Add: Cacher interface and cache types

1. Add: Cacher interface and cache types. Fastcache implements this interface.

cachemdl/cache.go

+package cachemdl
+
+import (
+	"errors"
+	"time"
+
+	"github.com/patrickmn/go-cache"
+)
+
+const (
+	// TypeFastCache indicates fast cache as cache storage
+	TypeFastCache = iota + 1
+	// TypeRedisCache indicates redis server as cache storage. Use this in grid mode.
+	TypeRedisCache
+)
+
+var (
+	// ErrInvalidCacheType indicates provided cache type is not supportd
+	ErrInvalidCacheType = errors.New("invalid cache type provided")
+)
+
+// Cacher provides access to underlying cache, make sure all caches implement these methods.
+type Cacher interface {
+	// SET
+	Set(key string, val interface{})
+	SetWithExpiration(key string, val interface{}, exp time.Duration)
+	SetNoExpiration(key string, val interface{})
+
+	// GET
+	Get(key string) (interface{}, bool)
+	// GetAll() map[string]interface{}
+
+	// DELETE
+	Delete(key string)
+	// Purge()
+
+	// GetItemsCount
+	GetItemsCount() int
+}
+
+// GetCacheInstance returns a cache instance, panics if invalid cache type is provided
+func GetCacheInstance(cfg *CacheConfig) Cacher {
+	switch cfg.Type {
+	case TypeFastCache:
+		cfg.FastCache.Setup(10000, cache.NoExpiration, time.Minute*10)
+		return cfg.FastCache
+
+	default:
+		panic(ErrInvalidCacheType)
+	}
+}
+
+// CacheConfig -
+type CacheConfig struct {
+	Type      int
+	FastCache *FastCacheHelper
+}