PaperMC/paper-server/patches/sources/net/minecraft/server/level/DistanceManager.java.patch

--- a/net/minecraft/server/level/DistanceManager.java
+++ b/net/minecraft/server/level/DistanceManager.java
@@ -117,8 +117,17 @@
 
             ChunkHolder playerchunk;
 
+            // CraftBukkit start - SPIGOT-7780: Call chunk unload events before updateHighestAllowedStatus
             while (iterator.hasNext()) {
                 playerchunk = (ChunkHolder) iterator.next();
+                playerchunk.callEventIfUnloading(chunkLoadingManager);
+            }
+
+            iterator = this.chunksToUpdateFutures.iterator();
+            // CraftBukkit end
+
+            while (iterator.hasNext()) {
+                playerchunk = (ChunkHolder) iterator.next();
                 playerchunk.updateHighestAllowedStatus(chunkLoadingManager);
             }
 
@@ -165,30 +174,33 @@
         }
     }
 
-    void addTicket(long position, Ticket<?> ticket) {
-        SortedArraySet<Ticket<?>> arraysetsorted = this.getTickets(position);
+    boolean addTicket(long i, Ticket<?> ticket) { // CraftBukkit - void -> boolean
+        SortedArraySet<Ticket<?>> arraysetsorted = this.getTickets(i);
         int j = DistanceManager.getTicketLevelAt(arraysetsorted);
         Ticket<?> ticket1 = (Ticket) arraysetsorted.addOrGet(ticket);
 
         ticket1.setCreatedTick(this.ticketTickCounter);
         if (ticket.getTicketLevel() < j) {
-            this.ticketTracker.update(position, ticket.getTicketLevel(), true);
+            this.ticketTracker.update(i, ticket.getTicketLevel(), true);
         }
 
+        return ticket == ticket1; // CraftBukkit
     }
 
-    void removeTicket(long pos, Ticket<?> ticket) {
-        SortedArraySet<Ticket<?>> arraysetsorted = this.getTickets(pos);
+    boolean removeTicket(long i, Ticket<?> ticket) { // CraftBukkit - void -> boolean
+        SortedArraySet<Ticket<?>> arraysetsorted = this.getTickets(i);
 
+        boolean removed = false; // CraftBukkit
         if (arraysetsorted.remove(ticket)) {
-            ;
+            removed = true; // CraftBukkit
         }
 
         if (arraysetsorted.isEmpty()) {
-            this.tickets.remove(pos);
+            this.tickets.remove(i);
         }
 
-        this.ticketTracker.update(pos, DistanceManager.getTicketLevelAt(arraysetsorted), false);
+        this.ticketTracker.update(i, DistanceManager.getTicketLevelAt(arraysetsorted), false);
+        return removed; // CraftBukkit
     }
 
     public <T> void addTicket(TicketType<T> type, ChunkPos pos, int level, T argument) {
@@ -202,19 +214,33 @@
     }
 
     public <T> void addRegionTicket(TicketType<T> type, ChunkPos pos, int radius, T argument) {
-        Ticket<T> ticket = new Ticket<>(type, ChunkLevel.byStatus(FullChunkStatus.FULL) - radius, argument);
-        long j = pos.toLong();
+        // CraftBukkit start
+        this.addRegionTicketAtDistance(type, pos, radius, argument);
+    }
 
-        this.addTicket(j, ticket);
+    public <T> boolean addRegionTicketAtDistance(TicketType<T> tickettype, ChunkPos chunkcoordintpair, int i, T t0) {
+        // CraftBukkit end
+        Ticket<T> ticket = new Ticket<>(tickettype, ChunkLevel.byStatus(FullChunkStatus.FULL) - i, t0);
+        long j = chunkcoordintpair.toLong();
+
+        boolean added = this.addTicket(j, ticket); // CraftBukkit
         this.tickingTicketsTracker.addTicket(j, ticket);
+        return added; // CraftBukkit
     }
 
     public <T> void removeRegionTicket(TicketType<T> type, ChunkPos pos, int radius, T argument) {
-        Ticket<T> ticket = new Ticket<>(type, ChunkLevel.byStatus(FullChunkStatus.FULL) - radius, argument);
-        long j = pos.toLong();
+        // CraftBukkit start
+        this.removeRegionTicketAtDistance(type, pos, radius, argument);
+    }
 
-        this.removeTicket(j, ticket);
+    public <T> boolean removeRegionTicketAtDistance(TicketType<T> tickettype, ChunkPos chunkcoordintpair, int i, T t0) {
+        // CraftBukkit end
+        Ticket<T> ticket = new Ticket<>(tickettype, ChunkLevel.byStatus(FullChunkStatus.FULL) - i, t0);
+        long j = chunkcoordintpair.toLong();
+
+        boolean removed = this.removeTicket(j, ticket); // CraftBukkit
         this.tickingTicketsTracker.removeTicket(j, ticket);
+        return removed; // CraftBukkit
     }
 
     private SortedArraySet<Ticket<?>> getTickets(long position) {
@@ -253,9 +279,10 @@
         ChunkPos chunkcoordintpair = pos.chunk();
         long i = chunkcoordintpair.toLong();
         ObjectSet<ServerPlayer> objectset = (ObjectSet) this.playersPerChunk.get(i);
+        if (objectset == null) return; // CraftBukkit - SPIGOT-6208
 
-        objectset.remove(player);
-        if (objectset.isEmpty()) {
+        if (objectset != null) objectset.remove(player); // Paper - some state corruption happens here, don't crash, clean up gracefully
+        if (objectset == null || objectset.isEmpty()) { // Paper
             this.playersPerChunk.remove(i);
             this.naturalSpawnChunkCounter.update(i, Integer.MAX_VALUE, false);
             this.playerTicketManager.update(i, Integer.MAX_VALUE, false);
@@ -358,7 +385,7 @@
     }
 
     public void removeTicketsOnClosing() {
-        ImmutableSet<TicketType<?>> immutableset = ImmutableSet.of(TicketType.UNKNOWN);
+        ImmutableSet<TicketType<?>> immutableset = ImmutableSet.of(TicketType.UNKNOWN, TicketType.POST_TELEPORT, TicketType.FUTURE_AWAIT); // Paper - add additional tickets to preserve
         ObjectIterator<Entry<SortedArraySet<Ticket<?>>>> objectiterator = this.tickets.long2ObjectEntrySet().fastIterator();
 
         while (objectiterator.hasNext()) {
@@ -389,7 +416,27 @@
 
     public boolean hasTickets() {
         return !this.tickets.isEmpty();
+    }
+
+    // CraftBukkit start
+    public <T> void removeAllTicketsFor(TicketType<T> ticketType, int ticketLevel, T ticketIdentifier) {
+        Ticket<T> target = new Ticket<>(ticketType, ticketLevel, ticketIdentifier);
+
+        for (java.util.Iterator<Entry<SortedArraySet<Ticket<?>>>> iterator = this.tickets.long2ObjectEntrySet().fastIterator(); iterator.hasNext();) {
+            Entry<SortedArraySet<Ticket<?>>> entry = iterator.next();
+            SortedArraySet<Ticket<?>> tickets = entry.getValue();
+            if (tickets.remove(target)) {
+                // copied from removeTicket
+                this.ticketTracker.update(entry.getLongKey(), DistanceManager.getTicketLevelAt(tickets), false);
+
+                // can't use entry after it's removed
+                if (tickets.isEmpty()) {
+                    iterator.remove();
+                }
+            }
+        }
     }
+    // CraftBukkit end
 
     private class ChunkTicketTracker extends ChunkTracker {