README
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tokenbucket
Token bucket implementation in Go
Documentation
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Index ¶
- type TokenBucket
- func (tb *TokenBucket) Adjust(delta Tokens)
- func (tb *TokenBucket) Available() Tokens
- func (tb *TokenBucket) EnsureLowerBound(minTokens Tokens)
- func (tb *TokenBucket) Exhausted() time.Duration
- func (tb *TokenBucket) Init(rate TokensPerSecond, burst Tokens)
- func (tb *TokenBucket) InitWithNowFn(rate TokensPerSecond, burst Tokens, nowFn func() time.Time)
- func (tb *TokenBucket) Reset()
- func (tb *TokenBucket) TestingInternalParameters() (rate TokensPerSecond, burst, available Tokens)
- func (tb *TokenBucket) TryToFulfill(amount Tokens) (fulfilled bool, tryAgainAfter time.Duration)
- func (tb *TokenBucket) Update()
- func (tb *TokenBucket) UpdateConfig(rate TokensPerSecond, burst Tokens)
- func (tb *TokenBucket) Wait(amount Tokens)
- func (tb *TokenBucket) WaitCtx(ctx context.Context, amount Tokens) error
- type Tokens
- type TokensPerSecond
Constants ¶
This section is empty.
Variables ¶
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Functions ¶
This section is empty.
Types ¶
type TokenBucket ¶
type TokenBucket struct {
// contains filtered or unexported fields
}
TokenBucket implements the basic accounting for a token bucket.
A token bucket has a rate of replenishment and a burst limit. Tokens are replenished over time, up to the burst limit.
The token bucket keeps track of the current amount and updates it as time passes. The bucket can go into debt (i.e. negative current amount).
func (*TokenBucket) Adjust ¶
func (tb *TokenBucket) Adjust(delta Tokens)
Adjust returns tokens to the bucket (positive delta) or accounts for a debt of tokens (negative delta).
func (*TokenBucket) Available ¶
func (tb *TokenBucket) Available() Tokens
Available returns the currently available tokens (can be -ve). Exported only for metrics.
func (*TokenBucket) EnsureLowerBound ¶
func (tb *TokenBucket) EnsureLowerBound(minTokens Tokens)
EnsureLowerBound ensures that the current number of tokens is at least minTokens. The value of minTokens can be negative. This is useful in scenarios where the use of Adjust can be used to subtract a large amount of tokens, resulting in a token bucket with a very low negative number of tokens which would take a long time to recover to zero. In such scenarios, a periodic call to EnsureLowerBound is useful to reset to a better state.
func (*TokenBucket) Exhausted ¶
func (tb *TokenBucket) Exhausted() time.Duration
Exhausted returns the cumulative duration over which this token bucket was exhausted. Exported only for metrics.
func (*TokenBucket) Init ¶
func (tb *TokenBucket) Init(rate TokensPerSecond, burst Tokens)
Init the token bucket.
func (*TokenBucket) InitWithNowFn ¶
func (tb *TokenBucket) InitWithNowFn(rate TokensPerSecond, burst Tokens, nowFn func() time.Time)
Init the token bucket with a custom "Now" function. Note that Wait/WaitCtx cannot be used with a custom time function.
func (*TokenBucket) Reset ¶
func (tb *TokenBucket) Reset()
Reset resets the current tokens to whatever the burst is.
func (*TokenBucket) TestingInternalParameters ¶
func (tb *TokenBucket) TestingInternalParameters() (rate TokensPerSecond, burst, available Tokens)
TestingInternalParameters returns the refill rate (configured), burst tokens (configured), and number of available tokens where available <= burst. It's used in tests.
func (*TokenBucket) TryToFulfill ¶
func (tb *TokenBucket) TryToFulfill(amount Tokens) (fulfilled bool, tryAgainAfter time.Duration)
TryToFulfill either removes the given amount if is available, or returns a time after which the request should be retried.
func (*TokenBucket) Update ¶
func (tb *TokenBucket) Update()
Update moves the time forward, accounting for the replenishment since the last update.
func (*TokenBucket) UpdateConfig ¶
func (tb *TokenBucket) UpdateConfig(rate TokensPerSecond, burst Tokens)
UpdateConfig updates the rate and burst limits. The change in burst will be applied to the current token quantity. For example, if the RateLimiter currently had 5 available tokens and the burst is updated from 10 to 20, the amount will increase to 15. Similarly, if the burst is decreased by 10, the current quota will decrease accordingly, potentially putting the limiter into debt.
func (*TokenBucket) Wait ¶
func (tb *TokenBucket) Wait(amount Tokens)
Wait removes the given amount, waiting as long as necessary.
type TokensPerSecond ¶
type TokensPerSecond float64
TokensPerSecond is the rate of token replenishment.
Source Files