Add chunk unload delay so we can re-use them if we return

src/main/java/de/johni0702/minecraft/bobby/BobbyConfig.java

@@ -8,15 +8,23 @@ public class BobbyConfig {
     public static final BobbyConfig DEFAULT = new BobbyConfig();
 
     private boolean enabled = true;
+    @Comment("Delays the unloading of chunks which are outside your view distance.\nSaves you from having to reload all chunks when leaving the area for a short moment (e.g. cut scenes).\nDoes not work across dimensions.")
+    private int unloadDelaySecs = 60;
     @Comment("Changes the maximum value configurable for Render Distance.\n\nRequires Sodium.")
     private int maxRenderDistance = 32;
     @Comment("Overwrites the view-distance of the integrated server.\nThis allows Bobby to be useful in Singleplayer.\n\nDisabled when at 0.\nBobby is active in singleplayer only if this is enabled.\nRequires re-log to en-/disable.")
     private int viewDistanceOverwrite = 0;
 
     public BobbyConfig() {}
 
-    public BobbyConfig(boolean enabled, int maxRenderDistance, int viewDistanceOverwrite) {
+    public BobbyConfig(
+            boolean enabled,
+            int unloadDelaySecs,
+            int maxRenderDistance,
+            int viewDistanceOverwrite
+    ) {
         this.enabled = enabled;
+        this.unloadDelaySecs = unloadDelaySecs;
         this.maxRenderDistance = maxRenderDistance;
         this.viewDistanceOverwrite = viewDistanceOverwrite;
     }
@@ -25,6 +33,10 @@ public boolean isEnabled() {
         return enabled;
     }
 
+    public int getUnloadDelaySecs() {
+        return unloadDelaySecs;
+    }
+
     public int getMaxRenderDistance() {
         return maxRenderDistance;
     }

src/main/java/de/johni0702/minecraft/bobby/BobbyConfigScreenFactory.java

@@ -27,6 +27,12 @@ public static Screen createConfigScreen(Screen parent, BobbyConfig config, Consu
                 .setDefaultValue(defaultConfig.isEnabled())
                 .build();
 
+        IntegerListEntry unloadDelaySecs = entryBuilder
+                .startIntField(new TranslatableText("option.bobby.unload_delay"), config.getUnloadDelaySecs())
+                .setTooltip(new TranslatableText("tooltip.option.bobby.unload_delay"))
+                .setDefaultValue(defaultConfig.getUnloadDelaySecs())
+                .build();
+
         IntegerListEntry maxRenderDistance = entryBuilder
                 .startIntField(new TranslatableText("option.bobby.max_render_distance"), config.getMaxRenderDistance())
                 .setTooltip(new TranslatableText("tooltip.option.bobby.max_render_distance"))
@@ -41,11 +47,13 @@ public static Screen createConfigScreen(Screen parent, BobbyConfig config, Consu
 
         ConfigCategory general = builder.getOrCreateCategory(new TranslatableText("category.bobby.general"));
         general.addEntry(enabled);
+        general.addEntry(unloadDelaySecs);
         general.addEntry(maxRenderDistance);
         general.addEntry(viewDistanceOverwrite);
 
         builder.setSavingRunnable(() -> update.accept(new BobbyConfig(
                 enabled.getValue(),
+                unloadDelaySecs.getValue(),
                 maxRenderDistance.getValue(),
                 viewDistanceOverwrite.getValue()
         )));

src/main/java/de/johni0702/minecraft/bobby/FakeChunkManager.java

@@ -5,12 +5,11 @@
 import de.johni0702.minecraft.bobby.mixin.LightingProviderAccessor;
 import de.johni0702.minecraft.bobby.mixin.sodium.SodiumChunkManagerAccessor;
 import io.netty.util.concurrent.DefaultThreadFactory;
+import it.unimi.dsi.fastutil.longs.Long2LongMap;
+import it.unimi.dsi.fastutil.longs.Long2LongOpenHashMap;
 import it.unimi.dsi.fastutil.longs.Long2ObjectMap;
 import it.unimi.dsi.fastutil.longs.Long2ObjectMaps;
 import it.unimi.dsi.fastutil.longs.Long2ObjectOpenHashMap;
-import it.unimi.dsi.fastutil.longs.LongIterator;
-import it.unimi.dsi.fastutil.longs.LongOpenHashSet;
-import it.unimi.dsi.fastutil.longs.LongSet;
 import it.unimi.dsi.fastutil.objects.ObjectIterator;
 import me.jellysquid.mods.sodium.client.world.ChunkStatusListener;
 import me.jellysquid.mods.sodium.client.world.SodiumChunkManager;
@@ -50,6 +49,8 @@
 import java.io.File;
 import java.io.IOException;
 import java.nio.file.Path;
+import java.util.ArrayDeque;
+import java.util.Deque;
 import java.util.Optional;
 import java.util.concurrent.CompletableFuture;
 import java.util.concurrent.ExecutionException;
@@ -70,7 +71,11 @@ public class FakeChunkManager {
 
     private final Long2ObjectMap<WorldChunk> fakeChunks = Long2ObjectMaps.synchronize(new Long2ObjectOpenHashMap<>());
     private int centerX, centerZ, viewDistance;
-    private final LongSet toBeUnloaded = new LongOpenHashSet();
+    private final Long2LongMap toBeUnloaded = new Long2LongOpenHashMap();
+    // Contains chunks in order to be unloaded. We keep the chunk and time so we can cross-reference it with
+    // [toBeUnloaded] to see if the entry has since been removed / the time reset. This way we do not need
+    // to remove entries from the middle of the queue.
+    private final Deque<Pair<Long, Long>> unloadQueue = new ArrayDeque<>();
 
     // There unfortunately is only a synchronous api for loading chunks (even though that one just waits on a
     // CompletableFuture, annoying but oh well), so we call that blocking api from a separate thread pool.
@@ -132,6 +137,9 @@ public void update(BooleanSupplier shouldKeepTicking) {
             return;
         }
 
+        BobbyConfig config = Bobby.getInstance().getConfig();
+        long time = Util.getMeasuringTimeMs();
+
         int oldCenterX = this.centerX;
         int oldCenterZ = this.centerZ;
         int oldViewDistance = this.viewDistance;
@@ -146,7 +154,9 @@ public void update(BooleanSupplier shouldKeepTicking) {
                     boolean zOutsideNew = z < newCenterZ - newViewDistance || z > newCenterZ + newViewDistance;
                     if (xOutsideNew || zOutsideNew) {
                         cancelLoad(x, z);
-                        toBeUnloaded.add(ChunkPos.toLong(x, z));
+                        long chunkPos = ChunkPos.toLong(x, z);
+                        toBeUnloaded.put(chunkPos, time);
+                        unloadQueue.add(new Pair<>(chunkPos, time));
                     }
                 }
             }
@@ -161,6 +171,7 @@ public void update(BooleanSupplier shouldKeepTicking) {
 
                         // We want this chunk, so don't unload it if it's still here
                         toBeUnloaded.remove(chunkPos);
+                        // Not removing it from [unloadQueue], we check [toBeUnloaded] when we poll it.
 
                         // If there already is a chunk loaded, there's nothing to do
                         if (clientChunkManager.getChunk(x, z, ChunkStatus.FULL, false) != null) {
@@ -181,10 +192,34 @@ public void update(BooleanSupplier shouldKeepTicking) {
         }
 
         // Anything remaining in the set is no longer needed and can now be unloaded
-        LongIterator unloadingIter = toBeUnloaded.iterator();
-        while (unloadingIter.hasNext()) {
-            long chunkPos = unloadingIter.nextLong();
-            unloadingIter.remove();
+        long unloadTime = time - config.getUnloadDelaySecs() * 1000L;
+        while (true) {
+            Pair<Long, Long> next = unloadQueue.pollFirst();
+            if (next == null) {
+                break;
+            }
+            long chunkPos = next.getLeft();
+            long queuedTime = next.getRight();
+
+            if (queuedTime > unloadTime) {
+                // Unload is still being delayed, put the entry back into the queue
+                // and be done for this update.
+                unloadQueue.addFirst(next);
+                break;
+            }
+
+            long actualQueuedTime = toBeUnloaded.remove(chunkPos);
+            if (actualQueuedTime != queuedTime) {
+                // The chunk has either been un-queued or re-queued.
+                if (actualQueuedTime != 0) {
+                    // If it was re-queued, put it back in the map.
+                    toBeUnloaded.put(chunkPos, actualQueuedTime);
+                }
+                // Either way, skip it for now and go to the next entry.
+                continue;
+            }
+
+            // This chunk is due for unloading
             unload(ChunkPos.getPackedX(chunkPos), ChunkPos.getPackedZ(chunkPos), false);
         }
 

src/main/resources/assets/bobby/lang/en_us.json

@@ -1,6 +1,8 @@
 {
   "title.bobby.config": "Bobby Config",
   "option.bobby.enabled": "Enabled",
+  "option.bobby.unload_delay": "Chunk Unload Delay (Seconds)",
+  "tooltip.option.bobby.unload_delay": "Delays the unloading of chunks which are outside your view distance.\nSaves you from having to reload all chunks when\nleaving an area for a short moment (e.g. cut scenes).\nDoes not work across dimensions.",
   "option.bobby.max_render_distance": "Max Render Distance",
   "tooltip.option.bobby.max_render_distance": "Changes the maximum value configurable for Render Distance.\n\nRequires Sodium.",
   "option.bobby.view_distance_overwrite": "Singleplayer Server View Distance",