Implemented random_subsetting converter for xDS

Author: Zgoda91

xds/src/main/java/io/grpc/xds/LoadBalancerConfigFactory.java

@@ -32,6 +32,7 @@
 import io.envoyproxy.envoy.extensions.load_balancing_policies.client_side_weighted_round_robin.v3.ClientSideWeightedRoundRobin;
 import io.envoyproxy.envoy.extensions.load_balancing_policies.least_request.v3.LeastRequest;
 import io.envoyproxy.envoy.extensions.load_balancing_policies.pick_first.v3.PickFirst;
+import io.envoyproxy.envoy.extensions.load_balancing_policies.random_subsetting.v3.RandomSubsetting;
 import io.envoyproxy.envoy.extensions.load_balancing_policies.ring_hash.v3.RingHash;
 import io.envoyproxy.envoy.extensions.load_balancing_policies.round_robin.v3.RoundRobin;
 import io.envoyproxy.envoy.extensions.load_balancing_policies.wrr_locality.v3.WrrLocality;
@@ -92,6 +93,9 @@ class LoadBalancerConfigFactory {
 
   static final String ERROR_UTILIZATION_PENALTY = "errorUtilizationPenalty";
 
+  static final String RANDOM_SUBSETTING_FIELD_NAME = "random_subsetting";
+  static final String SUBSET_SIZE = "subsetSize";
+
   /**
    * Factory method for creating a new {link LoadBalancerConfigConverter} for a given xDS {@link
    * Cluster}.
@@ -200,6 +204,20 @@ class LoadBalancerConfigFactory {
     return ImmutableMap.of(PICK_FIRST_FIELD_NAME, configBuilder.buildOrThrow());
   }
 
+  /**
+   * Builds a service config JSON object for the random_subsetting load balancer config based on the
+   * given config values.
+   */
+  private static ImmutableMap<String, ?> buildRandomSubsettingConfig(
+      RandomSubsetting randomSubsetting) {
+    return ImmutableMap.of(
+        RANDOM_SUBSETTING_FIELD_NAME,
+        ImmutableMap.of(
+            SUBSET_SIZE, randomSubsetting.getSubsetSize(),
+            CHILD_POLICY_FIELD, randomSubsetting.getChildPolicy()
+        ));
+  }
+
   /**
    * Responsible for converting from a {@code envoy.config.cluster.v3.LoadBalancingPolicy} proto
    * message to a gRPC service config format.
@@ -236,6 +254,9 @@ static class LoadBalancingPolicyConverter {
                 typedConfig.unpack(ClientSideWeightedRoundRobin.class));
           } else if (typedConfig.is(PickFirst.class)) {
             serviceConfig = convertPickFirstConfig(typedConfig.unpack(PickFirst.class));
+          } else if (typedConfig.is(RandomSubsetting.class)) {
+            serviceConfig = convertRandomSubsettingConfig(
+                typedConfig.unpack(RandomSubsetting.class));
           } else if (typedConfig.is(com.github.xds.type.v3.TypedStruct.class)) {
             serviceConfig = convertCustomConfig(
                 typedConfig.unpack(com.github.xds.type.v3.TypedStruct.class));
@@ -324,6 +345,14 @@ static class LoadBalancingPolicyConverter {
       return buildPickFirstConfig(pickFirst.getShuffleAddressList());
     }
 
+    /**
+     * "Converts" a random_subsetting configuration to service config format.
+     */
+    private static ImmutableMap<String, ?> convertRandomSubsettingConfig(
+        RandomSubsetting randomSubsetting) {
+      return buildRandomSubsettingConfig(randomSubsetting);
+    }
+
     /**
      * Converts a least_request {@link Any} configuration to service config format.
      */

xds/third_party/envoy/src/main/proto/envoy/extensions/load_balancing_policies/random_subsetting/v3/random_subsetting.proto

@@ -0,0 +1,33 @@
+syntax = "proto3";
+
+package envoy.extensions.load_balancing_policies.random_subsetting.v3;
+
+import "envoy/config/cluster/v3/cluster.proto";
+
+import "google/protobuf/wrappers.proto";
+
+import "udpa/annotations/status.proto";
+import "validate/validate.proto";
+
+option java_package = "io.envoyproxy.envoy.extensions.load_balancing_policies.random_subsetting.v3";
+option java_outer_classname = "RandomSubsettingProto";
+option java_multiple_files = true;
+option go_package = "github.com/envoyproxy/go-control-plane/envoy/extensions/load_balancing_policies/random_subsetting/v3;random_subsettingv3";
+option (udpa.annotations.file_status).package_version_status = ACTIVE;
+
+// [#protodoc-title: Random Subsetting Load Balancing Policy]
+// [#extension: envoy.load_balancing_policies.random_subsetting]
+
+message RandomSubsetting {
+    // subset_size indicates how many backends every client will be connected to.
+    // The value must be greater than 0.
+    google.protobuf.UInt32Value subset_size = 1 [
+        (validate.rules).uint32 = {gt: 0}
+    ];
+
+    // The config for the child policy.
+    // The value is required.
+    config.cluster.v3.LoadBalancingPolicy child_policy = 2 [
+        (validate.rules).message = {required: true}
+    ];
+}