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| 1 | +/* |
| 2 | + * Copyright 2019-2020 the original author or authors. |
| 3 | + * |
| 4 | + * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | + * you may not use this file except in compliance with the License. |
| 6 | + * You may obtain a copy of the License at |
| 7 | + * |
| 8 | + * https://www.apache.org/licenses/LICENSE-2.0 |
| 9 | + * |
| 10 | + * Unless required by applicable law or agreed to in writing, software |
| 11 | + * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | + * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | + * See the License for the specific language governing permissions and |
| 14 | + * limitations under the License. |
| 15 | + */ |
| 16 | + |
| 17 | +package io.r2dbc.postgresql.util; |
| 18 | + |
| 19 | +import org.reactivestreams.Subscriber; |
| 20 | +import org.reactivestreams.Subscription; |
| 21 | +import reactor.core.CoreSubscriber; |
| 22 | +import reactor.core.publisher.Flux; |
| 23 | +import reactor.core.publisher.FluxOperator; |
| 24 | +import reactor.core.publisher.Operators; |
| 25 | +import reactor.util.Logger; |
| 26 | +import reactor.util.Loggers; |
| 27 | +import reactor.util.context.Context; |
| 28 | + |
| 29 | +import java.util.concurrent.atomic.AtomicBoolean; |
| 30 | + |
| 31 | +/** |
| 32 | + * A decorating operator that replays signals from its source to a {@link Subscriber} and drains the source upon {@link Subscription#cancel() cancel} and drops data signals until termination. |
| 33 | + * Draining data is required to complete a particular request/response window and clear the protocol state as client code expects to start a request/response conversation without any previous |
| 34 | + * response state. |
| 35 | + */ |
| 36 | +class FluxDiscardOnCancel<T> extends FluxOperator<T, T> { |
| 37 | + |
| 38 | + private static final Logger logger = Loggers.getLogger(FluxDiscardOnCancel.class); |
| 39 | + |
| 40 | + private final Runnable cancelConsumer; |
| 41 | + |
| 42 | + FluxDiscardOnCancel(Flux<? extends T> source, Runnable cancelConsumer) { |
| 43 | + super(source); |
| 44 | + this.cancelConsumer = cancelConsumer; |
| 45 | + } |
| 46 | + |
| 47 | + @Override |
| 48 | + public void subscribe(CoreSubscriber<? super T> actual) { |
| 49 | + this.source.subscribe(new FluxDiscardOnCancelSubscriber<>(actual, this.cancelConsumer)); |
| 50 | + } |
| 51 | + |
| 52 | + static class FluxDiscardOnCancelSubscriber<T> extends AtomicBoolean implements CoreSubscriber<T>, Subscription { |
| 53 | + |
| 54 | + final CoreSubscriber<T> actual; |
| 55 | + |
| 56 | + final Context ctx; |
| 57 | + |
| 58 | + final Runnable cancelConsumer; |
| 59 | + |
| 60 | + Subscription s; |
| 61 | + |
| 62 | + FluxDiscardOnCancelSubscriber(CoreSubscriber<T> actual, Runnable cancelConsumer) { |
| 63 | + |
| 64 | + this.actual = actual; |
| 65 | + this.ctx = actual.currentContext(); |
| 66 | + this.cancelConsumer = cancelConsumer; |
| 67 | + } |
| 68 | + |
| 69 | + @Override |
| 70 | + public void onSubscribe(Subscription s) { |
| 71 | + |
| 72 | + if (Operators.validate(this.s, s)) { |
| 73 | + this.s = s; |
| 74 | + this.actual.onSubscribe(this); |
| 75 | + } |
| 76 | + } |
| 77 | + |
| 78 | + @Override |
| 79 | + public void onNext(T t) { |
| 80 | + |
| 81 | + if (this.get()) { |
| 82 | + Operators.onDiscard(t, this.ctx); |
| 83 | + return; |
| 84 | + } |
| 85 | + |
| 86 | + this.actual.onNext(t); |
| 87 | + } |
| 88 | + |
| 89 | + @Override |
| 90 | + public void onError(Throwable t) { |
| 91 | + if (this.get()) { |
| 92 | + Operators.onErrorDropped(t, this.ctx); |
| 93 | + } else { |
| 94 | + this.actual.onError(t); |
| 95 | + } |
| 96 | + } |
| 97 | + |
| 98 | + @Override |
| 99 | + public void onComplete() { |
| 100 | + if (!this.get()) { |
| 101 | + this.actual.onComplete(); |
| 102 | + } |
| 103 | + } |
| 104 | + |
| 105 | + @Override |
| 106 | + public void request(long n) { |
| 107 | + this.s.request(n); |
| 108 | + } |
| 109 | + |
| 110 | + @Override |
| 111 | + public void cancel() { |
| 112 | + |
| 113 | + if (compareAndSet(false, true)) { |
| 114 | + if (logger.isDebugEnabled()) { |
| 115 | + logger.debug("received cancel signal"); |
| 116 | + } |
| 117 | + try { |
| 118 | + this.cancelConsumer.run(); |
| 119 | + } catch (Exception e) { |
| 120 | + Operators.onErrorDropped(e, this.ctx); |
| 121 | + } |
| 122 | + this.s.request(Long.MAX_VALUE); |
| 123 | + } |
| 124 | + } |
| 125 | + } |
| 126 | +} |
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