common/http: rename to common/httpserver

This is a preparation to introduce an httpclient common package. And it
makes it easier to use http from the standard library.

common/httpserver/cache.go

@@ -0,0 +1,66 @@
+// SPDX-FileCopyrightText: 2022 Free Mobile
+// SPDX-License-Identifier: AGPL-3.0-only
+
+package httpserver
+
+import (
+	"bytes"
+	"crypto"
+	"io/ioutil"
+	"time"
+
+	cache "github.com/chenyahui/gin-cache"
+	"github.com/gin-gonic/gin"
+
+	"akvorado/common/reporter"
+)
+
+// CacheByRequestPath is a middleware to cache the request using path as key
+func (c *Component) CacheByRequestPath(expire time.Duration) gin.HandlerFunc {
+	opts := c.commonCacheOptions()
+	opts = append(opts, cache.WithCacheStrategyByRequest(func(gc *gin.Context) (bool, cache.Strategy) {
+		return true, cache.Strategy{
+			CacheKey: gc.Request.URL.Path,
+		}
+	}))
+	return cache.Cache(c.cacheStore, expire, opts...)
+}
+
+// CacheByRequestBody is a middleware to cache the request using body as key
+func (c *Component) CacheByRequestBody(expire time.Duration) gin.HandlerFunc {
+	opts := c.commonCacheOptions()
+	opts = append(opts, cache.WithCacheStrategyByRequest(func(gc *gin.Context) (bool, cache.Strategy) {
+		requestBody, err := gc.GetRawData()
+		gc.Request.Body = ioutil.NopCloser(bytes.NewBuffer(requestBody))
+		if err != nil {
+			return false, cache.Strategy{}
+		}
+		h := crypto.SHA256.New()
+		bodyHash := string(h.Sum(requestBody))
+		return true, cache.Strategy{
+			CacheKey: bodyHash,
+		}
+	}))
+	return cache.Cache(c.cacheStore, expire, opts...)
+}
+
+func (c *Component) commonCacheOptions() []cache.Option {
+	return []cache.Option{
+		cache.WithLogger(cacheLogger{c.r}),
+		cache.WithOnHitCache(func(gc *gin.Context) {
+			c.metrics.cacheHit.WithLabelValues(gc.Request.URL.Path, gc.Request.Method).Inc()
+		}),
+		cache.WithOnMissCache(func(gc *gin.Context) {
+			c.metrics.cacheMiss.WithLabelValues(gc.Request.URL.Path, gc.Request.Method).Inc()
+		}),
+		cache.WithPrefixKey("cache-"),
+	}
+}
+
+type cacheLogger struct {
+	r *reporter.Reporter
+}
+
+func (cl cacheLogger) Errorf(msg string, args ...interface{}) {
+	cl.r.Error().Msgf(msg, args...)
+}