Add support for child span count (#332)

* Add support for child span count

* remove extra line

* remove unwanted check for child count

packages/opencensus-core/src/trace/model/root-span.ts

@@ -33,6 +33,8 @@ export class RootSpan extends SpanBase implements types.RootSpan {
   private traceStateLocal: types.TraceState;
   /** set isRootSpan = true */
   readonly isRootSpan = true;
+  /** A number of children. */
+  private numberOfChildrenLocal: number;
 
   /**
    * Constructs a new RootSpanImpl instance.
@@ -56,6 +58,7 @@ export class RootSpan extends SpanBase implements types.RootSpan {
         context && context.kind ? context.kind : types.SpanKind.UNSPECIFIED;
     this.logger = tracer.logger || logger.logger();
     this.activeTraceParams = tracer.activeTraceParams;
+    this.numberOfChildrenLocal = 0;
   }
 
   /** Gets span list from rootspan instance. */
@@ -73,6 +76,11 @@ export class RootSpan extends SpanBase implements types.RootSpan {
     return this.traceStateLocal;
   }
 
+  /** Gets the number of child span created for this span. */
+  get numberOfChildren(): number {
+    return this.numberOfChildrenLocal;
+  }
+
   /** Starts a rootspan instance. */
   start() {
     super.start();
@@ -121,6 +129,7 @@ export class RootSpan extends SpanBase implements types.RootSpan {
           this.className, {id: this.id, name: this.name, kind: this.kind});
       return null;
     }
+    this.numberOfChildrenLocal++;
     const newSpan = new Span(this);
     let spanName;
     let spanKind;

packages/opencensus-core/src/trace/model/types.ts

@@ -458,6 +458,9 @@ export interface RootSpan extends Span {
   /** Get the span list from RootSpan instance */
   readonly spans: Span[];
 
+  /** Gets the number of child span created for this span. */
+  readonly numberOfChildren: number;
+
   /** Starts a new Span instance in the RootSpan instance */
   startChildSpan(name?: string, kind?: SpanKind, parentSpanId?: string): Span;
   startChildSpan(options?: SpanOptions): Span;

packages/opencensus-core/test/test-root-span.ts

@@ -70,6 +70,21 @@ describe('RootSpan', () => {
     });
   });
 
+  describe('get numberOfChildren()', () => {
+    it('should get numberOfChildren from rootspan instance', () => {
+      const root = new RootSpan(tracer);
+      root.start();
+      assert.equal(root.numberOfChildren, 0);
+      root.startChildSpan('spanName', types.SpanKind.UNSPECIFIED);
+      assert.equal(root.numberOfChildren, 1);
+
+      for (let i = 0; i < 10; i++) {
+        root.startChildSpan('spanName' + i, types.SpanKind.UNSPECIFIED);
+      }
+      assert.equal(root.numberOfChildren, 11);
+    });
+  });
+
   /**
    * Should get trace id from rootspan instance
    */
@@ -209,7 +224,6 @@ describe('RootSpan', () => {
       rootSpan.addAnnotation('description test', {} as Attributes, Date.now());
 
       assert.ok(rootSpan.annotations.length > 0);
-      assert.equal(rootSpan.droppedAnnotationsCount, 0);
       assert.ok(instanceOfAnnotation(rootSpan.annotations[0]));
     });