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, 185 insertions, 0 deletions

diff --git a/patches/server/0168-AsyncTabCompleteEvent.patch b/patches/server/0168-AsyncTabCompleteEvent.patch
new file mode 100644
index 0000000000..ddced42488
--- /dev/null
+++ b/patches/server/0168-AsyncTabCompleteEvent.patch
@@ -0,0 +1,185 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Jason Penilla <[email protected]>
+Date: Sun, 26 Nov 2017 13:19:58 -0500
+Subject: [PATCH] AsyncTabCompleteEvent
+
+Let plugins be able to control tab completion of commands and chat async.
+
+This will be useful for frameworks like ACF so we can define async safe completion handlers,
+and avoid going to main for tab completions.
+
+Especially useful if you need to query a database in order to obtain the results for tab
+completion, such as offline players.
+
+Also adds isCommand and getLocation to the sync TabCompleteEvent
+
+Co-authored-by: Aikar <[email protected]>
+
+diff --git a/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java b/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
+index e40eeb5e04d96fb55283ded82cea0a5539a2fad5..90bd5c1a010a3a9d24328e5c719053603e206626 100644
+--- a/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
++++ b/src/main/java/net/minecraft/server/network/ServerGamePacketListenerImpl.java
+@@ -784,12 +784,16 @@ public class ServerGamePacketListenerImpl implements ServerPlayerConnection, Tic
+ 
+     }
+ 
++    // Paper start
++    private static final java.util.concurrent.ExecutorService TAB_COMPLETE_EXECUTOR = java.util.concurrent.Executors.newFixedThreadPool(4,
++        new com.google.common.util.concurrent.ThreadFactoryBuilder().setDaemon(true).setNameFormat("Async Tab Complete Thread - #%d").setUncaughtExceptionHandler(new net.minecraft.DefaultUncaughtExceptionHandlerWithName(net.minecraft.server.MinecraftServer.LOGGER)).build());
++    // Paper end
+     @Override
+     public void handleCustomCommandSuggestions(ServerboundCommandSuggestionPacket packet) {
+-        PacketUtils.ensureRunningOnSameThread(packet, this, this.player.getLevel());
++        // PacketUtils.ensureRunningOnSameThread(packet, this, this.player.getLevel()); // Paper - run this async
+         // CraftBukkit start
+         if (this.chatSpamTickCount.addAndGet(1) > 500 && !this.server.getPlayerList().isOp(this.player.getGameProfile())) {
+-            this.disconnect(Component.translatable("disconnect.spam"));
++            server.scheduleOnMain(() -> this.disconnect(Component.translatable("disconnect.spam", new Object[0]))); // Paper
+             return;
+         }
+         // Paper start
+@@ -800,18 +804,45 @@ public class ServerGamePacketListenerImpl implements ServerPlayerConnection, Tic
+         }
+         // Paper end
+         // CraftBukkit end
++        // Paper start - async tab completion
++        TAB_COMPLETE_EXECUTOR.execute(() -> {
+         StringReader stringreader = new StringReader(packet.getCommand());
+ 
+         if (stringreader.canRead() && stringreader.peek() == '/') {
+             stringreader.skip();
+         }
++            final String command = packet.getCommand();
++            final com.destroystokyo.paper.event.server.AsyncTabCompleteEvent event = new com.destroystokyo.paper.event.server.AsyncTabCompleteEvent(this.getCraftPlayer(), command, true, null);
++            event.callEvent();
++            final java.util.List<com.destroystokyo.paper.event.server.AsyncTabCompleteEvent.Completion> completions = event.isCancelled() ? com.google.common.collect.ImmutableList.of() : event.completions();
++            // If the event isn't handled, we can assume that we have no completions, and so we'll ask the server
++            if (!event.isHandled()) {
++                if (!event.isCancelled()) {
+ 
+-        ParseResults<CommandSourceStack> parseresults = this.server.getCommands().getDispatcher().parse(stringreader, this.player.createCommandSourceStack());
++                    this.server.scheduleOnMain(() -> { // This needs to be on main
++                        ParseResults<CommandSourceStack> parseresults = this.server.getCommands().getDispatcher().parse(stringreader, this.player.createCommandSourceStack());
+ 
+-        this.server.getCommands().getDispatcher().getCompletionSuggestions(parseresults).thenAccept((suggestions) -> {
+-            if (suggestions.isEmpty()) return; // CraftBukkit - don't send through empty suggestions - prevents [<args>] from showing for plugins with nothing more to offer
+-            this.connection.send(new ClientboundCommandSuggestionsPacket(packet.getId(), suggestions));
++                        this.server.getCommands().getDispatcher().getCompletionSuggestions(parseresults).thenAccept((suggestions) -> {
++                            if (suggestions.isEmpty()) return; // CraftBukkit - don't send through empty suggestions - prevents [<args>] from showing for plugins with nothing more to offer
++                            this.connection.send(new ClientboundCommandSuggestionsPacket(packet.getId(), suggestions));
++                        });
++                    });
++                }
++            } else if (!completions.isEmpty()) {
++                final com.mojang.brigadier.suggestion.SuggestionsBuilder builder0 = new com.mojang.brigadier.suggestion.SuggestionsBuilder(command, stringreader.getTotalLength());
++                final com.mojang.brigadier.suggestion.SuggestionsBuilder builder = builder0.createOffset(builder0.getInput().lastIndexOf(' ') + 1);
++                completions.forEach(completion -> {
++                    final Integer intSuggestion = com.google.common.primitives.Ints.tryParse(completion.suggestion());
++                    if (intSuggestion != null) {
++                        builder.suggest(intSuggestion, PaperAdventure.asVanilla(completion.tooltip()));
++                    } else {
++                        builder.suggest(completion.suggestion(), PaperAdventure.asVanilla(completion.tooltip()));
++                    }
++                });
++                player.connection.send(new ClientboundCommandSuggestionsPacket(packet.getId(), builder.buildFuture().join()));
++            }
+         });
++        // Paper end - async tab completion
+     }
+ 
+     @Override
+diff --git a/src/main/java/org/bukkit/craftbukkit/CraftServer.java b/src/main/java/org/bukkit/craftbukkit/CraftServer.java
+index 7013b11fc0cd5fbb5a7e62be45d84d54d3052237..ca6bb66e8ba1e17f025b82091910ca223185ad3b 100644
+--- a/src/main/java/org/bukkit/craftbukkit/CraftServer.java
++++ b/src/main/java/org/bukkit/craftbukkit/CraftServer.java
+@@ -2086,7 +2086,7 @@ public final class CraftServer implements Server {
+             offers = this.tabCompleteChat(player, message);
+         }
+ 
+-        TabCompleteEvent tabEvent = new TabCompleteEvent(player, message, offers);
++        TabCompleteEvent tabEvent = new TabCompleteEvent(player, message, offers, message.startsWith("/") || forceCommand, pos != null ? net.minecraft.server.MCUtil.toLocation(((CraftWorld) player.getWorld()).getHandle(), new BlockPos(pos)) : null); // Paper
+         this.getPluginManager().callEvent(tabEvent);
+ 
+         return tabEvent.isCancelled() ? Collections.EMPTY_LIST : tabEvent.getCompletions();
+diff --git a/src/main/java/org/bukkit/craftbukkit/command/ConsoleCommandCompleter.java b/src/main/java/org/bukkit/craftbukkit/command/ConsoleCommandCompleter.java
+index b996fde481cebbbcce80a6c267591136db7cc0bc..14cd8ae69d9b25dc5edad4ff96ff4a9acb1f22cb 100644
+--- a/src/main/java/org/bukkit/craftbukkit/command/ConsoleCommandCompleter.java
++++ b/src/main/java/org/bukkit/craftbukkit/command/ConsoleCommandCompleter.java
+@@ -28,6 +28,61 @@ public class ConsoleCommandCompleter implements Completer {
+     public void complete(LineReader reader, ParsedLine line, List<Candidate> candidates) {
+         final CraftServer server = this.server.server;
+         final String buffer = line.line();
++        // Async Tab Complete
++        final com.destroystokyo.paper.event.server.AsyncTabCompleteEvent event =
++            new com.destroystokyo.paper.event.server.AsyncTabCompleteEvent(server.getConsoleSender(), buffer, true, null);
++        event.callEvent();
++        final List<com.destroystokyo.paper.event.server.AsyncTabCompleteEvent.Completion> completions = event.isCancelled() ? com.google.common.collect.ImmutableList.of() : event.completions();
++
++        if (event.isCancelled() || event.isHandled()) {
++            // Still fire sync event with the provided completions, if someone is listening
++            if (!event.isCancelled() && TabCompleteEvent.getHandlerList().getRegisteredListeners().length > 0) {
++                List<com.destroystokyo.paper.event.server.AsyncTabCompleteEvent.Completion> finalCompletions = new java.util.ArrayList<>(completions);
++                Waitable<List<String>> syncCompletions = new Waitable<List<String>>() {
++                    @Override
++                    protected List<String> evaluate() {
++                        org.bukkit.event.server.TabCompleteEvent syncEvent = new org.bukkit.event.server.TabCompleteEvent(server.getConsoleSender(), buffer,
++                            finalCompletions.stream()
++                                .map(com.destroystokyo.paper.event.server.AsyncTabCompleteEvent.Completion::suggestion)
++                                .collect(java.util.stream.Collectors.toList()));
++                        return syncEvent.callEvent() ? syncEvent.getCompletions() : com.google.common.collect.ImmutableList.of();
++                    }
++                };
++                server.getServer().processQueue.add(syncCompletions);
++                try {
++                    final List<String> legacyCompletions = syncCompletions.get();
++                    completions.removeIf(it -> !legacyCompletions.contains(it.suggestion())); // remove any suggestions that were removed
++                    // add any new suggestions
++                    for (final String completion : legacyCompletions) {
++                        if (notNewSuggestion(completions, completion)) {
++                            continue;
++                        }
++                        completions.add(com.destroystokyo.paper.event.server.AsyncTabCompleteEvent.Completion.completion(completion));
++                    }
++                } catch (InterruptedException | ExecutionException e1) {
++                    e1.printStackTrace();
++                }
++            }
++
++            if (!completions.isEmpty()) {
++                for (final com.destroystokyo.paper.event.server.AsyncTabCompleteEvent.Completion completion : completions) {
++                    if (completion.suggestion().isEmpty()) {
++                        continue;
++                    }
++                    candidates.add(new Candidate(
++                        completion.suggestion(),
++                        completion.suggestion(),
++                        null,
++                        io.papermc.paper.adventure.PaperAdventure.PLAIN.serializeOr(completion.tooltip(), null),
++                        null,
++                        null,
++                        false
++                    ));
++                }
++            }
++            return;
++        }
++
+         // Paper end
+         Waitable<List<String>> waitable = new Waitable<List<String>>() {
+             @Override
+@@ -73,4 +128,15 @@ public class ConsoleCommandCompleter implements Completer {
+             Thread.currentThread().interrupt();
+         }
+     }
++
++    // Paper start
++    private boolean notNewSuggestion(final List<com.destroystokyo.paper.event.server.AsyncTabCompleteEvent.Completion> completions, final String completion) {
++        for (final com.destroystokyo.paper.event.server.AsyncTabCompleteEvent.Completion it : completions) {
++            if (it.suggestion().equals(completion)) {
++                return true;
++            }
++        }
++        return false;
++    }
++    // Paper end
+ }