mirror of
https://github.com/binwiederhier/ntfy.git
synced 2024-12-23 10:12:38 +01:00
110 lines
3.3 KiB
Go
110 lines
3.3 KiB
Go
package util
|
|
|
|
import (
|
|
"errors"
|
|
"golang.org/x/time/rate"
|
|
"io"
|
|
"sync"
|
|
"time"
|
|
)
|
|
|
|
// ErrLimitReached is the error returned by the Limiter and LimitWriter when the predefined limit has been reached
|
|
var ErrLimitReached = errors.New("limit reached")
|
|
|
|
// Limiter is an interface that implements a rate limiting mechanism, e.g. based on time or a fixed value
|
|
type Limiter interface {
|
|
// Allow adds n to the limiters internal value, or returns ErrLimitReached if the limit has been reached
|
|
Allow(n int64) error
|
|
}
|
|
|
|
// FixedLimiter is a helper that allows adding values up to a well-defined limit. Once the limit is reached
|
|
// ErrLimitReached will be returned. FixedLimiter may be used by multiple goroutines.
|
|
type FixedLimiter struct {
|
|
value int64
|
|
limit int64
|
|
mu sync.Mutex
|
|
}
|
|
|
|
// NewFixedLimiter creates a new Limiter
|
|
func NewFixedLimiter(limit int64) *FixedLimiter {
|
|
return &FixedLimiter{
|
|
limit: limit,
|
|
}
|
|
}
|
|
|
|
// Allow adds n to the limiters internal value, but only if the limit has not been reached. If the limit was
|
|
// exceeded after adding n, ErrLimitReached is returned.
|
|
func (l *FixedLimiter) Allow(n int64) error {
|
|
l.mu.Lock()
|
|
defer l.mu.Unlock()
|
|
if l.value+n > l.limit {
|
|
return ErrLimitReached
|
|
}
|
|
l.value += n
|
|
return nil
|
|
}
|
|
|
|
// RateLimiter is a Limiter that wraps a rate.Limiter, allowing a floating time-based limit.
|
|
type RateLimiter struct {
|
|
limiter *rate.Limiter
|
|
}
|
|
|
|
// NewRateLimiter creates a new RateLimiter
|
|
func NewRateLimiter(r rate.Limit, b int) *RateLimiter {
|
|
return &RateLimiter{
|
|
limiter: rate.NewLimiter(r, b),
|
|
}
|
|
}
|
|
|
|
// NewBytesLimiter creates a RateLimiter that is meant to be used for a bytes-per-interval limit,
|
|
// e.g. 250 MB per day. And example of the underlying idea can be found here: https://go.dev/play/p/0ljgzIZQ6dJ
|
|
func NewBytesLimiter(bytes int, interval time.Duration) *RateLimiter {
|
|
return NewRateLimiter(rate.Limit(bytes)*rate.Every(interval), bytes)
|
|
}
|
|
|
|
// Allow adds n to the limiters internal value, but only if the limit has not been reached. If the limit was
|
|
// exceeded after adding n, ErrLimitReached is returned.
|
|
func (l *RateLimiter) Allow(n int64) error {
|
|
if n <= 0 {
|
|
return nil // No-op. Can't take back bytes you're written!
|
|
}
|
|
if !l.limiter.AllowN(time.Now(), int(n)) {
|
|
return ErrLimitReached
|
|
}
|
|
return nil
|
|
}
|
|
|
|
// LimitWriter implements an io.Writer that will pass through all Write calls to the underlying
|
|
// writer w until any of the limiter's limit is reached, at which point a Write will return ErrLimitReached.
|
|
// Each limiter's value is increased with every write.
|
|
type LimitWriter struct {
|
|
w io.Writer
|
|
written int64
|
|
limiters []Limiter
|
|
mu sync.Mutex
|
|
}
|
|
|
|
// NewLimitWriter creates a new LimitWriter
|
|
func NewLimitWriter(w io.Writer, limiters ...Limiter) *LimitWriter {
|
|
return &LimitWriter{
|
|
w: w,
|
|
limiters: limiters,
|
|
}
|
|
}
|
|
|
|
// Write passes through all writes to the underlying writer until any of the given limiter's limit is reached
|
|
func (w *LimitWriter) Write(p []byte) (n int, err error) {
|
|
w.mu.Lock()
|
|
defer w.mu.Unlock()
|
|
for i := 0; i < len(w.limiters); i++ {
|
|
if err := w.limiters[i].Allow(int64(len(p))); err != nil {
|
|
for j := i - 1; j >= 0; j-- {
|
|
w.limiters[j].Allow(-int64(len(p))) // Revert limiters limits if allowed
|
|
}
|
|
return 0, ErrLimitReached
|
|
}
|
|
}
|
|
n, err = w.w.Write(p)
|
|
w.written += int64(n)
|
|
return
|
|
}
|