1 /*
   2  * Copyright (c) 2015, 2018, 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.internal.net.http;
  27 
  28 import java.time.Duration;
  29 import java.time.Instant;
  30 import java.util.concurrent.atomic.AtomicLong;
  31 
  32 /**
  33  * Timeout event notified by selector thread. Executes the given handler if
  34  * the timer not canceled first.
  35  *
  36  * Register with {@link HttpClientImpl#registerTimer(TimeoutEvent)}.
  37  *
  38  * Cancel with {@link HttpClientImpl#cancelTimer(TimeoutEvent)}.
  39  */
  40 abstract class TimeoutEvent implements Comparable<TimeoutEvent> {
  41 
  42     private static final AtomicLong COUNTER = new AtomicLong();
  43     // we use id in compareTo to make compareTo consistent with equals
  44     // see TimeoutEvent::compareTo below;
  45     private final long id = COUNTER.incrementAndGet();
  46     private final Instant deadline;
  47 
  48     TimeoutEvent(Duration duration) {
  49         deadline = Instant.now().plus(duration);
  50     }
  51 
  52     public abstract void handle();
  53 
  54     public Instant deadline() {
  55         return deadline;
  56     }
  57 
  58     @Override
  59     public int compareTo(TimeoutEvent other) {
  60         if (other == this) return 0;
  61         // if two events have the same deadline, but are not equals, then the
  62         // smaller is the one that was created before (has the smaller id).
  63         // This is arbitrary and we don't really care which is smaller or
  64         // greater, but we need a total order, so two events with the
  65         // same deadline cannot compare == 0 if they are not equals.
  66         final int compareDeadline = this.deadline.compareTo(other.deadline);
  67         if (compareDeadline == 0 && !this.equals(other)) {
  68             long diff = this.id - other.id; // should take care of wrap around
  69             if (diff < 0) return -1;
  70             else if (diff > 0) return 1;
  71             else assert false : "Different events with same id and deadline";
  72         }
  73         return compareDeadline;
  74     }
  75 
  76     @Override
  77     public String toString() {
  78         return "TimeoutEvent[id=" + id + ", deadline=" + deadline + "]";
  79     }
  80 }