Flush cache section
===================

A flushcache pipeline section flushes zope cache every so often, which has an
effect of freeing up memory. This section is useful while performing migration
on a weak system with a low memory. The flushcache section blueprint name is
``quintagroup.transmogrifier.flushcache``.

A flushcache section takes an optional ``every`` option, which defaults to
1000; cache is being flushed every ``every`` items passing through the pipe.
A flushcache section doesn't alter the items in any way:

>>> flushcache = """
... [transmogrifier]
... pipeline =
...     source
...     flushcache
...     
... [source]
... blueprint = collective.transmogrifier.sections.tests.rangesource
... size = 10
... 
... [flushcache]
... blueprint = quintagroup.transmogrifier.flushcache
... every = 3
... """
>>> registerConfig(u'quintagroup.transmogrifier.tests.flushcache', flushcache)

We'll show caching is flushed using dedicated variable on dummy plone instance
called 'cacheMinimized'. Which is a number of caches performed.

>>> transmogrifier(u'quintagroup.transmogrifier.tests.flushcache')
>>> transmogrifier.context.cacheMinimized
3