Merge pull request #355 from hello-wn/feat-cachext-monitor

monitor cache hit rate by prometheus

extensions/cachext/cached.go

@@ -10,6 +10,7 @@ import (
 	"time"
 
 	"github.com/RichardKnop/machinery/v1/log"
+	"github.com/prometheus/client_golang/prometheus"
 )
 
 const Nil = cacheNil("cache result is nil")
@@ -61,7 +62,16 @@ func (c *CachedConfig) GetResult(ctx context.Context, out interface{}, strArgs [
 	if err != nil {
 		return err
 	}
+	labels := prometheus.Labels{prefixName: c.cache.prefix, funcName: c.funcName}
+	if c.cache.requestCounter != nil {
+		// Increment request counter.
+		c.cache.requestCounter.With(labels).Inc()
+	}
 	if data != nil {
+		if c.cache.hitCounter != nil {
+			// Increment hit counter.
+			c.cache.hitCounter.With(labels).Inc()
+		}
 		if c.cacheNil && decodeIsNil(data) {
 			// 无法直接把out设置为nil，这里通过返回特殊的错误来表示nil。调用方需要判断
 			return Nil

extensions/cachext/ext.go

@@ -12,6 +12,8 @@ import (
 	"github.com/shanbay/gobay"
 	"github.com/spf13/viper"
 	"github.com/vmihailenco/msgpack"
+	"github.com/prometheus/client_golang/prometheus"
+	"github.com/prometheus/client_golang/prometheus/promauto"
 )
 
 type void struct{}
@@ -24,6 +26,8 @@ type CacheExt struct {
 	prefix         string
 	initialized    bool
 	cachedFuncName map[string]void
+	requestCounter *prometheus.CounterVec
+	hitCounter     *prometheus.CounterVec
 }
 
 var (
@@ -32,6 +36,13 @@ var (
 	mu         sync.Mutex
 )
 
+const (
+	prefixName = "prefix_name"
+	funcName   = "func_name"
+)
+
+var cacheLabels = []string{prefixName, funcName}
+
 // CacheBackend
 type CacheBackend interface {
 	Init(*viper.Viper) error
@@ -73,6 +84,10 @@ func (c *CacheExt) Init(app *gobay.Application) error {
 	} else {
 		return errors.New("No backend found for cache_backend:" + backendConfig)
 	}
+	if config.GetBool("monitor_enable") {
+		c.requestCounter = newCacheRequestCounter()
+		c.hitCounter = newCacheHitCounter()
+	}
 
 	c.initialized = true
 	return nil
@@ -240,3 +255,25 @@ func decodeIsNil(data interface{}) bool {
 	}
 	return false
 }
+
+// Create a collector for total cache request counter
+func newCacheRequestCounter() *prometheus.CounterVec {
+	return promauto.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "cache_request_counter",
+			Help: "Number of cache requests",
+		},
+		cacheLabels,
+	)
+}
+
+// Create a collector for cache hit counter
+func newCacheHitCounter() *prometheus.CounterVec {
+	return promauto.NewCounterVec(
+		prometheus.CounterOpts{
+			Name: "cache_hit_counter",
+			Help: "Number of cache hits",
+		},
+		cacheLabels,
+	)
+}

extensions/cachext/ext_test.go

@@ -3,13 +3,19 @@ package cachext_test
 import (
 	"context"
 	"fmt"
+	"io/ioutil"
+	"log"
 	"strings"
 	"testing"
 	"time"
 
+	"net/http"
+
+	"github.com/prometheus/client_golang/prometheus/promhttp"
 	"github.com/shanbay/gobay"
 	"github.com/shanbay/gobay/extensions/cachext"
 	_ "github.com/shanbay/gobay/extensions/cachext/backend/memory"
+	"github.com/stretchr/testify/assert"
 )
 
 func ExampleCacheExt_Set() {
@@ -577,3 +583,52 @@ func Benchmark_Cached(b *testing.B) {
 		}
 	}
 }
+
+func TestCacheExt_Cached_Monitor(t *testing.T) {
+	// 准备数据
+	cache := &cachext.CacheExt{NS: "cache_"}
+	exts := map[gobay.Key]gobay.Extension{
+		"cache": cache,
+	}
+	_, err := gobay.CreateApp("../../testdata/", "cachemonitored", exts)
+	assert.Nil(t, err)
+
+	fetchMetricData := func() string {
+		resp, err := http.Get("http://localhost:2112/metrics")
+		if err != nil {
+			t.Error(err)
+		}
+		defer resp.Body.Close()
+		rawData, err := ioutil.ReadAll(resp.Body)
+		if err != nil {
+			t.Error(err)
+		}
+		return string(rawData)
+	}
+
+	go func() {
+		http.Handle("/metrics", promhttp.Handler())
+		if err := http.ListenAndServe(":2112", nil); err != nil {
+			log.Fatalf("error when start prometheus server: %v\n", err)
+		}
+	}()
+
+	// Cache method
+	f_str := func(_ context.Context, keys []string, args []int64) (interface{}, error) {
+		return keys[0], nil
+	}
+	c_f_str := cache.Cached("f_str", f_str, cachext.WithTTL(10*time.Second))
+	str := ""
+
+	// Get result from function
+	c_f_str.GetResult(context.Background(), &str, []string{"hello"}, []int64{})
+	data := fetchMetricData()
+	assert.Contains(t, data, `cache_request_counter{func_name="f_str",prefix_name="github"} 1`)
+	assert.NotContains(t, data, `cache_hit_counter`)
+
+	// Get result from cache
+	c_f_str.GetResult(context.Background(), &str, []string{"hello"}, []int64{})
+	data = fetchMetricData()
+	assert.Contains(t, data, `cache_request_counter{func_name="f_str",prefix_name="github"} 2`)
+	assert.Contains(t, data, `cache_hit_counter{func_name="f_str",prefix_name="github"} 1`)
+}

go.mod

@@ -22,6 +22,7 @@ require (
 	github.com/mattn/go-sqlite3 v1.14.6
 	github.com/mitchellh/mapstructure v1.4.1
 	github.com/pkg/errors v0.9.1
+	github.com/prometheus/client_golang v1.11.0
 	github.com/prometheus/procfs v0.7.1 // indirect
 	github.com/satori/go.uuid v1.2.0
 	github.com/spf13/cobra v1.1.1