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

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

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)
-        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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