cron

Cron

Cron is the module that implements a cron specific parser and notifications about scheduler events.

Usage

The example describes usage of cron module.

To import module in your code, write the following line:

import "github.com/dipdup-net/indexer-sdk/pkg/modules/cron"

Cron module implements interface Module. So you can use it like any other module. For example:

// create cron module
cronModule, err := cron.NewModule(cfg.Cron)
if err != nil {
    log.Panic(err)
}
// start cron module
cronModule.Start(ctx)

// your code is here

// close cron module
if err := cronModule.Close(); err != nil {
    log.Panic(err)
}

Config

Default yaml config of cron module contains only one field jobs. It's a map of job names to a cron pattern. Job names are used like subscription id in inner-message communication.

cron:
  jobs:
    half_an_hour: "0 30 * * * *"
    every_minute: "* 1 * * * *"
    every_five_second: "@every 5s"
    every_second: "* * * * * *"

Output

Module sends to its outputs empty struct which notifies all connected modules about scheduled event. Each job of cron module has its own output with names pointed in the configuration file. So if your module should execute some work on every_second scheduled events from example you should connect it:

// with helper function

if err := modules.Connect(cronModule, customModule, "every_second", "custom_module_every_second_input"); err != nil {
    log.Panic(err)
}

// or directly to module

if err := customModule.AttachTo(cronModule, "every_second", "custom_module_every_second_input"); err != nil {
    log.Panic(err)
}

Example of a handling message from cron's outputs:

for {
    select {
    case <-ctx.Done():
        return
    case <-m.everySecond.Listen():
        log.Info().Msg("arrived from cron module")
    case <-m.everyFiveSecond.Listen():
        log.Info().Msg("arrived from cron module")
    }
}

everySecond and everyFiveSecond are inputs of your modules.