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Fix potential deadlock on instance join

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themode 2022-03-16 06:54:30 +01:00
parent 2f5661b313
commit 1e58318a3a
1 changed files with 31 additions and 23 deletions
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54
src/main/java/net/minestom/server/entity/Player.java
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@ -67,7 +67,7 @@ import net.minestom.server.snapshot.EntitySnapshot;
import net.minestom.server.snapshot.PlayerSnapshot;
import net.minestom.server.snapshot.SnapshotUpdater;
import net.minestom.server.statistic.PlayerStatistic;
import net.minestom.server.timer.SchedulerManager;
import net.minestom.server.timer.Scheduler;
import net.minestom.server.utils.MathUtils;
import net.minestom.server.utils.PacketUtils;
import net.minestom.server.utils.async.AsyncUtils;
@ -92,7 +92,7 @@ import java.nio.charset.StandardCharsets;
import java.time.Duration;
import java.util.*;
import java.util.concurrent.CompletableFuture;
import java.util.concurrent.atomic.AtomicBoolean;
import java.util.concurrent.CountDownLatch;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.function.Consumer;
import java.util.function.UnaryOperator;
@ -529,41 +529,49 @@ public class Player extends LivingEntity implements CommandSender, Localizable,
}
// Must update the player chunks
final boolean dimensionChange = !Objects.equals(dimensionType, instance.getDimensionType());
final Thread runThread = Thread.currentThread();
final Consumer<Instance> runnable = (i) -> spawnPlayer(i, spawnPosition,
currentInstance == null, dimensionChange, true);
// Wait for all surrounding chunks to load
List<CompletableFuture<Chunk>> futures = new ArrayList<>();
ChunkUtils.forChunksInRange(spawnPosition, MinecraftServer.getChunkViewDistance(),
(chunkX, chunkZ) -> futures.add(instance.loadOptionalChunk(chunkX, chunkZ)));
SchedulerManager scheduler = MinecraftServer.getSchedulerManager();
AtomicBoolean join = new AtomicBoolean();
// Ensure that surrounding chunks are loaded
List<CompletableFuture<Chunk>> futures = new ArrayList<>();
ChunkUtils.forChunksInRange(spawnPosition, MinecraftServer.getChunkViewDistance(), (chunkX, chunkZ) -> {
final CompletableFuture<Chunk> future = instance.loadOptionalChunk(chunkX, chunkZ);
if (!future.isDone()) futures.add(future);
});
if (futures.isEmpty()) {
// All chunks are already loaded
runnable.accept(instance);
return AsyncUtils.VOID_FUTURE;
}
// One or more chunks need to be loaded
final Thread runThread = Thread.currentThread();
CountDownLatch latch = new CountDownLatch(1);
Scheduler scheduler = scheduler();
CompletableFuture<Void> future = new CompletableFuture<>() {
@Override
public Void join() {
// Prevent deadlock
scheduler.process();
join.set(true);
final Void result = super.join();
join.set(false);
return result;
if (runThread == Thread.currentThread()) {
try {
latch.await();
} catch (InterruptedException e) {
throw new RuntimeException(e);
}
scheduler.process();
assert isDone();
}
return super.join();
}
};
CompletableFuture.allOf(futures.toArray(CompletableFuture[]::new))
.thenRun(() -> {
if (runThread == Thread.currentThread()) {
scheduler.scheduleNextProcess(() -> {
runnable.accept(instance);
future.complete(null);
} else {
scheduler.scheduleNextProcess(() -> {
runnable.accept(instance);
future.complete(null);
});
if (join.compareAndSet(true, false))
scheduler.process();
}
});
latch.countDown();
});
return future;
}