cron

README

Cron

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

Usage

Usage of cron module is described by the example.

To import module in your code write 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 cron pattern. Job names is 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 own output with names pointed in 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", "every_second"); err != nil {
    log.Panic(err)
}

// or directly to module

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

Example of 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.

Documentation

Index

• type Config
• type Module
  • func NewModule(cfg *Config) (*Module, error)
  • func (module *Module) AttachTo(name string, input *modules.Input) error
  • func (module *Module) Close() error
  • func (module *Module) Input(name string) (*modules.Input, error)
  • func (*Module) Name() string
  • func (module *Module) Output(name string) (*modules.Output, error)
  • func (module *Module) Start(ctx context.Context)

Types

type Config

type Config struct {
	Jobs map[string]string `yaml:"jobs" validate:"required"`
}

Config -

type Module

type Module struct {
	// contains filtered or unexported fields
}

Module - cron module

func NewModule

func NewModule(cfg *Config) (*Module, error)

NewModule - creates cron module

func (*Module) AttachTo

func (module *Module) AttachTo(name string, input *modules.Input) error

AttachTo -

func (*Module) Close

func (module *Module) Close() error

Close - closes cron scheduler

func (*Module) Input

func (module *Module) Input(name string) (*modules.Input, error)

Input -

func (*Module) Name

func (*Module) Name() string

Name -

func (*Module) Output

func (module *Module) Output(name string) (*modules.Output, error)

Output -

func (*Module) Start

func (module *Module) Start(ctx context.Context)

Start - starts cron scheduler