status-im/status-go

package subscription

import (
    "sync"
)

type Subscription struct {
    sync.RWMutex

    err  error
    done chan struct{}
}

func New() *Subscription {
    return &Subscription{
        done: make(chan struct{}),
    }
}

func (s *Subscription) Cancel(err error) {
    s.Lock()
    defer s.Unlock()

    if s.done == nil {
        return
    }

    close(s.done)
    s.done = nil
    s.err = err
}

func (s *Subscription) Unsubscribe() {
    s.Lock()
    defer s.Unlock()

    if s.done == nil {
        return
    }

    close(s.done)
    s.done = nil
}

func (s *Subscription) Err() error {
    s.RLock()
    defer s.RUnlock()
    return s.err
}

func (s *Subscription) Done() <-chan struct{} {
    s.RLock()
    defer s.RUnlock()
    return s.done
}