diff options
Diffstat (limited to 'teleirc/matterbridge/vendor/github.com/shazow/rateio/limiter.go')
| -rw-r--r-- | teleirc/matterbridge/vendor/github.com/shazow/rateio/limiter.go | 71 |
1 files changed, 71 insertions, 0 deletions
diff --git a/teleirc/matterbridge/vendor/github.com/shazow/rateio/limiter.go b/teleirc/matterbridge/vendor/github.com/shazow/rateio/limiter.go new file mode 100644 index 0000000..a18ce3c --- /dev/null +++ b/teleirc/matterbridge/vendor/github.com/shazow/rateio/limiter.go @@ -0,0 +1,71 @@ +package rateio + +import ( + "errors" + "time" +) + +const minInt = -int(^uint(0)>>1) - 1 + +// ErrRateExceeded is the error returned when the read rate exceeds our specification. +var ErrRateExceeded = errors.New("Read rate exceeded.") + +// Limiter is an interface for a rate limiter. +// There are a few example limiters included in the package, but feel free to go wild with your own. +type Limiter interface { + // Apply this many bytes to the limiter, return ErrRateExceeded if the defined rate is exceeded. + Count(int) error +} + +// simpleLimiter is a rate limiter that restricts Amount bytes in Frequency duration. +type simpleLimiter struct { + Amount int + Frequency time.Duration + + numRead int + timeRead time.Time +} + +// NewSimpleLimiter creates a Limiter that restricts a given number of bytes per frequency. +func NewSimpleLimiter(amount int, frequency time.Duration) *simpleLimiter { + return &simpleLimiter{ + Amount: amount, + Frequency: frequency, + } +} + +// NewGracefulLimiter returns a Limiter that is the same as a +// SimpleLimiter but adds a grace period at the start of the rate +// limiting where it allows unlimited bytes to be read during that +// period. +func NewGracefulLimiter(amount int, frequency time.Duration, grace time.Duration) *simpleLimiter { + return &simpleLimiter{ + Amount: amount, + Frequency: frequency, + numRead: minInt, + timeRead: time.Now().Add(grace), + } +} + +// Count applies n bytes to the limiter. +func (limit *simpleLimiter) Count(n int) error { + now := time.Now() + if now.After(limit.timeRead) { + limit.numRead = 0 + limit.timeRead = now.Add(limit.Frequency) + } + limit.numRead += n + if limit.numRead > limit.Amount { + return ErrRateExceeded + } + return nil +} + +// Delay returns a channel that can be used to block until next window +func (limit *simpleLimiter) Delay() <-chan time.Time { + waitTill := time.Now() + if limit.numRead >= limit.Amount { + waitTill = waitTill.Add(limit.Frequency) + } + return time.NewTimer(time.Until(waitTill)).C +} |
