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/* |
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* Copyright (C) 2023 jimj316 |
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* |
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* This program is free software: you can redistribute it and/or modify |
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* it under the terms of the GNU General Public License as published by |
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* the Free Software Foundation, either version 3 of the License, or |
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* (at your option) any later version. |
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* |
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* This program is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU General Public License for more details. |
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* |
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* You should have received a copy of the GNU General Public License |
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/ |
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package moe.nekojimi.chords; |
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import java.util.ArrayList; |
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import java.util.LinkedList; |
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import java.util.List; |
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import java.util.Queue; |
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import java.util.function.Consumer; |
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/** |
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* |
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* @author jimj316 |
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*/ |
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public abstract class QueueThing<I, O> implements Consumer<I> |
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{ |
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// TODO: better name
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protected final Queue<I> inputQueue; |
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protected final List<QueueThing<?, I>> sources = new ArrayList<>(); |
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protected final List<QueueThing<O, ?>> sinks = new ArrayList<>(); |
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protected final Queue<Promise<I, O>> pendingPromises = new LinkedList<>(); |
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protected int queueTargetSize = 0; |
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protected QueueThing(Queue<I> inputQueue) |
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{ |
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this.inputQueue = inputQueue; |
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} |
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@Override |
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public void accept(I t) |
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{ |
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// if we've got pending promises, fullfill them, otherwise just put it in the queue and notify the sinks
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if (pendingPromises.isEmpty()) |
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{ |
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inputQueue.add(t); |
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notifyNewInput(); |
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} else |
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{ |
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Promise<I, O> promise = pendingPromises.poll(); |
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promise.setInput(t); |
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handlePromise(promise); |
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} |
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} |
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/** |
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* Called to notify downstream modules that there's input upstream - |
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* consider requesting it to pull it through |
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*/ |
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protected void notifyNewInput() |
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{ |
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if (inputQueue.size() < queueTargetSize) |
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demandInput(queueTargetSize - inputQueue.size()); |
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for (QueueThing<O, ?> sink : sinks) |
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{ |
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sink.notifyNewInput(); |
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} |
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} |
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public List<Promise<I, O>> request(int count, Consumer<O> destination) |
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{ |
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List<Promise<I, O>> ret = new ArrayList<>(); |
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int demands = 0; |
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for (int i = 0; i < count; i++) |
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{ |
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I input = null; |
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if (!inputQueue.isEmpty()) |
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{ |
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input = inputQueue.poll(); |
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} |
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Promise<I, O> promise = new Promise<>(input, destination); |
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boolean ok = handlePromise(promise); |
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if (ok) |
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{ |
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// we got a promise of output so we can tell the client
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ret.add(promise); |
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} else |
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{ |
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// we need to get more input from sources
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demands++; |
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} |
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} |
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demands += queueTargetSize - inputQueue.size(); |
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if (demands > 0) |
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{ |
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// try to get more input from sources
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int sourcePromises = demandInput(demands); |
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// each promise of input we get represents a promise of output we can give
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for (int i = 0; i < sourcePromises; i++) |
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{ |
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Promise<I, O> myPromise = new Promise<>(destination); |
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pendingPromises.add(myPromise); |
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ret.add(myPromise); |
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} |
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} |
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return ret; |
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} |
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private boolean handlePromise(Promise<I, O> promise) |
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{ |
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boolean ok; |
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ok = completePromise(promise); |
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return ok; |
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} |
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protected abstract boolean completePromise(Promise<I, O> request); |
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/** |
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* Requests from sources a certain about of input, to be provided later. |
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* |
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* @param count the number of input items to request. |
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* @return a number Promises of input items. May be more or less than count. |
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*/ |
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protected int demandInput(int count) |
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{ |
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int ret = 0; |
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for (QueueThing<?, I> source : sources) |
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{ |
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List<Promise<?, I>> promises = (List<Promise<?, I>>) source.request(count - ret, this); |
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ret += promises.size(); |
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if (ret >= count) |
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break; |
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} |
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return ret; |
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} |
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public void addSource(QueueThing<?, I> source) |
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{ |
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sources.add(source); |
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source.addSink(this); |
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} |
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public void removeSource(QueueThing<?, I> source) |
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{ |
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sources.remove(source); |
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source.removeSink(this); |
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} |
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private void addSink(QueueThing<O, ?> sink) |
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{ |
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sinks.add(sink); |
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} |
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private void removeSink(QueueThing<O, ?> sink) |
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{ |
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sinks.remove(sink); |
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} |
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public static class Promise<I, O> |
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{ |
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private I input; |
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private final Consumer<O> output; |
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public Promise(I input, Consumer<O> output) |
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{ |
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this.input = input; |
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this.output = output; |
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} |
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public Promise(Consumer<O> output) |
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{ |
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this.output = output; |
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} |
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public void setInput(I input) |
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{ |
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this.input = input; |
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} |
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public void complete(O out) |
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{ |
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output.accept(out); |
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} |
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public I getInput() |
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{ |
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return input; |
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} |
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} |
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// protected void submit(O output)
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// {
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// if (nextStage != null)
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// nextStage.accept(output);
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// }
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} |
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