loadbalancer-experimental: adjust LoadBalancerObserver API (#3140)

Modifications: - Remove default implementation for `onHostSetChanged(Collection)`; - Change `onNoHostsAvailable()` to `onNoAvailableHostException(NoAvailableHostException)`; - Rename `onNoActiveHostsAvailable` to `onNoActiveHostException`;
apple · Dec 17, 2024 · 4ec119a · 4ec119a
1 parent 85fd41b
commit 4ec119a
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Showing 4 changed files with 25 additions and 22 deletions.
diff --git a/...r/src/main/java/io/servicetalk/loadbalancer/experimental/DefaultLoadBalancerObserver.java b/...r/src/main/java/io/servicetalk/loadbalancer/experimental/DefaultLoadBalancerObserver.java
@@ -16,6 +16,7 @@
 package io.servicetalk.loadbalancer.experimental;
 
 import io.servicetalk.client.api.NoActiveHostException;
+import io.servicetalk.client.api.NoAvailableHostException;
 import io.servicetalk.client.api.ServiceDiscovererEvent;
 import io.servicetalk.loadbalancer.LoadBalancerObserver;
 
@@ -42,23 +43,13 @@ public HostObserver hostObserver(Object resolvedAddress) {
         return new HostObserverImpl(resolvedAddress);
     }
 
-    @Override
-    public void onNoHostsAvailable() {
-        LOGGER.debug("{}- onNoHostsAvailable()", lbDescription);
-    }
-
     @Override
     public void onServiceDiscoveryEvent(Collection<? extends ServiceDiscovererEvent<?>> events, int oldHostSetSize,
                                         int newHostSetSize) {
         LOGGER.debug("{}- onServiceDiscoveryEvent(events: {}, oldHostSetSize: {}, newHostSetSize: {})",
                 lbDescription, events, oldHostSetSize, newHostSetSize);
     }
 
-    @Override
-    public void onNoActiveHostsAvailable(int hostSetSize, NoActiveHostException exception) {
-        LOGGER.debug("{}- No active hosts available. Host set size: {}.", lbDescription, hostSetSize, exception);
-    }
-
     @Override
     public void onHostSetChanged(Collection<? extends Host> newHosts) {
         if (LOGGER.isDebugEnabled()) {
@@ -73,6 +64,16 @@ public void onHostSetChanged(Collection<? extends Host> newHosts) {
         }
     }
 
+    @Override
+    public void onNoAvailableHostException(final NoAvailableHostException exception) {
+        LOGGER.debug("{}- onNoAvailableHostException()", lbDescription, exception);
+    }
+
+    @Override
+    public void onNoActiveHostException(int hostSetSize, NoActiveHostException exception) {
+        LOGGER.debug("{}- onNoActiveHostException(hostSetSize: {})", lbDescription, hostSetSize, exception);
+    }
+
     private final class HostObserverImpl implements HostObserver {
 
         private final Object resolvedAddress;

diff --git a/...dbalancer-experimental/src/main/java/io/servicetalk/loadbalancer/DefaultLoadBalancer.java b/...dbalancer-experimental/src/main/java/io/servicetalk/loadbalancer/DefaultLoadBalancer.java
@@ -541,10 +541,10 @@ private Single<C> selectConnection0(final Predicate<C> selector, @Nullable final
                         subscribeToEvents(true);
                     }
                 }
-                loadBalancerObserver.onNoActiveHostsAvailable(
+                loadBalancerObserver.onNoActiveHostException(
                         currentHostSelector.hostSetSize(), (NoActiveHostException) exn);
             } else if (exn instanceof NoAvailableHostException) {
-                loadBalancerObserver.onNoHostsAvailable();
+                loadBalancerObserver.onNoAvailableHostException((NoAvailableHostException) exn);
             }
         });
     }

diff --git a/...balancer-experimental/src/main/java/io/servicetalk/loadbalancer/LoadBalancerObserver.java b/...balancer-experimental/src/main/java/io/servicetalk/loadbalancer/LoadBalancerObserver.java
@@ -16,6 +16,7 @@
 package io.servicetalk.loadbalancer;
 
 import io.servicetalk.client.api.NoActiveHostException;
+import io.servicetalk.client.api.NoAvailableHostException;
 import io.servicetalk.client.api.ServiceDiscovererEvent;
 
 import java.util.Collection;
@@ -49,20 +50,20 @@ void onServiceDiscoveryEvent(Collection<? extends ServiceDiscovererEvent<?>> eve
      * algorithm may use.
      * @param newHosts the new set of hosts used by the selection algorithm.
      */
-    default void onHostSetChanged(Collection<? extends Host> newHosts) {
-    }
+    void onHostSetChanged(Collection<? extends Host> newHosts);
 
     /**
      * Callback for when connection selection fails due to no hosts being available.
+     * @param exception an exception with more details about the failure.
      */
-    void onNoHostsAvailable();
+    void onNoAvailableHostException(NoAvailableHostException exception);
 
     /**
      * Callback for when connection selection fails due to all hosts being inactive.
-     * @param hostSetSize the size of the current host set.
+     * @param hostSetSize the size of the current host set where all hosts are inactive.
      * @param exception an exception with more details about the failure.
      */
-    void onNoActiveHostsAvailable(int hostSetSize, NoActiveHostException exception);
+    void onNoActiveHostException(int hostSetSize, NoActiveHostException exception);
 
     /**
      * An observer for {@link io.servicetalk.loadbalancer.Host} events.

diff --git a/...ncer-experimental/src/main/java/io/servicetalk/loadbalancer/NoopLoadBalancerObserver.java b/...ncer-experimental/src/main/java/io/servicetalk/loadbalancer/NoopLoadBalancerObserver.java
@@ -16,6 +16,7 @@
 package io.servicetalk.loadbalancer;
 
 import io.servicetalk.client.api.NoActiveHostException;
+import io.servicetalk.client.api.NoAvailableHostException;
 import io.servicetalk.client.api.ServiceDiscovererEvent;
 
 import java.util.Collection;
@@ -36,23 +37,23 @@ public HostObserver hostObserver(Object resolvedAddress) {
     }
 
     @Override
-    public void onNoHostsAvailable() {
+    public void onServiceDiscoveryEvent(Collection<? extends ServiceDiscovererEvent<?>> events,
+                                        int oldHostSetSize, int newHostSetSize) {
         // noop
     }
 
     @Override
-    public void onNoActiveHostsAvailable(int hostSetSize, NoActiveHostException exn) {
+    public void onHostSetChanged(Collection<? extends Host> newHosts) {
         // noop
     }
 
     @Override
-    public void onServiceDiscoveryEvent(Collection<? extends ServiceDiscovererEvent<?>> events,
-                                        int oldHostSetSize, int newHostSetSize) {
+    public void onNoAvailableHostException(NoAvailableHostException exception) {
         // noop
     }
 
     @Override
-    public void onHostSetChanged(Collection<? extends Host> newHosts) {
+    public void onNoActiveHostException(int hostSetSize, NoActiveHostException exn) {
         // noop
     }