fix: zipkin-exporter: don't export after shutdown (#526)

* fix: zipkin-exporter: don't export after shutdown

According to spec and exporter should return FailedNotRetryable error
after shutdown was called.

* chore: use setTimeout instead setImmediate for browsers

* chore: rename shutdown to isShutdown

packages/opentelemetry-exporter-zipkin/src/zipkin.ts

@@ -39,6 +39,7 @@ export class ZipkinExporter implements SpanExporter {
   private readonly _statusCodeTagName: string;
   private readonly _statusDescriptionTagName: string;
   private readonly _reqOpts: http.RequestOptions;
+  private _isShutdown: boolean;
 
   constructor(config: zipkinTypes.ExporterConfig) {
     const urlStr = config.url || ZipkinExporter.DEFAULT_URL;
@@ -60,6 +61,7 @@ export class ZipkinExporter implements SpanExporter {
     this._statusCodeTagName = config.statusCodeTagName || statusCodeTagName;
     this._statusDescriptionTagName =
       config.statusDescriptionTagName || statusDescriptionTagName;
+    this._isShutdown = false;
   }
 
   /**
@@ -70,6 +72,10 @@ export class ZipkinExporter implements SpanExporter {
     resultCallback: (result: ExportResult) => void
   ) {
     this._logger.debug('Zipkin exporter export');
+    if (this._isShutdown) {
+      setTimeout(() => resultCallback(ExportResult.FAILED_NOT_RETRYABLE));
+      return;
+    }
     return this._sendSpans(spans, resultCallback);
   }
 
@@ -78,6 +84,10 @@ export class ZipkinExporter implements SpanExporter {
    */
   shutdown() {
     this._logger.debug('Zipkin exporter shutdown');
+    if (this._isShutdown) {
+      return;
+    }
+    this._isShutdown = true;
     // Make an optimistic flush.
     if (this._forceFlush) {
       // @todo get spans from span processor (batch)

packages/opentelemetry-exporter-zipkin/test/zipkin.test.ts

@@ -311,6 +311,20 @@ describe('ZipkinExporter', () => {
         assert.strictEqual(result, ExportResult.FAILED_RETRYABLE);
       });
     });
+
+    it('should return FailedNonRetryable after shutdown', done => {
+      const exporter = new ZipkinExporter({
+        serviceName: 'my-service',
+        logger: new NoopLogger(),
+      });
+
+      exporter.shutdown();
+
+      exporter.export([getReadableSpan()], (result: ExportResult) => {
+        assert.strictEqual(result, ExportResult.FAILED_NOT_RETRYABLE);
+        done();
+      });
+    });
   });
 
   describe('shutdown', () => {