add transformSpan callback (#1331)

Author: waltjones

src/tracing/spanProcessor.js

@@ -1,6 +1,9 @@
+import logger from '../logger.js';
+
 export class SpanProcessor {
-  constructor(exporter) {
+  constructor(exporter, options = {}) {
     this.exporter = exporter;
+    this.options = options;
     this.pendingSpans = new Map()
   }
 
@@ -9,6 +12,13 @@ export class SpanProcessor {
   }
 
   onEnd(span) {
+    try {
+      if (this.options.transformSpan) {
+        this.options.transformSpan({span: span.span});
+      }
+    } catch (e) {
+      logger.error('Error running transformSpan callback', e);
+    }
     this.exporter.export([span.export()])
     this.pendingSpans.delete(span.span.spanContext.spanId);
   }

src/tracing/tracing.js

@@ -60,7 +60,7 @@ export default class Tracing {
   createTracer() {
     this.contextManager = new ContextManager();
     this.exporter = new SpanExporter();
-    this.spanProcessor = new SpanProcessor(this.exporter);
+    this.spanProcessor = new SpanProcessor(this.exporter, this.options.tracing);
     this.tracer = new Tracer(this, this.spanProcessor);
   }
 

test/tracing/spanProcessor.test.js

@@ -67,4 +67,57 @@ describe('SpanProcessor()', function () {
 
     done();
   });
+
+  it('should transform spans', function (done) {
+    const tracingOptions = {
+      transformSpan: ({span}) => {
+        span.attributes['test-group'] = 'blue';
+        span.resource.attributes['rollbar.environment'] = 'prod-3';
+      },
+    };
+    const exporter = new SpanExporter();
+    const spanProcessor = new SpanProcessor(exporter, tracingOptions);
+
+    expect(spanProcessor.pendingSpans.size).to.equal(0);
+
+    const overrides = {
+      spanProcessor: spanProcessor,
+    };
+    const span = new Span(spanOptions(overrides));
+
+    expect(spanProcessor.pendingSpans.size).to.equal(1);
+
+    span.end();
+
+    expect(span.span.attributes['test-group']).to.equal('blue');
+    expect(span.span.resource.attributes['rollbar.environment']).to.equal('prod-3');
+    expect(spanProcessor.pendingSpans.size).to.equal(0);
+
+    done();
+  });
+
+  it('should catch exception in transformSpan', function (done) {
+    const tracingOptions = {
+      transformSpan: ({span}) => {
+        throw new Error('test error');
+      },
+    };
+    const exporter = new SpanExporter();
+    const spanProcessor = new SpanProcessor(exporter, tracingOptions);
+
+    expect(spanProcessor.pendingSpans.size).to.equal(0);
+
+    const overrides = {
+      spanProcessor: spanProcessor,
+    };
+    const span = new Span(spanOptions(overrides));
+
+    expect(spanProcessor.pendingSpans.size).to.equal(1);
+
+    span.end();
+
+    expect(spanProcessor.pendingSpans.size).to.equal(0);
+
+    done();
+  });
 });