public ReadOperation(
String operationName,
Reader<?> reader,
OutputReceiver[] receivers,
String counterPrefix,
String systemStageName,
CounterSet.AddCounterMutator addCounterMutator,
StateSampler stateSampler) {
super(
operationName,
receivers,
counterPrefix,
addCounterMutator,
stateSampler,
reader.getStateSamplerStateKind());
this.reader = reader;
this.byteCount =
addCounterMutator.addCounter(
Counter.longs(bytesCounterName(counterPrefix, operationName), SUM));
reader.addObserver(new ReaderObserver());
reader.setStateSamplerAndOperationName(stateSampler, operationName);
this.totalParallelismCounter =
addCounterMutator.addCounter(
Counter.doubles(totalParallelismCounterName(systemStageName), SUM));
// Set only when a task is started or split.
totalParallelismCounter.resetToValue(boundParallelism(reader.getTotalParallelism()));
this.remainingParallelismCounter =
addCounterMutator.addCounter(
Counter.doubles(remainingParallelismCounterName(systemStageName), SUM));
}
private void setProgressFromIterator() {
try {
progress.set(readerIterator.getProgress());
remainingParallelismCounter.resetToValue(
boundParallelism(readerIterator.getRemainingParallelism()));
} catch (UnsupportedOperationException e) {
// Ignore: same semantics as null.
} catch (Exception e) {
// This is not a normal situation, but should not kill the task.
LOG.warn("Progress estimation failed", e);
}
}
/** Relays the split request to {@code ReaderIterator}. */
public Reader.DynamicSplitResult requestDynamicSplit(Reader.DynamicSplitRequest splitRequest) {
synchronized (initializationStateLock) {
if (isFinished()) {
LOG.warn("Iterator is in the Finished state, returning null stop position.");
return null;
}
if (readerIterator == null) {
LOG.warn("Iterator has not been initialized, refusing to split at {}", splitRequest);
return null;
}
Reader.DynamicSplitResult result = readerIterator.requestDynamicSplit(splitRequest);
if (result != null) {
// After a successful split, the stop position changed and progress has to be recomputed.
setProgressFromIterator();
totalParallelismCounter.resetToValue(boundParallelism(reader.getTotalParallelism()));
}
return result;
}
}