internal Container Resize(int newSize)
{
Debug.Assert(IsPowerOfTwo(newSize));
// Reallocate both buckets and entries and rebuild the bucket and entries from scratch.
// This serves both to scrub entries with expired keys and to put the new entries in the proper bucket.
int[] newBuckets = new int[newSize];
for (int bucketIndex = 0; bucketIndex < newSize; bucketIndex++)
{
newBuckets[bucketIndex] = -1;
}
Entry[] newEntries = new Entry[newSize];
int newEntriesIndex = 0;
// Migrate existing entries to the new table.
for (int entriesIndex = 0; entriesIndex < _entries.Length; entriesIndex++)
{
int hashCode = _entries[entriesIndex].hashCode;
DependentHandle depHnd = _entries[entriesIndex].depHnd;
if (hashCode != -1 && depHnd.IsAllocated && depHnd.GetPrimary() != null)
{
// Entry is used and has not expired. Link it into the appropriate bucket list.
// Note that we have to copy the DependentHandle, since the original copy will be freed
// by the Container's finalizer.
newEntries[newEntriesIndex].hashCode = hashCode;
newEntries[newEntriesIndex].depHnd = depHnd.AllocateCopy();
int bucket = hashCode & (newBuckets.Length - 1);
newEntries[newEntriesIndex].next = newBuckets[bucket];
newBuckets[bucket] = newEntriesIndex;
newEntriesIndex++;
}
}
GC.KeepAlive(this); // ensure we don't get finalized while accessing DependentHandles.
return(new Container(newBuckets, newEntries, newEntriesIndex));
}
internal Container Resize()
{
// Start by assuming we won't resize.
int newSize = _buckets.Length;
// If any expired or removed keys exist, we won't resize.
bool hasExpiredEntries = false;
int entriesIndex;
for (entriesIndex = 0; entriesIndex < _entries.Length; entriesIndex++)
{
if (_entries[entriesIndex].hashCode == -1)
{
// the entry was removed
hasExpiredEntries = true;
break;
}
if (_entries[entriesIndex].depHnd.IsAllocated && _entries[entriesIndex].depHnd.GetPrimary() == null)
{
// the entry has expired
hasExpiredEntries = true;
break;
}
}
if (!hasExpiredEntries)
{
newSize = System.Collections.HashHelpers.GetPrime(_buckets.Length == 0 ? _initialCapacity + 1 : _buckets.Length * 2);
}
// Reallocate both buckets and entries and rebuild the bucket and freelists from scratch.
// This serves both to scrub entries with expired keys and to put the new entries in the proper bucket.
int newFreeList = -1;
int[] newBuckets = new int[newSize];
for (int bucketIndex = 0; bucketIndex < newSize; bucketIndex++)
{
newBuckets[bucketIndex] = -1;
}
Entry[] newEntries = new Entry[newSize];
// Migrate existing entries to the new table.
for (entriesIndex = 0; entriesIndex < _entries.Length; entriesIndex++)
{
DependentHandle depHnd = _entries[entriesIndex].depHnd;
if (_entries[entriesIndex].hashCode != -1 && depHnd.IsAllocated && depHnd.GetPrimary() != null)
{
// Entry is used and has not expired. Link it into the appropriate bucket list.
// Note that we have to copy the DependentHandle, since the original copy will be freed
// by the Container's finalizer.
int bucket = _entries[entriesIndex].hashCode % newSize;
newEntries[entriesIndex].depHnd = depHnd.AllocateCopy();
newEntries[entriesIndex].hashCode = _entries[entriesIndex].hashCode;
newEntries[entriesIndex].next = newBuckets[bucket];
newBuckets[bucket] = entriesIndex;
}
else
{
// Entry has either expired or was on the freelist to begin with. Either way
// insert it on the new freelist.
// We do not free the underlying GC handle here, as we may be racing with readers who already saw
// the old Container. The GC handle will be free'd in Container's finalizer.
newEntries[entriesIndex].depHnd = new DependentHandle();
newEntries[entriesIndex].next = newFreeList;
newFreeList = entriesIndex;
}
}
// Add remaining entries to freelist.
while (entriesIndex != newEntries.Length)
{
newEntries[entriesIndex].depHnd = new DependentHandle();
newEntries[entriesIndex].next = newFreeList;
newFreeList = entriesIndex;
entriesIndex++;
}
GC.KeepAlive(this); // ensure we don't get finalized while accessing DependentHandles.
return(new Container()
{
_buckets = newBuckets,
_entries = newEntries,
_freeList = newFreeList
});
}
