scheduler

Documentation

Index

• type BasicTokenBucket
  • func NewBasicTokenBucket(now time.Time, fillRate float64, metrics *TokenBucketMetrics) *BasicTokenBucket
  • func (btb *BasicTokenBucket) GetFillRate() float64
  • func (btb *BasicTokenBucket) PassThrough() bool
  • func (btb *BasicTokenBucket) PreprocessRequest(now time.Time, rContext Request) bool
  • func (btb *BasicTokenBucket) Return(tokens float64)
  • func (btb *BasicTokenBucket) SetFillRate(now time.Time, fillRate float64)
  • func (btb *BasicTokenBucket) SetPassThrough(passThrough bool)
  • func (btb *BasicTokenBucket) Take(now time.Time, tokens float64) (time.Duration, bool)
  • func (btb *BasicTokenBucket) TakeIfAvailable(now time.Time, tokens float64) bool
• type Request
• type Scheduler
  • func NewWFQScheduler(tokenManger TokenManager, clk clockwork.Clock, metrics *WFQMetrics) Scheduler
• type TokenBucketLoadMultiplier
  • func NewTokenBucketLoadMultiplier(now time.Time, slotCount uint8, slotDuration time.Duration, ...) *TokenBucketLoadMultiplier
  • func (tbls *TokenBucketLoadMultiplier) LoadMultiplier() float64
  • func (tbls *TokenBucketLoadMultiplier) PassThrough() bool
  • func (tbls *TokenBucketLoadMultiplier) PreprocessRequest(now time.Time, rContext Request) bool
  • func (tbls *TokenBucketLoadMultiplier) Return(tokens float64)
  • func (tbls *TokenBucketLoadMultiplier) SetContinuousTracking(continuousTracking bool)
  • func (tbls *TokenBucketLoadMultiplier) SetLoadMultiplier(now time.Time, lm float64)
  • func (tbls *TokenBucketLoadMultiplier) SetPassThrough(passThrough bool)
  • func (tbls *TokenBucketLoadMultiplier) Take(now time.Time, tokens float64) (time.Duration, bool)
  • func (tbls *TokenBucketLoadMultiplier) TakeIfAvailable(now time.Time, tokens float64) bool
• type TokenBucketLoadMultiplierMetrics
• type TokenBucketMetrics
• type TokenManager
• type WFQMetrics
• type WFQScheduler
  • func (sched *WFQScheduler) GetPendingFlows() int
  • func (sched *WFQScheduler) GetPendingRequests() int
  • func (sched *WFQScheduler) Schedule(ctx context.Context, request Request) bool
• type WindowedCounter
  • func NewWindowedCounter(now time.Time, totalSlots uint8, slotDuration time.Duration) *WindowedCounter
  • func (counter *WindowedCounter) AddTokens(now time.Time, tokens uint64) bool
  • func (counter *WindowedCounter) CalculateTokenRate() float64
  • func (counter *WindowedCounter) IsBootstrapping() bool

Types

type BasicTokenBucket

type BasicTokenBucket struct {
	// contains filtered or unexported fields
}

BasicTokenBucket is a basic token bucket implementation.

func NewBasicTokenBucket

func NewBasicTokenBucket(now time.Time, fillRate float64, metrics *TokenBucketMetrics) *BasicTokenBucket

NewBasicTokenBucket creates a new BasicTokenBucket with adjusted fill rate.

func (*BasicTokenBucket) GetFillRate

func (btb *BasicTokenBucket) GetFillRate() float64

GetFillRate returns the fill rate of the BasicTokenBucket.

func (*BasicTokenBucket) PassThrough

func (btb *BasicTokenBucket) PassThrough() bool

PassThrough returns the passThrough flag of the BasicTokenBucket.

func (*BasicTokenBucket) PreprocessRequest

func (btb *BasicTokenBucket) PreprocessRequest(now time.Time, rContext Request) bool

PreprocessRequest is a no-op for BasicTokenBucket and by default, it rejects the request.

func (*BasicTokenBucket) Return

func (btb *BasicTokenBucket) Return(tokens float64)

Return returns tokens to the basic token bucket.

func (*BasicTokenBucket) SetFillRate

func (btb *BasicTokenBucket) SetFillRate(now time.Time, fillRate float64)

SetFillRate adjusts the fill rate of the BasicTokenBucket.

func (*BasicTokenBucket) SetPassThrough

func (btb *BasicTokenBucket) SetPassThrough(passThrough bool)

SetPassThrough sets the passThrough flag of the BasicTokenBucket.

func (*BasicTokenBucket) Take

func (btb *BasicTokenBucket) Take(now time.Time, tokens float64) (time.Duration, bool)

Take takes tokens from the basic token bucket even if available tokens are less than asked. If tokens are not available at the moment, it will return amount of wait time and checks whether the operation was successful or not.

func (*BasicTokenBucket) TakeIfAvailable

func (btb *BasicTokenBucket) TakeIfAvailable(now time.Time, tokens float64) bool

TakeIfAvailable takes tokens from the basic token bucket if available, otherwise return false.

type Request

type Request struct {
	FairnessLabel string // for enforcing fairness
	Tokens        uint64 // tokens (e.g. expected latency or complexity) for this request
	Priority      uint8  // larger values represent higher priority
}

Request is metadata for request in a flow that is to be allowed or dropped based on controlled delay and queue limits.

type Scheduler

type Scheduler interface {
	// Schedule sends RequestContext to the underlying scheduler and returns a boolean value,
	// where true means accept and false means reject.
	Schedule(ctx context.Context, request Request) bool
}

Scheduler : Interface for schedulers.

func NewWFQScheduler

func NewWFQScheduler(tokenManger TokenManager, clk clockwork.Clock, metrics *WFQMetrics) Scheduler

NewWFQScheduler creates a new weighted fair queue scheduler.

type TokenBucketLoadMultiplier

type TokenBucketLoadMultiplier struct {
	// contains filtered or unexported fields
}

TokenBucketLoadMultiplier is a token bucket with load multiplier.

func NewTokenBucketLoadMultiplier

func NewTokenBucketLoadMultiplier(now time.Time,
	slotCount uint8,
	slotDuration time.Duration,
	metrics *TokenBucketLoadMultiplierMetrics,
) *TokenBucketLoadMultiplier

NewTokenBucketLoadMultiplier creates a new TokenBucketLoadMultiplier.

func (*TokenBucketLoadMultiplier) LoadMultiplier

func (tbls *TokenBucketLoadMultiplier) LoadMultiplier() float64

LoadMultiplier returns the current load multiplier.

func (*TokenBucketLoadMultiplier) PassThrough

func (tbls *TokenBucketLoadMultiplier) PassThrough() bool

PassThrough gets value of PassThrough flag.

func (*TokenBucketLoadMultiplier) PreprocessRequest

func (tbls *TokenBucketLoadMultiplier) PreprocessRequest(now time.Time, rContext Request) bool

PreprocessRequest preprocesses a request and makes decision whether to accept or reject the request.

func (*TokenBucketLoadMultiplier) Return

func (tbls *TokenBucketLoadMultiplier) Return(tokens float64)

Return returns tokens to the token bucket.

func (*TokenBucketLoadMultiplier) SetContinuousTracking

func (tbls *TokenBucketLoadMultiplier) SetContinuousTracking(continuousTracking bool)

SetContinuousTracking sets whether to continuously track the token rate and adjust the fill rate based on load multiplier.

func (*TokenBucketLoadMultiplier) SetLoadMultiplier

func (tbls *TokenBucketLoadMultiplier) SetLoadMultiplier(now time.Time, lm float64)

SetLoadMultiplier sets the load multiplier number --> 0 = no load accepted, 1 = accept up to 100% of current load, 2 = accept up to 200% of current load.

func (*TokenBucketLoadMultiplier) SetPassThrough

func (tbls *TokenBucketLoadMultiplier) SetPassThrough(passThrough bool)

SetPassThrough sets PassThrough flag which decides whether to pass through requests.

func (*TokenBucketLoadMultiplier) Take

func (tbls *TokenBucketLoadMultiplier) Take(now time.Time, tokens float64) (time.Duration, bool)

Take takes tokens from the token bucket even if available tokens are less than asked. If tokens are not available at the moment, it will return amount of wait time and checks whether the operation was successful or not.

func (*TokenBucketLoadMultiplier) TakeIfAvailable

func (tbls *TokenBucketLoadMultiplier) TakeIfAvailable(now time.Time, tokens float64) bool

TakeIfAvailable takes tokens from the token bucket if available, otherwise return false.

type TokenBucketLoadMultiplierMetrics

type TokenBucketLoadMultiplierMetrics struct {
	LMGauge            prometheus.Gauge
	TokenBucketMetrics *TokenBucketMetrics
}

TokenBucketLoadMultiplierMetrics holds metrics related to internals of TokenBucketLoadMultiplier.

type TokenBucketMetrics

type TokenBucketMetrics struct {
	FillRateGauge        prometheus.Gauge
	BucketCapacityGauge  prometheus.Gauge
	AvailableTokensGauge prometheus.Gauge
}

TokenBucketMetrics holds metrics related to internals of TokenBucket.

type TokenManager

type TokenManager interface {
	// Take tokens if available, otherwise return false
	TakeIfAvailable(now time.Time, tokens float64) bool
	// Take tokens even if available tokens are less than asked - returns wait time if tokens are not available immediately. The other return value conveys whether the operation was successful or not.
	Take(now time.Time, tokens float64) (time.Duration, bool)
	// Return tokens, useful when requests choose to drop themselves on timeout or cancellation
	Return(tokens float64)
	// Provides TokenManager the request that the scheduler processing -- some TokenManager implementations use this level of visibility for their algorithms. Return value decides whether the request has to be accepted right away in case TokenManger is not yet ready or configured to accept all traffic (short circuit).
	PreprocessRequest(now time.Time, request Request) bool
}

TokenManager : Interface for token managers.

type WFQMetrics

type WFQMetrics struct {
	FlowsGauge        prometheus.Gauge
	HeapRequestsGauge prometheus.Gauge
}

WFQMetrics holds metrics related to internal workings of WFQScheduler.

type WFQScheduler

type WFQScheduler struct {
	// contains filtered or unexported fields
}

WFQScheduler : Weighted Fair Queue Scheduler.

func (*WFQScheduler) GetPendingFlows

func (sched *WFQScheduler) GetPendingFlows() int

GetPendingFlows returns the number of flows in the scheduler.

func (*WFQScheduler) GetPendingRequests

func (sched *WFQScheduler) GetPendingRequests() int

GetPendingRequests returns the number of requests in the scheduler.

func (*WFQScheduler) Schedule

func (sched *WFQScheduler) Schedule(ctx context.Context, request Request) bool

Schedule blocks until the request is scheduled or until timeout. Return value - true: Accept, false: Reject.

type WindowedCounter

type WindowedCounter struct {
	// contains filtered or unexported fields
}

WindowedCounter is a token bucket with a windowed counter.

func NewWindowedCounter

func NewWindowedCounter(now time.Time, totalSlots uint8, slotDuration time.Duration) *WindowedCounter

NewWindowedCounter creates a new WindowedCounter with extra slot for the current window.

func (*WindowedCounter) AddTokens

func (counter *WindowedCounter) AddTokens(now time.Time, tokens uint64) bool

AddTokens to the counter. Return value is true when counter shifted slots and the all the slots in the counter is valid.

func (*WindowedCounter) CalculateTokenRate

func (counter *WindowedCounter) CalculateTokenRate() float64

CalculateTokenRate returns the calculated token rate in the current window.

func (*WindowedCounter) IsBootstrapping

func (counter *WindowedCounter) IsBootstrapping() bool

IsBootstrapping checks whether the counter is in bootstrapping mode.