kkonstantine commented on a change in pull request #9878: URL: https://github.com/apache/kafka/pull/9878#discussion_r662652853
########## 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; + } else { + KafkaCompletableFuture<U> result = new KafkaCompletableFuture<>(); + tCompletableFuture.whenComplete((x, y) -> { + if (y != null) { + result.kafkaCompleteExceptionally(y); + } else { + result.kafkaComplete(x); + } + }); + res = result; + } + return res; } /** * @see KafkaFutureImpl#thenApply(BaseFunction) + * @deprecated Since Kafka 3.0. */ + @Deprecated @Override public <R> KafkaFuture<R> thenApply(Function<T, R> function) { return thenApply((BaseFunction<T, R>) function); } - private static class WhenCompleteBiConsumer<T> implements BiConsumer<T, Throwable> { - private final KafkaFutureImpl<T> future; - private final BiConsumer<? super T, ? super Throwable> biConsumer; - - WhenCompleteBiConsumer(KafkaFutureImpl<T> future, BiConsumer<? super T, ? super Throwable> biConsumer) { - this.future = future; - this.biConsumer = biConsumer; - } - - @Override - public void accept(T val, Throwable exception) { + @Override + public KafkaFuture<T> whenComplete(final BiConsumer<? super T, ? super Throwable> biConsumer) { + CompletableFuture<T> tCompletableFuture = completableFuture.whenComplete((java.util.function.BiConsumer<? super T, ? super Throwable>) (a, b) -> { try { - if (exception != null) { - biConsumer.accept(null, exception); + biConsumer.accept(a, b); + } catch (Throwable t) { + if (t instanceof CompletionException) { + throw new CompletionException(t); } else { - biConsumer.accept(val, null); + throw t; } - } catch (Throwable e) { - if (exception == null) { - exception = e; - } - } - if (exception != null) { - future.completeExceptionally(exception); - } else { - future.complete(val); } - } + }); + return new KafkaFutureImpl<>(true, toKafkaCompletableFuture(tCompletableFuture)); } - @Override - public KafkaFuture<T> whenComplete(final BiConsumer<? super T, ? super Throwable> biConsumer) { - final KafkaFutureImpl<T> future = new KafkaFutureImpl<>(); - addWaiter(new WhenCompleteBiConsumer<>(future, biConsumer)); - return future; - } - - protected synchronized void addWaiter(BiConsumer<? super T, ? super Throwable> action) { - if (exception != null) { - action.accept(null, exception); - } else if (done) { - action.accept(value, null); - } else { - waiters.add(action); - } - } @Override public synchronized boolean complete(T newValue) { - List<BiConsumer<? super T, ? super Throwable>> oldWaiters; - synchronized (this) { - if (done) - return false; - value = newValue; - done = true; - oldWaiters = waiters; - waiters = null; - } - for (BiConsumer<? super T, ? super Throwable> waiter : oldWaiters) { - waiter.accept(newValue, null); - } - return true; + return completableFuture.kafkaComplete(newValue); } @Override public boolean completeExceptionally(Throwable newException) { - List<BiConsumer<? super T, ? super Throwable>> oldWaiters; - synchronized (this) { - if (done) - return false; - exception = newException; - done = true; - oldWaiters = waiters; - waiters = null; - } - for (BiConsumer<? super T, ? super Throwable> waiter : oldWaiters) { - waiter.accept(null, newException); - } - return true; + // CF#get() always wraps the _cause_ of a CompletionException in EE (which KF does not) Review comment: Not sure what EE is here. ########## File path: clients/src/main/java/org/apache/kafka/common/internals/KafkaFutureImpl.java ########## @@ -267,50 +173,77 @@ public T get() throws InterruptedException, ExecutionException { @Override public T get(long timeout, TimeUnit unit) throws InterruptedException, ExecutionException, TimeoutException { - SingleWaiter<T> waiter = new SingleWaiter<>(); - addWaiter(waiter); - return waiter.await(timeout, unit); + try { + return completableFuture.get(timeout, unit); + } catch (ExecutionException e) { + maybeRewrapAndThrow(e.getCause()); + throw e; + } } /** * Returns the result value (or throws any encountered exception) if completed, else returns * the given valueIfAbsent. */ @Override - public synchronized T getNow(T valueIfAbsent) throws InterruptedException, ExecutionException { - if (exception != null) - wrapAndThrow(exception); - if (done) - return value; - return valueIfAbsent; + public synchronized T getNow(T valueIfAbsent) throws ExecutionException { + try { + return completableFuture.getNow(valueIfAbsent); + } catch (CompletionException e) { + maybeRewrapAndThrow(e.getCause()); + // Note, unlike CF#get() which throws ExecutionException, CF#getNow() throws CompletionException + // thus needs rewrapping to conform to KafkaFuture API, where KF#getNow() throws ExecutionException. + throw new ExecutionException(e.getCause()); + } } /** * Returns true if this CompletableFuture was cancelled before it completed normally. */ @Override public synchronized boolean isCancelled() { - return exception instanceof CancellationException; + if (isDependant) { + Throwable exception; + try { + completableFuture.getNow(null); + return false; + } catch (Exception e) { + exception = e; + } + return exception instanceof CompletionException + && exception.getCause() instanceof CancellationException; + } else { + return completableFuture.isCancelled(); + } } /** * Returns true if this CompletableFuture completed exceptionally, in any way. */ @Override public synchronized boolean isCompletedExceptionally() { - return exception != null; + return completableFuture.isCompletedExceptionally(); } /** * Returns true if completed in any fashion: normally, exceptionally, or via cancellation. */ @Override public synchronized boolean isDone() { - return done; + return completableFuture.isDone(); } @Override public String toString() { - return String.format("KafkaFuture{value=%s,exception=%s,done=%b}", value, exception, done); + T value = null; + Throwable ex = null; Review comment: the naming used above seems better here ```suggestion Throwable exception = null; ``` ########## File path: clients/src/main/java/org/apache/kafka/common/internals/KafkaFutureImpl.java ########## @@ -267,50 +173,77 @@ public T get() throws InterruptedException, ExecutionException { @Override public T get(long timeout, TimeUnit unit) throws InterruptedException, ExecutionException, TimeoutException { - SingleWaiter<T> waiter = new SingleWaiter<>(); - addWaiter(waiter); - return waiter.await(timeout, unit); + try { + return completableFuture.get(timeout, unit); + } catch (ExecutionException e) { + maybeRewrapAndThrow(e.getCause()); + throw e; + } } /** * Returns the result value (or throws any encountered exception) if completed, else returns * the given valueIfAbsent. */ @Override - public synchronized T getNow(T valueIfAbsent) throws InterruptedException, ExecutionException { - if (exception != null) - wrapAndThrow(exception); - if (done) - return value; - return valueIfAbsent; + public synchronized T getNow(T valueIfAbsent) throws ExecutionException { + try { + return completableFuture.getNow(valueIfAbsent); + } catch (CompletionException e) { + maybeRewrapAndThrow(e.getCause()); + // Note, unlike CF#get() which throws ExecutionException, CF#getNow() throws CompletionException + // thus needs rewrapping to conform to KafkaFuture API, where KF#getNow() throws ExecutionException. + throw new ExecutionException(e.getCause()); + } } /** * Returns true if this CompletableFuture was cancelled before it completed normally. */ @Override public synchronized boolean isCancelled() { - return exception instanceof CancellationException; + if (isDependant) { + Throwable exception; Review comment: I believe just returning from the catch branch is fine. No need for this variable. (you return from any path) ########## 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; Review comment: the fact that two variables are used here must be a remainder of an earlier iteration. ```suggestion KafkaCompletableFuture<U> result; ``` can be declared here at the top level and we can remove the inner declaration. ########## 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 -> { Review comment: Not a big fan of variable shadowing, which below you avoid by calling the local variable `tCompletableFuture`. Probably good idea to apply the naming here to and remove `this.` -- This is an automated message from the Apache Git Service. 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