adds proxy RSocket for WeightedStatsRequestInterceptor (#976)

Author: spencergibb

rsocket-core/src/main/java/io/rsocket/loadbalance/WeightedStats.java

@@ -1,7 +1,9 @@
 package io.rsocket.loadbalance;
 
+import io.rsocket.RSocket;
+
 /**
- * Representation of stats used by the {@link WeightedLoadbalanceStrategy}
+ * Representation of stats used by the {@link WeightedLoadbalanceStrategy}.
  *
  * @since 1.1
  */
@@ -16,4 +18,15 @@ public interface WeightedStats {
   double predictedLatency();
 
   double weightedAvailability();
+
+  /**
+   * Wraps an RSocket with a proxy that implements WeightedStats.
+   *
+   * @param rsocket the RSocket to proxy.
+   * @return the wrapped RSocket.
+   * @since 1.1.1
+   */
+  default RSocket wrap(RSocket rsocket) {
+    return new WeightedStatsRSocketProxy(rsocket, this);
+  }
 }

rsocket-core/src/main/java/io/rsocket/loadbalance/WeightedStatsRSocketProxy.java

@@ -0,0 +1,47 @@
+package io.rsocket.loadbalance;
+
+import io.rsocket.RSocket;
+import io.rsocket.util.RSocketProxy;
+
+/**
+ * {@link RSocketProxy} that implements {@link WeightedStats} and delegates to an existing {@link
+ * WeightedStats} instance.
+ */
+class WeightedStatsRSocketProxy extends RSocketProxy implements WeightedStats {
+
+  private final WeightedStats weightedStats;
+
+  public WeightedStatsRSocketProxy(RSocket source, WeightedStats weightedStats) {
+    super(source);
+    this.weightedStats = weightedStats;
+  }
+
+  @Override
+  public double higherQuantileLatency() {
+    return this.weightedStats.higherQuantileLatency();
+  }
+
+  @Override
+  public double lowerQuantileLatency() {
+    return this.weightedStats.lowerQuantileLatency();
+  }
+
+  @Override
+  public int pending() {
+    return this.weightedStats.pending();
+  }
+
+  @Override
+  public double predictedLatency() {
+    return this.weightedStats.predictedLatency();
+  }
+
+  @Override
+  public double weightedAvailability() {
+    return this.weightedStats.weightedAvailability();
+  }
+
+  public WeightedStats getDelegate() {
+    return this.weightedStats;
+  }
+}