chore: Fix flaky metrics tests (googleapis#1865)

This fixes a few flaky unit tests that relied on `Thread.sleep` to ensure that all metrics processing was done.  Rather than using `Thread.sleep`, we can instead use an inline event queue in the OpenCensus stats component to execute all work inline, removing the need to wait for anything to finish.

google-cloud-bigtable/src/test/java/com/google/cloud/bigtable/data/v2/stub/metrics/BigtableTracerCallableTest.java

@@ -19,6 +19,7 @@
 import static org.junit.Assert.fail;
 
 import com.google.api.gax.rpc.ClientContext;
+import com.google.api.gax.rpc.ServerStream;
 import com.google.api.gax.rpc.UnavailableException;
 import com.google.bigtable.v2.BigtableGrpc.BigtableImplBase;
 import com.google.bigtable.v2.CheckAndMutateRowRequest;
@@ -54,7 +55,6 @@
 import io.grpc.Status;
 import io.grpc.StatusRuntimeException;
 import io.grpc.stub.StreamObserver;
-import io.opencensus.impl.stats.StatsComponentImpl;
 import io.opencensus.stats.StatsComponent;
 import io.opencensus.tags.TagKey;
 import io.opencensus.tags.TagValue;
@@ -74,7 +74,7 @@ public class BigtableTracerCallableTest {
 
   private FakeService fakeService = new FakeService();
 
-  private final StatsComponent localStats = new StatsComponentImpl();
+  private final StatsComponent localStats = new SimpleStatsComponent();
   private EnhancedBigtableStub stub;
   private EnhancedBigtableStub noHeaderStub;
   private int attempts;
@@ -157,10 +157,9 @@ public void tearDown() {
   }
 
   @Test
-  public void testGFELatencyMetricReadRows() throws InterruptedException {
-    stub.readRowsCallable().call(Query.create(TABLE_ID));
-
-    Thread.sleep(WAIT_FOR_METRICS_TIME_MS);
+  public void testGFELatencyMetricReadRows() {
+    ServerStream<?> call = stub.readRowsCallable().call(Query.create(TABLE_ID));
+    call.forEach(r -> {});
 
     long latency =
         StatsTestUtils.getAggregationValueAsLong(

google-cloud-bigtable/src/test/java/com/google/cloud/bigtable/data/v2/stub/metrics/BuiltinMetricsTracerTest.java

@@ -109,6 +109,7 @@ public class BuiltinMetricsTracerTest {
   private static final long FAKE_SERVER_TIMING = 50;
   private static final long SERVER_LATENCY = 100;
   private static final long APPLICATION_LATENCY = 200;
+  private static final long SLEEP_VARIABILITY = 15;
 
   private static final long CHANNEL_BLOCKING_LATENCY = 75;
 
@@ -353,7 +354,11 @@ public void onComplete() {
         .recordOperation(status.capture(), tableId.capture(), zone.capture(), cluster.capture());
 
     assertThat(counter.get()).isEqualTo(fakeService.getResponseCounter().get());
-    assertThat(applicationLatency.getValue()).isAtLeast(APPLICATION_LATENCY * counter.get());
+    // Thread.sleep might not sleep for the requested amount depending on the interrupt period
+    // defined by the OS.
+    // On linux this is ~1ms but on windows may be as high as 15-20ms.
+    assertThat(applicationLatency.getValue())
+        .isAtLeast((APPLICATION_LATENCY - SLEEP_VARIABILITY) * counter.get());
     assertThat(applicationLatency.getValue())
         .isAtMost(operationLatency.getValue() - SERVER_LATENCY);
   }

google-cloud-bigtable/src/test/java/com/google/cloud/bigtable/data/v2/stub/metrics/MetricsTracerTest.java

@@ -55,7 +55,7 @@
 import io.grpc.Status;
 import io.grpc.StatusRuntimeException;
 import io.grpc.stub.StreamObserver;
-import io.opencensus.impl.stats.StatsComponentImpl;
+import io.opencensus.stats.StatsComponent;
 import io.opencensus.tags.TagKey;
 import io.opencensus.tags.TagValue;
 import io.opencensus.tags.Tags;
@@ -85,6 +85,7 @@ public class MetricsTracerTest {
   private static final String INSTANCE_ID = "fake-instance";
   private static final String APP_PROFILE_ID = "default";
   private static final String TABLE_ID = "fake-table";
+  private static final long SLEEP_VARIABILITY = 15;
 
   private static final ReadRowsResponse DEFAULT_READ_ROWS_RESPONSES =
       ReadRowsResponse.newBuilder()
@@ -105,7 +106,7 @@ public class MetricsTracerTest {
   @Mock(answer = Answers.CALLS_REAL_METHODS)
   private BigtableGrpc.BigtableImplBase mockService;
 
-  private final StatsComponentImpl localStats = new StatsComponentImpl();
+  private final StatsComponent localStats = new SimpleStatsComponent();
   private EnhancedBigtableStub stub;
   private BigtableDataSettings settings;
 
@@ -157,9 +158,6 @@ public Object answer(InvocationOnMock invocation) throws Throwable {
     Lists.newArrayList(stub.readRowsCallable().call(Query.create(TABLE_ID)));
     long elapsed = stopwatch.elapsed(TimeUnit.MILLISECONDS);
 
-    // Give OpenCensus a chance to update the views asynchronously.
-    Thread.sleep(100);
-
     long opLatency =
         StatsTestUtils.getAggregationValueAsLong(
             localStats,
@@ -193,9 +191,6 @@ public Object answer(InvocationOnMock invocation) {
     Lists.newArrayList(stub.readRowsCallable().call(Query.create(TABLE_ID)));
     Lists.newArrayList(stub.readRowsCallable().call(Query.create(TABLE_ID)));
 
-    // Give OpenCensus a chance to update the views asynchronously.
-    Thread.sleep(100);
-
     long opLatency =
         StatsTestUtils.getAggregationValueAsLong(
             localStats,
@@ -247,8 +242,6 @@ public void testReadRowsFirstRow() throws InterruptedException {
     }
     long elapsed = stopwatch.elapsed(TimeUnit.MILLISECONDS);
 
-    // Give OpenCensus a chance to update the views asynchronously.
-    Thread.sleep(100);
     executor.shutdown();
 
     long firstRowLatency =
@@ -260,7 +253,10 @@ public void testReadRowsFirstRow() throws InterruptedException {
             INSTANCE_ID,
             APP_PROFILE_ID);
 
-    assertThat(firstRowLatency).isIn(Range.closed(beforeSleep, elapsed - afterSleep));
+    assertThat(firstRowLatency)
+        .isIn(
+            Range.closed(
+                beforeSleep - SLEEP_VARIABILITY, elapsed - afterSleep + SLEEP_VARIABILITY));
   }
 
   @Test
@@ -292,9 +288,6 @@ public Object answer(InvocationOnMock invocation) {
 
     Lists.newArrayList(stub.readRowsCallable().call(Query.create(TABLE_ID)));
 
-    // Give OpenCensus a chance to update the views asynchronously.
-    Thread.sleep(100);
-
     long opLatency =
         StatsTestUtils.getAggregationValueAsLong(
             localStats,
@@ -341,9 +334,6 @@ public Object answer(InvocationOnMock invocation) throws Throwable {
     Lists.newArrayList(stub.readRowsCallable().call(Query.create(TABLE_ID)));
     long elapsed = stopwatch.elapsed(TimeUnit.MILLISECONDS);
 
-    // Give OpenCensus a chance to update the views asynchronously.
-    Thread.sleep(100);
-
     long attemptLatency =
         StatsTestUtils.getAggregationValueAsLong(
             localStats,
@@ -360,12 +350,11 @@ public Object answer(InvocationOnMock invocation) throws Throwable {
   }
 
   @Test
-  public void testInvalidRequest() throws InterruptedException {
+  public void testInvalidRequest() {
     try {
       stub.bulkMutateRowsCallable().call(BulkMutation.create(TABLE_ID));
       Assert.fail("Invalid request should throw exception");
     } catch (IllegalStateException e) {
-      Thread.sleep(100);
       // Verify that the latency is recorded with an error code (in this case UNKNOWN)
       long attemptLatency =
           StatsTestUtils.getAggregationValueAsLong(
@@ -403,9 +392,6 @@ public Object answer(InvocationOnMock invocation) {
       batcher.add(ByteString.copyFromUtf8("row1"));
       batcher.sendOutstanding();
 
-      // Give OpenCensus a chance to update the views asynchronously.
-      Thread.sleep(100);
-
       long throttledTimeMetric =
           StatsTestUtils.getAggregationValueAsLong(
               localStats,
@@ -476,7 +462,6 @@ public Object answer(InvocationOnMock invocation) {
     batcher.add(RowMutationEntry.create("key"));
     batcher.sendOutstanding();
 
-    Thread.sleep(100);
     long throttledTimeMetric =
         StatsTestUtils.getAggregationValueAsLong(
             localStats,

google-cloud-bigtable/src/test/java/com/google/cloud/bigtable/data/v2/stub/metrics/SimpleStatsComponent.java

@@ -0,0 +1,27 @@
+/*
+ * Copyright 2020 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.cloud.bigtable.data.v2.stub.metrics;
+
+import io.opencensus.implcore.common.MillisClock;
+import io.opencensus.implcore.internal.SimpleEventQueue;
+import io.opencensus.implcore.stats.StatsComponentImplBase;
+
+/** A StatsComponent implementation for testing that executes all events inline. */
+public class SimpleStatsComponent extends StatsComponentImplBase {
+  public SimpleStatsComponent() {
+    super(new SimpleEventQueue(), MillisClock.getInstance());
+  }
+}