void UtlHashMap::destroyAll()
{
OsLock take(mContainerLock);
size_t i;
size_t toBeDestroyed;
for (i = 0, toBeDestroyed = mElements;
i < numberOfBuckets() && toBeDestroyed;
i++
) // for each bucket
{
while(!mpBucket[i].isUnLinked()) // bucket is not empty yet
{
UtlPair* pair = static_cast<UtlPair*>(mpBucket[i].head());
notifyIteratorsOfRemove(pair);
pair->detachFromList(&mpBucket[i]);
delete pair->data;
if (pair->value != INTERNAL_NULL)
{
delete pair->value;
}
pair->release();
toBeDestroyed--;
}
}
mElements = 0;
}
/*
* Allocate additional buckets and redistribute existing contents.
* This should only be called through resizeIfNeededAndSafe.
*/
void UtlHashBag::resize()
{
// already holding the mContainerLock
UtlChain* newBucket;
size_t newBucketBits;
// if an iterator had prevented resizing while many elements were added,
// we might need to double more than once to restore the target ratio.
for (newBucketBits = mBucketBits+1;
mElements / NUM_HASHBAG_BUCKETS(newBucketBits) >= 3;
newBucketBits++
)
{
}
// allocate the new buckets
newBucket = new UtlChain[NUM_HASHBAG_BUCKETS(newBucketBits)];
if (newBucket)
{
// save the old buckets until we move the entries out of them
UtlChain* oldBucket = mpBucket;
size_t numOldBuckets = numberOfBuckets();
// put in the new buckets
mBucketBits = newBucketBits;
mpBucket = newBucket;
// move all the entries to the new buckets
size_t old;
size_t toBeMoved;
for (old = 0, toBeMoved = mElements;
old < numOldBuckets && toBeMoved;
old++
)
{
while(!oldBucket[old].isUnLinked()) // old bucket is not empty yet
{
UtlLink* link = static_cast<UtlLink*>(oldBucket[old].head());
link->detachFromList(&oldBucket[old]);
insert(link, &mpBucket[bucketNumber(link->hash)]);
toBeMoved--;
}
}
delete [] oldBucket; // finished with the old empty buckets
}
else
{
assert(newBucket); // failed to allocate new buckets
}
}
/**
* Search for the designated object by reference.
* @return the object if found, otherwise NULL.
*/
UtlContainable* UtlHashBag::findReference(const UtlContainable* object) const
{
UtlContainable* found = NULL;
if (object)
{
OsLock take(mContainerLock);
UtlLink* link = NULL;
UtlChain* bucket;
UtlLink* check;
// walk the buckets
for (size_t i = 0; link == NULL && i < numberOfBuckets(); i++)
{
bucket = &mpBucket[i];
for (link = NULL, check = static_cast<UtlLink*>(bucket->listHead());
( !link // not found
&& check // not end of list
);
check = check->next()
)
{
if (check->data == object)
{
link = check; // found it
}
}
}
if (link)
{
found = link->data;
}
}
return found;
}
void UtlHashBag::removeAll()
{
OsLock take(mContainerLock);
size_t i;
size_t toBeRemoved;
for (i = 0, toBeRemoved = mElements;
i < numberOfBuckets() && toBeRemoved;
i++
) // for each bucket
{
while(!mpBucket[i].isUnLinked()) // bucket is not empty yet
{
UtlLink* link = static_cast<UtlLink*>(mpBucket[i].head());
notifyIteratorsOfRemove(link);
link->detachFromList(&mpBucket[i]);
link->release();
toBeRemoved--;
}
}
mElements = 0;
}
size_t UtlHashMap::bucketNumber(unsigned hash) const
{
/*
* We only use mBucketBits of the hash to index mpBucket, but we don't want to
* loose the information in the higher bits of the hash code. So we 'fold' the
* high order bits by XORing them mBucketBits at a time into the bits we'll
* use until there are no non-zero high order bits left.
*/
size_t foldedHash;
size_t highBits;
size_t lowBitsMask = numberOfBuckets() - 1;
for ( (foldedHash = hash & lowBitsMask, // get the low bits we want into the folded value
highBits = hash // don't bother masking off the low bits
);
(highBits = highBits >> mBucketBits); // shift out bits already used until zero
foldedHash ^= highBits & lowBitsMask // incorporate non-zero
)
{
}
return foldedHash;
}
// Destructor
UtlHashBag::~UtlHashBag()
{
UtlContainer::acquireIteratorConnectionLock();
OsLock take(mContainerLock);
invalidateIterators();
UtlContainer::releaseIteratorConnectionLock();
// still holding the mContainerLock
// walk the buckets
for (size_t i = 0; i < numberOfBuckets(); i++)
{
// empty each bucket and release each UtlPair back to the pool
while (!mpBucket[i].isUnLinked())
{
UtlLink* link = static_cast<UtlLink*>(mpBucket[i].listHead());
link->detachFromList(&mpBucket[i]);
link->release();
}
}
delete [] mpBucket; // free the bucket headers
}
