/*
Copyright 2010 Nathan Marz
Project and contact information: http://www.cascalog.org/
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package cascalog;
import java.util.Arrays;
import java.util.List;
import cascading.flow.FlowProcess;
import cascading.operation.FunctionCall;
import cascading.operation.OperationCall;
import cascading.tuple.Fields;
import cascading.tuple.Tuple;
import cascading.tuple.TupleEntryCollector;
import cascalog.aggregator.CombinerSpec;
import clojure.lang.IFn;
import clojure.lang.ISeq;
import clojure.lang.RT;
public class ClojureBufferCombiner extends ClojureCombinerBase {
private CombinerSpec spec;
public ClojureBufferCombiner(Fields groupFields, Fields sortFields, Fields args, Fields outFields,
CombinerSpec spec) {
super(groupFields, true, sortFields, Arrays.asList(args), outFields, Arrays
.asList((ParallelAgg) new ClojureParallelAgg(spec)), "cascalog.combiner.buffer.size", 200);
this.spec = spec;
}
private IFn extract_fn = null;
@Override
public void prepare(FlowProcess flowProcess, OperationCall operationCall) {
super.prepare(flowProcess, operationCall);
extract_fn = Util.deserializeFn(spec.presentFn);
}
@Override
protected void write(Tuple group, List<Object> vals, OperationCall opCall) {
TupleEntryCollector output = ((FunctionCall) opCall).getOutputCollector();
if (vals.size() != 1) {
throw new RuntimeException(
"Should only have one object in buffer combiner before extraction " + vals.size() + ":"
+ vals.toString());
}
Object val = vals.get(0);
try {
ISeq result_seq = RT.seq(extract_fn.invoke(val));
while (result_seq != null) {
Tuple t = Util.coerceToTuple(result_seq.first());
Tuple emit = new Tuple(group);
emit.addAll(t);
output.add(emit);
result_seq = result_seq.next();
}
} catch (Exception e) {
throw new RuntimeException(e);
}
}
}