haro

README

Haro

Topic-based pubsub library.

Usage

Install with:

go get github.com/dewadg/haro

Declaring topic

intTopic := haro.DeclareTopic[int]()

stringTopic := haro.DeclareTopic[string]()

Registering subscribers

intTopic.Subscribe(func(ctx context.Context, p int) error {
    return nil
})

stringTopic.Subscribe(func(ctx context.Context, p string) error {
    return nil
})

Publishing

var err error

err = intTopic.Publish(context.Background(), 5)

err = stringTopic.Publish(context.Background(), "test")

Limitations

• It's not a distributed pubsub mechanism, it means pubsub across different instances won't work (eg: across docker container replication)
• No recovery since it doesn't utilize any external storage, it's purely using Channel to store the published messages

Documentation

Index

• Variables
• type Subscriber
• type SubscriberConfigFunc
  • func DelayRetry(delay time.Duration) SubscriberConfigFunc
  • func OnError(onError func(error)) SubscriberConfigFunc
  • func OnSuccess(onSuccess func()) SubscriberConfigFunc
  • func Retry(count int) SubscriberConfigFunc
• type Topic
  • func DeclareTopic[Payload any]() Topic[Payload]

Variables

var ErrPayloadTypeMismatch = errors.New("Mismatch parameter between subscriber and event payload")

ErrPayloadTypeMismatch indicates if the payload type between subscriber and event not match

var ErrSubscriberInvalidFirstParameter = errors.New("Subscriber should have `context.Context` as the first parameter")

ErrSubscriberInvalidFirstParameter indicates if the subscriber's first parameter should be context.Context

var ErrSubscriberInvalidFirstReturnType = errors.New("Subscriber should have return type `error`")

ErrSubscriberInvalidFirstReturnType indicates if the subscriber's return type should be error

var ErrSubscriberInvalidParameters = errors.New("Subscriber should have exactly 2 parameters")

ErrSubscriberInvalidParameters indicates if the subscriber doesn't have 2 parameters

var ErrSubscriberInvalidReturnTypes = errors.New("Subscriber should have 1 return type")

ErrSubscriberInvalidReturnTypes indicates if the subscriber should only have 1 return type

var ErrSubscriberNotAFunction = errors.New("Subscriber should be a function")

ErrSubscriberNotAFunction indicates if the subscriber is not a function

Types

type Subscriber

type Subscriber[Payload any] func(context.Context, Payload) error

type SubscriberConfigFunc

type SubscriberConfigFunc func(*subscriberConfig)

SubscriberConfigFunc is signature of function for doing configuration

func DelayRetry

func DelayRetry(delay time.Duration) SubscriberConfigFunc

DelayRetry configures delay between each retry

func OnError

func OnError(onError func(error)) SubscriberConfigFunc

OnError specify what to do when error occured

func OnSuccess

func OnSuccess(onSuccess func()) SubscriberConfigFunc

OnSuccess specify what to do when no error occured

func Retry

func Retry(count int) SubscriberConfigFunc

Retry configures how many times should the subscriber retries before really failing

type Topic

type Topic[Payload any] interface {
	Publish(context.Context, Payload) error

	Subscribe(sub Subscriber[Payload], configurators ...SubscriberConfigFunc)
}

func DeclareTopic

func DeclareTopic[Payload any]() Topic[Payload]