[#131] registry: Allow to create cycled/forward selectors

Signed-off-by: Dmitrii Stepanov <d.stepanov@yadro.com>

cmd/xk6-registry-exporter/root.go

@@ -78,7 +78,7 @@ func rootCmdRun(cmd *cobra.Command, args []string) error {
 	}
 
 	objRegistry := registry.NewObjRegistry(cmd.Context(), args[0])
-	objSelector := registry.NewObjSelector(objRegistry, 0, &registry.ObjFilter{
+	objSelector := registry.NewObjSelector(objRegistry, 0, false, &registry.ObjFilter{
 		Status: status,
 		Age:    age,
 	})

internal/registry/obj_selector.go

@@ -20,6 +20,7 @@ type ObjSelector struct {
 	boltDB    *bbolt.DB
 	filter    *ObjFilter
 	cacheSize int
+	looped    bool
 }
 
 // objectSelectCache is the default maximum size of a batch to select from DB.
@@ -27,7 +28,7 @@ const objectSelectCache = 1000
 
 // NewObjSelector creates a new instance of object selector that can iterate over
 // objects in the specified registry.
-func NewObjSelector(registry *ObjRegistry, selectionSize int, filter *ObjFilter) *ObjSelector {
+func NewObjSelector(registry *ObjRegistry, selectionSize int, looped bool, filter *ObjFilter) *ObjSelector {
 	if selectionSize <= 0 {
 		selectionSize = objectSelectCache
 	}
@@ -40,6 +41,7 @@ func NewObjSelector(registry *ObjRegistry, selectionSize int, filter *ObjFilter)
 		filter:    filter,
 		objChan:   make(chan *ObjectInfo, selectionSize*2),
 		cacheSize: selectionSize,
+		looped:    looped,
 	}
 
 	go objSelector.selectLoop()
@@ -160,13 +162,16 @@ func (o *ObjSelector) selectLoop() {
 			}
 		}
 
-		if len(cache) != o.cacheSize {
+		if !o.looped && len(cache) != o.cacheSize {
 			// no more objects, wait a little; the logic could be improved.
 			select {
 			case <-time.After(time.Second):
 			case <-o.ctx.Done():
 				return
 			}
+		}
+
+		if o.looped && len(cache) != o.cacheSize {
 			lastID = 0
 		}
 

internal/registry/registry.go

@@ -75,6 +75,14 @@ func (r *Registry) open(dbFilePath string) *ObjRegistry {
 }
 
 func (r *Registry) GetSelector(dbFilePath string, name string, cacheSize int, filter map[string]string) *ObjSelector {
+	return r.getSelectorInternal(dbFilePath, name, cacheSize, false, filter)
+}
+
+func (r *Registry) GetLoopedSelector(dbFilePath string, name string, cacheSize int, filter map[string]string) *ObjSelector {
+	return r.getSelectorInternal(dbFilePath, name, cacheSize, true, filter)
+}
+
+func (r *Registry) getSelectorInternal(dbFilePath string, name string, cacheSize int, looped bool, filter map[string]string) *ObjSelector {
 	objFilter, err := parseFilter(filter)
 	if err != nil {
 		panic(err)
@@ -86,7 +94,7 @@ func (r *Registry) GetSelector(dbFilePath string, name string, cacheSize int, fi
 	selector := r.root.selectors[name]
 	if selector == nil {
 		registry := r.open(dbFilePath)
-		selector = NewObjSelector(registry, cacheSize, objFilter)
+		selector = NewObjSelector(registry, cacheSize, looped, objFilter)
 		r.root.selectors[name] = selector
 	} else if !reflect.DeepEqual(selector.filter, objFilter) {
 		panic(fmt.Sprintf("selector %s already has been created with a different filter", name))

scenarios/grpc.js

@@ -57,7 +57,7 @@ if (registry_enabled && delete_age) {
 const read_age = __ENV.READ_AGE ? parseInt(__ENV.READ_AGE) : 10;
 let obj_to_read_selector = undefined;
 if (registry_enabled) {
-    obj_to_read_selector = registry.getSelector(
+    obj_to_read_selector = registry.getLoopedSelector(
         __ENV.REGISTRY_FILE,
         "obj_to_read",
         __ENV.SELECTION_SIZE ? parseInt(__ENV.SELECTION_SIZE) : 0,

scenarios/grpc_car.js

@@ -57,7 +57,7 @@ if (registry_enabled && delete_age) {
 const read_age = __ENV.READ_AGE ? parseInt(__ENV.READ_AGE) : 10;
 let obj_to_read_selector = undefined;
 if (registry_enabled) {
-    obj_to_read_selector = registry.getSelector(
+    obj_to_read_selector = registry.getLoopedSelector(
         __ENV.REGISTRY_FILE,
         "obj_to_read",
         __ENV.SELECTION_SIZE ? parseInt(__ENV.SELECTION_SIZE) : 0,

scenarios/s3.js

@@ -56,7 +56,7 @@ if (registry_enabled && delete_age) {
 const read_age = __ENV.READ_AGE ? parseInt(__ENV.READ_AGE) : 10;
 let obj_to_read_selector = undefined;
 if (registry_enabled) {
-    obj_to_read_selector = registry.getSelector(
+    obj_to_read_selector = registry.getLoopedSelector(
         __ENV.REGISTRY_FILE,
         "obj_to_read",
         __ENV.SELECTION_SIZE ? parseInt(__ENV.SELECTION_SIZE) : 0,

scenarios/s3_car.js

@@ -56,7 +56,7 @@ if (registry_enabled && delete_age) {
 const read_age = __ENV.READ_AGE ? parseInt(__ENV.READ_AGE) : 10;
 let obj_to_read_selector = undefined;
 if (registry_enabled) {
-    obj_to_read_selector = registry.getSelector(
+    obj_to_read_selector = registry.getLoopedSelector(
         __ENV.REGISTRY_FILE,
         "obj_to_read",
         __ENV.SELECTION_SIZE ? parseInt(__ENV.SELECTION_SIZE) : 0,

scenarios/s3local.js

@@ -54,7 +54,7 @@ const obj_registry = registry_enabled ? registry.open(__ENV.REGISTRY_FILE) : und
 
 let obj_to_read_selector = undefined;
 if (registry_enabled) {
-    obj_to_read_selector = registry.getSelector(
+    obj_to_read_selector = registry.getLoopedSelector(
         __ENV.REGISTRY_FILE,
         "obj_to_read",
         __ENV.SELECTION_SIZE ? parseInt(__ENV.SELECTION_SIZE) : 0,