Web Dev Cody
Web Dev Cody•6mo ago

Need help understanding the mutations and OCC

I'm working on a million checkboxes type of clone, and I have a function called toggleCheckbox which will first query a record, toggle a bit on or off in the number, and then write that number. This all seems to work fine. I'm also using another metadata table to keep a running sum of how many checkboxes are on or off. It seems like the counts are getting off for some reason. I created a cron which randomly toggles a bit using that same method described above every second in the first set of checkboxes. That also seems to work fine. The issue is when I manually start clicking checkboxes while the cron is running that my count seems to get off. I think there is something I'm not understanding about the concurrency model.
3 Replies
Web Dev Cody
Web Dev CodyOP•6mo ago
here is some code for context 
// checkboxes.ts
export const updateCheckbox = mutation({
  args: {
    partition: v.number(),
    index: v.number(),
  },
  async handler(ctx, args) {
    const partition = await ctx.db
      .query("checkboxes")
      .withIndex("by_partition", (q) => q.eq("partition", args.partition))
      .first();

    if (!partition) {
      await ctx.db.insert("checkboxes", {
        partition: args.partition,
        value: 1 << args.index,
      });
      await ctx.scheduler.runAfter(0, internal.metadata.updateRunningSum, {
        isToggledOn: true,
      });
    } else {
      const bit = 1 << args.index;
      partition.value = bit ^ partition.value;
      await ctx.db.patch(partition._id, partition);
      await ctx.scheduler.runAfter(0, internal.metadata.updateRunningSum, {
        isToggledOn: (partition.value & bit) > 0,
      });
    }
  },
});

export const randomlyCheckABox = internalMutation({
  async handler(ctx) {
    const index = Math.floor(Math.random() * 32);
    await ctx.scheduler.runAfter(0, api.checkboxes.updateCheckbox, {
      partition: 0,
      index,
    });
  },
});
// checkboxes.ts
export const updateCheckbox = mutation({
  args: {
    partition: v.number(),
    index: v.number(),
  },
  async handler(ctx, args) {
    const partition = await ctx.db
      .query("checkboxes")
      .withIndex("by_partition", (q) => q.eq("partition", args.partition))
      .first();

    if (!partition) {
      await ctx.db.insert("checkboxes", {
        partition: args.partition,
        value: 1 << args.index,
      });
      await ctx.scheduler.runAfter(0, internal.metadata.updateRunningSum, {
        isToggledOn: true,
      });
    } else {
      const bit = 1 << args.index;
      partition.value = bit ^ partition.value;
      await ctx.db.patch(partition._id, partition);
      await ctx.scheduler.runAfter(0, internal.metadata.updateRunningSum, {
        isToggledOn: (partition.value & bit) > 0,
      });
    }
  },
});

export const randomlyCheckABox = internalMutation({
  async handler(ctx) {
    const index = Math.floor(Math.random() * 32);
    await ctx.scheduler.runAfter(0, api.checkboxes.updateCheckbox, {
      partition: 0,
      index,
    });
  },
});
// metadata.ts

export const updateRunningSum = internalMutation({
  args: {
    isToggledOn: v.boolean(),
  },
  async handler(ctx, args) {
    const metadata = (await ctx.db.query("metadata").first())!;
    metadata.totalChecked += args.isToggledOn ? 1 : -1;
    await ctx.db.patch(metadata._id, {
      totalChecked: metadata.totalChecked,
    });
  },
});

export const getTotalChecked = query({
  async handler(ctx) {
    const metadata = await ctx.db.query("metadata").first();
    return metadata ? metadata.totalChecked : 0;
  },
});
// metadata.ts

export const updateRunningSum = internalMutation({
  args: {
    isToggledOn: v.boolean(),
  },
  async handler(ctx, args) {
    const metadata = (await ctx.db.query("metadata").first())!;
    metadata.totalChecked += args.isToggledOn ? 1 : -1;
    await ctx.db.patch(metadata._id, {
      totalChecked: metadata.totalChecked,
    });
  },
});

export const getTotalChecked = query({
  async handler(ctx) {
    const metadata = await ctx.db.query("metadata").first();
    return metadata ? metadata.totalChecked : 0;
  },
});
all the UI does is call updateCheckbox({ index: index % BITS, partition: partitionIndex, }); when a checkbox is clicked, so the mutation should be able to figure out the final state of the box just found the issue 😆 const index = Math.floor(Math.random() * 31); // need to use 31 not 32
ian
ian•6mo ago
Web Dev Cody
Web Dev CodyOP•6mo ago
yeah, am using that as a reference a bit but doing my own approach

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