[15972] | 1 | #region License Information
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| 2 | /* SimSharp - A .NET port of SimPy, discrete event simulation framework
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[17053] | 3 | Copyright (C) 2019 Heuristic and Evolutionary Algorithms Laboratory (HEAL)
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[15972] | 4 |
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| 5 | This program is free software: you can redistribute it and/or modify
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| 6 | it under the terms of the GNU General Public License as published by
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| 7 | the Free Software Foundation, either version 3 of the License, or
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| 8 | (at your option) any later version.
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| 9 |
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| 10 | This program is distributed in the hope that it will be useful,
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| 11 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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| 12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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| 13 | GNU General Public License for more details.
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| 14 |
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| 15 | You should have received a copy of the GNU General Public License
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| 16 | along with this program. If not, see <http://www.gnu.org/licenses/>.*/
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| 17 | #endregion
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| 18 |
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| 19 | using System;
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| 20 | using System.Collections.Generic;
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| 21 | using System.Linq;
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| 22 |
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| 23 | namespace SimSharp {
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[17053] | 24 | /// <summary>
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| 25 | /// A PreemptiveResource is similar to a <see cref="PriorityResource"/>. However,
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| 26 | /// it may be possible to interrupt a lower-priority user and hand over the resource.
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| 27 | ///
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| 28 | /// PreemptiveResource holds a fixed amount of anonymous entities.
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| 29 | /// Requests are processed in this order: priority, time, preemption, and finally FIFO.
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| 30 | /// Releases are processed in FIFO order (usually no simulation time passes for a Release).
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| 31 | /// </summary>
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| 32 | /// <remarks>
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| 33 | /// Working with PreemptiveResource, a process holding a request must always call
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| 34 | /// <see cref="Process.HandleFault"/> after yielding an event and handle a potential
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| 35 | /// interruption.
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| 36 | /// </remarks>
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[15972] | 37 | public class PreemptiveResource {
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| 38 |
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| 39 | public int Capacity { get; protected set; }
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| 40 |
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| 41 | public int InUse { get { return Users.Count; } }
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| 42 |
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| 43 | public int Remaining { get { return Capacity - InUse; } }
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| 44 |
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[17053] | 45 | protected Simulation Environment { get; private set; }
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[15972] | 46 |
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[17053] | 47 | protected SimplePriorityQueue<PreemptiveRequest> RequestQueue { get; private set; }
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[15972] | 48 | protected Queue<Release> ReleaseQueue { get; private set; }
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[17053] | 49 | protected HashSet<PreemptiveRequest> Users { get; private set; }
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| 50 | protected List<Event> WhenAnyQueue { get; private set; }
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| 51 | protected List<Event> WhenFullQueue { get; private set; }
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| 52 | protected List<Event> WhenEmptyQueue { get; private set; }
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| 53 | protected List<Event> WhenChangeQueue { get; private set; }
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[15972] | 54 |
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[17053] | 55 | public PreemptiveResource(Simulation environment, int capacity = 1) {
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[15972] | 56 | if (capacity <= 0) throw new ArgumentException("Capacity must be > 0.", "capacity");
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| 57 | Environment = environment;
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| 58 | Capacity = capacity;
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[17053] | 59 | RequestQueue = new SimplePriorityQueue<PreemptiveRequest>();
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[15972] | 60 | ReleaseQueue = new Queue<Release>();
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[17053] | 61 | Users = new HashSet<PreemptiveRequest>();
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| 62 | WhenAnyQueue = new List<Event>();
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| 63 | WhenFullQueue = new List<Event>();
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| 64 | WhenEmptyQueue = new List<Event>();
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| 65 | WhenChangeQueue = new List<Event>();
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[15972] | 66 | }
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| 67 |
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[17053] | 68 | public virtual PreemptiveRequest Request(double priority = 1, bool preempt = false) {
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[15972] | 69 | var request = new PreemptiveRequest(Environment, TriggerRelease, DisposeCallback, priority, preempt);
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[17053] | 70 | RequestQueue.Enqueue(request);
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[15972] | 71 | TriggerRequest();
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| 72 | return request;
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| 73 | }
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| 74 |
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| 75 | public virtual Release Release(PreemptiveRequest request) {
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| 76 | var release = new Release(Environment, request, TriggerRequest);
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| 77 | ReleaseQueue.Enqueue(release);
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| 78 | TriggerRelease();
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| 79 | return release;
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| 80 | }
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| 81 |
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[17053] | 82 | public virtual Event WhenAny() {
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| 83 | var whenAny = new Event(Environment);
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| 84 | WhenAnyQueue.Add(whenAny);
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| 85 | TriggerWhenAny();
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| 86 | return whenAny;
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| 87 | }
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| 88 |
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| 89 | public virtual Event WhenFull() {
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| 90 | var whenFull = new Event(Environment);
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| 91 | WhenFullQueue.Add(whenFull);
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| 92 | TriggerWhenFull();
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| 93 | return whenFull;
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| 94 | }
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| 95 |
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| 96 | public virtual Event WhenEmpty() {
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| 97 | var whenEmpty = new Event(Environment);
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| 98 | WhenEmptyQueue.Add(whenEmpty);
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| 99 | TriggerWhenEmpty();
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| 100 | return whenEmpty;
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| 101 | }
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| 102 |
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| 103 | public virtual Event WhenChange() {
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| 104 | var whenChange = new Event(Environment);
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| 105 | WhenChangeQueue.Add(whenChange);
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| 106 | return whenChange;
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| 107 | }
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| 108 |
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[15972] | 109 | protected void DisposeCallback(Event @event) {
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| 110 | var request = @event as PreemptiveRequest;
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| 111 | if (request != null) Release(request);
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| 112 | }
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| 113 |
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| 114 | protected virtual void DoRequest(PreemptiveRequest request) {
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| 115 | if (Users.Count >= Capacity && request.Preempt) {
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| 116 | // Check if we can preempt another process
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[17053] | 117 | // MaxItems are the least important according to priorty, time, and preemption flag
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| 118 | var preempt = Users.MaxItems(x => x).Last();
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| 119 | if (preempt.CompareTo(request) > 0) {
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| 120 | preempt.IsPreempted = true;
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| 121 | Users.Remove(preempt);
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| 122 | preempt.Owner?.Interrupt(new Preempted(request.Owner, preempt.Time));
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[15972] | 123 | }
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| 124 | }
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| 125 | if (Users.Count < Capacity) {
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| 126 | Users.Add(request);
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| 127 | request.Succeed();
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| 128 | }
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| 129 | }
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| 130 |
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| 131 | protected virtual void DoRelease(Release release) {
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[17053] | 132 | var req = (PreemptiveRequest)release.Request;
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| 133 | if (!Users.Remove(req) && !req.IsPreempted)
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| 134 | throw new InvalidOperationException("Released request does not have a user.");
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[15972] | 135 | release.Succeed();
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| 136 | }
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| 137 |
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| 138 | protected virtual void TriggerRequest(Event @event = null) {
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[17053] | 139 | while (RequestQueue.Count > 0) {
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| 140 | var request = RequestQueue.First;
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| 141 | DoRequest(request);
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| 142 | if (request.IsTriggered) {
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| 143 | RequestQueue.Dequeue();
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| 144 | TriggerWhenEmpty();
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| 145 | TriggerWhenChange();
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| 146 | } else break;
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[15972] | 147 | }
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| 148 | }
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| 149 |
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| 150 | protected virtual void TriggerRelease(Event @event = null) {
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| 151 | while (ReleaseQueue.Count > 0) {
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| 152 | var release = ReleaseQueue.Peek();
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[17053] | 153 | if (release.Request.IsAlive) {
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| 154 | if (!RequestQueue.TryRemove((PreemptiveRequest)release.Request))
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| 155 | throw new InvalidOperationException("Failed to cancel a request.");
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| 156 | release.Succeed();
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[15972] | 157 | ReleaseQueue.Dequeue();
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[17053] | 158 | } else {
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| 159 | DoRelease(release);
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| 160 | if (release.IsTriggered) {
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| 161 | ReleaseQueue.Dequeue();
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| 162 | TriggerWhenAny();
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| 163 | TriggerWhenFull();
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| 164 | TriggerWhenChange();
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| 165 | } else break;
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| 166 | }
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[15972] | 167 | }
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| 168 | }
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[17053] | 169 |
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| 170 | protected virtual void TriggerWhenAny() {
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| 171 | if (Remaining > 0) {
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| 172 | if (WhenAnyQueue.Count == 0) return;
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| 173 | foreach (var evt in WhenAnyQueue)
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| 174 | evt.Succeed();
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| 175 | WhenAnyQueue.Clear();
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| 176 | }
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| 177 | }
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| 178 |
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| 179 | protected virtual void TriggerWhenFull() {
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| 180 | if (InUse == 0) {
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| 181 | if (WhenFullQueue.Count == 0) return;
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| 182 | foreach (var evt in WhenFullQueue)
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| 183 | evt.Succeed();
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| 184 | WhenFullQueue.Clear();
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| 185 | }
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| 186 | }
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| 187 |
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| 188 | protected virtual void TriggerWhenEmpty() {
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| 189 | if (Remaining == 0) {
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| 190 | if (WhenEmptyQueue.Count == 0) return;
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| 191 | foreach (var evt in WhenEmptyQueue)
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| 192 | evt.Succeed();
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| 193 | WhenEmptyQueue.Clear();
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| 194 | }
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| 195 | }
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| 196 |
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| 197 | protected virtual void TriggerWhenChange() {
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| 198 | if (WhenChangeQueue.Count == 0) return;
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| 199 | foreach (var evt in WhenChangeQueue)
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| 200 | evt.Succeed();
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| 201 | WhenChangeQueue.Clear();
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| 202 | }
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[15972] | 203 | }
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| 204 | }
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