Package semaphore

Variables

ErrNoTickets is the error returned by Acquire when it could not acquire a ticket from the semaphore within the configured timeout.

var ErrNoTickets = errors.New("could not acquire semaphore ticket")

type Semaphore ¶

Semaphore implements the semaphore resiliency pattern

type Semaphore struct {
    // contains filtered or unexported fields
}

sem := New(3, 1*time.Second)

for i := 0; i < 10; i++ {
    go func() {
        if err := sem.Acquire(); err != nil {
            return //could not acquire semaphore
        }
        defer sem.Release()

        // do something semaphore-guarded
    }()
}

func New ¶

func New(tickets int, timeout time.Duration) *Semaphore

New constructs a new Semaphore with the given ticket-count and timeout.

func (*Semaphore) Acquire ¶

func (s *Semaphore) Acquire() error

Acquire tries to acquire a ticket from the semaphore. If it can, it returns nil. If it cannot after "timeout" amount of time, it returns ErrNoTickets. It is safe to call Acquire concurrently on a single Semaphore.

func (*Semaphore) Release ¶

func (s *Semaphore) Release()

Release releases an acquired ticket back to the semaphore. It is safe to call Release concurrently on a single Semaphore. It is an error to call Release on a Semaphore from which you have not first acquired a ticket.