estransport: remove enableMetrics

These fields are redundant, as you can check that metrics is non-nil.

(cherry picked from commit 5ac2b99)

Author: axw

estransport/connection.go

@@ -40,8 +40,7 @@ type Connection struct {
 type singleConnectionPool struct {
 	connection *Connection
 
-	metrics       *metrics
-	enableMetrics bool
+	metrics *metrics
 
 	debugLogger DebuggingLogger
 }
@@ -54,8 +53,7 @@ type roundRobinConnectionPool struct {
 	dead []*Connection // List of dead connections
 	orig []*url.URL    // List of original URLs, passed in during initialization
 
-	metrics       *metrics
-	enableMetrics bool
+	metrics *metrics
 
 	debugLogger DebuggingLogger
 }
@@ -74,12 +72,7 @@ func newRoundRobinConnectionPool(u ...*url.URL) *roundRobinConnectionPool {
 
 	cp := roundRobinConnectionPool{live: conns, orig: u, curr: -1}
 
-	if cp.enableMetrics {
-		cp.metrics.Lock()
-		cp.metrics.live = cp.live
-		cp.metrics.dead = cp.dead
-		cp.metrics.Unlock()
-	}
+	// BUG the transport's metrics should be initialised with the live list
 
 	return &cp
 }
@@ -171,7 +164,7 @@ func (cp *roundRobinConnectionPool) Remove(c *Connection) error {
 	copy(cp.live[index:], cp.live[index+1:])
 	cp.live = cp.live[:len(cp.live)-1]
 
-	if cp.enableMetrics {
+	if cp.metrics != nil {
 		cp.metrics.Lock()
 		cp.metrics.dead = cp.dead
 		cp.metrics.live = cp.live
@@ -223,7 +216,7 @@ func (cp *roundRobinConnectionPool) resurrectLocked(c *Connection, removeDead bo
 		}
 	}
 
-	if cp.enableMetrics {
+	if cp.metrics != nil {
 		cp.metrics.Lock()
 		cp.metrics.dead = cp.dead
 		cp.metrics.live = cp.live

estransport/estransport.go

@@ -78,8 +78,7 @@ type Client struct {
 	maxRetries           int
 	retryBackoff         func(attempt int) time.Duration
 
-	enableMetrics bool
-	metrics       *metrics
+	metrics *metrics
 
 	enableDebugLogger bool
 	debugLogger       DebuggingLogger
@@ -125,7 +124,6 @@ func New(cfg Config) *Client {
 		maxRetries:           cfg.MaxRetries,
 		retryBackoff:         cfg.RetryBackoff,
 
-		enableMetrics:     cfg.EnableMetrics,
 		enableDebugLogger: cfg.EnableDebugLogger,
 
 		transport: cfg.Transport,
@@ -137,12 +135,10 @@ func New(cfg Config) *Client {
 		// FIXME(karmi): Type assertion to interface
 		if pool, ok := client.pool.(*singleConnectionPool); ok {
 			client.metrics = &metrics{responses: make(map[int]int)}
-			pool.enableMetrics = true
 			pool.metrics = client.metrics
 		}
 		if pool, ok := client.pool.(*roundRobinConnectionPool); ok {
 			client.metrics = &metrics{responses: make(map[int]int)}
-			pool.enableMetrics = true
 			pool.metrics = client.metrics
 		}
 	}
@@ -171,7 +167,7 @@ func (c *Client) Perform(req *http.Request) (*http.Response, error) {
 
 	// Record metrics, when enabled
 	//
-	if c.enableMetrics {
+	if c.metrics != nil {
 		c.metrics.Lock()
 		c.metrics.requests++
 		c.metrics.Unlock()
@@ -243,7 +239,7 @@ func (c *Client) Perform(req *http.Request) (*http.Response, error) {
 		if err != nil {
 			// Record metrics, when enabled
 			//
-			if c.enableMetrics {
+			if c.metrics != nil {
 				c.metrics.Lock()
 				c.metrics.failures++
 				c.metrics.Unlock()
@@ -268,7 +264,7 @@ func (c *Client) Perform(req *http.Request) (*http.Response, error) {
 			conn.Unlock()
 		}
 
-		if res != nil && c.enableMetrics {
+		if res != nil && c.metrics != nil {
 			c.metrics.Lock()
 			c.metrics.responses[res.StatusCode]++
 			c.metrics.Unlock()

estransport/metrics.go

@@ -67,7 +67,7 @@ type metrics struct {
 // Metrics returns the transport metrics.
 //
 func (c *Client) Metrics() (Metrics, error) {
-	if !c.enableMetrics {
+	if c.metrics == nil {
 		return Metrics{}, errors.New("transport metrics not enabled")
 	}
 	c.metrics.RLock()