26d0083faf
commit a1a37d335a8e89ac89d85c00c8585d3fc02e064a
Author: Josh Baker <joshbaker77@gmail.com>
Date: Thu Oct 5 07:36:54 2017 -0700
use symlink instead of copy
commit 96399c2c92620f633611c778e5473200bfd48d41
Author: Josh Baker <joshbaker77@gmail.com>
Date: Thu Oct 5 07:19:26 2017 -0700
use dep for vendoring
46 lines
1.3 KiB
Go
46 lines
1.3 KiB
Go
// Package semaphore implements the semaphore resiliency pattern for Go.
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package semaphore
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import (
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"errors"
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"time"
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)
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// ErrNoTickets is the error returned by Acquire when it could not acquire
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// a ticket from the semaphore within the configured timeout.
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var ErrNoTickets = errors.New("could not aquire semaphore ticket")
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// Semaphore implements the semaphore resiliency pattern
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type Semaphore struct {
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sem chan struct{}
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timeout time.Duration
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}
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// New constructs a new Semaphore with the given ticket-count
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// and timeout.
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func New(tickets int, timeout time.Duration) *Semaphore {
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return &Semaphore{
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sem: make(chan struct{}, tickets),
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timeout: timeout,
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}
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}
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// Acquire tries to acquire a ticket from the semaphore. If it can, it returns nil.
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// If it cannot after "timeout" amount of time, it returns ErrNoTickets. It is
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// safe to call Acquire concurrently on a single Semaphore.
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func (s *Semaphore) Acquire() error {
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select {
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case s.sem <- struct{}{}:
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return nil
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case <-time.After(s.timeout):
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return ErrNoTickets
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}
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}
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// Release releases an acquired ticket back to the semaphore. It is safe to call
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// Release concurrently on a single Semaphore. It is an error to call Release on
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// a Semaphore from which you have not first acquired a ticket.
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func (s *Semaphore) Release() {
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<-s.sem
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}
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