From 1f8c2563131456529f8a9db8e7d2de1cf5f54b53 Mon Sep 17 00:00:00 2001
From: "d.reznichenko" <d.reznichenko@pin-up.tech>
Date: Thu, 18 Apr 2024 10:26:34 +0200
Subject: [PATCH] add metric decorator

---
 go.mod     |   4 +-
 go.sum     |   5 ++
 metrics.go | 141 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 149 insertions(+), 1 deletion(-)
 create mode 100644 metrics.go

diff --git a/go.mod b/go.mod
index 630a3eb..c9b70b0 100644
--- a/go.mod
+++ b/go.mod
@@ -6,7 +6,7 @@ require (
 	github.com/caarlos0/env/v10 v10.0.0
 	github.com/dmitrorezn/golang-lru/v2 v2.0.2
 	github.com/redis/go-redis/v9 v9.5.1
-	github.com/stretchr/testify v1.8.1
+	github.com/stretchr/testify v1.9.0
 	go.uber.org/zap v1.27.0
 	golang.org/x/sync v0.6.0
 )
@@ -17,6 +17,8 @@ require (
 	github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
 	github.com/vmihailenco/go-tinylfu v0.2.2 // indirect
+	go.opentelemetry.io/otel v1.25.0 // indirect
+	go.opentelemetry.io/otel/metric v1.25.0 // indirect
 	go.uber.org/multierr v1.10.0 // indirect
 	google.golang.org/protobuf v1.33.0 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
diff --git a/go.sum b/go.sum
index 91570cc..372ce8e 100644
--- a/go.sum
+++ b/go.sum
@@ -26,8 +26,13 @@ github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/
 github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
 github.com/stretchr/testify v1.8.1 h1:w7B6lhMri9wdJUVmEZPGGhZzrYTPvgJArz7wNPgYKsk=
 github.com/stretchr/testify v1.8.1/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
+github.com/stretchr/testify v1.9.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
 github.com/vmihailenco/go-tinylfu v0.2.2 h1:H1eiG6HM36iniK6+21n9LLpzx1G9R3DJa2UjUjbynsI=
 github.com/vmihailenco/go-tinylfu v0.2.2/go.mod h1:CutYi2Q9puTxfcolkliPq4npPuofg9N9t8JVrjzwa3Q=
+go.opentelemetry.io/otel v1.25.0 h1:gldB5FfhRl7OJQbUHt/8s0a7cE8fbsPAtdpRaApKy4k=
+go.opentelemetry.io/otel v1.25.0/go.mod h1:Wa2ds5NOXEMkCmUou1WA7ZBfLTHWIsp034OVD7AO+Vg=
+go.opentelemetry.io/otel/metric v1.25.0 h1:LUKbS7ArpFL/I2jJHdJcqMGxkRdxpPHE0VU/D4NuEwA=
+go.opentelemetry.io/otel/metric v1.25.0/go.mod h1:rkDLUSd2lC5lq2dFNrX9LGAbINP5B7WBkC78RXCpH5s=
 go.uber.org/goleak v1.3.0 h1:2K3zAYmnTNqV73imy9J1T3WC+gmCePx2hEGkimedGto=
 go.uber.org/goleak v1.3.0/go.mod h1:CoHD4mav9JJNrW/WLlf7HGZPjdw8EucARQHekz1X6bE=
 go.uber.org/multierr v1.10.0 h1:S0h4aNzvfcFsC3dRF1jLoaov7oRaKqRGC/pUEJ2yvPQ=
diff --git a/metrics.go b/metrics.go
new file mode 100644
index 0000000..bce6627
--- /dev/null
+++ b/metrics.go
@@ -0,0 +1,141 @@
+package wredis
+
+import (
+	"context"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/metric"
+
+	"github.com/redis/go-redis/v9"
+)
+
+type MetricsClient struct {
+	UniversalClient
+	meter *Meter
+}
+
+func NewMetricsClient(
+	name string,
+	client UniversalClient,
+	metricProvider metric.MeterProvider,
+) *MetricsClient {
+	return &MetricsClient{
+		UniversalClient: client,
+		meter:           NewMeter(name, metricProvider.Meter("wredis")),
+	}
+}
+
+type Meter struct {
+	name string
+
+	cmu      sync.RWMutex
+	counters map[string]metric.Int64Counter
+
+	hmu        sync.RWMutex
+	histograms map[string]metric.Float64Histogram
+
+	gauge map[string]atomic.Int64
+
+	meter metric.Meter
+}
+
+func NewMeter(name string, meter metric.Meter) *Meter {
+	return &Meter{
+		name:  name,
+		meter: meter,
+	}
+}
+
+func (m *Meter) Observe(ctx context.Context, cmd string) func(err error) {
+	var (
+		start   = time.Now()
+		attrOpt = metric.WithAttributes(
+			attribute.String("name", m.name),
+			attribute.String("cmd", cmd),
+		)
+	)
+	m.cmu.RLock()
+	cnt, ok := m.counters[cmd]
+	m.cmu.RUnlock()
+	var err error
+	if !ok {
+		if cnt, err = m.meter.Int64Counter(cmd); err == nil {
+			m.cmu.Lock()
+			m.counters[cmd] = cnt
+			m.cmu.Unlock()
+		}
+	}
+
+	gauge, ok := m.gauge[cmd]
+	if !ok {
+		_, _ = m.meter.Int64ObservableGauge(cmd, metric.WithInt64Callback(func(ctx context.Context, observer metric.Int64Observer) error {
+			observer.Observe(gauge.Load(), attrOpt)
+			return nil
+		}))
+	}
+	gauge.Add(1)
+
+	m.hmu.RLock()
+	histogram, ok := m.histograms[cmd]
+	m.hmu.RUnlock()
+	if !ok {
+		if histogram, err = m.meter.Float64Histogram(cmd); err == nil {
+			m.cmu.Lock()
+			m.histograms[cmd] = histogram
+			m.cmu.Unlock()
+		}
+	}
+
+	return func(err error) {
+		cnt.Add(ctx, 1, attrOpt, metric.WithAttributes(attribute.Bool("error", err != nil)))
+
+		histogram.Record(
+			ctx,
+			time.Since(start).Seconds(),
+			attrOpt,
+			metric.WithAttributes(
+				attribute.Bool("error", err != nil),
+			),
+		)
+
+		gauge.Add(-1)
+	}
+}
+
+func (s *MetricsClient) Get(ctx context.Context, key string) (cmd *redis.StringCmd) {
+	defer s.meter.Observe(ctx, "Get")(cmd.Err())
+
+	return s.UniversalClient.Get(ctx, key)
+}
+
+func (s *MetricsClient) HGet(ctx context.Context, key, field string) (cmd *redis.StringCmd) {
+	defer s.meter.Observe(ctx, "HGet")(cmd.Err())
+
+	return s.UniversalClient.HGet(ctx, key, field)
+}
+
+func (s *MetricsClient) GetDel(ctx context.Context, key string) (cmd *redis.StringCmd) {
+	defer s.meter.Observe(ctx, "GetDel")(cmd.Err())
+
+	return s.UniversalClient.GetDel(ctx, key)
+}
+
+func (s *MetricsClient) HMGet(ctx context.Context, key string, field ...string) (cmd *redis.SliceCmd) {
+	defer s.meter.Observe(ctx, "HMGet")(cmd.Err())
+
+	return s.UniversalClient.HMGet(ctx, key, field...)
+}
+
+func (s *MetricsClient) HGetAll(ctx context.Context, key string) (cmd *redis.MapStringStringCmd) {
+	defer s.meter.Observe(ctx, "HGetAll")(cmd.Err())
+
+	return s.UniversalClient.HGetAll(ctx, key)
+}
+
+/*
+	TO DO
+	....
+*/