From 72a62b678f83dac0698b1202fd852568a01dbf5e Mon Sep 17 00:00:00 2001
From: mountain <mountain@action2quare.com>
Date: Thu, 16 Nov 2023 19:56:47 +0900
Subject: [PATCH] =?UTF-8?q?metric=20=ED=8C=A8=ED=82=A4=EC=A7=80=20?=
 =?UTF-8?q?=EC=B6=94=EA=B0=80?=
MIME-Version: 1.0
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Content-Transfer-Encoding: 8bit

---
 metric/metric.go | 108 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 108 insertions(+)
 create mode 100644 metric/metric.go

diff --git a/metric/metric.go b/metric/metric.go
new file mode 100644
index 0000000..1893a3e
--- /dev/null
+++ b/metric/metric.go
@@ -0,0 +1,108 @@
+package metric
+
+import (
+	"crypto/md5"
+	"encoding/binary"
+	"encoding/hex"
+	"encoding/json"
+	"math"
+	"os"
+	"sync"
+)
+
+const (
+	METRIC_HEAD_INLINE = byte(1)
+	METRIC_TAIL_INLINE = byte(2)
+)
+
+type MetricType int
+
+const (
+	MetricCounter   = MetricType(1)
+	MetricGuage     = MetricType(2)
+	metric_key_size = 8
+)
+
+type MetricDescription struct {
+	Key         string
+	Type        MetricType
+	Name        string            `json:",omitempty"`
+	Help        string            `json:",omitempty"`
+	ConstLabels map[string]string `json:",omitempty"`
+}
+
+type writeRequest struct {
+	key string
+	val float64
+}
+
+type metricCollection struct {
+	writerChan chan *writeRequest
+}
+
+var mc = metricCollection{
+	writerChan: make(chan *writeRequest, 100),
+}
+
+type MetricWriter func(float64)
+
+func (mc *metricCollection) metricWriter() {
+	// head + metric_key_size + 8byte + tail + cr = 19
+	var buff [20]byte
+	buff[0] = METRIC_HEAD_INLINE
+	buff[17] = METRIC_TAIL_INLINE
+	buff[18] = '\n'
+
+	for req := range mc.writerChan {
+		copy(buff[1:], []byte(req.key))
+		binary.BigEndian.PutUint64(buff[9:], math.Float64bits(req.val))
+		os.Stdout.Write(buff[:])
+	}
+}
+
+var metricWriterFlag sync.Once
+
+func NewMetric(mt MetricType, name string, help string, constLabel ...string) (writer MetricWriter) {
+	metricWriterFlag.Do(func() {
+		go mc.metricWriter()
+	})
+
+	hash := md5.New()
+	hash.Write([]byte(name))
+
+	var constLabels map[string]string
+	if len(constLabel) > 0 {
+		constLabels = make(map[string]string)
+		for i := 0; i < len(constLabel); i = i + 2 {
+			constLabels[constLabel[i]] = ""
+			hash.Write([]byte(constLabel[i]))
+		}
+
+		for i := 1; i < len(constLabel); i = i + 2 {
+			constLabels[constLabel[i-1]] = constLabel[i]
+			hash.Write([]byte(constLabel[i]))
+		}
+	}
+
+	key := hex.EncodeToString(hash.Sum(nil))[:metric_key_size]
+	temp, _ := json.Marshal(MetricDescription{
+		Key:         key,
+		Type:        mt,
+		Name:        name,
+		Help:        help,
+		ConstLabels: constLabels,
+	})
+
+	writer = func(val float64) {
+		mc.writerChan <- &writeRequest{
+			key: key,
+			val: val,
+		}
+	}
+
+	output := append([]byte{METRIC_HEAD_INLINE}, temp...)
+	output = append(output, METRIC_TAIL_INLINE, '\n')
+	os.Stdout.Write(output)
+
+	return
+}