/** @see niagara.query_engine.PhysicalOperator#processTuple(Tuple, int) */
protected void processTuple(Tuple tuple, int streamId)
throws ShutdownException, InterruptedException {
String hash = hasher.hashKey(tuple);
// ignore null attributes...
if (hash == null) return;
// Have we seen this group before?
Tuple representativeTuple = (Tuple) hash2tuple.get(hash);
if (representativeTuple == null) {
// Output tuples contain the groupby attributes plus
// two more fields: previous and current group info
representativeTuple = new Tuple(true, groupAttrs.length + 2);
// Copy the groupby attributes
for (int i = 0; i < groupAttrs.length; i++) {
representativeTuple.appendAttribute(tuple.getAttribute(groupAttrs[i]));
}
// Initialize the group hashtable entries
hash2partial.put(hash, emptyGroupValue());
hash2final.put(hash, emptyGroupValue());
hash2tuple.put(hash, representativeTuple);
}
Tuple newTuple = new Tuple(tuple.isPartial(), groupAttrs.length + 2);
newTuple.appendTuple(representativeTuple);
Node oldResult = null;
Node newResult;
// partial tuples only affect partial results
Object oldGroupInfo = hash2partial.get(hash);
if (logicalGroupOperator.outputOldValue()) oldResult = constructOutput(oldGroupInfo);
Object newGroupInfo = processTuple(tuple, oldGroupInfo);
newResult = constructOutput(newGroupInfo);
hash2partial.put(hash, newGroupInfo);
// final tuples affect both final and partial results
if (!tuple.isPartial()) {
// final tuples affect both final and partial results
oldGroupInfo = hash2final.get(hash);
if (logicalGroupOperator.outputOldValue()) oldResult = constructOutput(oldGroupInfo);
newGroupInfo = processTuple(tuple, hash2final.get(hash));
newResult = constructOutput(newGroupInfo);
hash2final.put(hash, newGroupInfo);
}
if (newGroupInfo == oldGroupInfo) {
// There was no change in the group,
// do not output a tuple
return;
}
if (logicalGroupOperator.outputOldValue()) newTuple.appendAttribute(oldResult);
newTuple.appendAttribute(newResult);
putTuple(newTuple, 0);
}
/**
* This function initializes the data structures for an operator. This over-rides the
* corresponding function in the base class.
*
* @return True if the operator is to continue and false otherwise
*/
protected void opInitialize() {
// Get the grouping attributes
skolem grouping = logicalGroupOperator.getSkolemAttributes();
Vector groupVars = grouping.getVarList();
hasher = new Hasher(groupVars);
groupAttrs = new int[groupVars.size()];
for (int i = 0; i < groupAttrs.length; i++) {
groupAttrs[i] = inputTupleSchemas[0].getPosition(((Attribute) groupVars.get(i)).getName());
}
hasher.resolveVariables(inputTupleSchemas[0]);
// Initialize the hash tables
hash2final = new HashMap();
hash2partial = new HashMap();
hash2tuple = new HashMap();
}