/**
* Remove all the local of a context (but keep global).
*
* @param context a counter context
* @return a version of {@code context} where no shards are local.
*/
public ByteBuffer clearAllLocal(ByteBuffer context) {
int count = Math.abs(context.getShort(context.position()));
if (count == 0) return context; // no local or global shards present.
List<Short> globalShardIndexes = new ArrayList<>(count);
for (int i = 0; i < count; i++) {
short elt = context.getShort(context.position() + HEADER_SIZE_LENGTH + i * HEADER_ELT_LENGTH);
if (elt < 0) globalShardIndexes.add(elt);
}
if (count == globalShardIndexes.size()) return context; // no local shards detected.
// allocate a smaller BB for the cleared context - with no local header elts.
ByteBuffer cleared =
ByteBuffer.allocate(
context.remaining() - (count - globalShardIndexes.size()) * HEADER_ELT_LENGTH);
cleared.putShort(cleared.position(), (short) globalShardIndexes.size());
for (int i = 0; i < globalShardIndexes.size(); i++)
cleared.putShort(
cleared.position() + HEADER_SIZE_LENGTH + i * HEADER_ELT_LENGTH,
globalShardIndexes.get(i));
int origHeaderLength = headerLength(context);
ByteBufferUtil.arrayCopy(
context,
context.position() + origHeaderLength,
cleared,
cleared.position() + headerLength(cleared),
context.remaining() - origHeaderLength);
return cleared;
}
/**
* Mark context to delete local references afterward. Marking is done by multiply #elt by -1 to
* preserve header length and #elt count in order to clear all local refs later.
*
* @param context a counter context
* @return context that marked to delete local refs
*/
public ByteBuffer markLocalToBeCleared(ByteBuffer context) {
short count = context.getShort(context.position());
if (count <= 0) return context; // already marked or all are remote.
boolean hasLocalShards = false;
for (int i = 0; i < count; i++) {
if (context.getShort(context.position() + HEADER_SIZE_LENGTH + i * HEADER_ELT_LENGTH) >= 0) {
hasLocalShards = true;
break;
}
}
if (!hasLocalShards) return context; // all shards are global or remote.
ByteBuffer marked = ByteBuffer.allocate(context.remaining());
marked.putShort(marked.position(), (short) (count * -1));
ByteBufferUtil.arrayCopy(
context,
context.position() + HEADER_SIZE_LENGTH,
marked,
marked.position() + HEADER_SIZE_LENGTH,
context.remaining() - HEADER_SIZE_LENGTH);
return marked;
}
@Override
public final void readFully(byte[] bytes) throws IOException {
ByteBufferUtil.arrayCopy(buffer, buffer.position() + position, bytes, 0, bytes.length);
position += bytes.length;
}
