restore all "named" notes quickly after their deletion, #3517

src/services/handlers.js

@@ -4,6 +4,8 @@ const treeService = require('./tree');
 const noteService = require('./notes');
 const becca = require('../becca/becca');
 const Attribute = require('../becca/entities/attribute');
+const hiddenSubtreeService = require("./hidden_subtree");
+const oneTimeTimer = require("./one_time_timer");
 
 function runAttachedRelations(note, relationName, originEntity) {
     if (!note) {
@@ -206,6 +208,16 @@ eventService.subscribe(eventService.ENTITY_DELETED, ({ entityName, entity }) =>
     if (entityName === 'branches') {
         runAttachedRelations(entity.getNote(), 'runOnBranchDeletion', entity);
     }
+
+    if (entityName === 'notes' && entity.noteId.startsWith("_")) {
+        // "named" note has been deleted, we will probably need to rebuild the hidden subtree
+        // scheduling so that bulk deletes won't trigger so many checks
+        oneTimeTimer.scheduleExecution('hidden-subtree-check', 1000, () => {
+            console.log("Checking hidden subtree");
+
+            hiddenSubtreeService.checkHiddenSubtree();
+        });
+    }
 });
 
 module.exports = {

src/services/one_time_timer.js

@@ -0,0 +1,25 @@
+const scheduledExecutions = {};
+
+/**
+ * Subsequent calls will not move the timer to future. The first caller determines the time of execution.
+ *
+ * The good thing about synchronous better-sqlite3 is that this cannot interrupt transaction. The execution will be called
+ * only outside of a transaction.
+ */
+function scheduleExecution(name, milliseconds, cb) {
+    if (name in scheduledExecutions) {
+        return;
+    }
+
+    scheduledExecutions[name] = true;
+
+    setTimeout(() => {
+        delete scheduledExecutions[name];
+
+        cb();
+    }, milliseconds);
+}
+
+module.exports = {
+    scheduleExecution
+};

src/services/special_notes.js

@@ -218,7 +218,7 @@ function resetLauncher(noteId) {
         log.info(`Note ${noteId} is not a resettable launcher note.`);
     }
 
-    hiddenSubtreeService.checkHiddenSubtree();
+    // the re-building deleted launchers will be done in handlers
 }
 
 /**