caching the Zabbix API Queries (#807)

go.mod

@@ -9,5 +9,6 @@ require (
 	github.com/hashicorp/go-hclog v0.9.2
 	github.com/hashicorp/go-plugin v1.0.1
 	github.com/kr/pretty v0.1.0 // indirect
+	github.com/patrickmn/go-cache v2.1.0+incompatible
 	golang.org/x/net v0.0.0-20180826012351-8a410e7b638d
 )

go.sum

@@ -26,6 +26,8 @@ github.com/mitchellh/go-testing-interface v0.0.0-20171004221916-a61a99592b77 h1:
 github.com/mitchellh/go-testing-interface v0.0.0-20171004221916-a61a99592b77/go.mod h1:kRemZodwjscx+RGhAo8eIhFbs2+BFgRtFPeD/KE+zxI=
 github.com/oklog/run v1.0.0 h1:Ru7dDtJNOyC66gQ5dQmaCa0qIsAUFY3sFpK1Xk8igrw=
 github.com/oklog/run v1.0.0/go.mod h1:dlhp/R75TPv97u0XWUtDeV/lRKWPKSdTuV0TZvrmrQA=
+github.com/patrickmn/go-cache v2.1.0+incompatible h1:HRMgzkcYKYpi3C8ajMPV8OFXaaRUnok+kx1WdO15EQc=
+github.com/patrickmn/go-cache v2.1.0+incompatible/go.mod h1:3Qf8kWWT7OJRJbdiICTKqZju1ZixQ/KpMGzzAfe6+WQ=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=

pkg/cache.go

@@ -0,0 +1,38 @@
+package main
+
+import (
+	"crypto/sha1"
+	"encoding/hex"
+	"time"
+
+	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)
+}
+
+// Hash converts the given text string to hash string
+func Hash(text string) string {
+	hash := sha1.New()
+	hash.Write([]byte(text))
+	return hex.EncodeToString(hash.Sum(nil))
+}

pkg/zabbix_api.go

@@ -38,9 +38,14 @@ var httpClient = &http.Client{
 	Timeout: time.Duration(time.Second * 30),
 }
 
+var queryCache = NewCache(10*time.Minute, 10*time.Minute)
+
 var zabbixAuth string = ""
 
 func (ds *ZabbixDatasource) ZabbixAPIQuery(ctx context.Context, tsdbReq *datasource.DatasourceRequest) (*datasource.DatasourceResponse, error) {
+	result, queryExistInCache := queryCache.Get(Hash(tsdbReq.String()))
+
+	if !queryExistInCache {
 		dsInfo := tsdbReq.GetDatasource()
 		zabbixUrlStr := dsInfo.GetUrl()
 		zabbixUrl, err := url.Parse(zabbixUrlStr)
@@ -81,16 +86,18 @@ func (ds *ZabbixDatasource) ZabbixAPIQuery(ctx context.Context, tsdbReq *datasou
 		apiMethod := jsonQuery.Get("method").MustString()
 		apiParams := jsonQuery.Get("params")
 
-	result, err := ds.ZabbixRequest(ctx, dsInfo, apiMethod, apiParams)
+		result, err = ds.ZabbixRequest(ctx, dsInfo, apiMethod, apiParams)
+		queryCache.Set(Hash(tsdbReq.String()), result)
 		if err != nil {
 			ds.logger.Debug("ZabbixAPIQuery", "error", err)
 			return nil, errors.New("ZabbixAPIQuery is not implemented yet")
 		}
+	}
 
-	resultByte, err := result.MarshalJSON()
+	resultByte, _ := result.(*simplejson.Json).MarshalJSON()
 	ds.logger.Debug("ZabbixAPIQuery", "result", string(resultByte))
 
-	return ds.BuildResponse(result)
+	return ds.BuildResponse(result.(*simplejson.Json))
 }
 
 func (ds *ZabbixDatasource) BuildResponse(result *simplejson.Json) (*datasource.DatasourceResponse, error) {