On 11/03/2015 10:42 PM, Roger Riggs wrote:
I’m in two minds that it sounds sensible for this Cleaner API to
extend for soft/weak references whereas I am not certain of the use
cases. Anyone can share the known use cases that would be helpful.
Besides the cases already mentioned on the thread... Anyone?
A developer at JavaOne wanted more control over the policy for
clearing SoftReferences
possibly taking into account the cost of creating the cache entry.
A technique I proposed was to use a SoftReference, not for the cached
resource itself
but as a sentinel for the VM needing to free 'soft' memory.
One possible use for a SoftCleaner is to implement a sensible cleaning
strategy for
a Cache. The CleaningFunction was would be triggered when freeing
SoftReferences
was needed by VM GC policy and could be used as a hook to use its own
algorithm
to free some of its cached values.
...and register another Soft CleaningFunction at the same time...
Clever! So you get periodic call-backs from GC when GC thinks it's time
to do some soft cleaning, and implement the strategy of cleaning the
data structure yourself, like:
void doPeriodicCleaningWhenGcThinksItsTime(Cleaner cleaner, Runnable
strategy) {
cleaner.softCleanable(new Object(), () -> {
strategy.run();
doPeriodicCleaningWhenGcThinksItsTime(cleaner, strategy);
});
}
Regards, Peter
