Simultaneous Cron Alarms

[Brayden]

Purpose

This enables StarbaseDB instances to be able to declare hooks in the /src/index.ts file to execute custom code at defined crontab intervals. By default Durable Objects can support 1 Alarm at a time (and Workers can support 3 cron jobs) but we need the ability to expand it so any number of events can signup to execute code at any interval. See below example for implementation.

Currently there is a hardcoded limit of supporting 10 simultaneous events to trigger at any given interval which can easily be updated by adding more WHEN cases to the query. This was a technical decision for the moment to prevent accidental setups of recursively added calls but can easily be updated to support N events at any time.

Tasks

• When a request comes in, ensure an alarm is set if a task is defined in tmp_cron_tasks table
• If multiple tasks should happen at the same time, both should emit an event individually
• Setup retries for failed alarms

Verify

Each task should have an entry in the tmp_cron_tasks table of your StarbaseDB instance. An example row might look like:

{
    "name": "Even minutes",
    "cron_tab": "*/2 * * * *",
    "payload": "",
    "callback_host": "https://starbasedb-{MY-IDENTIFIER}.workers.dev"
}

Then your code in your /src/index.ts would implement the plugin setup like below:

import { CronPlugin } from '../plugins/cron'

// ....
// ....

const cronPlugin = new CronPlugin()
cronPlugin.onEvent(({ name, cron_tab, payload }) => {
    console.log('CRON EVENT: ', name, cron_tab, payload)

    if (name === 'Even minutes') {
        console.log('Payload: ', JSON.stringify(payload))
    }
}, ctx)

const plugins = [
    // ...
    cronPlugin,
] satisfies StarbasePlugin[]

Before

After

[github-actions]

Coverage Report

Status	Category	Percentage	Covered / Total
🔴	Lines	2.02% (🎯 75%)	21 / 1039
🔴	Statements	1.93% (🎯 75%)	21 / 1086
🔴	Functions	2.89% (🎯 75%)	5 / 173
🔴	Branches	0% (🎯 75%)	0 / 600

File Coverage

File	Stmts	Branches	Functions	Lines	Uncovered Lines
Changed Files
src/do.ts	0%	0%	0%	0%	21-324
src/index.ts	0%	0%	0%	0%	17-297

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