Make poolhttp thread safe.

authority/poolhttp/poolhttp.go

@@ -17,6 +17,7 @@ type Transporter interface {
 // clients. It implements the [provisioner.HTTPClient] and [Transporter]
 // interfaces. This is the HTTP client used by the provisioners.
 type Client struct {
+	rw   sync.RWMutex
 	pool sync.Pool
 }
 
@@ -31,18 +32,31 @@ func New(fn func() *http.Client) *Client {
 }
 
 // SetNew replaces the inner pool with a new [sync.Pool] with the given New
-// function. This method should not be used concurrently with other methods.
+// function. This method can be use concurrently with other methods of this
+// package.
 func (c *Client) SetNew(fn func() *http.Client) {
+	c.rw.Lock()
 	c.pool = sync.Pool{
 		New: func() any { return fn() },
 	}
+	c.rw.Unlock()
+}
+
+// getClient gets a client from the pool.
+func (c *Client) getClient() *http.Client {
+	c.rw.RLock()
+	defer c.rw.RUnlock()
+	if hc, ok := c.pool.Get().(*http.Client); ok && hc != nil {
+		return hc
+	}
+	return nil
 }
 
 // Get issues a GET request to the specified URL. If the response is one of the
 // following redirect codes, Get follows the redirect after calling the
 // [Client.CheckRedirect] function:
 func (c *Client) Get(u string) (resp *http.Response, err error) {
-	if hc, ok := c.pool.Get().(*http.Client); ok && hc != nil {
+	if hc := c.getClient(); hc != nil {
 		resp, err = hc.Get(u)
 		c.pool.Put(hc)
 	} else {
@@ -55,7 +69,7 @@ func (c *Client) Get(u string) (resp *http.Response, err error) {
 // Do sends an HTTP request and returns an HTTP response, following policy (such
 // as redirects, cookies, auth) as configured on the client.
 func (c *Client) Do(req *http.Request) (resp *http.Response, err error) {
-	if hc, ok := c.pool.Get().(*http.Client); ok && hc != nil {
+	if hc := c.getClient(); hc != nil {
 		resp, err = hc.Do(req)
 		c.pool.Put(hc)
 	} else {
@@ -68,7 +82,7 @@ func (c *Client) Do(req *http.Request) (resp *http.Response, err error) {
 // Transport() returns a clone of the http.Client Transport or returns the
 // default transport.
 func (c *Client) Transport() *http.Transport {
-	if hc, ok := c.pool.Get().(*http.Client); ok && hc != nil {
+	if hc := c.getClient(); hc != nil {
 		tr, ok := hc.Transport.(*http.Transport)
 		c.pool.Put(hc)
 		if ok {