move cache to the separate package

pkg/cache/cache.go

@@ -0,0 +1,49 @@
+package cache
+
+import (
+	"crypto/sha1"
+	"encoding/hex"
+	"encoding/json"
+	"time"
+
+	"github.com/grafana/grafana-plugin-sdk-go/backend"
+	cache "github.com/patrickmn/go-cache"
+)
+
+// Cache is a abstraction over go-cache.
+type Cache struct {
+	cache *cache.Cache
+}
+
+// NewCache creates a go-cache with expiration(ttl) time and cleanupInterval.
+func NewCache(ttl time.Duration, cleanupInterval time.Duration) *Cache {
+	return &Cache{
+		cache.New(ttl, cleanupInterval),
+	}
+}
+
+// Set the value of the key "request" to "rersponse" with default expiration time.
+func (c *Cache) Set(request string, response interface{}) {
+	c.cache.SetDefault(request, response)
+}
+
+// Get the value associated with request from the cache
+func (c *Cache) Get(request string) (interface{}, bool) {
+	return c.cache.Get(request)
+}
+
+// HashString converts the given text string to hash string
+func HashString(text string) string {
+	hash := sha1.New()
+	hash.Write([]byte(text))
+	return hex.EncodeToString(hash.Sum(nil))
+}
+
+// HashDatasourceInfo converts the given datasource info to hash string
+func HashDatasourceInfo(dsInfo *backend.DataSourceInstanceSettings) string {
+	digester := sha1.New()
+	if err := json.NewEncoder(digester).Encode(dsInfo); err != nil {
+		panic(err) // This shouldn't be possible but just in case DatasourceInfo changes
+	}
+	return hex.EncodeToString(digester.Sum(nil))
+}