tombentley commented on a change in pull request #9878:
URL: https://github.com/apache/kafka/pull/9878#discussion_r662832035
##########
File path:
clients/src/main/java/org/apache/kafka/common/internals/KafkaFutureImpl.java
##########
@@ -27,217 +28,107 @@
/**
* A flexible future which supports call chaining and other asynchronous
programming patterns.
- * This will eventually become a thin shim on top of Java 8's
CompletableFuture.
*/
public class KafkaFutureImpl<T> extends KafkaFuture<T> {
- /**
- * A convenience method that throws the current exception, wrapping it if
needed.
- *
- * In general, KafkaFuture throws CancellationException and
InterruptedException directly, and
- * wraps all other exceptions in an ExecutionException.
- */
- private static void wrapAndThrow(Throwable t) throws InterruptedException,
ExecutionException {
- if (t instanceof CancellationException) {
- throw (CancellationException) t;
- } else if (t instanceof InterruptedException) {
- throw (InterruptedException) t;
- } else {
- throw new ExecutionException(t);
- }
- }
- private static class Applicant<A, B> implements BiConsumer<A, Throwable> {
- private final BaseFunction<A, B> function;
- private final KafkaFutureImpl<B> future;
+ private final KafkaCompletableFuture<T> completableFuture;
- Applicant(BaseFunction<A, B> function, KafkaFutureImpl<B> future) {
- this.function = function;
- this.future = future;
- }
+ private final boolean isDependant;
- @Override
- public void accept(A a, Throwable exception) {
- if (exception != null) {
- future.completeExceptionally(exception);
- } else {
- try {
- B b = function.apply(a);
- future.complete(b);
- } catch (Throwable t) {
- future.completeExceptionally(t);
- }
- }
- }
+ public KafkaFutureImpl() {
+ this(false, new KafkaCompletableFuture<>());
}
- private static class SingleWaiter<R> implements BiConsumer<R, Throwable> {
- private R value = null;
- private Throwable exception = null;
- private boolean done = false;
-
- @Override
- public synchronized void accept(R newValue, Throwable newException) {
- this.value = newValue;
- this.exception = newException;
- this.done = true;
- this.notifyAll();
- }
-
- synchronized R await() throws InterruptedException, ExecutionException
{
- while (true) {
- if (exception != null)
- wrapAndThrow(exception);
- if (done)
- return value;
- this.wait();
- }
- }
-
- R await(long timeout, TimeUnit unit)
- throws InterruptedException, ExecutionException,
TimeoutException {
- long startMs = System.currentTimeMillis();
- long waitTimeMs = unit.toMillis(timeout);
- long delta = 0;
- synchronized (this) {
- while (true) {
- if (exception != null)
- wrapAndThrow(exception);
- if (done)
- return value;
- if (delta >= waitTimeMs) {
- throw new TimeoutException();
- }
- this.wait(waitTimeMs - delta);
- delta = System.currentTimeMillis() - startMs;
- }
- }
- }
+ public KafkaFutureImpl(KafkaCompletableFuture<T> completableFuture) {
+ this(false, completableFuture);
}
- /**
- * True if this future is done.
- */
- private boolean done = false;
-
- /**
- * The value of this future, or null. Protected by the object monitor.
- */
- private T value = null;
-
- /**
- * The exception associated with this future, or null. Protected by the
object monitor.
- */
- private Throwable exception = null;
+ private KafkaFutureImpl(boolean isDependant, KafkaCompletableFuture<T>
completableFuture) {
+ this.isDependant = isDependant;
+ this.completableFuture = completableFuture;
+ }
- /**
- * A list of objects waiting for this future to complete (either
successfully or
- * exceptionally). Protected by the object monitor.
- */
- private List<BiConsumer<? super T, ? super Throwable>> waiters = new
ArrayList<>();
+ @Override
+ public CompletionStage<T> toCompletionStage() {
+ return completableFuture;
+ }
/**
* Returns a new KafkaFuture that, when this future completes normally, is
executed with this
* futures's result as the argument to the supplied function.
*/
@Override
public <R> KafkaFuture<R> thenApply(BaseFunction<T, R> function) {
- KafkaFutureImpl<R> future = new KafkaFutureImpl<>();
- addWaiter(new Applicant<>(function, future));
- return future;
+ CompletableFuture<R> completableFuture =
this.completableFuture.thenApply((java.util.function.Function<? super T, ?
extends R>) value -> {
+ try {
+ return function.apply(value);
+ } catch (Throwable t) {
+ if (t instanceof CompletionException) {
+ throw new CompletionException(t);
+ } else {
+ throw t;
+ }
+ }
+ });
+ return new KafkaFutureImpl<>(true,
toKafkaCompletableFuture(completableFuture));
}
- public <R> void copyWith(KafkaFuture<R> future, BaseFunction<R, T>
function) {
- KafkaFutureImpl<R> futureImpl = (KafkaFutureImpl<R>) future;
- futureImpl.addWaiter(new Applicant<>(function, this));
+ private <U> KafkaCompletableFuture<U>
toKafkaCompletableFuture(CompletableFuture<U> tCompletableFuture) {
+ KafkaCompletableFuture<U> res;
+ if (tCompletableFuture instanceof KafkaCompletableFuture) {
+ res = (KafkaCompletableFuture<U>) tCompletableFuture;
Review comment:
The lambda passed to `whenComplete` needs to complete the
`KafkaCompletableFuture`, so needs a captured variable, but I'll declare
`result` in the `else` branch only.
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