RFR: [6904367]: (coll) IdentityHashMap is resized before exceeding the expected maximum size

[Jeff Hain]

Hi.




>WEBREV: http://cr.openjdk.java.net/~igerasim/6904367/0/webrev/
The "while" loop in put(...) supposes that there is at least one free slot,
which was the case
 before (that could be added as comment).

Now if you try to go past max capacity, instead of getting an IllegalStateException,
you get an infinite loop.

It's easy to test with a loop of 1000 puts and MAX_CAPACITY = 1<<8
(=256, needs to be larger than DEFAULT_CAPACITY, else it can be "ignored").
With previous version you get IllegalStateException on trying to add 255th mapping
(on the resize that occurs when just-after-put-size is 255 >= threshold = 255),
and with new version you get infinite loop on trying to add 257th mapping.

Solutions I see would be adding a throw if size >= MAX_CAPACITY
before the loop, or not adding that overhead and instead throwing when
"size >= MAX_CAPACITY-1" instead of when "size >= MAX_CAPACITY".

I would also rather use "==" over ">=" for these tests, to
 underline the fact
that size is not supposed to be larger, but there might be some reasons not to.


-Jeff