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118 lines
3.4 KiB
Markdown
118 lines
3.4 KiB
Markdown
# ratelimit
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--
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import "github.com/juju/ratelimit"
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The ratelimit package provides an efficient token bucket implementation. See
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http://en.wikipedia.org/wiki/Token_bucket.
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## Usage
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#### func Reader
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```go
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func Reader(r io.Reader, bucket *Bucket) io.Reader
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```
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Reader returns a reader that is rate limited by the given token bucket. Each
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token in the bucket represents one byte.
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#### func Writer
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```go
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func Writer(w io.Writer, bucket *Bucket) io.Writer
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```
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Writer returns a writer that is rate limited by the given token bucket. Each
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token in the bucket represents one byte.
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#### type Bucket
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```go
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type Bucket struct {
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}
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```
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Bucket represents a token bucket that fills at a predetermined rate. Methods on
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Bucket may be called concurrently.
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#### func NewBucket
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```go
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func NewBucket(fillInterval time.Duration, capacity int64) *Bucket
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```
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NewBucket returns a new token bucket that fills at the rate of one token every
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fillInterval, up to the given maximum capacity. Both arguments must be positive.
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The bucket is initially full.
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#### func NewBucketWithQuantum
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```go
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func NewBucketWithQuantum(fillInterval time.Duration, capacity, quantum int64) *Bucket
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```
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NewBucketWithQuantum is similar to NewBucket, but allows the specification of
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the quantum size - quantum tokens are added every fillInterval.
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#### func NewBucketWithRate
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```go
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func NewBucketWithRate(rate float64, capacity int64) *Bucket
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```
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NewBucketWithRate returns a token bucket that fills the bucket at the rate of
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rate tokens per second up to the given maximum capacity. Because of limited
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clock resolution, at high rates, the actual rate may be up to 1% different from
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the specified rate.
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#### func (*Bucket) Rate
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```go
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func (tb *Bucket) Rate() float64
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```
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Rate returns the fill rate of the bucket, in tokens per second.
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#### func (*Bucket) Take
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```go
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func (tb *Bucket) Take(count int64) time.Duration
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```
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Take takes count tokens from the bucket without blocking. It returns the time
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that the caller should wait until the tokens are actually available.
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Note that if the request is irrevocable - there is no way to return tokens to
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the bucket once this method commits us to taking them.
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#### func (*Bucket) TakeAvailable
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```go
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func (tb *Bucket) TakeAvailable(count int64) int64
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```
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TakeAvailable takes up to count immediately available tokens from the bucket. It
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returns the number of tokens removed, or zero if there are no available tokens.
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It does not block.
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#### func (*Bucket) TakeMaxDuration
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```go
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func (tb *Bucket) TakeMaxDuration(count int64, maxWait time.Duration) (time.Duration, bool)
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```
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TakeMaxDuration is like Take, except that it will only take tokens from the
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bucket if the wait time for the tokens is no greater than maxWait.
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If it would take longer than maxWait for the tokens to become available, it does
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nothing and reports false, otherwise it returns the time that the caller should
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wait until the tokens are actually available, and reports true.
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#### func (*Bucket) Wait
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```go
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func (tb *Bucket) Wait(count int64)
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```
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Wait takes count tokens from the bucket, waiting until they are available.
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#### func (*Bucket) WaitMaxDuration
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```go
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func (tb *Bucket) WaitMaxDuration(count int64, maxWait time.Duration) bool
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```
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WaitMaxDuration is like Wait except that it will only take tokens from the
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bucket if it needs to wait for no greater than maxWait. It reports whether any
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tokens have been removed from the bucket If no tokens have been removed, it
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returns immediately.
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