67 lines
1.2 KiB
Go
67 lines
1.2 KiB
Go
package rate
|
|
|
|
import (
|
|
"context"
|
|
"sync"
|
|
"time"
|
|
)
|
|
|
|
type Limiter struct {
|
|
mu sync.Mutex
|
|
nextReqTime time.Time
|
|
interval time.Duration
|
|
}
|
|
|
|
func NewLimiter(interval time.Duration) *Limiter {
|
|
return &Limiter{interval: interval}
|
|
}
|
|
|
|
// Wait enforces minimum spacing between upstream Jikan requests.
|
|
func (l *Limiter) Wait(ctx context.Context) error {
|
|
select {
|
|
case <-ctx.Done():
|
|
return ctx.Err()
|
|
default:
|
|
}
|
|
|
|
waitUntil := l.reserve(time.Now())
|
|
if waitUntil.IsZero() {
|
|
return nil
|
|
}
|
|
|
|
timer := time.NewTimer(time.Until(waitUntil))
|
|
defer timer.Stop()
|
|
|
|
select {
|
|
case <-timer.C:
|
|
return nil
|
|
case <-ctx.Done():
|
|
l.release(waitUntil)
|
|
return ctx.Err()
|
|
}
|
|
}
|
|
|
|
func (l *Limiter) reserve(now time.Time) time.Time {
|
|
l.mu.Lock()
|
|
defer l.mu.Unlock()
|
|
|
|
if l.nextReqTime.IsZero() || now.After(l.nextReqTime) {
|
|
l.nextReqTime = now.Add(l.interval)
|
|
return time.Time{}
|
|
}
|
|
|
|
waitUntil := l.nextReqTime
|
|
l.nextReqTime = l.nextReqTime.Add(l.interval)
|
|
return waitUntil
|
|
}
|
|
|
|
func (l *Limiter) release(waitUntil time.Time) {
|
|
l.mu.Lock()
|
|
defer l.mu.Unlock()
|
|
|
|
reservationEnd := waitUntil.Add(l.interval)
|
|
if l.nextReqTime.Equal(reservationEnd) {
|
|
l.nextReqTime = waitUntil
|
|
}
|
|
}
|