client

Documentation

Overview

Package client provides interface to perform api call to external services.

It also provides the retryer interface which can be overridden with our own function.

Index

• Constants
• type Client
  • func DefaultClient() Client
• type HTTPClient
• type Request
  • func (r *Request) Perform(ctx context.Context, url string, method string, requestBody interface{}, ...) error
• type Requester
• type Retry
  • func DefaultRetryer() *Retry
  • func (r *Retry) Run(ctx context.Context, fn func(ctx context.Context) error) error
  • func (r *Retry) SetMaxRetries(n int)
• type Retryer

Constants

const (
	// DefaultRetryDelay is the time to wait between two retries.
	DefaultRetryDelay = 2 * time.Second
	DefaultMaxRetries = 3
)

const (
	// DefaultHTTPTimeout expires requests after this period unless overridden by a context.
	DefaultHTTPTimeout = 30 * time.Second
)

Types

type Client

type Client HTTPClient

func DefaultClient

func DefaultClient() Client

DefaultClient returns a HTTP client with default timeout.

type HTTPClient

type HTTPClient interface {
	Do(*http.Request) (*http.Response, error)
}

type Request

type Request struct {
	Client Client
	APIKey string
	Logger logger.Logger
	// Debug flag activates verbose mode. It prints out http request and response objects if set to true.
	Debug bool
}

func (*Request) Perform

func (r *Request) Perform(ctx context.Context, url string, method string, requestBody interface{}, target interface{}) error

MakeRequest performs api call to given url with supplied arguments. It will include "requestBody" in the request if it is non-nil. Response from server will be deserialized to "target" interface.

type Requester

type Requester interface {
	Perform(ctx context.Context, url string, method string, requestBody interface{}, target interface{}) error
}

type Retry

type Retry struct {
	// Delay is time to wait before until next retry
	Delay time.Duration
	// MaxRetries is the number attempts to try running given function.
	MaxRetries int
}

func DefaultRetryer

func DefaultRetryer() *Retry

func (*Retry) Run

func (r *Retry) Run(ctx context.Context, fn func(ctx context.Context) error) error

Run executes given function with constant backoff strategy. It uses a fixed delay window to wait after each retry and executes for 'n' times.

Example:

func testFunction(ctx context.Context) (string, error) {
	time.Sleep(time.Second)
	// do some work here
	return "Hi! I am done", nil
}

r := NewRetryer().WithMaxRetries(5)
ctx:= context.WithDeadline(context.Background(), time.Now().Add(10*time.Second))

execErr := r.Run(ctx, func(ctx context.Context) error {
// it it not compulsory to pass context to your function
	fResp, fErr = testFunction(ctx)
	return fErr
})

func (*Retry) SetMaxRetries

func (r *Retry) SetMaxRetries(n int)

SetMaxRetries overrides default max retries but provided value is non-zero.

type Retryer

type Retryer interface {
	Run(ctx context.Context, fn func(ctx context.Context) error) error
	SetMaxRetries(n int)
}