minecraft-src/net/minecraft/util/thread/ProcessorMailbox.java

package net.minecraft.util.thread;

import com.google.common.collect.ImmutableList;
import com.mojang.logging.LogUtils;
import it.unimi.dsi.fastutil.ints.Int2BooleanFunction;
import java.util.List;
import java.util.concurrent.ConcurrentLinkedQueue;
import java.util.concurrent.Executor;
import java.util.concurrent.RejectedExecutionException;
import java.util.concurrent.atomic.AtomicInteger;
import net.minecraft.Util;
import net.minecraft.util.profiling.metrics.MetricCategory;
import net.minecraft.util.profiling.metrics.MetricSampler;
import net.minecraft.util.profiling.metrics.MetricsRegistry;
import net.minecraft.util.profiling.metrics.ProfilerMeasured;
import org.slf4j.Logger;

public class ProcessorMailbox<T> implements ProfilerMeasured, ProcessorHandle<T>, AutoCloseable, Runnable {
	private static final Logger LOGGER = LogUtils.getLogger();
	private static final int CLOSED_BIT = 1;
	private static final int SCHEDULED_BIT = 2;
	private final AtomicInteger status = new AtomicInteger(0);
	private final StrictQueue<? super T, ? extends Runnable> queue;
	private final Executor dispatcher;
	private final String name;

	public static ProcessorMailbox<Runnable> create(Executor dispatcher, String name) {
		return new ProcessorMailbox<>(new StrictQueue.QueueStrictQueue<>(new ConcurrentLinkedQueue()), dispatcher, name);
	}

	public ProcessorMailbox(StrictQueue<? super T, ? extends Runnable> queue, Executor dispatcher, String name) {
		this.dispatcher = dispatcher;
		this.queue = queue;
		this.name = name;
		MetricsRegistry.INSTANCE.add(this);
	}

	private boolean setAsScheduled() {
		int i;
		do {
			i = this.status.get();
			if ((i & 3) != 0) {
				return false;
			}
		} while (!this.status.compareAndSet(i, i | 2));

		return true;
	}

	private void setAsIdle() {
		int i;
		do {
			i = this.status.get();
		} while (!this.status.compareAndSet(i, i & -3));
	}

	private boolean canBeScheduled() {
		return (this.status.get() & 1) != 0 ? false : !this.queue.isEmpty();
	}

	@Override
	public void close() {
		int i;
		do {
			i = this.status.get();
		} while (!this.status.compareAndSet(i, i | 1));
	}

	private boolean shouldProcess() {
		return (this.status.get() & 2) != 0;
	}

	private boolean pollTask() {
		if (!this.shouldProcess()) {
			return false;
		} else {
			Runnable runnable = this.queue.pop();
			if (runnable == null) {
				return false;
			} else {
				Util.wrapThreadWithTaskName(this.name, runnable).run();
				return true;
			}
		}
	}

	public void run() {
		try {
			this.pollUntil(i -> i == 0);
		} finally {
			this.setAsIdle();
			this.registerForExecution();
		}
	}

	public void runAll() {
		try {
			this.pollUntil(i -> true);
		} finally {
			this.setAsIdle();
			this.registerForExecution();
		}
	}

	@Override
	public void tell(T task) {
		this.queue.push(task);
		this.registerForExecution();
	}

	private void registerForExecution() {
		if (this.canBeScheduled() && this.setAsScheduled()) {
			try {
				this.dispatcher.execute(this);
			} catch (RejectedExecutionException var4) {
				try {
					this.dispatcher.execute(this);
				} catch (RejectedExecutionException var3) {
					LOGGER.error("Cound not schedule mailbox", (Throwable)var3);
				}
			}
		}
	}

	private int pollUntil(Int2BooleanFunction continuePolling) {
		int i = 0;

		while (continuePolling.get(i) && this.pollTask()) {
			i++;
		}

		return i;
	}

	public int size() {
		return this.queue.size();
	}

	public boolean hasWork() {
		return this.shouldProcess() && !this.queue.isEmpty();
	}

	public String toString() {
		return this.name + " " + this.status.get() + " " + this.queue.isEmpty();
	}

	@Override
	public String name() {
		return this.name;
	}

	@Override
	public List<MetricSampler> profiledMetrics() {
		return ImmutableList.of(MetricSampler.create(this.name + "-queue-size", MetricCategory.MAIL_BOXES, this::size));
	}
}