Aleksey Savchuk
b52a5e1d2d
Added different implementations of a semaphore used in the limiter. They'll be compared to choose one with best perfomance, then may drop others in the future. Signed-off-by: Aleksey Savchuk <a.savchuk@yadro.com>
74 lines
1.2 KiB
Go
74 lines
1.2 KiB
Go
package limiting
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import (
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"sync/atomic"
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)
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type atomicSemaphore struct {
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countdown atomic.Int64
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}
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func newAtomicSemaphore(size int64) *atomicSemaphore {
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sem := new(atomicSemaphore)
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sem.countdown.Store(size)
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return sem
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}
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func (s *atomicSemaphore) acquire() bool {
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for {
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v := s.countdown.Load()
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if v == 0 {
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return false
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}
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if s.countdown.CompareAndSwap(v, v-1) {
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return true
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}
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}
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}
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func (s *atomicSemaphore) release() {
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s.countdown.Add(1)
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}
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type burstAtomicSemaphore struct {
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count atomic.Int64
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limit int64
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}
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func newBurstAtomicSemaphore(size int64) *burstAtomicSemaphore {
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return &burstAtomicSemaphore{limit: size}
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}
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func (s *burstAtomicSemaphore) acquire() bool {
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v := s.count.Add(1)
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if v > s.limit {
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s.count.Add(-1)
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return false
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}
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return true
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}
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func (s *burstAtomicSemaphore) release() {
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s.count.Add(-1)
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}
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type channelSemaphore struct {
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ch chan struct{}
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}
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func newChannelSemaphore(size int64) *channelSemaphore {
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return &channelSemaphore{make(chan struct{}, size)}
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}
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func (s *channelSemaphore) acquire() 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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func (s *channelSemaphore) release() {
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<-s.ch
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}
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