/
client.go
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/
client.go
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package gohttp
import (
"errors"
"net/http"
"github.com/cenk/backoff"
"github.com/meshhq/funnel"
)
// HTTP Methods
const (
GET = "GET"
POST = "POST"
PUT = "PUT"
PATCH = "PATCH"
DELETE = "DELETE"
)
// HTTP Header Constants
const (
ContentType = "Content-Type"
ContentLength = "Content-Length"
Accept = "Accept"
Authorization = "Authorization"
UserAgent = "User-Agent"
)
// Client models an HTTP client.
//
// A GoHTTP Client can contain global request parameters, such as a BaseURL,
// a set of Headers, or Basic Authentication Credentials. All global parameters
// will be applied to each request executed by the client.
//
// The GoHTTP client also has built in support support for retry (with
// exponential backoff and rate limiting).
type Client struct {
// BaseURL is base URL used for all requests executed by the client.
BaseURL string
// Headers model the global headers to be used for all requests issued by the client.
Headers http.Header
// BasicAuth
BasicAuth *BasicAuth
// RetryableStatusCodes is an array of codes that are retryable.
RetryableStatusCodes []int
// Backoff ...
Backoff *backoff.ExponentialBackOff
// rateLimiter is a rate limiter.
rateLimiter *funnel.RateLimiter
// goClient is the underlying `http.Client` that is used to issue requests.
goClient *http.Client
}
//------------------------------------------------------------------------------
// Initialization
//------------------------------------------------------------------------------
// NewClient instantiates a new instance of a gohttp.Client.
func NewClient(baseURL string, headers http.Header) *Client {
if headers == nil {
headers = http.Header{}
}
client := new(Client)
client.BaseURL = baseURL
client.Headers = headers
client.goClient = &http.Client{}
client.Backoff = Backoff()
client.RetryableStatusCodes = []int{http.StatusRequestTimeout, 429, 500}
return client
}
//------------------------------------------------------------------------------
// Basic Authentication
//------------------------------------------------------------------------------
// SetBasicAuth configures basic authentication credentials for the client.
func (c *Client) SetBasicAuth(username string, password string) {
basicAuth := &BasicAuth{
Username: username,
Password: password,
}
c.BasicAuth = basicAuth
}
//------------------------------------------------------------------------------
// Rate Limiting
//------------------------------------------------------------------------------
// SetRateLimiterInfo provides..
func (c *Client) SetRateLimiterInfo(limitInfo *funnel.RateLimitInfo) error {
limiter, err := funnel.NewLimiter(limitInfo)
if err != nil {
return err
}
c.rateLimiter = limiter
return nil
}
//------------------------------------------------------------------------------
// Request Execution
//------------------------------------------------------------------------------
// Execute executes the HTTPc request described with the given `gohttp.Request`.
func (c *Client) Execute(req *Request) (*Response, error) {
var err error
var response *Response
switch req.Method {
case GET:
response, err = c.Get(req)
case POST:
response, err = c.Post(req)
case DELETE:
response, err = c.Delete(req)
case PUT:
response, err = c.Put(req)
case PATCH:
response, err = c.Patch(req)
}
if response != nil {
response.Request = req
}
return response, err
}
//------------------------------------------------------------------------------
// Convenience
//------------------------------------------------------------------------------
// Get performs an HTTP GET request with the supplied request object.
func (c *Client) Get(request *Request) (*Response, error) {
req, err := request.Translate(c)
if err != nil {
return nil, err
}
return c.executeRequest(req)
}
// Post performs an HTTP POST request with the supplied request object.
func (c *Client) Post(request *Request) (*Response, error) {
req, err := request.Translate(c)
if err != nil {
return nil, err
}
return c.executeRequest(req)
}
// Delete performs an HTTP DELETE request with the supplied request object.
func (c *Client) Delete(request *Request) (*Response, error) {
req, err := request.Translate(c)
if err != nil {
return nil, err
}
return c.executeRequest(req)
}
// Put performs an HTTP PUT request with the supplied URL string and
// parameters.
func (c *Client) Put(request *Request) (*Response, error) {
req, err := request.Translate(c)
if err != nil {
return nil, err
}
return c.executeRequest(req)
}
// Patch performs an HTTP PATCH request with the supplied URL string and
// parameters.
func (c *Client) Patch(request *Request) (*Response, error) {
req, err := request.Translate(c)
if err != nil {
return nil, err
}
return c.executeRequest(req)
}
//------------------------------------------------------------------------------
// Request Execution
//------------------------------------------------------------------------------
func (c *Client) executeRequest(req *http.Request) (*Response, error) {
var parsedError error
var parsedResponse *Response
// Setup our retryable operation.
retry := func() error {
// Execute the actual request.
response, err := c.goClient.Do(req)
if err != nil {
parsedError = err
return nil
}
// Defer closing response body if it exists.
if response != nil {
defer response.Body.Close()
}
// Parse our response into a gohttp.Response object.
parsedResponse, parsedError = NewResponse(response)
if parsedError != nil {
return nil
}
// Retry status code checks.
//
// If the client encounters a retryable status code, we return
// an error to signal a retry should occur
for _, code := range c.RetryableStatusCodes {
if code == parsedResponse.Code {
return errors.New("encountered retryable status code")
}
}
return nil
}
// Rate Limiter - If we are using a rate limiter, we enter here.
//
// This will block until the rate limiter is satisfied.
if c.rateLimiter != nil {
err := c.rateLimiter.Enter()
if err != nil {
return nil, err
}
}
// Execute the retryable operation
err := backoff.Retry(retry, c.Backoff)
if err != nil {
return nil, err
}
return parsedResponse, parsedError
}