1 /*
   2  * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package jdk.incubator.http;
  27 
  28 import java.util.concurrent.Flow;
  29 import java.util.concurrent.atomic.AtomicBoolean;
  30 
  31 // Completes the subscription on first request. Never calls onNext()
  32 
  33 class PseudoPublisher<T> implements Flow.Publisher<T> {
  34 
  35     private final Throwable throwable;
  36 
  37     PseudoPublisher() {
  38         this(null);
  39     }
  40 
  41     PseudoPublisher(Throwable throwable) {
  42         this.throwable = throwable;
  43     }
  44 
  45     @Override
  46     public void subscribe(Flow.Subscriber<? super T> subscriber) {
  47         subscriber.onSubscribe(new Subscription(subscriber));
  48     }
  49 
  50     private class Subscription implements Flow.Subscription {
  51 
  52         private final Flow.Subscriber<? super T> subscriber;
  53         private final AtomicBoolean done = new AtomicBoolean();
  54 
  55         Subscription(Flow.Subscriber<? super T> subscriber) {
  56             this.subscriber = subscriber;
  57         }
  58 
  59         @Override
  60         public void request(long n) {
  61             if (done.compareAndSet(false, true)) {
  62                 if (n > 0) {
  63                     if (throwable == null) {
  64                         subscriber.onComplete();
  65                     } else {
  66                         subscriber.onError(throwable);
  67                     }
  68                 } else {
  69                     subscriber.onError(new IllegalArgumentException("request(" + n + ")"));
  70                 }
  71             }
  72         }
  73 
  74         @Override
  75         public void cancel() {
  76             done.set(true);
  77         }
  78 
  79     }
  80 }