Split setting.go as multiple files (#6014)

* split setting.go as multiple files

* fix comments

modules/setting/cache.go

@@ -0,0 +1,43 @@
+// Copyright 2019 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package setting
+
+import (
+	"strings"
+	"time"
+
+	"code.gitea.io/gitea/modules/log"
+)
+
+// Cache represents cache settings
+type Cache struct {
+	Adapter  string
+	Interval int
+	Conn     string
+	TTL      time.Duration
+}
+
+var (
+	// CacheService the global cache
+	CacheService *Cache
+)
+
+func newCacheService() {
+	sec := Cfg.Section("cache")
+	CacheService = &Cache{
+		Adapter: sec.Key("ADAPTER").In("memory", []string{"memory", "redis", "memcache"}),
+	}
+	switch CacheService.Adapter {
+	case "memory":
+		CacheService.Interval = sec.Key("INTERVAL").MustInt(60)
+	case "redis", "memcache":
+		CacheService.Conn = strings.Trim(sec.Key("HOST").String(), "\" ")
+	default:
+		log.Fatal(4, "Unknown cache adapter: %s", CacheService.Adapter)
+	}
+	CacheService.TTL = sec.Key("ITEM_TTL").MustDuration(16 * time.Hour)
+
+	log.Info("Cache Service Enabled")
+}