Auto-updating observables

Instead of scheduling tasks for auto-updating elements such as items with .updatePeriodically or the contents of a referencing inventory, make Observables capable of declaring auto-update intervals in which they want to be queried.

This commit also changes all observer implementations to use concurrent collections instead of synchronization where necessary to prevent calling into other methods like notifyUpdate while holding a lock.

Author: NichtStudioCode

invui/src/main/java/xyz/xenondevs/invui/Observable.java

@@ -7,19 +7,33 @@ public interface Observable {
 
     /**
      * Adds an {@link Observer} to this {@link Observable}.
-     * @param who The {@link Observer} to that observes this {@link Observable}.
+     *
+     * @param who  The {@link Observer} to that observes this {@link Observable}.
      * @param what An integer specifying what part of this {@link Observable} the {@link Observer} is observing.
-     * @param how An integer specifying how the {@link Observer} is observing this {@link Observable}.
-     *            Used to {@link Observer#notifyUpdate(int) notify} the {@link Observer} about updates.
+     * @param how  An integer specifying how the {@link Observer} is observing this {@link Observable}.
+     *             Used to {@link Observer#notifyUpdate(int) notify} the {@link Observer} about updates.
      */
     void addObserver(Observer who, int what, int how);
 
     /**
      * Removes an {@link Observer} from this {@link Observable}.
-     * @param who The {@link Observer} that is no longer observes this {@link Observable}.
+     *
+     * @param who  The {@link Observer} that is no longer observes this {@link Observable}.
      * @param what An integer specifying what part of this {@link Observable} the {@link Observer} was observing.
-     * @param how An integer specifying how the {@link Observer} was observing this {@link Observable}.
+     * @param how  An integer specifying how the {@link Observer} was observing this {@link Observable}.
      */
     void removeObserver(Observer who, int what, int how);
 
+    /**
+     * Instead of calling {@link Observer#notifyUpdate(int)}, {@link Observable Observables} may
+     * also define an auto-update period after which {@link Observer Obervers} should automatically
+     * query for updates.
+     *
+     * @param what An integer specifying what part of this {@link Observable} the update period is requested for.
+     * @return The update period of this {@link Observable} in ticks, or <= 0 for no auto-updates.
+     */
+    default int getUpdatePeriod(int what) {
+        return -1;
+    }
+    
 }

invui/src/main/java/xyz/xenondevs/invui/Observer.java

@@ -1,7 +1,5 @@
 package xyz.xenondevs.invui;
 
-import io.papermc.paper.threadedregions.scheduler.EntityScheduler;
-
 /**
  * Something that can observe an {@link Observable}.
  */
@@ -15,10 +13,4 @@ public interface Observer {
      */
     void notifyUpdate(int i);
 
-    /**
-     * @return An {@link EntityScheduler} that can be used to schedule tasks for this {@link Observer},
-     *        or {@code null} if no such scheduler is available.
-     */
-    EntityScheduler getScheduler();
-    
 }

invui/src/main/java/xyz/xenondevs/invui/gui/AbstractGui.java

@@ -29,6 +29,7 @@
 import xyz.xenondevs.invui.window.WindowManager;
 
 import java.util.*;
+import java.util.concurrent.ConcurrentHashMap;
 import java.util.function.Consumer;
 import java.util.function.Supplier;
 import java.util.stream.Collectors;
@@ -43,7 +44,7 @@ non-sealed abstract class AbstractGui implements Gui {
     private final int height;
     private final int size;
     private final @Nullable SlotElement[] slotElements;
-    private final @Nullable Set<ObserverAtSlot>[] observers;
+    private final List<Set<ObserverAtSlot>> observers;
 
     private final MutableProperty<Boolean> frozen;
     private final MutableProperty<Boolean> ignoreObscuredInventorySlots;
@@ -63,7 +64,6 @@ non-sealed abstract class AbstractGui implements Gui {
         );
     }
 
-    @SuppressWarnings("unchecked")
     AbstractGui(
         int width, int height,
         MutableProperty<Boolean> frozen,
@@ -79,7 +79,7 @@ non-sealed abstract class AbstractGui implements Gui {
         this.background = background;
 
         slotElements = new SlotElement[size];
-        observers = new Set[size];
+        observers = CollectionUtils.newList(size, x -> ConcurrentHashMap.newKeySet());
 
         this.background.observeWeak(this, AbstractGui::notifyWindowsOnBackgroundSlots);
     }
@@ -533,91 +533,59 @@ private Map<? extends Inventory, Set<Integer>> getAllActiveInventorySlots(Invent
 
     @Override
     public void notifyWindows() {
-        synchronized (observers) {
-            for (var observerSet : observers) {
-                if (observerSet != null) {
-                    for (var viewerAtSlot : observerSet) {
-                        viewerAtSlot.notifyUpdate();
-                    }
-                }
+        for (var observerSet : observers) {
+            for (var viewerAtSlot : observerSet) {
+                viewerAtSlot.notifyUpdate();
             }
         }
     }
 
     @Override
     public void notifyWindows(int index) {
-        var element = getSlotElement(index);
-        if (element == null)
-            return;
-        
-        synchronized (observers) {
-            var observerSet = observers[index];
-            if (observerSet == null)
-                return;
-            
-            for (var viewerAtSlot : observerSet) {
-                viewerAtSlot.notifyUpdate();
-            }
+        for (var viewerAtSlot : observers.get(index)) {
+            viewerAtSlot.notifyUpdate();
         }
     }
 
     private void notifyWindowsOnBackgroundSlots() {
-        synchronized (observers) {
-            for (int i = 0; i < getSize(); i++) {
-                if (slotElements[i] != null)
-                    continue;
-                
-                var observerSet = observers[i];
-                if (observerSet == null)
-                    continue;
-                
-                for (var viewerAtSlot : observerSet) {
-                    viewerAtSlot.notifyUpdate();
-                }
-            }
+        for (int i = 0; i < getSize(); i++) {
+            if (slotElements[i] != null)
+                continue;
+            
+            notifyWindows(i);
         }
     }
 
     @Override
     public void addObserver(Observer who, int what, int how) {
-        synchronized (observers) {
-            var observerSet = this.observers[what];
-            if (observerSet == null) {
-                observerSet = new HashSet<>();
-                this.observers[what] = observerSet;
-            }
-            observerSet.add(new ObserverAtSlot(who, how));
-        }
+        observers.get(what).add(new ObserverAtSlot(who, how));
     }
 
     @Override
     public void removeObserver(Observer who, int what, int how) {
-        synchronized (observers) {
-            var observerSet = this.observers[what];
-            if (observerSet != null) {
-                observerSet.remove(new ObserverAtSlot(who, how));
-                if (observerSet.isEmpty())
-                    this.observers[what] = null;
-            }
-        }
+        observers.get(what).remove(new ObserverAtSlot(who, how));
+    }
+    
+    @Override
+    public int getUpdatePeriod(int what) {
+        var element = getSlotElement(what);
+        if (element != null)
+            return element.getUpdatePeriod();
+        return -1;
     }
 
     @Override
     public @Unmodifiable Collection<Window> getWindows() {
-        synchronized (observers) {
-            var windows = new HashSet<Window>();
-            for (var observerSet : observers) {
-                if (observerSet == null)
+        var windows = new HashSet<Window>();
+        for (var observerSet : observers) {
+            for (var viewerAtSlot : observerSet) {
+                if (!(viewerAtSlot.observer() instanceof Window w))
                     continue;
-                for (var viewerAtSlot : observerSet) {
-                    if (!(viewerAtSlot.observer() instanceof Window w))
-                        continue;
-                    windows.add(w);
-                }
+                windows.add(w);
             }
-            
-            return Collections.unmodifiableSet(windows);
         }
+        
+        return Collections.unmodifiableSet(windows);
     }
 
     @Override
@@ -731,12 +699,7 @@ public void setSlotElement(int index, @Nullable SlotElement slotElement) {
         }
 
         // notify parents that a slot element has been changed
-        var viewers = this.observers[index];
-        if (viewers != null) {
-            for (var viewer : viewers) {
-                viewer.notifyUpdate();
-            }
-        }
+        notifyWindows(index);
     }
 
     @Override

invui/src/main/java/xyz/xenondevs/invui/gui/SlotElement.java

@@ -53,6 +53,13 @@ public sealed interface SlotElement {
      */
     void removeObserver(Observer who, int how);
 
+    /**
+     * Gets the {@link Observable#getUpdatePeriod(int)} of the content of this {@link SlotElement}.
+     *
+     * @return The update period in ticks, or <= 0 for no auto-updates.
+     */
+    int getUpdatePeriod();
+    
     /**
      * Contains an {@link xyz.xenondevs.invui.item.Item}
      *
@@ -86,6 +93,11 @@ public void removeObserver(Observer who, int how) {
             item.removeObserver(who, 0, how);
         }
 
+        @Override
+        public int getUpdatePeriod() {
+            return item.getUpdatePeriod(0);
+        }
+        
     }
 
     /**
@@ -130,6 +142,11 @@ public void removeObserver(Observer who, int how) {
             inventory.removeObserver(who, slot, how);
         }
 
+        @Override
+        public int getUpdatePeriod() {
+            return inventory.getUpdatePeriod(slot);
+        }
+        
     }
 
     /**
@@ -190,6 +207,10 @@ public void removeObserver(Observer who, int how) {
             gui.removeObserver(who, slot, how);
         }
 
+        @Override
+        public int getUpdatePeriod() {
+            return gui.getUpdatePeriod(slot);
+        }
     }
 
 }

invui/src/main/java/xyz/xenondevs/invui/internal/menu/CustomContainerMenu.java

@@ -588,7 +588,8 @@ protected void handleButtonClick(int buttonId) {
     protected void runInInteractionContext(Runnable run) {
         try {
             run.run();
-            getWindowEvents().updateSlots();
+            if (getWindow().isOpen())
+                getWindowEvents().updateSlots();
         } catch (Throwable t) {
             InvUI.getInstance().handleException("An exception occurred while handling a window interaction", t);
         }

invui/src/main/java/xyz/xenondevs/invui/internal/util/CollectionUtils.java

@@ -57,7 +57,7 @@ public static <T> void forEachCatching(Iterable<? extends T> iterable, Consumer<
      * @return A new {@link List} of the specified size, filled with the results of the
      */
     public static <T> List<T> newList(int size, Function<? super Integer, ? extends T> initializer) {
-        var list = new ArrayList<T>();
+        var list = new ArrayList<T>(size);
         for (int i = 0; i < size; i++) {
             list.add(initializer.apply(i));
         }

invui/src/main/java/xyz/xenondevs/invui/inventory/CompositeInventory.java

@@ -237,4 +237,10 @@ public InventorySlot getBackingSlot(int slot) {
         return invSlot.inventory().getBackingSlot(invSlot.slot());
     }
 
+    @Override
+    public int getUpdatePeriod(int what) {
+        var invSlot = findInventory(what);
+        return invSlot.inventory().getUpdatePeriod(invSlot.slot());
+    }
+    
 }