Overwrite the sampling probability to default for stats exporters. (#1219)

* Overwrite the sampling probability to default for stats exporters.

* Fix a typo

3 files changed, 20 insertions, 4 deletions

diff --git a/exporters/stats/prometheus/src/main/java/io/opencensus/exporter/stats/prometheus/PrometheusStatsCollector.java b/exporters/stats/prometheus/src/main/java/io/opencensus/exporter/stats/prometheus/PrometheusStatsCollector.java
index 2f4d189d..5c089ab2 100644
--- a/exporters/stats/prometheus/src/main/java/io/opencensus/exporter/stats/prometheus/PrometheusStatsCollector.java
+++ b/exporters/stats/prometheus/src/main/java/io/opencensus/exporter/stats/prometheus/PrometheusStatsCollector.java
@@ -28,10 +28,12 @@ import io.opencensus.stats.Stats;
 import io.opencensus.stats.View;
 import io.opencensus.stats.ViewData;
 import io.opencensus.stats.ViewManager;
+import io.opencensus.trace.Sampler;
 import io.opencensus.trace.Span;
 import io.opencensus.trace.Status;
 import io.opencensus.trace.Tracer;
 import io.opencensus.trace.Tracing;
+import io.opencensus.trace.samplers.Samplers;
 import io.prometheus.client.Collector;
 import io.prometheus.client.CollectorRegistry;
 import java.util.List;
@@ -48,6 +50,7 @@ public final class PrometheusStatsCollector extends Collector implements Collect
 
   private static final Logger logger = Logger.getLogger(PrometheusStatsCollector.class.getName());
   private static final Tracer tracer = Tracing.getTracer();
+  private static final Sampler probabilitySampler = Samplers.probabilitySampler(0.0001);
 
   private final ViewManager viewManager;
 
@@ -91,7 +94,12 @@ public final class PrometheusStatsCollector extends Collector implements Collect
   @Override
   public List<MetricFamilySamples> collect() {
     List<MetricFamilySamples> samples = Lists.newArrayList();
-    Span span = tracer.spanBuilder("ExportStatsToPrometheus").setRecordEvents(true).startSpan();
+    Span span =
+        tracer
+            .spanBuilder("ExportStatsToPrometheus")
+            .setSampler(probabilitySampler)
+            .setRecordEvents(true)
+            .startSpan();
     span.addAnnotation("Collect Prometheus Metric Samples.");
     try (Scope scope = tracer.withSpan(span)) {
       for (View view : viewManager.getAllExportedViews()) {
@@ -126,7 +134,11 @@ public final class PrometheusStatsCollector extends Collector implements Collect
   public List<MetricFamilySamples> describe() {
     List<MetricFamilySamples> samples = Lists.newArrayList();
     Span span =
-        tracer.spanBuilder("DescribeMetricsForPrometheus").setRecordEvents(true).startSpan();
+        tracer
+            .spanBuilder("DescribeMetricsForPrometheus")
+            .setSampler(probabilitySampler)
+            .setRecordEvents(true)
+            .startSpan();
     span.addAnnotation("Describe Prometheus Metrics.");
     try (Scope scope = tracer.withSpan(span)) {
       for (View view : viewManager.getAllExportedViews()) {
diff --git a/exporters/stats/stackdriver/src/main/java/io/opencensus/exporter/stats/stackdriver/StackdriverExporterWorker.java b/exporters/stats/stackdriver/src/main/java/io/opencensus/exporter/stats/stackdriver/StackdriverExporterWorker.java
index 1a2dce19..5025c519 100644
--- a/exporters/stats/stackdriver/src/main/java/io/opencensus/exporter/stats/stackdriver/StackdriverExporterWorker.java
+++ b/exporters/stats/stackdriver/src/main/java/io/opencensus/exporter/stats/stackdriver/StackdriverExporterWorker.java
@@ -31,10 +31,12 @@ import io.opencensus.common.Scope;
 import io.opencensus.stats.View;
 import io.opencensus.stats.ViewData;
 import io.opencensus.stats.ViewManager;
+import io.opencensus.trace.Sampler;
 import io.opencensus.trace.Span;
 import io.opencensus.trace.Status;
 import io.opencensus.trace.Tracer;
 import io.opencensus.trace.Tracing;
+import io.opencensus.trace.samplers.Samplers;
 import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
@@ -72,6 +74,7 @@ final class StackdriverExporterWorker implements Runnable {
   private final Map<View.Name, View> registeredViews = new HashMap<View.Name, View>();
 
   private static final Tracer tracer = Tracing.getTracer();
+  private static final Sampler probabilitySampler = Samplers.probabilitySampler(0.0001);
 
   StackdriverExporterWorker(
       String projectId,
@@ -204,6 +207,7 @@ final class StackdriverExporterWorker implements Runnable {
           tracer
               .spanBuilder("ExportStatsToStackdriverMonitoring")
               .setRecordEvents(true)
+              .setSampler(probabilitySampler)
               .startSpan();
       try (Scope scope = tracer.withSpan(span)) {
         export();
diff --git a/exporters/trace/stackdriver/src/main/java/io/opencensus/exporter/trace/stackdriver/StackdriverV2ExporterHandler.java b/exporters/trace/stackdriver/src/main/java/io/opencensus/exporter/trace/stackdriver/StackdriverV2ExporterHandler.java
index 2e339400..4c0a6673 100644
--- a/exporters/trace/stackdriver/src/main/java/io/opencensus/exporter/trace/stackdriver/StackdriverV2ExporterHandler.java
+++ b/exporters/trace/stackdriver/src/main/java/io/opencensus/exporter/trace/stackdriver/StackdriverV2ExporterHandler.java
@@ -69,7 +69,7 @@ import org.checkerframework.checker.nullness.qual.Nullable;
 /** Exporter to Stackdriver Trace API v2. */
 final class StackdriverV2ExporterHandler extends SpanExporter.Handler {
   private static final Tracer tracer = Tracing.getTracer();
-  private static final Sampler probabilitySpampler = Samplers.probabilitySampler(0.0001);
+  private static final Sampler probabilitySampler = Samplers.probabilitySampler(0.0001);
   private static final String AGENT_LABEL_KEY = "g.co/agent";
   private static final String AGENT_LABEL_VALUE_STRING =
       "opencensus-java [" + OpenCensusLibraryInformation.VERSION + "]";
@@ -330,7 +330,7 @@ final class StackdriverV2ExporterHandler extends SpanExporter.Handler {
     try (Scope scope =
         tracer
             .spanBuilder("ExportStackdriverTraces")
-            .setSampler(probabilitySpampler)
+            .setSampler(probabilitySampler)
             .setRecordEvents(true)
             .startScopedSpan()) {
       List<Span> spans = new ArrayList<>(spanDataList.size());