Dmitry VerkhoturovandUmputun
09110c792f
Updates every backend dependency with a newer release available, and tidies the example module alongside as any change to backend/go.mod requires.
43 lines
902 B
Go
43 lines
902 B
Go
package syncs
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import "sync"
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// Locker is a superset of sync.Locker interface with TryLock method.
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type Locker interface {
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sync.Locker
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TryLock() bool
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}
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// Semaphore implementation, counted lock only. Implements Locker interface, thread safe.
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type semaphore struct {
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ch chan struct{}
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}
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// NewSemaphore makes Semaphore with given capacity
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func NewSemaphore(capacity int) Locker {
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if capacity <= 0 {
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capacity = 1
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}
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return &semaphore{ch: make(chan struct{}, capacity)}
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}
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// Lock acquires semaphore, can block if out of capacity.
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func (s *semaphore) Lock() {
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s.ch <- struct{}{}
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}
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// Unlock releases semaphore, can block if nothing acquired before.
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func (s *semaphore) Unlock() {
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<-s.ch
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}
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// TryLock acquires semaphore if possible, returns true if acquired, false otherwise.
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func (s *semaphore) TryLock() bool {
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select {
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case s.ch <- struct{}{}:
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return true
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default:
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return false
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}
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}
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