5
0
mirror of https://github.com/cwinfo/yggdrasil-go.git synced 2024-12-23 12:15:39 +00:00

add cancellation code to util, like context but just the cancellation parts + some error logic

This commit is contained in:
Arceliar 2019-07-17 21:09:22 -05:00
parent c36da7b814
commit 06e8403aaf

83
src/util/cancellation.go Normal file
View File

@ -0,0 +1,83 @@
package util
import (
"errors"
"sync"
"time"
"runtime"
)
type Cancellation interface {
Finished() <-chan struct{}
Cancel(error) error
Error() error
}
func CancellationFinalizer(c Cancellation) {
c.Cancel(errors.New("finalizer called"))
}
type cancellation struct {
signal chan error
cancel chan struct{}
errMtx sync.RWMutex
err error
}
func (c *cancellation) worker() {
// Launch this in a separate goroutine when creating a cancellation
err := <-c.signal
c.errMtx.Lock()
c.err = err
c.errMtx.Unlock()
close(c.cancel)
}
func NewCancellation() Cancellation {
c := cancellation{
signal: make(chan error),
cancel: make(chan struct{}),
}
runtime.SetFinalizer(&c, CancellationFinalizer)
go c.worker()
return &c
}
func (c *cancellation) Finished() <-chan struct{} {
return c.cancel
}
func (c *cancellation) Cancel(err error) error {
select {
case c.signal<-err:
return nil
case <-c.cancel:
return c.Error()
}
}
func (c *cancellation) Error() error {
c.errMtx.RLock()
err := c.err
c.errMtx.RUnlock()
return err
}
func CancellationWithTimeout(parent Cancellation, timeout time.Duration) Cancellation {
child := NewCancellation()
go func() {
timer := time.NewTimer(timeout)
defer TimerStop(timer)
select {
case <-parent.Finished():
child.Cancel(parent.Error())
case <-timer.C:
child.Cancel(errors.New("timeout"))
}
}()
return child
}
func CancellationWithDeadline(parent Cancellation, deadline time.Time) Cancellation {
return CancellationWithTimeout(parent, deadline.Sub(time.Now()))
}