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async.go
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async.go
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package async
import (
"strings"
"golang.org/x/net/context"
)
type Async interface {
Cancel()
Result() <-chan error
}
type asyncImpl struct {
promise <-chan error
cancel func()
}
func (a *asyncImpl) Cancel() {
a.cancel()
}
func (a *asyncImpl) Result() <-chan error {
return a.promise
}
func New(parent context.Context, f func(ctx context.Context) error) Async {
ctx, cancel := context.WithCancel(parent)
return &asyncImpl{
promise: Promise(func() error {
return f(ctx)
}),
cancel: cancel,
}
}
type GroupError struct {
Errs []error
}
func (e *GroupError) Error() string {
v := make([]string, 0, len(e.Errs))
for _, err := range e.Errs {
v = append(v, err.Error())
}
return strings.Join(v, "; ")
}
// group asyncs and return err in Result for the first async with error
func Any(asyncs ...Async) Async {
return &asyncImpl{
cancel: func() {
for _, a := range asyncs {
a.Cancel()
}
},
promise: Promise(func() error {
// TODO (m0sth8): rewrite this with select for every async
for _, a := range asyncs {
err := <-a.Result()
if err != nil {
return err
}
}
return nil
}),
}
}
// group asyncs and return grouped err after all async is finished
func All(asyncs ...Async) Async {
return &asyncImpl{
cancel: func() {
for _, a := range asyncs {
a.Cancel()
}
},
promise: Promise(func() error {
errs := make([]error, 0)
for _, a := range asyncs {
err := <-a.Result()
if err != nil {
errs = append(errs, err)
}
}
if len(errs) > 0 {
return &GroupError{Errs: errs}
}
return nil
}),
}
}