Do not schedule to main for getChunkImmediately type calls (#2362)

They are MT-Safe already. These changes reduce deadlock chances
given these calls are used in Entity#isValid(), and plugins
check this in packet handling...

Spigot-Server-Patches/Actually-Limit-Natural-Spawns-To-Limit.patch

@@ -5,7 +5,7 @@ Subject: [PATCH] Actually-Limit-Natural-Spawns-To-Limit
 
 
 diff --git a/src/main/java/net/minecraft/server/ChunkProviderServer.java b/src/main/java/net/minecraft/server/ChunkProviderServer.java
-index 744fa825e6..3b7288c6cb 100644
+index a58cfc14bb..26216fe72c 100644
 --- a/src/main/java/net/minecraft/server/ChunkProviderServer.java
 +++ b/src/main/java/net/minecraft/server/ChunkProviderServer.java
 @@ -0,0 +0,0 @@ public class ChunkProviderServer extends IChunkProvider {

Spigot-Server-Patches/Fix-World-isChunkGenerated-calls.patch

@@ -8,7 +8,7 @@ This patch also adds a chunk status cache on region files (note that
 its only purpose is to cache the status on DISK)
 
 diff --git a/src/main/java/net/minecraft/server/ChunkProviderServer.java b/src/main/java/net/minecraft/server/ChunkProviderServer.java
-index 220cd197fa..775b5f7fe3 100644
+index 9765eaf24c..d714b8d01b 100644
 --- a/src/main/java/net/minecraft/server/ChunkProviderServer.java
 +++ b/src/main/java/net/minecraft/server/ChunkProviderServer.java
 @@ -0,0 +0,0 @@ public class ChunkProviderServer extends IChunkProvider {
@@ -27,24 +27,9 @@ index 220cd197fa..775b5f7fe3 100644
 +
 +    @Nullable
 +    public IChunkAccess getChunkAtImmediately(int x, int z) {
-+        if (Thread.currentThread() != this.serverThread) {
-+            return CompletableFuture.supplyAsync(() -> {
-+                return this.getChunkAtImmediately(x, z);
-+            }, this.serverThreadQueue).join();
-+        }
-+
 +        long k = ChunkCoordIntPair.pair(x, z);
 +
-+        IChunkAccess ichunkaccess;
++        // Note: Bypass cache to make this MT-Safe
-+
-+        for (int l = 0; l < 4; ++l) {
-+            if (k == this.cachePos[l]) {
-+                ichunkaccess = this.cacheChunk[l];
-+                if (ichunkaccess != null) { // CraftBukkit - the chunk can become accessible in the meantime TODO for non-null chunks it might also make sense to check that the chunk's state hasn't changed in the meantime
-+                    return ichunkaccess;
-+                }
-+            }
-+        }
 +
 +        PlayerChunk playerChunk = this.getChunk(k);
 +        if (playerChunk == null) {

Spigot-Server-Patches/MC-Utils.patch

@@ -167,7 +167,7 @@ index 857b2f8868..bbf136614c 100644
      }
  
 diff --git a/src/main/java/net/minecraft/server/ChunkProviderServer.java b/src/main/java/net/minecraft/server/ChunkProviderServer.java
-index 36a89817f8..dd6e69a0f1 100644
+index 36a89817f8..baf3bd461b 100644
 --- a/src/main/java/net/minecraft/server/ChunkProviderServer.java
 +++ b/src/main/java/net/minecraft/server/ChunkProviderServer.java
 @@ -0,0 +0,0 @@ public class ChunkProviderServer extends IChunkProvider {
@@ -178,24 +178,9 @@ index 36a89817f8..dd6e69a0f1 100644
 +    // Note: Partially copied from the getChunkAt method below
 +    @Nullable
 +    public Chunk getChunkAtIfCachedImmediately(int x, int z) {
-+        if (Thread.currentThread() != this.serverThread) {
-+            return CompletableFuture.supplyAsync(() -> {
-+                return this.getChunkAtIfCachedImmediately(x, z);
-+            }, this.serverThreadQueue).join();
-+        }
-+
 +        long k = ChunkCoordIntPair.pair(x, z);
 +
-+        IChunkAccess ichunkaccess;
++        // Note: Bypass cache to make this MT-Safe
-+
-+        for (int l = 0; l < 4; ++l) {
-+            if (k == this.cachePos[l] && ChunkStatus.FULL == this.cacheStatus[l]) {
-+                ichunkaccess = this.cacheChunk[l];
-+                if (ichunkaccess instanceof Chunk) { // CraftBukkit - the chunk can become accessible in the meantime TODO for non-null chunks it might also make sense to check that the chunk's state hasn't changed in the meantime
-+                    return (Chunk)ichunkaccess;
-+                }
-+            }
-+        }
 +
 +        PlayerChunk playerChunk = this.getChunk(k);
 +        if (playerChunk == null) {
@@ -207,15 +192,9 @@ index 36a89817f8..dd6e69a0f1 100644
 +
 +    @Nullable
 +    public Chunk getChunkAtIfLoadedImmediately(int x, int z) {
-+        if (Thread.currentThread() != this.serverThread) {
-+            return CompletableFuture.supplyAsync(() -> {
-+                return this.getChunkAtIfLoadedImmediately(x, z);
-+            }, this.serverThreadQueue).join();
-+        }
-+
 +        long k = ChunkCoordIntPair.pair(x, z);
 +
-+        // Note: Bypass cache since we need to check ticket level
++        // Note: Bypass cache since we need to check ticket level, and to make this MT-Safe
 +
 +        PlayerChunk playerChunk = this.getChunk(k);
 +        if (playerChunk == null) {
@@ -326,7 +305,7 @@ index 613d534aeb..f31a996aa5 100644
          // CraftBukkit start - fire event
          setGoalTarget(entityliving, EntityTargetEvent.TargetReason.UNKNOWN, true);
 diff --git a/src/main/java/net/minecraft/server/EntityLiving.java b/src/main/java/net/minecraft/server/EntityLiving.java
-index 35a67665a2..5c863860ae 100644
+index 9c3e95bbbc..dcbc4ea7e1 100644
 --- a/src/main/java/net/minecraft/server/EntityLiving.java
 +++ b/src/main/java/net/minecraft/server/EntityLiving.java
 @@ -0,0 +0,0 @@ public abstract class EntityLiving extends Entity {

Spigot-Server-Patches/Timings-v2.patch

@@ -358,7 +358,7 @@ index 3ed48be382..c4d989f702 100644
          }
      }
 diff --git a/src/main/java/net/minecraft/server/ChunkProviderServer.java b/src/main/java/net/minecraft/server/ChunkProviderServer.java
-index dd6e69a0f1..978a9f9172 100644
+index baf3bd461b..f351d021dc 100644
 --- a/src/main/java/net/minecraft/server/ChunkProviderServer.java
 +++ b/src/main/java/net/minecraft/server/ChunkProviderServer.java
 @@ -0,0 +0,0 @@ public class ChunkProviderServer extends IChunkProvider {