Adds Tracing.getExportComponent().flushAndShutdown() for use within application shutdown hooks. (#1141)

Adds the ability to flush pending spans via a call to Tracing.getExportComponent().shutdown()

This allows a developer to force a flush from within a shutdown hook or other means.

Unfortunately the underlying Disruptor instance only provides a #shutdown() call, not a flush, or a public method
for testing for backlog. Thus shutdown has propagated up to the above api call.

1 files changed, 7 insertions, 0 deletions

diff --git a/api/src/main/java/io/opencensus/trace/export/ExportComponent.java b/api/src/main/java/io/opencensus/trace/export/ExportComponent.java
index 63447a76..bf06089c 100644
--- a/api/src/main/java/io/opencensus/trace/export/ExportComponent.java
+++ b/api/src/main/java/io/opencensus/trace/export/ExportComponent.java
@@ -66,6 +66,13 @@ public abstract class ExportComponent {
    */
   public abstract SampledSpanStore getSampledSpanStore();
 
+  /**
+   * Will shutdown this ExportComponent after flushing any pending spans.
+   *
+   * @since 0.13
+   */
+  public void shutdown() {}
+
   private static final class NoopExportComponent extends ExportComponent {
     private final SampledSpanStore noopSampledSpanStore =
         SampledSpanStore.newNoopSampledSpanStore();