Scheduler

The scheduler option provided by TServiceParams provides a few mechanisms for creating different schedules. Operations set up by the scheduler are lifecycle aware, meaning that they will:

• only start when the application is fully ready
• automatically stop when you teardown the application

🛠 Methods

⏰ Cron

A canned set of expressions are provided in the CronExpression enum. You may also provide an expression.

scheduler.cron({
  schedule: CronExpression.MONDAY_TO_FRIDAY_AT_09_30AM,
  exec: () => logger.info("running on a cron"),
});

scheduler.cron({
  schedule: "0 1-23/2 * * *",
  exec: () => logger.info("complex schedules"),
});

🕺 Sliding

Sliding schedules are just as powerful as they are awkward to use. Their intent is to have a 2 part time calculation system:

1. A function to calculate the next run time
2. A schedule to re-calculate at

This can be used to set up a schedule that resets at midnight, and happens at a random time within the day

scheduler.sliding({
  reset: CronExpression.MONDAY_TO_FRIDAY_AT_8AM,
  next: () => dayjs().add(Math.floor(Math.random() * 8 * 60), "minute"),
  exec: () => logger.info("random time during the workday"),
});

⏳ setInterval / setTimeout

These methods operate the same as their node counterparts, you can simply add scheduler. in front of the existing call to take advantage.

These are most helpful for unit tests, where timers need to be automatically stopped

scheduler.setInterval(() => {
  console.log("hello world");
}, 1000);

scheduler.setTimeout(() => {
  console.log("hello world");
}, 1000);

🛑 Stopping Schedules

All schedules use the same rules for stopping & removal. When the application tears down, schedules will automatically be stopped. Schedules can additionally be stopped using the return of each method

const stop = scheduler.setTimeout(() => {
  // logic
}, 5000);

function onSpecialEvent() {
  // remove the timer
  stop();
}