fix semaphore pattern

This commit is contained in:
Edward 2020-05-21 17:45:23 +08:00
parent 6ec8f1ebb5
commit 3877727a5c

View File

@ -5,23 +5,24 @@ import (
"time" "time"
) )
//error info
var ( var (
ErrNoTickets = errors.New("semaphore: could not aquire semaphore") ErrNoTickets = errors.New("could not acquire semaphore")
ErrIllegalRelease = errors.New("semaphore: can't release the semaphore without acquiring it first") ErrIllegalRelease = errors.New("can't release the semaphore without acquiring it first")
) )
// Interface contains the behavior of a semaphore that can be acquired and/or released. // ISemaphore contains the behavior of a semaphore that can be acquired and/or released.
type Interface interface { type ISemaphore interface {
Acquire() error Acquire() error
Release() error Release() error
} }
type implementation struct { type semp struct {
sem chan struct{} sem chan struct{}
timeout time.Duration timeout time.Duration
} }
func (s *implementation) Acquire() error { func (s *semp) Acquire() error {
select { select {
case s.sem <- struct{}{}: case s.sem <- struct{}{}:
return nil return nil
@ -30,19 +31,19 @@ func (s *implementation) Acquire() error {
} }
} }
func (s *implementation) Release() error { func (s *semp) Release() error {
select { select {
case _ = <-s.sem: case <-s.sem:
return nil return nil
case <-time.After(s.timeout): case <-time.After(s.timeout):
return ErrIllegalRelease return ErrIllegalRelease
} }
return nil
} }
func New(tickets int, timeout time.Duration) Interface { //New return a new Semaphore
return &implementation{ func New(tickets int, timeout time.Duration) ISemaphore {
return &semp{
sem: make(chan struct{}, tickets), sem: make(chan struct{}, tickets),
timeout: timeout, timeout: timeout,
} }