Add WrapExecutor

client.go

@@ -84,6 +84,12 @@ type (
 
 	// ErrorHook type is for reacting to request errors, called after all retries were attempted
 	ErrorHook func(*Request, error)
+
+	// Executor executes a Request
+	Executor func(req *Request) (*Response, error)
+
+	// ExecutorMiddleware type wraps the execution of a request
+	ExecutorMiddleware func(req *Request, next Executor) (*Response, error)
 )
 
 // Client struct is used to create Resty client with client level settings,
@@ -136,6 +142,7 @@ type Client struct {
 	requestLog         RequestLogCallback
 	responseLog        ResponseLogCallback
 	errorHooks         []ErrorHook
+	executor           Executor
 }
 
 // User type is to hold an username and password information
@@ -423,6 +430,28 @@ func (c *Client) OnError(h ErrorHook) *Client {
 	return c
 }
 
+// WrapExecutor wraps the execution of a request, granting full access to the request, response, and error.
+// Runs on every request attempt, before any request hook and after any response or error hook.
+// Can be useful to introduce throttling or add hooks that always fire, regardless of success or error.
+//
+//		c.WrapExecutor(func(req *Request, next Executor) (*Response, error) {
+//			// do something with the Request
+//			// e.g. Acquire a lock
+//
+//			resp, err := next(req)
+//			// do something with the Response or error
+//			// e.g. Release a lock
+//
+//			return resp, err
+//		})
+func (c *Client) WrapExecutor(e ExecutorMiddleware) *Client {
+	next := c.executor
+	c.executor = func(req *Request) (*Response, error) {
+		return e(req, next)
+	}
+	return c
+}
+
 // SetPreRequestHook method sets the given pre-request function into resty client.
 // It is called right before the request is fired.
 //
@@ -1068,6 +1097,8 @@ func createClient(hc *http.Client) *Client {
 	// Logger
 	c.SetLogger(createLogger())
 
+	c.executor = c.execute
+
 	// default before request middlewares
 	c.beforeRequest = []RequestMiddleware{
 		parseRequestURL,

client_test.go

@@ -735,6 +735,45 @@ func TestClientOnResponseError(t *testing.T) {
 	}
 }
 
+func TestWrapExecutor(t *testing.T) {
+	ts := createGetServer(t)
+	defer ts.Close()
+
+	t.Run("abort", func(t *testing.T) {
+		c := dc()
+		c.WrapExecutor(func(req *Request, next Executor) (*Response, error) {
+			return nil, fmt.Errorf("abort")
+		})
+
+		resp, err := c.R().Get(ts.URL)
+		assertNil(t, resp)
+		assertEqual(t, "abort", err.Error())
+	})
+
+	t.Run("noop", func(t *testing.T) {
+		c := dc()
+		c.WrapExecutor(func(req *Request, next Executor) (*Response, error) {
+			return next(req)
+		})
+
+		resp, err := c.R().Get(ts.URL)
+		assertNil(t, err)
+		assertEqual(t, 200, resp.StatusCode())
+	})
+
+	t.Run("add error", func(t *testing.T) {
+		c := dc()
+		c.WrapExecutor(func(req *Request, next Executor) (*Response, error) {
+			resp, _ := next(req)
+			return resp, fmt.Errorf("error")
+		})
+
+		resp, err := c.R().Get(ts.URL)
+		assertEqual(t, "error", err.Error())
+		assertEqual(t, 200, resp.StatusCode())
+	})
+}
+
 func TestResponseError(t *testing.T) {
 	err := errors.New("error message")
 	re := &ResponseError{

example_test.go

@@ -12,6 +12,7 @@ import (
 	"net/http"
 	"os"
 	"strconv"
+	"sync"
 	"time"
 
 	"golang.org/x/net/proxy"
@@ -241,3 +242,35 @@ func Example_socks5Proxy() {
 func printOutput(resp *resty.Response, err error) {
 	fmt.Println(resp, err)
 }
+
+//
+// Throttling
+//
+
+func ExampleClient_throttling() {
+	// Consider the use of proper throttler, possibly waiting for resources to free up
+	// e.g. https://github.com/throttled/throttled or https://pkg.go.dev/golang.org/x/time/rate
+	var lock sync.Mutex
+	currentConcurrent := 0
+	maxConcurrent := 10
+
+	resty.New().WrapExecutor(func(req *resty.Request, next resty.Executor) (*resty.Response, error) {
+		lock.Lock()
+		current := currentConcurrent
+		if current == maxConcurrent {
+			lock.Unlock()
+			return nil, fmt.Errorf("max concurrency exceeded")
+		}
+
+		current++
+		lock.Unlock()
+
+		defer func() {
+			lock.Lock()
+			current--
+			lock.Unlock()
+		}()
+
+		return next(req)
+	})
+}

request.go

@@ -754,7 +754,7 @@ func (r *Request) Execute(method, url string) (*Response, error) {
 	if r.client.RetryCount == 0 {
 		r.Attempt = 1
 		r.client.onErrorHooks(r, resp, err)
-		return r.client.execute(r)
+		return r.client.executor(r)
 	}
 
 	err = Backoff(
@@ -763,7 +763,7 @@ func (r *Request) Execute(method, url string) (*Response, error) {
 
 			r.URL = r.selectAddr(addrs, url, r.Attempt)
 
-			resp, err = r.client.execute(r)
+			resp, err = r.client.executor(r)
 			if err != nil {
 				r.client.log.Errorf("%v, Attempt %v", err, r.Attempt)
 			}