open-telemetry
Make built-in spanProcessor extendable
Is your feature request related to a problem? Please describe. A clear and concise description of what the problem is. The implementations of SpanProcessor are final class, we cannot extend it.
Describe the solution you'd like A clear and concise description of what you want to happen. Make them extendable.
Can you explain what your use-case is, and why you need to extend, rather than just create a wrapper that delegates some functionality to the underlying SpanProcessor?
I want BatchSpanProcessor to skip executing forceFlush when shutdown. It's impossible to create a wrapper that delegates the shutdown because it's a private method of the inner class Worker.
Seems easy enough to have your delegate keep track of the shutdown state, and just use that to make forceFlush a no-op after shutdown has been called. Am I missing something?
Seems easy enough to have your delegate keep track of the
shutdownstate, and just use that to makeforceFlusha no-op after shutdown has been called. Am I missing something?
Sorry, I can't get it. Would you please show me a code example?
Seems easy enough to have your delegate keep track of the
shutdownstate, and just use that to makeforceFlusha no-op after shutdown has been called. Am I missing something?Sorry, I can't get it. Would you please show me a code example?
public class DelegatingSpanProcessor implements SpanProcessor {
private final SpanProcessor delegate;
private final AtomicBoolean isShutdown = new AtomicBoolean();
public DelegatingSpanProcessor(SpanProcessor delegate) {this.delegate = delegate;}
@Override
public CompletableResultCode shutdown() {
CompletableResultCode shutdown = delegate.shutdown();
isShutdown.set(true);
return shutdown;
}
@Override
public CompletableResultCode forceFlush() {
if (isShutdown.get()) {
return CompletableResultCode.ofSuccess();
}
return delegate.forceFlush();
}
@Override
public void onStart(Context parentContext, ReadWriteSpan span) {
delegate.onStart(parentContext, span);
}
@Override
public boolean isStartRequired() {
return delegate.isStartRequired();
}
@Override
public void onEnd(ReadableSpan span) {
delegate.onEnd(span);
}
@Override
public boolean isEndRequired() {
return delegate.isEndRequired();
}
@Override
public void close() {
delegate.close();
}
}
delegate.shutdown() calls worker.shutdown(), and then the worker will flush itself. The forceFlush of BatchSpanProcessor itself doesn't make sense.
Let's see the implementation of the forceFlush of BatchSpanProcessor:
@Override
public CompletableResultCode shutdown() {
if (isShutdown.getAndSet(true)) {
return CompletableResultCode.ofSuccess();
}
return worker.shutdown(); // <=== I want to skip this flush
}
Making the BatchSpanProcessor extendable wouldn't solve your issue, then, since we will still need to shut down the worker thread, even if it doesn't flush its spans before doing so.
I recommend making a copy of the BatchSpanProcessor code and modifying it to your liking. If you need this as a first-class feature (skipping the flushing of the spans on shutdown), I recommend creating an issue in the specification for it, as this is required behavior from the BatchSpanProcessor. See here for the specific requirement.
I think a sufficient workaround has been proposed here, and I think we collectively feel pretty strongly about preventing users from inheriting from core otel classes. Please feel free to reopen if this needs to be discussed further.
