scheduler

package
v2.12.0 Latest Latest
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 Go to latest Published: Aug 14, 2023 License: Apache-2.0 Imports: 12 Imported by: 0

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Functions

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Types

type BasicTokenBucket 

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

BasicTokenBucket is a basic token bucket implementation.

func NewBasicTokenBucket 

func NewBasicTokenBucket(clk clockwork.Clock, 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) GetPassThrough 

func (btb *BasicTokenBucket) GetPassThrough() bool

GetPassThrough returns the passThrough flag of the BasicTokenBucket.

func (*BasicTokenBucket) PreprocessRequest 

func (btb *BasicTokenBucket) PreprocessRequest(_ context.Context, request *Request) bool

PreprocessRequest decides whether to proactively accept a request.

func (*BasicTokenBucket) Return 

func (btb *BasicTokenBucket) Return(_ context.Context, tokens float64)

Return returns tokens to the basic token bucket.

func (*BasicTokenBucket) SetFillRate 

func (btb *BasicTokenBucket) SetFillRate(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(ctx context.Context, 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(_ context.Context, tokens float64) bool

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

type GlobalTokenBucket 

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

GlobalTokenBucket is a distributed rate-limiter token bucket implementation.

func NewGlobalTokenBucket 

func NewGlobalTokenBucket(key string, limiter ratelimiter.RateLimiter) *GlobalTokenBucket

NewGlobalTokenBucket creates a new instance of RateLimiterTokenBucket.

func (*GlobalTokenBucket) GetPassThrough 

func (rltb *GlobalTokenBucket) GetPassThrough() bool

GetPassThrough returns the passthrough value.

func (*GlobalTokenBucket) PreprocessRequest 

func (rltb *GlobalTokenBucket) PreprocessRequest(_ context.Context, request *Request) bool

PreprocessRequest is a no-op.

func (*GlobalTokenBucket) Return 

func (rltb *GlobalTokenBucket) Return(ctx context.Context, tokens float64)

Return returns tokens.

func (*GlobalTokenBucket) SetPassThrough 

func (rltb *GlobalTokenBucket) SetPassThrough(passthrough bool)

SetPassThrough sets the passthrough value.

func (*GlobalTokenBucket) Take 

func (rltb *GlobalTokenBucket) Take(ctx context.Context, tokens float64) (time.Duration, bool)

Take takes tokens.

func (*GlobalTokenBucket) TakeIfAvailable 

func (rltb *GlobalTokenBucket) TakeIfAvailable(ctx context.Context, tokens float64) bool

TakeIfAvailable takes tokens if available.

type LoadMultiplierTokenBucket 

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

LoadMultiplierTokenBucket is a token bucket with load multiplier.

func NewLoadMultiplierTokenBucket 

func NewLoadMultiplierTokenBucket(
	clk clockwork.Clock,
	slotCount uint8,
	slotDuration time.Duration,
	lmGauge prometheus.Gauge,
	tbMetrics *TokenBucketMetrics,
) *LoadMultiplierTokenBucket

NewLoadMultiplierTokenBucket creates a new TokenBucketLoadMultiplier.

func (*LoadMultiplierTokenBucket) GetPassThrough 

func (tbls *LoadMultiplierTokenBucket) GetPassThrough() bool

GetPassThrough gets value of passThrough flag.

func (*LoadMultiplierTokenBucket) LoadMultiplier 

func (tbls *LoadMultiplierTokenBucket) LoadMultiplier() float64

LoadMultiplier returns the current load multiplier.

func (*LoadMultiplierTokenBucket) PreprocessRequest 

func (tbls *LoadMultiplierTokenBucket) PreprocessRequest(_ context.Context, request *Request) bool

PreprocessRequest preprocesses a request and makes decision whether to pro-actively accept a request.

func (*LoadMultiplierTokenBucket) Return 

func (tbls *LoadMultiplierTokenBucket) Return(_ context.Context, tokens float64)

Return returns tokens to the token bucket.

func (*LoadMultiplierTokenBucket) SetContinuousTracking 

func (tbls *LoadMultiplierTokenBucket) SetContinuousTracking(continuousTracking bool)

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

func (*LoadMultiplierTokenBucket) SetLoadDecisionValues added in v2.5.0 

func (tbls *LoadMultiplierTokenBucket) SetLoadDecisionValues(loadDecision *policysyncv1.LoadDecision)

SetLoadDecisionValues 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 (*LoadMultiplierTokenBucket) SetPassThrough 

func (tbls *LoadMultiplierTokenBucket) SetPassThrough(passThrough bool)

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

func (*LoadMultiplierTokenBucket) Take 

func (tbls *LoadMultiplierTokenBucket) Take(ctx context.Context, 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 (*LoadMultiplierTokenBucket) TakeIfAvailable 

func (tbls *LoadMultiplierTokenBucket) TakeIfAvailable(_ context.Context, tokens float64) bool

TakeIfAvailable takes tokens from the 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
	InvPriority   float64 // 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.

func NewRequest added in v2.5.0 

func NewRequest(fairnessLabel string, tokens uint64, invPriority float64) *Request

NewRequest calculates the inverse priority and returns a new Request.

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
	// Revert "unschedules" a request.
	// Useful in case the request was rejected by any
	// other scheduler and the tokens are returned
	// back to the scheduler.
	Revert(ctx context.Context, tokens uint64)
	// Info returns the last access time and number of requests that are currently in the queue.
	Info() (time.Time, int)
}

Scheduler : Interface for schedulers.

func NewWFQScheduler 

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

NewWFQScheduler creates a new weighted fair queue scheduler.

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(ctx context.Context, 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(ctx context.Context, tokens float64) (time.Duration, bool)
	// Return tokens, useful when requests choose to drop themselves on timeout or cancellation
	Return(ctx context.Context, 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(ctx context.Context, request *Request) (accept bool)
	// SetPassThrough sets the pass through flag for the token manager.
	SetPassThrough(passThrough bool)
	// GetPassThrough returns the pass through flag for the token manager.
	GetPassThrough() bool
}

TokenManager : Interface for token managers.

type WFQMetrics 

type WFQMetrics struct {
	FlowsGauge            prometheus.Gauge
	HeapRequestsGauge     prometheus.Gauge
	IncomingTokensCounter prometheus.Counter
	AcceptedTokensCounter prometheus.Counter
}

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) Info 

func (sched *WFQScheduler) Info() (time.Time, int)

Info returns the last access time and number of requests that are currently in the queue.

func (*WFQScheduler) Revert 

func (sched *WFQScheduler) Revert(ctx context.Context, tokens uint64)

Revert returns tokens to the token bucket.

func (*WFQScheduler) Schedule 

func (sched *WFQScheduler) Schedule(ctx context.Context, request *Request) (accepted 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(clk clockwork.Clock, 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(request *Request) 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.

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