From 36c27cbe0544697299d69a748aecfb23a66424fd Mon Sep 17 00:00:00 2001
From: themode <themode@outlook.fr>
Date: Sun, 13 Feb 2022 15:52:01 +0100
Subject: [PATCH] Fix rare case where the phaser gets terminated on ARM cpus

---
 .../server/thread/ThreadDispatcher.java       | 14 ++++++++-----
 .../minestom/server/thread/TickThread.java    | 20 ++++++++++---------
 2 files changed, 20 insertions(+), 14 deletions(-)

diff --git a/src/main/java/net/minestom/server/thread/ThreadDispatcher.java b/src/main/java/net/minestom/server/thread/ThreadDispatcher.java
index eb5153cea..308d073c4 100644
--- a/src/main/java/net/minestom/server/thread/ThreadDispatcher.java
+++ b/src/main/java/net/minestom/server/thread/ThreadDispatcher.java
@@ -9,7 +9,7 @@ import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Unmodifiable;
 
 import java.util.*;
-import java.util.concurrent.Phaser;
+import java.util.concurrent.CountDownLatch;
 
 /**
  * Used to link chunks into multiple groups.
@@ -29,12 +29,11 @@ public final class ThreadDispatcher<P> {
 
     // Requests consumed at the end of each tick
     private final MessagePassingQueue<DispatchUpdate<P>> updates = new MpscUnboundedArrayQueue<>(1024);
-    private final Phaser phaser = new Phaser(1);
 
     private ThreadDispatcher(ThreadProvider<P> provider, int threadCount) {
         this.provider = provider;
         TickThread[] threads = new TickThread[threadCount];
-        Arrays.setAll(threads, i -> new TickThread(phaser, i));
+        Arrays.setAll(threads, i -> new TickThread(i));
         this.threads = List.of(threads);
         this.threads.forEach(Thread::start);
     }
@@ -73,8 +72,13 @@ public final class ThreadDispatcher<P> {
             }
         });
         // Tick all partitions
-        for (TickThread thread : threads) thread.startTick(time);
-        this.phaser.arriveAndAwaitAdvance();
+        CountDownLatch latch = new CountDownLatch(threads.size());
+        for (TickThread thread : threads) thread.startTick(latch, time);
+        try {
+            latch.await();
+        } catch (InterruptedException e) {
+            throw new RuntimeException(e);
+        }
     }
 
     /**
diff --git a/src/main/java/net/minestom/server/thread/TickThread.java b/src/main/java/net/minestom/server/thread/TickThread.java
index 770b026a8..4b60891ee 100644
--- a/src/main/java/net/minestom/server/thread/TickThread.java
+++ b/src/main/java/net/minestom/server/thread/TickThread.java
@@ -10,7 +10,7 @@ import org.jetbrains.annotations.NotNull;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.List;
-import java.util.concurrent.Phaser;
+import java.util.concurrent.CountDownLatch;
 import java.util.concurrent.locks.LockSupport;
 import java.util.concurrent.locks.ReentrantLock;
 
@@ -22,15 +22,14 @@ import java.util.concurrent.locks.ReentrantLock;
 @ApiStatus.Internal
 public final class TickThread extends MinestomThread {
     private final ReentrantLock lock = new ReentrantLock();
-    private final Phaser phaser;
     private volatile boolean stop;
 
+    private CountDownLatch latch;
     private long tickTime;
     private final List<ThreadDispatcher.Partition> entries = new ArrayList<>();
 
-    public TickThread(Phaser phaser, int number) {
+    public TickThread(int number) {
         super(MinecraftServer.THREAD_NAME_TICK + "-" + number);
-        this.phaser = phaser;
     }
 
     @Override
@@ -45,7 +44,7 @@ public final class TickThread extends MinestomThread {
             }
             this.lock.unlock();
             // #acquire() callbacks
-            this.phaser.arriveAndDeregister();
+            this.latch.countDown();
             LockSupport.park(this);
         }
     }
@@ -69,10 +68,13 @@ public final class TickThread extends MinestomThread {
         }
     }
 
-    void startTick(long tickTime) {
-        if (entries.isEmpty())
-            return; // Nothing to tick
-        this.phaser.register();
+    void startTick(CountDownLatch latch, long tickTime) {
+        if (entries.isEmpty()) {
+            // Nothing to tick
+            latch.countDown();
+            return;
+        }
+        this.latch = latch;
         this.tickTime = tickTime;
         this.stop = false;
         LockSupport.unpark(this);