Unexport newQueue and newQueueMetrics; improve function documentation

internal/queueing/queue.go

@@ -23,7 +23,13 @@ type queueMetrics struct {
 	queueingErrors       *prometheus.CounterVec
 }
 
-func NewQueueMetrics(name string, timeout time.Duration) *queueMetrics {
+// newQueueMetrics prepares Prometheus metrics for queueing mechanism
+// name specifies name of the queue, used to label metrics with ConstLabel `queue_name`
+//      Don't call newQueueMetrics twice with the same name argument!
+// timeout specifies the timeout of storing a request in queue - queueMetrics
+//         uses it to calculate histogram buckets for gitlab_workhorse_queueing_waiting_time
+//         metric
+func newQueueMetrics(name string, timeout time.Duration) *queueMetrics {
 	waitingTimeBuckets := []float64{
 		timeout.Seconds() * 0.01,
 		timeout.Seconds() * 0.05,
@@ -121,12 +127,14 @@ type Queue struct {
 	timeout   time.Duration
 }
 
-// NewQueue creates a new queue
+// newQueue creates a new queue
+// name specifies name used to label queue metrics.
+//      Don't call newQueue twice with the same name argument!
 // limit specifies number of requests run concurrently
 // queueLimit specifies maximum number of requests that can be queued
 // timeout specifies the time limit of storing the request in the queue
 // if the number of requests is above the limit
-func NewQueue(name string, limit, queueLimit uint, timeout time.Duration) *Queue {
+func newQueue(name string, limit, queueLimit uint, timeout time.Duration) *Queue {
 	queue := &Queue{
 		name:      name,
 		busyCh:    make(chan struct{}, limit),
@@ -134,7 +142,7 @@ func NewQueue(name string, limit, queueLimit uint, timeout time.Duration) *Queue
 		timeout:   timeout,
 	}
 
-	queue.queueMetrics = NewQueueMetrics(name, timeout)
+	queue.queueMetrics = newQueueMetrics(name, timeout)
 	queue.queueingLimit.Set(float64(limit))
 	queue.queueingQueueLimit.Set(float64(queueLimit))
 	queue.queueingQueueTimeout.Set(timeout.Seconds())

internal/queueing/queue_test.go

@@ -6,7 +6,7 @@ import (
 )
 
 func TestNormalQueueing(t *testing.T) {
-	q := NewQueue("queue 1", 2, 1, time.Microsecond)
+	q := newQueue("queue 1", 2, 1, time.Microsecond)
 	err1 := q.Acquire()
 	if err1 != nil {
 		t.Fatal("we should acquire a new slot")
@@ -31,7 +31,7 @@ func TestNormalQueueing(t *testing.T) {
 }
 
 func TestQueueLimit(t *testing.T) {
-	q := NewQueue("queue 2", 1, 0, time.Microsecond)
+	q := newQueue("queue 2", 1, 0, time.Microsecond)
 	err1 := q.Acquire()
 	if err1 != nil {
 		t.Fatal("we should acquire a new slot")
@@ -44,7 +44,7 @@ func TestQueueLimit(t *testing.T) {
 }
 
 func TestQueueProcessing(t *testing.T) {
-	q := NewQueue("queue 3", 1, 1, time.Second)
+	q := newQueue("queue 3", 1, 1, time.Second)
 	err1 := q.Acquire()
 	if err1 != nil {
 		t.Fatal("we should acquire a new slot")

internal/queueing/requests.go

@@ -9,6 +9,13 @@ import (
 
 const DefaultTimeout = 30 * time.Second
 
+// QueueRequests creates a new request queue
+// name specifies the name of queue, used to label Prometheus metrics
+//      Don't call QueueRequests twice with the same name argument!
+// h specifies a http.Handler which will handle the queue requests
+// limit specifies number of requests run concurrently
+// queueLimit specifies maximum number of requests that can be queued
+// queueTimeout specifies the time limit of storing the request in the queue
 func QueueRequests(name string, h http.Handler, limit, queueLimit uint, queueTimeout time.Duration) http.Handler {
 	if limit == 0 {
 		return h
@@ -17,7 +24,7 @@ func QueueRequests(name string, h http.Handler, limit, queueLimit uint, queueTim
 		queueTimeout = DefaultTimeout
 	}
 
-	queue := NewQueue(name, limit, queueLimit, queueTimeout)
+	queue := newQueue(name, limit, queueLimit, queueTimeout)
 
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		err := queue.Acquire()