diff --git a/lib/pacelimiter/pacelimiter.go b/lib/pacelimiter/pacelimiter.go index 1d5714041..462a0ef6c 100644 --- a/lib/pacelimiter/pacelimiter.go +++ b/lib/pacelimiter/pacelimiter.go @@ -2,6 +2,7 @@ package pacelimiter import ( "sync" + "sync/atomic" ) // PaceLimiter throttles WaitIfNeeded callers while the number of Inc calls is bigger than the number of Dec calls. @@ -14,7 +15,7 @@ type PaceLimiter struct { mu sync.Mutex cond *sync.Cond delaysTotal uint64 - n int + n int32 } // New returns pace limiter that throttles WaitIfNeeded callers while the number of Inc calls is bigger than the number of Dec calls. @@ -26,27 +27,27 @@ func New() *PaceLimiter { // Inc increments pl. func (pl *PaceLimiter) Inc() { - pl.mu.Lock() - pl.n++ - pl.mu.Unlock() + atomic.AddInt32(&pl.n, 1) } // Dec decrements pl. func (pl *PaceLimiter) Dec() { - pl.mu.Lock() - pl.n-- - if pl.n == 0 { + if atomic.AddInt32(&pl.n, -1) == 0 { // Wake up all the goroutines blocked in WaitIfNeeded, // since the number of Dec calls equals the number of Inc calls. pl.cond.Broadcast() } - pl.mu.Unlock() } // WaitIfNeeded blocks while the number of Inc calls is bigger than the number of Dec calls. func (pl *PaceLimiter) WaitIfNeeded() { + if atomic.LoadInt32(&pl.n) <= 0 { + // Fast path - there is no need in lock. + return + } + // Slow path - wait until Dec is called. pl.mu.Lock() - for pl.n > 0 { + for atomic.LoadInt32(&pl.n) > 0 { pl.delaysTotal++ pl.cond.Wait() }