Change execution filter to run action again if action is cached, but output type of the view isn't

[david]

Problem:

• Action with two Output Types A and B in the View
• Action runs, View runs with Output Type A, cache for Action and cache View (for Output Type A, not for B, obviously) is written
• Action runs again, with Output Type B, cache is not stale. Cache is used for the Action, but the View needs to be executed again, for Output Type B

This is possible already: you can include the attributes from the Action in the cache.

However, you might have tons and gigabytes of data for the View, and thus require to run the Action again.

My suggestion: in such a situation, the Action is executed again unless <action_attribute> configuration is given in the caching XML config

[david]

(In [2416]) change if to remove indent/braces, refs #742

[david]

The plan:

• if no <action_attributes> are defined, the Action will be run again if a cached version of the Action exists, but no cached (or a stale) version of the View
• the result of the newly run Action is written to the cache
• also, if the View name returned by this Action run differs from what's in the cache, all existing View caches will be purged, provided that the new View name is on the list of cacheable Views
• if the returned View name is not on the list of cacheable Views, all existing View caches will be purged and the (now definitely stale) Action cache will be removed
• a configuration flag could be used to allow people the disabling of View cache flushing for the situation where the View names differ, but the new View name is also allowed to be cached

[david]

(In [2424]) Make action run again if a cache was hit, but no view cache existed and no action_attributes are defined for caching, refs #742. More to come.

[david]

(In [2425]) automatic flushing of stale caches if previously cached actions with non-expired cache are run again and views differ or are not cacheable, closes #742