Rewrite chunk system (#8177)

Patch documentation to come

Issues with the old system that are fixed now:
- World generation does not scale with cpu cores effectively.
- Relies on the main thread for scheduling and maintaining chunk state, dropping chunk load/generate rates at lower tps.
- Unreliable prioritisation of chunk gen/load calls that block the main thread.
- Shutdown logic is utterly unreliable, as it has to wait for all chunks to unload - is it guaranteed that the chunk system is in a state on shutdown that it can reliably do this? Watchdog shutdown also typically failed due to thread checks, which is now resolved.
- Saving of data is not unified (i.e can save chunk data without saving entity data, poses problems for desync if shutdown is really abnormal.
- Entities are not loaded with chunks. This caused quite a bit of headache for Chunk#getEntities API, but now the new chunk system loads entities with chunks so that they are ready whenever the chunk loads in. Effectively brings the behavior back to 1.16 era, but still storing entities in their own separate regionfiles.

The above list is not complete. The patch documentation will complete it.

New chunk system hard relies on starlight and dataconverter, and most importantly the new concurrent utilities in ConcurrentUtil.

Some of the old async chunk i/o interface (i.e the old file io thread reroutes _some_ calls to the new file io thread) is kept for plugin compat reasons. It will be removed in the next major version of minecraft.

The old legacy chunk system patches have been moved to the removed folder in case we need them again.

1 files changed, 71 insertions, 0 deletions

diff --git a/patches/server/0444-Remove-streams-from-classes-related-villager-gossip.patch b/patches/server/0444-Remove-streams-from-classes-related-villager-gossip.patch
new file mode 100644
index 0000000000..b70ae30d26
--- /dev/null
+++ b/patches/server/0444-Remove-streams-from-classes-related-villager-gossip.patch
@@ -0,0 +1,71 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: JRoy <[email protected]>
+Date: Wed, 1 Jul 2020 18:01:49 -0400
+Subject: [PATCH] Remove streams from classes related villager gossip
+
+
+diff --git a/src/main/java/net/minecraft/world/entity/ai/gossip/GossipContainer.java b/src/main/java/net/minecraft/world/entity/ai/gossip/GossipContainer.java
+index 0de65462956fa734b6405614e047161696e596fb..aa277479f5552503a202a057b1a3ede379f2bbbf 100644
+--- a/src/main/java/net/minecraft/world/entity/ai/gossip/GossipContainer.java
++++ b/src/main/java/net/minecraft/world/entity/ai/gossip/GossipContainer.java
+@@ -58,8 +58,21 @@ public class GossipContainer {
+         });
+     }
+ 
++    // Paper start - Remove streams from reputation
++    private List<GossipContainer.GossipEntry> decompress() {
++        List<GossipContainer.GossipEntry> list = new it.unimi.dsi.fastutil.objects.ObjectArrayList<>();
++        for (Map.Entry<UUID, GossipContainer.EntityGossips> entry : getReputations().entrySet()) {
++            for (GossipContainer.GossipEntry cur : entry.getValue().decompress(entry.getKey())) {
++                if (cur.weightedValue() != 0)
++                    list.add(cur);
++            }
++        }
++        return list;
++    }
++    // Paper end
++
+     private Collection<GossipContainer.GossipEntry> selectGossipsForTransfer(RandomSource random, int count) {
+-        List<GossipContainer.GossipEntry> list = this.unpack().collect(Collectors.toList());
++        List<GossipContainer.GossipEntry> list = this.decompress(); // Paper - Remove streams from reputation
+         if (list.isEmpty()) {
+             return Collections.emptyList();
+         } else {
+@@ -153,7 +166,7 @@ public class GossipContainer {
+     }
+ 
+     public <T> Dynamic<T> store(DynamicOps<T> dynamicOps) {
+-        return new Dynamic<>(dynamicOps, dynamicOps.createList(this.unpack().map((gossipEntry) -> {
++        return new Dynamic<>(dynamicOps, dynamicOps.createList(this.decompress().stream().map((gossipEntry) -> {
+             return gossipEntry.store(dynamicOps);
+         }).map(Dynamic::getValue)));
+     }
+@@ -179,11 +192,23 @@ public class GossipContainer {
+         final Object2IntMap<GossipType> entries = new Object2IntOpenHashMap<>();
+ 
+         public int weightedValue(Predicate<GossipType> gossipTypeFilter) {
+-            return this.entries.object2IntEntrySet().stream().filter((entry) -> {
+-                return gossipTypeFilter.test(entry.getKey());
+-            }).mapToInt((entry) -> {
+-                return entry.getIntValue() * (entry.getKey()).weight;
+-            }).sum();
++            // Paper start - Remove streams from reputation
++            int weight = 0;
++            for (Object2IntMap.Entry<GossipType> entry : entries.object2IntEntrySet()) {
++                if (gossipTypeFilter.test(entry.getKey())) {
++                    weight += entry.getIntValue() * entry.getKey().weight;
++                }
++            }
++            return weight;
++        }
++
++        public List<GossipContainer.GossipEntry> decompress(UUID uuid) {
++            List<GossipContainer.GossipEntry> list = new it.unimi.dsi.fastutil.objects.ObjectArrayList<>();
++            for (Object2IntMap.Entry<GossipType> entry : entries.object2IntEntrySet()) {
++                list.add(new GossipContainer.GossipEntry(uuid, entry.getKey(), entry.getIntValue()));
++            }
++            return list;
++            // Paper - end
+         }
+ 
+         public Stream<GossipContainer.GossipEntry> unpack(UUID target) {