-like implementation
over which we have control.  This lets us decide exactly when the
handlers run (after each request has completed), and control what
the process state is when that occurs (and afterwards).

=== property cache ===

calllog: []
cached value (unfiltered): NOCACHE

= first access on unfiltered, should do a call
access: 0
calllog: [0]
cached value (unfiltered): 0

= second access on unfiltered, should not do call
access 0
calllog: [0]
cached value (unfiltered): 0

= first access on "visible" view, should do a call
cached value ("visible" view): NOCACHE
access: 7
calllog: [0, 7]
cached value (unfiltered): 0
cached value ("visible" view): 7

= second access on "visible view", should not do call
access: 7
calllog: [0, 7]
cached value (unfiltered): 0
cached value ("visible" view): 7

= no effect on other view
cached value ("immutable" view): NOCACHE
access: 9
calllog: [0, 7, 9]
cached value (unfiltered): 0
cached value ("visible" view): 7
cached value ("immutable" view): 9


=== unfiltered property cache ===

unficalllog: []
cached value (unfiltered):       NOCACHE
cached value ("visible" view):   NOCACHE
cached value ("immutable" view): NOCACHE

= first access on unfiltered, should do a call
access (unfiltered): 100
unficalllog: [100]
cached value (unfiltered):       100

= second access on unfiltered, should not do call
access (unfiltered): 100
unficalllog: [100]
cached value (unfiltered):       100

= access on view should use the unfiltered cache
access (unfiltered):       100
access ("visible" view):   100
access ("immutable" view): 100
unficalllog: [100]
cached value (unfiltered):       100
cached value ("visible" view):   NOCACHE
cached value ("immutable" view): NOCACHE

= even if we clear the unfiltered cache
cached value (unfiltered):       NOCACHE
cached value ("visible" view):   NOCACHE
cached value ("immutable" view): NOCACHE
unficalllog: [100]
access ("visible" view):   100
unficalllog: [100, 100]
cached value (unfiltered):       100
cached value ("visible" view):   NOCACHE
cached value ("immutable" view): NOCACHE
access ("immutable" view): 100
unficalllog: [100, 100]
cached value (unfiltered):       100
cached value ("visible" view):   NOCACHE
cached value ("immutable" view): NOCACHE
access (unfiltered):       100
unficalllog: [100, 100]
cached value (unfiltered):       100
cached value ("visible" view):   NOCACHE
cached value ("immutable" view): NOCACHE