/**
* Takes the results of running linkWalkFirstPhase and creates an m/r job from them
*
* @param firstPhaseResult the results of running linkWalkfirstPhase.
* @return the results from the intermediate bkeys of phase one.
* @throws IOException
*/
private MapReduceResult linkWalkSecondPhase(final MapReduceResult firstPhaseResult)
throws IOException {
try {
@SuppressWarnings("rawtypes")
Collection<LinkedList> bkeys = firstPhaseResult.getResult(LinkedList.class);
BucketKeyMapReduce mr = new BucketKeyMapReduce(this);
int stepCnt = 0;
for (LinkedList<List<String>> step : bkeys) {
// TODO find a way to *enforce* order here (custom
// deserializer?)
stepCnt++;
for (List<String> input : step) {
// use the step count as key data so we can aggregate the
// results into the correct steps when they come back
mr.addInput(input.get(0), input.get(1), Integer.toString(stepCnt));
}
}
mr.addReducePhase(new NamedErlangFunction("riak_kv_mapreduce", "reduce_set_union"), false);
mr.addMapPhase(
new JSSourceFunction("function(v, keyData) { return [{\"step\": keyData, \"v\": v}]; }"),
true);
return mr.execute();
} catch (ConversionException e) {
throw new IOException(e.getMessage());
} catch (RiakException e) {
throw (IOException) e.getCause();
}
}
/**
* Creates an m/r job from the supplied link spec and executes it
*
* @param linkWalkSpec the Link Walk spec
* @return {@link MapReduceResult} containing the end of the link and any intermediate bkeys for a
* second pass
* @throws IOException
*/
private MapReduceResult linkWalkFirstPhase(final LinkWalkSpec linkWalkSpec) throws IOException {
BucketKeyMapReduce mr = new BucketKeyMapReduce(this);
mr.addInput(linkWalkSpec.getStartBucket(), linkWalkSpec.getStartKey());
int size = linkWalkSpec.size();
int cnt = 0;
for (LinkWalkStep step : linkWalkSpec) {
cnt++;
boolean keep = linkAccumulateToLinkPhaseKeep(step.getKeep(), cnt == size);
mr.addLinkPhase(step.getBucket(), step.getTag(), keep);
}
// this is a bit of a hack. The low level API is using the high level
// API so must strip out the exception.
try {
return mr.execute();
} catch (RiakException e) {
throw (IOException) e.getCause();
}
}