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Make topKMetrics thread-safe in metrics limiter #1738

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Make topKMetrics thread-safe in metrics limiter #1738

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14 changes: 10 additions & 4 deletions plugins/processors/awsapplicationsignals/internal/cardinalitycontrol/metrics_limiter.go
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Original file line number Diff line number Diff line change
Expand Up @@ -265,6 +265,7 @@ type topKMetrics struct {
metricMap map[string]*MetricData
minMetric *MetricData
sizeLimit int
mutex sync.RWMutex
}

// newTopKMetrics creates a new topKMetrics with a specified size limit.
Expand All @@ -278,6 +279,8 @@ func newTopKMetrics(sizeLimit int) *topKMetrics {

// Push adds a key-value pair to the priority queue. If the value already exists, it updates the frequency.
func (t *topKMetrics) Push(oldMetric, newMetric *MetricData) {
t.mutex.Lock()
defer t.mutex.Unlock()
hashValue := oldMetric.hashKey
if t.minMetric == nil {
t.minMetric = oldMetric
Expand All @@ -290,7 +293,7 @@ func (t *topKMetrics) Push(oldMetric, newMetric *MetricData) {
// Check if this oldMetric is the new minimum, find the new minMetric after the updates
if t.minMetric.hashKey == hashValue {
// Find the new minMetrics after update the frequency
t.minMetric = t.findMinMetric()
t.minMetric = t.findMinMetricLocked()
}
return
}
Expand All @@ -300,7 +303,7 @@ func (t *topKMetrics) Push(oldMetric, newMetric *MetricData) {
if newMetric.frequency > t.minMetric.frequency {
delete(t.metricMap, t.minMetric.hashKey)
t.metricMap[hashValue] = newMetric
t.minMetric = t.findMinMetric()
t.minMetric = t.findMinMetricLocked()
}
} else {
// Check if this newMetric is the new minimum.
Expand All @@ -311,8 +314,9 @@ func (t *topKMetrics) Push(oldMetric, newMetric *MetricData) {
}
}

// findMinMetric removes and returns the key-value pair with the minimum value.
func (t *topKMetrics) findMinMetric() *MetricData {
// findMinMetricLocked removes and returns the key-value pair with the minimum value.
// It assumes the caller already holds the read/write lock.
func (t *topKMetrics) findMinMetricLocked() *MetricData {
// Find the new minimum metric and smallest frequency.
var newMinMetric *MetricData
smallestFrequency := int(^uint(0) >> 1) // Initialize with the maximum possible integer value
Expand All @@ -327,6 +331,8 @@ func (t *topKMetrics) findMinMetric() *MetricData {
}

func (s *service) admitMetricData(metric *MetricData) bool {
s.primaryTopK.mutex.RLock()
defer s.primaryTopK.mutex.RUnlock()
_, found := s.primaryTopK.metricMap[metric.hashKey]
if len(s.primaryTopK.metricMap) < s.primaryTopK.sizeLimit || found {
return true
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