add cancelCompute func

src/algorithm/Renderer.ts

@@ -24,7 +24,7 @@ export const options = {
 /**
  * compute the width and left of the blocks contained in each day
  */
-export async function computeBlockPositions(days: ScheduleDays) {
+export function computeBlockPositions(days: ScheduleDays) {
     const Module = window.NativeModule;
 
     console.time('native compute');

src/models/Schedule.ts

@@ -227,6 +227,10 @@ export default abstract class Schedule {
         this.hover(key, false);
     }
 
+    public cancelCompute() {
+        window.clearTimeout(this.pendingCompute);
+    }
+
     /**
      * Compute the schedule view based on `this.All` and `this.preview`.
      * If there is a pending compute task, remove that pending task.
@@ -236,18 +240,18 @@ export default abstract class Schedule {
      * However, because we're running on small input sets (usually contain no more than 20 sections), it usually completes within 50ms.
      * @note it is the caller's responsibility to call constructDateSeparators, which is necessary if new classes are added
      */
-    public async computeSchedule(sync = true, time = 100) {
-        window.clearTimeout(this.pendingCompute);
+    public computeSchedule(sync = true, time = 100) {
+        this.cancelCompute();
         if (sync) {
-            await this._computeSchedule();
+            this._computeSchedule();
         } else {
             this.pendingCompute = window.setTimeout(() => {
                 this._computeSchedule();
             }, time);
         }
     }
 
-    private async _computeSchedule() {
+    private _computeSchedule() {
         const catalog = window.catalog;
         if (!catalog) return;
 
@@ -336,7 +340,7 @@ export default abstract class Schedule {
         for (const event of this.events) if (event.display) this.place(event, days);
 
         // const tStart = performance.now();
-        await computeBlockPositions(days);
+        computeBlockPositions(days);
         // console.log('compute blocks', performance.now() - tStart);
 
         const totalBlocks = days.reduce((sum, blocks) => sum + blocks.length, 0);

src/store/index.ts

@@ -243,6 +243,8 @@ export default class Store extends Vue {
         } else {
             const semester = parsed.currentSemester || this.semester.semesters[0];
             if (force) this.noti.info(`Updating ${semester.name} data...`, 3600, true);
+            // rare case: if a pending compute occurs after semester switch, an error may occur due to difference in semester courses
+            this.schedule.cancelComputeAll();
             const msg = await this.semester.selectSemester(semester, force);
             this.noti.notify(msg);
             if (!msg.payload) return;
@@ -278,7 +280,7 @@ export default class Store extends Vue {
         if (this.schedule.generated) this.generateSchedules();
         else this.schedule.switchSchedule(false);
 
-        this.schedule.recomputeAll(false, 100); // need to compute all schedules for rendering
+        this.schedule.recomputeAll(true); // need to compute all schedules for rendering
     }
 
     /**
@@ -363,8 +365,7 @@ export default class Store extends Vue {
      * Select a semester and fetch all its associated data,
      * note that the first profile corresponding to the target semester will be loaded.
      *
-     * @param target the semester to switch to
-     * @param force whether to force-update semester data
+     * @param target the semester to switch to. If null, switch to the latest semester
      */
     async selectSemester(target: SemesterJSON | null) {
         if (!this.semester.semesters.length) {

src/store/schedule.ts

@@ -219,6 +219,13 @@ export class ScheduleStore implements StoreModule<ScheduleState, ScheduleStateJS
         });
     }
 
+    cancelComputeAll() {
+        if (this.currentSchedule !== this.proposedSchedule) {
+            this.currentSchedule.cancelCompute();
+        }
+        this.proposedSchedules.forEach(s => s.cancelCompute());
+    }
+
     /**
      * @note the schedules parsed from JSON are **not** computed (i.e. the `computeSchedule` method is not called)
      * @note the `currentSchedule` is not assigned.