Do not ignore preventOverrun in CronJob

[boristian]

Fixes #195

[kibertoad]

@Hexagon Could you take a look at the failing tests? It looks like after the protect flag is enabled with the true value, it never gets released.

[boristian]

Any updates on this? Is something wrong with the PR?

[kibertoad]

@boristian yes, functionality appears to be broken on @Hexagon end

[Hexagon]

Hello! Cannot find anything wrong with croner, tested both [email protected] used by toad-scheduler, and [email protected] which is the latest iteration.

Tested using this code:

import { Cron } from "npm:[email protected]";

// Demo blocking function
const blockForAWhile = (ms) => new Promise(resolve => setTimeout(resolve, ms));

// (Optional) Callback to be triggered on a blocked call
const protectCallback = (job) => console.log(`Call at ${new Date().toISOString()} were blocked by call started at ${job.currentRun().toISOString()}`);

Cron(
    "*/2 * * * * *",
    { 
        protect: protectCallback // <- Using a callback for overrun protection, but `true` would work just as well
    }, 
    async (job) => {
        console.log(`Call started at ${job.currentRun().toISOString()} started`);
        await blockForAWhile(6000);
        console.log(`Call started at ${job.currentRun().toISOString()} finished ${new Date().toISOString()}`);
    }
);

With this output

codespace@codespaces-56134a:/workspaces/croner master [?]> deno run test.ts
Call started at 2023-11-13T19:21:44.003Z started
  Call at 2023-11-13T19:21:46.002Z were blocked by call started at 2023-11-13T19:21:44.003Z
  Call at 2023-11-13T19:21:48.001Z were blocked by call started at 2023-11-13T19:21:44.003Z
  Call at 2023-11-13T19:21:50.002Z were blocked by call started at 2023-11-13T19:21:44.003Z
Call started at 2023-11-13T19:21:44.003Z finished 2023-11-13T19:21:50.005Z
Call started at 2023-11-13T19:21:52.001Z started
  Call at 2023-11-13T19:21:54.006Z were blocked by call started at 2023-11-13T19:21:52.001Z
  Call at 2023-11-13T19:21:56.007Z were blocked by call started at 2023-11-13T19:21:52.001Z
Call started at 2023-11-13T19:21:52.001Z finished 2023-11-13T19:21:58.002Z // <- Callback runs before actually unblocking, that's why this call is out of order
  Call at 2023-11-13T19:21:58.007Z were blocked by call started at 2023-11-13T19:21:52.001Z
Call started at 2023-11-13T19:22:00.002Z started
  Call at 2023-11-13T19:22:02.007Z were blocked by call started at 2023-11-13T19:22:00.002Z
  Call at 2023-11-13T19:22:04.006Z were blocked by call started at 2023-11-13T19:22:00.002Z
Call started at 2023-11-13T19:22:00.002Z finished 2023-11-13T19:22:06.004Z

@boristian @kibertoad Can you check the comments i made below?

    it('allows preventing CronJob execution overrun for async tasks', async () => {
      let counter = 0
      const scheduler = new ToadScheduler()
      const task = new AsyncTask('simple task', () => { // <- 1. The callback isn't flagged with async, is this correct?
        counter++
        advanceTimersByTime(6000) // Do this really delay the return of this async function?
        return Promise.resolve(undefined)
      })
      const job = new CronJob(
        {
          cronExpression: '*/2 * * * * *',
        },
        task,
        {
          preventOverrun: true,
        }
      )
      scheduler.addCronJob(job)

      expect(counter).toBe(0)           // Counter is expected to be 0, yes
      advanceTimersByTime(1000)
      advanceTimersByTime(1000)
      advanceTimersByTime(1000)
      advanceTimersByTime(1000)
      advanceTimersByTime(1000) 
      expect(counter).toBe(2) // 5 seconds elapsed, but advanceTimersByTime in callback is advanced 6 seconds... Counter should still be 1,
      advanceTimersByTime(1000) // somewhere around now
      advanceTimersByTime(1000) // or now - will the second callback call
      advanceTimersByTime(1000)
      advanceTimersByTime(1000)
      advanceTimersByTime(1000)
      expect(counter).toBe(5)         // Counter should be around 2 here, not 5
      advanceTimersByTime(1000)
      advanceTimersByTime(1000)
      advanceTimersByTime(1000)
      advanceTimersByTime(1000)
      advanceTimersByTime(1000)
      expect(counter).toBe(7)
      scheduler.stop()
    })
    ```