86 рядки
1,7 КіБ
Go
86 рядки
1,7 КіБ
Go
package tokenbucket
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import (
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"sync"
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"time"
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)
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type Bucket struct {
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capacity int64
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tokens chan struct{}
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rate time.Duration // Add a token to the bucket every 1/r units of time
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rateMutex sync.Mutex
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}
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func NewBucket(rate time.Duration, capacity int64) *Bucket {
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//A bucket is simply a channel with a buffer representing the maximum size
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tokens := make(chan struct{}, capacity)
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b := &Bucket{capacity, tokens, rate, sync.Mutex{}}
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//Set off a function that will continuously add tokens to the bucket
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go func(b *Bucket) {
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ticker := time.NewTicker(rate)
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for _ = range ticker.C {
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b.tokens <- struct{}{}
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}
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}(b)
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return b
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}
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func (b *Bucket) GetRate() time.Duration {
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b.rateMutex.Lock()
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tmp := b.rate
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b.rateMutex.Unlock()
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return tmp
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}
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func (b *Bucket) SetRate(rate time.Duration) {
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b.rateMutex.Lock()
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b.rate = rate
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b.rateMutex.Unlock()
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}
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//AddTokens manually adds n tokens to the bucket
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func (b *Bucket) AddToken(n int64) {
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}
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func (b *Bucket) withdrawTokens(n int64) error {
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for i := int64(0); i < n; i++ {
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<-b.tokens
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}
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return nil
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}
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func (b *Bucket) SpendToken(n int64) <-chan error {
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// Default to spending a single token
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if n < 0 {
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n = 1
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}
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c := make(chan error)
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go func(b *Bucket, n int64, c chan error) {
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c <- b.withdrawTokens(n)
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close(c)
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return
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}(b, n, c)
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return c
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}
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// Drain will empty all tokens in the bucket
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// If the tokens are being added too quickly (if the rate is too fast)
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// this will never drain
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func (b *Bucket) Drain() error{
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// TODO replace this with a more solid approach (such as replacing the channel altogether)
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for {
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select {
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case _ = <-b.tokens:
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continue
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default:
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return nil
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}
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}
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}
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