util: OutlierDetection should use Ticker, not TimeProvider (grpc#12110)

TimeProvider provides wall time. That can move forward and backward as time is adjusted. OutlierDetection is measuring durations, so it should use a monotonic clock.

Fixes grpc#11622

Author: vimanikag

util/src/main/java/io/grpc/util/OutlierDetectionLoadBalancer.java

@@ -22,6 +22,7 @@
 import static java.util.concurrent.TimeUnit.NANOSECONDS;
 
 import com.google.common.annotations.VisibleForTesting;
+import com.google.common.base.Ticker;
 import com.google.common.collect.ForwardingMap;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableSet;
@@ -39,7 +40,6 @@
 import io.grpc.Status;
 import io.grpc.SynchronizationContext;
 import io.grpc.SynchronizationContext.ScheduledHandle;
-import io.grpc.internal.TimeProvider;
 import java.net.SocketAddress;
 import java.util.ArrayList;
 import java.util.Collection;
@@ -82,7 +82,7 @@ public final class OutlierDetectionLoadBalancer extends LoadBalancer {
   private final SynchronizationContext syncContext;
   private final Helper childHelper;
   private final GracefulSwitchLoadBalancer switchLb;
-  private TimeProvider timeProvider;
+  private Ticker ticker;
   private final ScheduledExecutorService timeService;
   private ScheduledHandle detectionTimerHandle;
   private Long detectionTimerStartNanos;
@@ -95,14 +95,14 @@ public final class OutlierDetectionLoadBalancer extends LoadBalancer {
   /**
    * Creates a new instance of {@link OutlierDetectionLoadBalancer}.
    */
-  public OutlierDetectionLoadBalancer(Helper helper, TimeProvider timeProvider) {
+  public OutlierDetectionLoadBalancer(Helper helper, Ticker ticker) {
     logger = helper.getChannelLogger();
     childHelper = new ChildHelper(checkNotNull(helper, "helper"));
     switchLb = new GracefulSwitchLoadBalancer(childHelper);
     endpointTrackerMap = new EndpointTrackerMap();
     this.syncContext = checkNotNull(helper.getSynchronizationContext(), "syncContext");
     this.timeService = checkNotNull(helper.getScheduledExecutorService(), "timeService");
-    this.timeProvider = timeProvider;
+    this.ticker = ticker;
     logger.log(ChannelLogLevel.DEBUG, "OutlierDetection lb created.");
   }
 
@@ -151,7 +151,7 @@ public Status acceptResolvedAddresses(ResolvedAddresses resolvedAddresses) {
         // If a timer has started earlier we cancel it and use the difference between the start
         // time and now as the interval.
         initialDelayNanos = Math.max(0L,
-            config.intervalNanos - (timeProvider.currentTimeNanos() - detectionTimerStartNanos));
+            config.intervalNanos - (ticker.read() - detectionTimerStartNanos));
       }
 
       // If a timer has been previously created we need to cancel it and reset all the call counters
@@ -201,7 +201,7 @@ final class DetectionTimer implements Runnable {
 
     @Override
     public void run() {
-      detectionTimerStartNanos = timeProvider.currentTimeNanos();
+      detectionTimerStartNanos = ticker.read();
 
       endpointTrackerMap.swapCounters();
 
@@ -638,7 +638,7 @@ public boolean maxEjectionTimeElapsed(long currentTimeNanos) {
               config.baseEjectionTimeNanos * ejectionTimeMultiplier,
               maxEjectionDurationSecs);
 
-      return currentTimeNanos > maxEjectionTimeNanos;
+      return currentTimeNanos - maxEjectionTimeNanos > 0;
     }
 
     /** Tracks both successful and failed call counts. */

util/src/main/java/io/grpc/util/OutlierDetectionLoadBalancerProvider.java

@@ -16,14 +16,14 @@
 
 package io.grpc.util;
 
+import com.google.common.base.Ticker;
 import io.grpc.Internal;
 import io.grpc.LoadBalancer;
 import io.grpc.LoadBalancer.Helper;
 import io.grpc.LoadBalancerProvider;
 import io.grpc.NameResolver.ConfigOrError;
 import io.grpc.Status;
 import io.grpc.internal.JsonUtil;
-import io.grpc.internal.TimeProvider;
 import io.grpc.util.OutlierDetectionLoadBalancer.OutlierDetectionLoadBalancerConfig;
 import io.grpc.util.OutlierDetectionLoadBalancer.OutlierDetectionLoadBalancerConfig.FailurePercentageEjection;
 import io.grpc.util.OutlierDetectionLoadBalancer.OutlierDetectionLoadBalancerConfig.SuccessRateEjection;
@@ -34,7 +34,7 @@ public final class OutlierDetectionLoadBalancerProvider extends LoadBalancerProv
 
   @Override
   public LoadBalancer newLoadBalancer(Helper helper) {
-    return new OutlierDetectionLoadBalancer(helper, TimeProvider.SYSTEM_TIME_PROVIDER);
+    return new OutlierDetectionLoadBalancer(helper, Ticker.systemTicker());
   }
 
   @Override

util/src/test/java/io/grpc/util/OutlierDetectionLoadBalancerTest.java

@@ -227,7 +227,7 @@ public Void answer(InvocationOnMock invocation) throws Throwable {
     when(mockStreamTracerFactory.newClientStreamTracer(any(),
         any())).thenReturn(mockStreamTracer);
 
-    loadBalancer = new OutlierDetectionLoadBalancer(mockHelper, fakeClock.getTimeProvider());
+    loadBalancer = new OutlierDetectionLoadBalancer(mockHelper, fakeClock.getTicker());
   }
 
   @Test