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

[Martin Buchholz]

Ah, yes, now I see.

My latest attempt at this method looks like:

    private static int capacity(int expectedMaxSize) {
        // assert expectedMaxSize >= 0;
        return
            (expectedMaxSize > MAXIMUM_CAPACITY / 3) ? MAXIMUM_CAPACITY :
            (expectedMaxSize <= 2 * MINIMUM_CAPACITY / 3) ?
MINIMUM_CAPACITY :
            Integer.highestOneBit(expectedMaxSize + (expectedMaxSize << 1));
    }



On Mon, Jul 7, 2014 at 6:12 PM, Ivan Gerasimov <ivan.gerasimov at oracle.com>
wrote:

>
> On 08.07.2014 4:47, Martin Buchholz wrote:
>
>> I think this code has an off-by-factor-of-2 bug.
>>
>> +        if (expectedMaxSize > MAXIMUM_CAPACITY / 3)
>> +            return MAXIMUM_CAPACITY;
>>
>>
> No, even though it looks like a bug.
>
> (MAXIMUM_CAPACITY / 3) * (3 / 2) == MAXIMUM_CAPACITY / 2.
>
> if expected size > MAXIMUM_CAPACITY / 3,
> then the minimum capacity must be > MAXIMUM_CAPACITY / 2
> then the minimum capacity == MAXIMUM_CAPACITY.
>
>
>