/*
* creates a pipe for predicate counts
*/
private void setupPredicateCounts(Pipe pipe, Map<String, Tap> sinks, List<Pipe> pipes)
throws IOException {
String predicateGroupsTempPath =
distributedFileSystemManager.getPredicateGroupsTempPath(mConfiguration.resultsName);
FileSystem fs = FileSystem.get(mConfiguration.hadoopConfiguration);
if (fs.exists(new Path(predicateGroupsTempPath))) {
fs.delete(new Path(predicateGroupsTempPath), true);
}
Tap predicatesSink = new Hfs(new Fields(0, 1), predicateGroupsTempPath);
Pipe predicatesPipe = Utils.buildPredicateCountPipe(pipe);
sinks.put("predicatesPipe", predicatesSink);
pipes.add(predicatesPipe);
}
/*
* creates and processes a flow identified by {@code flowIdentificator}
* results are stored at {@code output} under the result named {@code resultName}
*/
private boolean processFlow(String resultName, String flowIdentificator, String output)
throws IOException {
boolean hasNewInferences = false;
String flowName = resultName + flowIdentificator;
Map<String, Tap> sources = prepareSourceTaps();
SequenceFile sinkScheme = new SequenceFile(fields);
// sinkScheme.setNumSinkParts(1); //FIXME
Tap headSink = new Hfs(sinkScheme, output, true);
Map<String, Tap> sinks = new HashMap<String, Tap>();
List<Pipe> pipes = new ArrayList<Pipe>();
sinks.put(pipe.getName(), headSink);
pipes.add(pipe);
if (mConfiguration.doPredicateIndexing) {
// calculate the count of the result and write it in the configuration
// if the predicate is a variable then we have to split also the result and put it in the
// right location
setupPredicateCounts(pipe, sinks, pipes);
}
flow =
new FlowConnector(mConfiguration.flowProperties)
.connect(flowName, sources, sinks, pipes.toArray(new Pipe[0]));
if (flow != null) {
// flow.writeDOT("flow.dot");
}
flow.complete();
try {
TupleEntryIterator iterator = flow.openSink(pipe.getName());
if (iterator.hasNext()) {
hasNewInferences = true;
}
iterator.close();
} catch (IOException e) {
logger.error("io exception", e);
throw new RuntimeException("io exception", e);
}
if (!hasNewInferences) {
deleteResults(new Path(path));
} else {
// merge part files FIXME
FileSystem fs = FileSystem.get(mConfiguration.hadoopConfiguration);
// delete empty results (could be from reducers running on no data)
int index = 0;
while (true) {
String value = String.valueOf(index);
String file = path + "/" + "part-" + "00000".substring(0, 5 - value.length()) + value;
Path filePath = new Path(file);
if (fs.exists(filePath)) {
Tap source = new Hfs(new Fields(0, 1, 2), file);
TupleEntryIterator tei = source.openForRead(mConfiguration.jobConf);
boolean noData = !tei.hasNext();
tei.close();
if (noData) {
logger.info("delete empty result : " + file);
fs.delete(filePath, false);
}
} else {
break;
}
index++;
}
}
if (hasNewInferences && mConfiguration.doPredicateIndexing) {
FileSystem fs = FileSystem.get(mConfiguration.hadoopConfiguration);
// update counts in configuration
List<PredicateCount> predicateCounts = Utils.readPredicateCounts(flow, "predicatesPipe");
distributedFileSystemManager.addPredicates(predicateCounts);
if (ruleStreams.getHeadStream().getPredicate() == null) {
// split result to the right locations (for variable predicate)
Tap source = new Hfs(sinkScheme, output, true);
Utils.splitStreamPerPredicates(
mConfiguration,
distributedFileSystemManager,
source,
predicateCounts,
resultName,
flowIdentificator);
fs.delete(new Path(output), true);
}
distributedFileSystemManager.savePredicateConfig();
String predicateGroupsTempPath =
distributedFileSystemManager.getPredicateGroupsTempPath(mConfiguration.resultsName);
fs.delete(new Path(predicateGroupsTempPath), true);
}
return hasNewInferences;
}