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

Martin Buchholz martinrb at google.com
Tue Jul 8 13:56:16 UTC 2014

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On Tue, Jul 8, 2014 at 5:30 AM, Peter Levart <peter.levart at gmail.com> wrote:

On 07/08/2014 02:20 PM, Peter Levart wrote:

That's right. Not in put(). But in putAll() it can overflow, since the argument Map can be of any size that fits in int... I took another look at putAll. I think we can do more simply, relying on the checks in capacity and resize:

      int n = m.size();
     if (n == 0)
         return;

•    if (n > threshold) // conservatively pre-expand

•        resize(capacity(n));

•    if (n > size)

•        resize(capacity(n)); // conservatively pre-expand
  
     for (Entry<? extends K, ? extends V> e : m.entrySet())
         put(e.getKey(), e.getValue());

Also, note I'm trying to avoid (relatively expensive) integer division, except at compile time.

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