66 lines
1.2 KiB
Go
66 lines
1.2 KiB
Go
package sync2
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import (
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"sync"
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"sync/atomic"
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"time"
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)
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func NewSemaphore(initialCount int) *Semaphore {
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res := &Semaphore{
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counter: int64(initialCount),
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}
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res.cond.L = &res.lock
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return res
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}
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type Semaphore struct {
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lock sync.Mutex
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cond sync.Cond
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counter int64
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}
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func (s *Semaphore) Release() {
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s.lock.Lock()
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s.counter += 1
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if s.counter >= 0 {
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s.cond.Signal()
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}
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s.lock.Unlock()
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}
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func (s *Semaphore) Acquire() {
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s.lock.Lock()
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for s.counter < 1 {
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s.cond.Wait()
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}
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s.counter -= 1
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s.lock.Unlock()
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}
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func (s *Semaphore) AcquireTimeout(timeout time.Duration) bool {
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done := make(chan bool, 1)
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// Gate used to communicate between the threads and decide what the result
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// is. If the main thread decides, we have timed out, otherwise we succeed.
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decided := new(int32)
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go func() {
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s.Acquire()
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if atomic.SwapInt32(decided, 1) == 0 {
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done <- true
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} else {
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// If we already decided the result, and this thread did not win
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s.Release()
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}
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}()
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select {
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case <-done:
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return true
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case <-time.NewTimer(timeout).C:
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if atomic.SwapInt32(decided, 1) == 1 {
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// The other thread already decided the result
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return true
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}
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return false
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}
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}
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