fix: previous optimizations broke entity remembering

server/traits/informed.trait.js

@@ -49,34 +49,35 @@ export class Informed extends decorate(Trait) {
     });
   }
 
-  entityStepFilter(op) {
+  entityStepFilter(op, invert) {
     return (step) => {
       if (op !== step.get('op')) {
-        return;
+        return invert;
       }
       const parts = step.get('parts');
       if (6 !== parts.length) {
-        return false;
+        return invert;
       }
       if ('room' !== parts[1]) {
-        return false;
+        return invert;
       }
       if ('layers' !== parts[2]) {
-        return false;
+        return invert;
       }
       if ('entityList' !== parts[4]) {
-        return false;
+        return invert;
       }
-      return true;
+      return !invert;
     };
   }
 
   rewriteEntityAdds(state, steps) {
-    return steps.withMutations((steps) => {
-      const filter = this.entityStepFilter('add');
-      const adds = steps.map((step) => {
-        return step.set('parts', step.get('path').split('/'));
-      }).filter(filter);
+    steps = steps.map((step) => {
+      return step.set('parts', step.get('path').split('/'));
+    });
+    const isAdd = this.entityStepFilter('add', false);
+    const adds = steps.filter(isAdd);
+    steps = steps.withMutations((steps) => {
       const iterator = adds.values();
       for (const add of iterator) {
         // Remember the entity.
@@ -87,7 +88,6 @@ export class Informed extends decorate(Trait) {
           continue;
         }
         const rememberedEntity = this._rememberedEntities[uuid];
-        delete this._rememberedEntities[uuid];
         // Take a diff from what the client remembers to now.
         const currentState = state.getIn(
           ['room', 'layers', layerId, 'entityList', uuid]
@@ -99,25 +99,41 @@ export class Informed extends decorate(Trait) {
         });
         steps.concat(fullAddSteps);
         // Add overrides.
-        steps.concat(this.entityOverrides(add.get('path'), (path) => {
-          return rememberedEntity.getIn(path);
-        }));
-      }
-      for (const add of iterator) {
-        // Remove adds.
-        steps.splice(steps.indexOf(add), 1);
+        const overrides = this.entityOverrides(
+          add.get('path'),
+          (path) => rememberedEntity.getIn(path),
+        );
+        for (let i = 0; i < overrides.size; ++i) {
+          steps.push(overrides.get(i));
+        }
       }
     });
+    // Filter adds for remembered entities.
+    steps = steps.filter((step) => {
+      if (!isAdd(step)) {
+        return true;
+      }
+      const parts = step.get('parts');
+      const uuid = parts[5];
+      return !(uuid in this._rememberedEntities);
+    });
+    // Forget all remembered entities.
+    adds.forEach((step) => {
+      const parts = step.get('parts');
+      const uuid = parts[5];
+      delete this._rememberedEntities[uuid];
+    });
+    return steps;
   }
 
   rewriteEntityRemovals(state, steps) {
-    return steps.withMutations((steps) => {
-      const filter = this.entityStepFilter('remove');
-      const removals = steps.map((step) => {
-        return step.set('parts', step.get('path').split('/'));
-      }).filter(filter);
-      const iterator = removals.values();
-      for (const removal of iterator) {
+    steps = steps.map((step) => {
+      return step.set('parts', step.get('path').split('/'));
+    });
+    const isRemove = this.entityStepFilter('remove', false);
+    const removals = steps.filter(isRemove);
+    steps = steps.withMutations((steps) => {
+      for (const removal of removals.values()) {
         // Remember the entity.
         const parts = removal.get('parts');
         const layerId = parts[3];
@@ -126,13 +142,19 @@ export class Informed extends decorate(Trait) {
           ['room', 'layers', layerId, 'entityList', uuid]
         );
         // Add overrides.
-        steps.concat(this.entityOverrides(removal.get('path'), () => false));
-      }
-      for (const removal of iterator) {
-        // Remove removals.
-        steps.splice(steps.indexOf(removal), 1);
+        const overrides = this.entityOverrides(
+          removal.get('path'),
+          () => false
+        );
+        for (let i = 0; i < overrides.size; ++i) {
+          steps.push(overrides.get(i));
+        }
       }
     });
+    // Remove all removes.
+    return steps.filter((step) => {
+      return !isRemove(step);
+    });
   }
 
   reduceState(state) {