Remove unused code in discovery queue creation (#17515)

Signed-off-by: Manan Gupta <manan@planetscale.com>

go/vt/vtorc/discovery/queue.go

@@ -33,12 +33,6 @@ import (
 	"vitess.io/vitess/go/vt/vtorc/config"
 )
 
-// QueueMetric contains the queue's active and queued sizes
-type QueueMetric struct {
-	Active int
-	Queued int
-}
-
 // Queue contains information for managing discovery requests
 type Queue struct {
 	sync.Mutex
@@ -48,67 +42,16 @@ type Queue struct {
 	queue        chan string
 	queuedKeys   map[string]time.Time
 	consumedKeys map[string]time.Time
-	metrics      []QueueMetric
-}
-
-// DiscoveryQueue contains the discovery queue which can then be accessed via an API call for monitoring.
-// Currently this is accessed by ContinuousDiscovery() but also from http api calls.
-// I may need to protect this better?
-var discoveryQueue map[string](*Queue)
-var dcLock sync.Mutex
-
-func init() {
-	discoveryQueue = make(map[string](*Queue))
 }
 
-// CreateOrReturnQueue allows for creation of a new discovery queue or
-// returning a pointer to an existing one given the name.
-func CreateOrReturnQueue(name string) *Queue {
-	dcLock.Lock()
-	defer dcLock.Unlock()
-	if q, found := discoveryQueue[name]; found {
-		return q
-	}
-
-	q := &Queue{
+// CreateQueue allows for creation of a new discovery queue
+func CreateQueue(name string) *Queue {
+	return &Queue{
 		name:         name,
 		queuedKeys:   make(map[string]time.Time),
 		consumedKeys: make(map[string]time.Time),
 		queue:        make(chan string, config.DiscoveryQueueCapacity),
 	}
-	go q.startMonitoring()
-
-	discoveryQueue[name] = q
-
-	return q
-}
-
-// monitoring queue sizes until we are told to stop
-func (q *Queue) startMonitoring() {
-	log.Infof("Queue.startMonitoring(%s)", q.name)
-	ticker := time.NewTicker(time.Second) // hard-coded at every second
-
-	for {
-		select {
-		case <-ticker.C: // do the periodic expiry
-			q.collectStatistics()
-		case <-q.done:
-			return
-		}
-	}
-}
-
-// do a check of the entries in the queue, both those active and queued
-func (q *Queue) collectStatistics() {
-	q.Lock()
-	defer q.Unlock()
-
-	q.metrics = append(q.metrics, QueueMetric{Queued: len(q.queuedKeys), Active: len(q.consumedKeys)})
-
-	// remove old entries if we get too big
-	if len(q.metrics) > config.DiscoveryQueueMaxStatisticsSize {
-		q.metrics = q.metrics[len(q.metrics)-config.DiscoveryQueueMaxStatisticsSize:]
-	}
 }
 
 // QueueLen returns the length of the queue (channel size + queued size)

go/vt/vtorc/logic/vtorc.go

@@ -108,7 +108,7 @@ func waitForLocksRelease() {
 // handleDiscoveryRequests iterates the discoveryQueue channel and calls upon
 // instance discovery per entry.
 func handleDiscoveryRequests() {
-	discoveryQueue = discovery.CreateOrReturnQueue("DEFAULT")
+	discoveryQueue = discovery.CreateQueue("DEFAULT")
 	// create a pool of discovery workers
 	for i := uint(0); i < config.DiscoveryMaxConcurrency; i++ {
 		go func() {