package com.lmax.disruptor;
import static java.util.Arrays.copyOf;
import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
class SequenceGroups
{
static <T> void addSequences(
final T holder,
final AtomicReferenceFieldUpdater<T, Sequence[]> updater,
final Cursored cursor,
final Sequence... sequencesToAdd)
{
long cursorSequence;
Sequence[] updatedSequences;
Sequence[] currentSequences;
do
{
currentSequences = updater.get(holder);
updatedSequences = copyOf(currentSequences, currentSequences.length + sequencesToAdd.length);
cursorSequence = cursor.getCursor();
int index = currentSequences.length;
for (Sequence sequence : sequencesToAdd)
{
sequence.set(cursorSequence);
updatedSequences[index++] = sequence;
}
}
while (!updater.compareAndSet(holder, currentSequences, updatedSequences));
cursorSequence = cursor.getCursor();
for (Sequence sequence : sequencesToAdd)
{
sequence.set(cursorSequence);
}
}
static <T> boolean removeSequence(
final T holder,
final AtomicReferenceFieldUpdater<T, Sequence[]> sequenceUpdater,
final Sequence sequence)
{
int numToRemove;
Sequence[] oldSequences;
Sequence[] newSequences;
do
{
oldSequences = sequenceUpdater.get(holder);
numToRemove = countMatching(oldSequences, sequence);
if (0 == numToRemove)
{
break;
}
final int oldSize = oldSequences.length;
newSequences = new Sequence[oldSize - numToRemove];
for (int i = 0, pos = 0; i < oldSize; i++)
{
final Sequence testSequence = oldSequences[i];
if (sequence != testSequence)
{
newSequences[pos++] = testSequence;
}
}
}
while (!sequenceUpdater.compareAndSet(holder, oldSequences, newSequences));
return numToRemove != 0;
}
private static <T> int countMatching(T[] values, final T toMatch)
{
int numToRemove = 0;
for (T value : values)
{
if (value == toMatch)
{
numToRemove++;
}
}
return numToRemove;
}
}