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/*
* Copyright (C) 2022 NotEnoughUpdates contributors
*
* This file is part of NotEnoughUpdates.
*
* NotEnoughUpdates is free software: you can redistribute it
* and/or modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation, either
* version 3 of the License, or (at your option) any later version.
*
* NotEnoughUpdates is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with NotEnoughUpdates. If not, see <https://www.gnu.org/licenses/>.
*/
package io.github.moulberry.notenoughupdates.util;
import java.util.Optional;
import java.util.concurrent.CompletableFuture;
import java.util.function.BiFunction;
import java.util.function.Function;
import java.util.function.Supplier;
class AsyncDependencyLoaderImpl<R, T> implements AsyncDependencyLoader<T> {
private final Supplier<R> supplyDependency;
private final Function<R, CompletableFuture<T>> generator;
private final BiFunction<R, R, Boolean> isDifferent;
private volatile CompletableFuture<T> lastValue;
private volatile R lastDependency;
private volatile boolean isFirstFire = true;
@Override
public synchronized Optional<T> peekValue() {
R nextDependency = supplyDependency.get();
if (isFirstFire || isDifferent.apply(nextDependency, lastDependency)) {
isFirstFire = false;
if (lastValue != null)
lastValue.cancel(true);
lastValue = generator.apply(nextDependency);
}
lastDependency = nextDependency;
return Optional.ofNullable(lastValue.getNow(null));
}
AsyncDependencyLoaderImpl(
Supplier<R> supplyDependency,
Function<R, CompletableFuture<T>> generator,
BiFunction<R, R, Boolean> isDifferent
) {
this.supplyDependency = supplyDependency;
this.generator = generator;
this.isDifferent = isDifferent;
}
}
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