Update serialization extension to support custom cache-size metric

[justinmimbs]

The current Serialization extension assumes the cache size is always the number of items in the cache. This PR allows serializing LRUs with custom by functions, where lru.currentsize != length(lru).

• Fixes Serialization does not support non-default by functions #51

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 81.97%. Comparing base (1cfbef2) to head (2185bb5).
Report is 2 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master      #52      +/-   ##
==========================================
+ Coverage   81.92%   81.97%   +0.05%     
==========================================
  Files           3        3              
  Lines         354      355       +1     
==========================================
+ Hits          290      291       +1     
  Misses         64       64              

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[ericphanson]

is there a way to detect there are no bytes left to deserialize and fallback to n_items = currentsize here? to continue supporting de-serializing old serialized files

[ericphanson]

(if not, I'm not sure this should be a patch release, it seems like it could unexpectedly break stuff. Not quite sure what folks use LRU serialization for though, is it for IPC only or for persistence?)

[justinmimbs]

That's a good point; this will break deserializing old serialized data. I think we can make this backward compatible, and that would be nicer in case there are some persisted LRUs out there.

Any existing file would have n_items in the currentsize position, so we can continue storing n_items there, and always recompute currentsize.

[justinmimbs]

I updated the PR. Thanks for pointing this out!

[ericphanson]

good solution!

[Jutho]

Thanks; this looks like a great PR. I have no additional comments. I suggest to leave this open one more day for maybe @jarbus or @lkdvos to take a look, and then merge and tag tomorrow.

[jarbus]

This seems good to me as well. Thanks for the great changes!

[lkdvos]

Also looks like a great improvement to me, I don't think I can spot any issues here.

[fingolfin]

This was approved and all people who were meant to comment did so... Merging...

[Jutho]

Thanks; seems like I had completely forgotten about this.