1 files changed, 109 insertions, 0 deletions
diff --git a/src/go/collectors/go.d.plugin/pkg/metrics/unique_counter.go b/src/go/collectors/go.d.plugin/pkg/metrics/unique_counter.go
new file mode 100644
index 000000000..dfc96126a
--- /dev/null
+++ b/src/go/collectors/go.d.plugin/pkg/metrics/unique_counter.go
@@ -0,0 +1,109 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+package metrics
+
+import (
+	"github.com/axiomhq/hyperloglog"
+	"github.com/netdata/netdata/go/go.d.plugin/pkg/stm"
+)
+
+type (
+	UniqueCounter interface {
+		stm.Value
+		Insert(s string)
+		Value() int
+		Reset()
+	}
+
+	mapUniqueCounter struct {
+		m map[string]bool
+	}
+
+	hyperLogLogUniqueCounter struct {
+		sketch *hyperloglog.Sketch
+	}
+
+	UniqueCounterVec struct {
+		useHyperLogLog bool
+		Items          map[string]UniqueCounter
+	}
+)
+
+var (
+	_ stm.Value = mapUniqueCounter{}
+	_ stm.Value = hyperLogLogUniqueCounter{}
+	_ stm.Value = UniqueCounterVec{}
+)
+
+func NewUniqueCounter(useHyperLogLog bool) UniqueCounter {
+	if useHyperLogLog {
+		return &hyperLogLogUniqueCounter{hyperloglog.New()}
+	}
+	return mapUniqueCounter{map[string]bool{}}
+}
+
+func (c mapUniqueCounter) WriteTo(rv map[string]int64, key string, mul, div int) {
+	rv[key] = int64(float64(c.Value()*mul) / float64(div))
+}
+
+func (c mapUniqueCounter) Insert(s string) {
+	c.m[s] = true
+}
+
+func (c mapUniqueCounter) Value() int {
+	return len(c.m)
+}
+
+func (c mapUniqueCounter) Reset() {
+	for key := range c.m {
+		delete(c.m, key)
+	}
+}
+
+// WriteTo writes its value into given map.
+func (c hyperLogLogUniqueCounter) WriteTo(rv map[string]int64, key string, mul, div int) {
+	rv[key] = int64(float64(c.Value()*mul) / float64(div))
+}
+
+func (c *hyperLogLogUniqueCounter) Insert(s string) {
+	c.sketch.Insert([]byte(s))
+}
+
+func (c *hyperLogLogUniqueCounter) Value() int {
+	return int(c.sketch.Estimate())
+}
+
+func (c *hyperLogLogUniqueCounter) Reset() {
+	c.sketch = hyperloglog.New()
+}
+
+func NewUniqueCounterVec(useHyperLogLog bool) UniqueCounterVec {
+	return UniqueCounterVec{
+		Items:          map[string]UniqueCounter{},
+		useHyperLogLog: useHyperLogLog,
+	}
+}
+
+// WriteTo writes its value into given map.
+func (c UniqueCounterVec) WriteTo(rv map[string]int64, key string, mul, div int) {
+	for name, value := range c.Items {
+		value.WriteTo(rv, key+"_"+name, mul, div)
+	}
+}
+
+// Get gets UniqueCounter instance by name
+func (c UniqueCounterVec) Get(name string) UniqueCounter {
+	item, ok := c.Items[name]
+	if ok {
+		return item
+	}
+	item = NewUniqueCounter(c.useHyperLogLog)
+	c.Items[name] = item
+	return item
+}
+
+func (c UniqueCounterVec) Reset() {
+	for _, value := range c.Items {
+		value.Reset()
+	}
+}