SiyaoIsHiding commented on code in PR #1743: URL: https://github.com/apache/cassandra-java-driver/pull/1743#discussion_r1516944635
########## core/src/main/java/com/datastax/oss/driver/internal/core/loadbalancing/DefaultLoadBalancingPolicy.java: ########## @@ -96,14 +99,38 @@ public class DefaultLoadBalancingPolicy extends BasicLoadBalancingPolicy impleme private static final int MAX_IN_FLIGHT_THRESHOLD = 10; private static final long RESPONSE_COUNT_RESET_INTERVAL_NANOS = MILLISECONDS.toNanos(200); - protected final Map<Node, AtomicLongArray> responseTimes = new ConcurrentHashMap<>(); + protected final LoadingCache<Node, AtomicLongArray> responseTimes; protected final Map<Node, Long> upTimes = new ConcurrentHashMap<>(); private final boolean avoidSlowReplicas; public DefaultLoadBalancingPolicy(@NonNull DriverContext context, @NonNull String profileName) { super(context, profileName); this.avoidSlowReplicas = profile.getBoolean(DefaultDriverOption.LOAD_BALANCING_POLICY_SLOW_AVOIDANCE, true); + CacheLoader<Node, AtomicLongArray> cacheLoader = + new CacheLoader<Node, AtomicLongArray>() { + @Override + public AtomicLongArray load(Node key) throws Exception { + // The array stores at most two timestamps, since we don't need more; + // the first one is always the least recent one, and hence the one to inspect. + long now = nanoTime(); + AtomicLongArray array = responseTimes.getIfPresent(key); + if (array == null) { + array = new AtomicLongArray(1); + array.set(0, now); + } else if (array.length() == 1) { + long previous = array.get(0); + array = new AtomicLongArray(2); + array.set(0, previous); + array.set(1, now); + } else { + array.set(0, array.get(1)); + array.set(1, now); + } + return array; + } + }; + this.responseTimes = CacheBuilder.newBuilder().weakKeys().build(cacheLoader); Review Comment: Thank you for your review. Would you please explain more about this? If GC collects a node, that means the node is gone. If the node is gone, why do we care about whether it's treated as healthy or not? Anyway, for `RemovalListener`, do you mean sth like this? ```java this.responseTimes = CacheBuilder.newBuilder().weakKeys().removalListener( (RemovalListener<Node, AtomicLongArray>) notification -> LOG.trace("[{}] Evicting response times for {}: {}", logPrefix, notification.getKey(), notification.getCause())) .build(cacheLoader); ``` -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: commits-unsubscr...@cassandra.apache.org For queries about this service, please contact Infrastructure at: us...@infra.apache.org --------------------------------------------------------------------- To unsubscribe, e-mail: commits-unsubscr...@cassandra.apache.org For additional commands, e-mail: commits-h...@cassandra.apache.org