throttling

Documentation

Overview

Package throttling implements wrapper around blob.Storage that adds throttling to all calls. Throttling is performed for both operations and byte counts (upload and download separately).

Index

• func NewWrapper(wrapped blob.Storage, throttler Throttler) blob.Storage
• type Limits
• type SettableThrottler
  • func NewThrottler(limits Limits, window time.Duration, initialFillRatio float64) (SettableThrottler, error)
• type Throttler
• type UpdatedHandler

Functions

func NewWrapper

func NewWrapper(wrapped blob.Storage, throttler Throttler) blob.Storage

NewWrapper returns a Storage wrapper that adds retry loop around all operations of the underlying storage.

Types

type Limits

type Limits struct {
	ReadsPerSecond         float64 `json:"readsPerSecond,omitempty"`
	WritesPerSecond        float64 `json:"writesPerSecond,omitempty"`
	ListsPerSecond         float64 `json:"listsPerSecond,omitempty"`
	UploadBytesPerSecond   float64 `json:"maxUploadSpeedBytesPerSecond,omitempty"`
	DownloadBytesPerSecond float64 `json:"maxDownloadSpeedBytesPerSecond,omitempty"`
	ConcurrentReads        int     `json:"concurrentReads,omitempty"`
	ConcurrentWrites       int     `json:"concurrentWrites,omitempty"`
}

Limits encapsulates all limits for a Throttler.

type SettableThrottler

type SettableThrottler interface {
	Throttler

	Limits() Limits
	SetLimits(limits Limits) error
	OnUpdate(handler UpdatedHandler)
}

SettableThrottler exposes methods to set throttling limits.

func NewThrottler

func NewThrottler(limits Limits, window time.Duration, initialFillRatio float64) (SettableThrottler, error)

NewThrottler returns a Throttler with provided limits.

type Throttler

type Throttler interface {
	BeforeOperation(ctx context.Context, op string)
	AfterOperation(ctx context.Context, op string)

	// BeforeDownload acquires the specified number of downloaded bytes
	// possibly blocking until enough are available.
	BeforeDownload(ctx context.Context, numBytes int64)

	// BeforeUpload acquires the specified number of upload bytes
	// possibly blocking until enough are available.
	BeforeUpload(ctx context.Context, numBytes int64)

	// ReturnUnusedDownloadBytes returns the specified number of unused download bytes.
	ReturnUnusedDownloadBytes(ctx context.Context, numBytes int64)
}

Throttler implements throttling policy by blocking before certain operations are attempted to ensure we don't exceed the desired rate of operations/bytes uploaded/downloaded.

type UpdatedHandler

type UpdatedHandler func(l Limits) error

UpdatedHandler is invoked as part of SetLimits() after limits are updated.