[GitHub] jolynch commented on a change in pull request #283: CASSANDRA-14459: DynamicEndpointSnitch should never prefer latent replicas

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jolynch commented on a change in pull request #283: CASSANDRA-14459: DynamicEndpointSnitch should never prefer latent replicas
URL: https://github.com/apache/cassandra/pull/283#discussion_r250741942
 
 

 ##########
 File path: src/java/org/apache/cassandra/locator/DynamicEndpointSnitch.java
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 @@ -21,133 +21,505 @@
 import java.net.InetAddress;
 import java.net.UnknownHostException;
 import java.util.*;
+import java.util.concurrent.CancellationException;
 import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.ExecutionException;
 import java.util.concurrent.ScheduledFuture;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+import java.util.concurrent.atomic.AtomicLong;
 import java.util.stream.Collectors;
 
-import com.codahale.metrics.ExponentiallyDecayingReservoir;
+import com.google.common.annotations.VisibleForTesting;
+import com.google.common.util.concurrent.Futures;
+import com.google.common.util.concurrent.MoreExecutors;
+import com.google.common.util.concurrent.RateLimiter;
+import com.google.common.util.concurrent.SettableFuture;
 
-import com.codahale.metrics.Snapshot;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import org.apache.cassandra.concurrent.DebuggableScheduledThreadPoolExecutor;
 import org.apache.cassandra.concurrent.ScheduledExecutors;
 import org.apache.cassandra.config.DatabaseDescriptor;
+import org.apache.cassandra.exceptions.RequestFailureReason;
 import org.apache.cassandra.gms.ApplicationState;
 import org.apache.cassandra.gms.EndpointState;
 import org.apache.cassandra.gms.Gossiper;
 import org.apache.cassandra.gms.VersionedValue;
+import org.apache.cassandra.locator.dynamicsnitch.DynamicEndpointSnitchHistogram;
+import org.apache.cassandra.net.IAsyncCallbackWithFailure;
+import org.apache.cassandra.net.LatencyMeasurementType;
+import org.apache.cassandra.net.MessageIn;
+import org.apache.cassandra.net.MessageOut;
 import org.apache.cassandra.net.MessagingService;
+import org.apache.cassandra.net.PingMessage;
 import org.apache.cassandra.service.StorageService;
 import org.apache.cassandra.utils.FBUtilities;
 import org.apache.cassandra.utils.MBeanWrapper;
 
+import static org.apache.cassandra.net.MessagingService.Verb.PING;
+import static org.apache.cassandra.net.async.OutboundConnectionIdentifier.ConnectionType.LARGE_MESSAGE;
+import static org.apache.cassandra.net.async.OutboundConnectionIdentifier.ConnectionType.SMALL_MESSAGE;
+
+
 /**
  * A dynamic snitch that sorts endpoints by latency with an adapted phi failure detector
+ * Note that the subclasses (e.g. {@link DynamicEndpointSnitchHistogram}) are responsible for actually measuring
+ * latency and providing an ISnitchMeasurement implementation back to this class.
  */
-public class DynamicEndpointSnitch extends AbstractEndpointSnitch implements ILatencySubscriber, DynamicEndpointSnitchMBean
+public abstract class DynamicEndpointSnitch extends AbstractEndpointSnitch implements ILatencySubscriber, DynamicEndpointSnitchMBean
 {
-    private static final boolean USE_SEVERITY = !Boolean.getBoolean("cassandra.ignore_dynamic_snitch_severity");
+    private static final Logger logger = LoggerFactory.getLogger(DynamicEndpointSnitch.class);
+
+    // Latency measurement and ranking. The samples contain latency measurements and the scores are used for ranking
+    protected boolean registered = false;
 
 Review comment:
   Ok, changed to `registeredForLatencyUpdates`.

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