Make native metrics handle creation singleton (#745)

* Make native metrics handle creation singleton
Fixes #743

* Add tests for making native metrics handle creation singleton

Co-authored-by: Sriramprabhu Sankaraguru <s.sankara@sea.samsung.com>

AutoCollection/NativePerformance.ts

@@ -81,8 +81,10 @@ export class AutoCollectNativePerformance {
         if (this._isEnabled && AutoCollectNativePerformance._emitter) {
             // enable self
             AutoCollectNativePerformance._emitter.enable(true, collectionInterval);
-            this._handle = setInterval(() => this._trackNativeMetrics(), collectionInterval);
-            this._handle.unref();
+            if (!this._handle) {
+                this._handle = setInterval(() => this._trackNativeMetrics(), collectionInterval);
+                this._handle.unref();
+            }
         } else if (AutoCollectNativePerformance._emitter) {
             // disable self
             AutoCollectNativePerformance._emitter.enable(false);

Tests/AutoCollection/NativePerformance.tests.ts

@@ -47,6 +47,19 @@ describe("AutoCollection/NativePerformance", () => {
                 assert.ok(disposeSpy.calledOnce, "dispose is called when second instance is constructed");
             });
 
+            it("Calling enable multiple times shoud not create multiple timers", () => {
+                var client = new TelemetryClient("1aa11111-bbbb-1ccc-8ddd-eeeeffff3333");
+                var native = new AutoCollectNativePerformance(client);
+                var setIntervalSpy = sinon.spy(global, "setInterval");
+
+                assert.ok(native);
+                assert.doesNotThrow(() => native.enable(true), "Does not throw when tryinig to enable");
+                assert.doesNotThrow(() => native.enable(true), "Does not throw when trying to enable");
+                assert.equal(setIntervalSpy.callCount, 1, "setInterval should be singleton");
+
+                setIntervalSpy.restore();
+            });
+
             it("Calling enable when metrics are not available should fail gracefully", () => {
                 var client = new TelemetryClient("1aa11111-bbbb-1ccc-8ddd-eeeeffff3333");
                 var native = new AutoCollectNativePerformance(client);