4.0.0 JNI/reflection invocation 2/4/8 times as slow as in 3.3.3

Fri Jan 28 10:02:00 GMT 2005

Ranjit Mathew writes:
 > On 2005年1月28日 09:47:04 +0000, Andrew Haley <aph@redhat.com> wrote:
 > >
 > > But I can't see that we handle collisions at all. Look at this:
 > > 
 > > public Object put(Object key, Object value)
 > > {
 > > // Rehash if the load factor is too high.
 > > if (size > threshold)
 > > {
 > > ...
 > > }
 > > 
 > > int h = hash(key);
 > > if (table[h] == key)
 > > {
 > > Object r = table[h + 1];
 > > table[h + 1] = value;
 > > return r;
 > > }
 > > 
 > > // At this point, we add a new mapping.
 > > modCount++;
 > > size++;
 > > table[h] = key;
 > > table[h + 1] = value;
 > > return null;
 > > }
 > > 
 > > Aren't we overwriting an existing key here? Surely we need to
 > > increment h until an empty entry is found.
 > 
 > Look at the implementation of hash() - it computes
 > the hash code and then also finds the appropriate bucket
 > for the key.
Oh yeuch, how nasty.
Okay, so we're using linear probing rather than double hashing, in
which case Algorithm R is appropriate.
Andrew.