ygerzhedovich commented on code in PR #4615: URL: https://github.com/apache/ignite-3/pull/4615#discussion_r1832278463
########## modules/api/src/main/java/org/apache/ignite/lang/CancelHandleImpl.java: ########## @@ -0,0 +1,150 @@ +/* + * Licensed to the Apache Software Foundation (ASF) under one or more + * contributor license agreements. See the NOTICE file distributed with + * this work for additional information regarding copyright ownership. + * The ASF licenses this file to You under the Apache License, Version 2.0 + * (the "License"); you may not use this file except in compliance with + * the License. You may obtain a copy of the License at + * + * http://www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an "AS IS" BASIS, + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +package org.apache.ignite.lang; + +import java.util.concurrent.CompletableFuture; +import java.util.concurrent.ConcurrentLinkedQueue; +import java.util.concurrent.atomic.AtomicReference; + +/** Implementation of {@link CancelHandle}. */ +final class CancelHandleImpl implements CancelHandle { + + private final CompletableFuture<Void> cancelFut = new CompletableFuture<>(); + + private final CancellationTokenImpl token; + + CancelHandleImpl() { + this.token = new CancellationTokenImpl(this); + } + + /** {@inheritDoc} */ + @Override + public void cancel() { + doCancelAsync(); + + cancelFut.join(); + } + + /** {@inheritDoc} */ + @Override + public CompletableFuture<Void> cancelAsync() { + doCancelAsync(); + + return cancelFut; + } + + /** {@inheritDoc} */ + @Override + public boolean isCancelled() { + return token.isCancelled(); + } + + /** {@inheritDoc} */ + @Override + public CancellationToken token() { + return token; + } + + private void doCancelAsync() { + token.cancel().whenComplete((r, t) -> { + if (t != null) { + cancelFut.completeExceptionally(t); + } else { + cancelFut.complete(null); + } + }); + } + + static final class CancellationTokenImpl implements CancellationToken { + + private final CancelHandleImpl handle; + + // Actions that trigger cancellations - action that triggers a cancellation + a future that completes, when a resource is closed. + private final ConcurrentLinkedQueue<Cancellation> cancellations = new ConcurrentLinkedQueue<>(); + + private final AtomicReference<CompletableFuture<Void>> cancelFutRef = new AtomicReference<>(); + + CancellationTokenImpl(CancelHandleImpl handle) { + this.handle = handle; + } + + boolean isCancelled() { + return cancelFutRef.get() != null; + } + + void addCancelAction(Runnable cancelAction, CompletableFuture<?> completionFut) { + assert cancelAction != null : "cancelAction must be not null"; + assert completionFut != null : "completionFut must be not null"; + + Cancellation cancellation = new Cancellation(cancelAction, completionFut); + if (handle.isCancelled()) { + cancellation.run(); + } else { + cancellations.add(cancellation); + } + } + + @SuppressWarnings("rawtypes") + private CompletableFuture<Void> cancel() { + CompletableFuture<Void> f = cancelFutRef.get(); + if (f != null) { + return f; + } + + // First assemble all completion futures + CompletableFuture[] futures = cancellations.stream() + .map(c -> c.completionFut) + .toArray(CompletableFuture[]::new); + + CompletableFuture<Void> cancelAll = CompletableFuture.allOf(futures); + CompletableFuture<Void> fut = cancelFutRef.compareAndExchange(null, cancelAll); + + // If cancel future has not been set, trigger cancellation actions. + if (fut == null) { + for (Cancellation cancellation : cancellations) { + cancellation.run(); + } + } + + return fut != null ? fut : cancelAll; + } + } + + /** + * Stores an action that triggers a cancellation and a completable future that completes when a resource is closed. + */ + private static class Cancellation { + + private final Runnable cancelAction; + + private final CompletableFuture<?> completionFut; + + private Cancellation(Runnable cancelAction, CompletableFuture<?> completionFut) { + this.cancelAction = cancelAction; + this.completionFut = completionFut; + } + + private void run() { + try { + cancelAction.run(); + } catch (Throwable ignore) { + // Ignore Review Comment: If we have bugs in any cancelation action that will throw an exception, how can we know about the exception? -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: notifications-unsubscr...@ignite.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org
