rls: child lb resolved address factory (#6886)

rls/src/main/java/io/grpc/rls/internal/ChildLbResolvedAddressFactory.java

@@ -0,0 +1,50 @@
+/*
+ * Copyright 2020 The gRPC Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.grpc.rls.internal;
+
+import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.base.Preconditions.checkNotNull;
+
+import io.grpc.Attributes;
+import io.grpc.EquivalentAddressGroup;
+import io.grpc.LoadBalancer.ResolvedAddresses;
+import java.util.Collections;
+import java.util.List;
+
+/** Factory to create {@link io.grpc.LoadBalancer.ResolvedAddresses} from child load-balancers. */
+public final class ChildLbResolvedAddressFactory {
+
+  private final List<EquivalentAddressGroup> addresses;
+  private final Attributes attributes;
+
+  /** Constructor. */
+  public ChildLbResolvedAddressFactory(
+      List<EquivalentAddressGroup> addresses, Attributes attributes) {
+    checkArgument(addresses != null && !addresses.isEmpty(), "Address must be provided");
+    this.addresses = Collections.unmodifiableList(addresses);
+    this.attributes = checkNotNull(attributes, "attributes");
+  }
+
+  /** Creates {@link ResolvedAddresses} with given child lb config. */
+  public ResolvedAddresses create(Object childLbConfig) {
+    return ResolvedAddresses.newBuilder()
+        .setAddresses(addresses)
+        .setAttributes(attributes)
+        .setLoadBalancingPolicyConfig(childLbConfig)
+        .build();
+  }
+}

rls/src/test/java/io/grpc/rls/internal/ChildLbResolvedAddressFactoryTest.java

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+/*
+ * Copyright 2020 The gRPC Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.grpc.rls.internal;
+
+import static com.google.common.truth.Truth.assertThat;
+import static org.mockito.Mockito.mock;
+
+import io.grpc.Attributes;
+import io.grpc.EquivalentAddressGroup;
+import io.grpc.LoadBalancer.ResolvedAddresses;
+import java.net.SocketAddress;
+import java.util.ArrayList;
+import java.util.List;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+@RunWith(JUnit4.class)
+public class ChildLbResolvedAddressFactoryTest {
+
+  @Test
+  public void create() {
+    List<EquivalentAddressGroup> addrs = new ArrayList<>();
+    addrs.add(new EquivalentAddressGroup(mock(SocketAddress.class)));
+    Attributes attr = Attributes.newBuilder().build();
+    ChildLbResolvedAddressFactory factory = new ChildLbResolvedAddressFactory(addrs, attr);
+    Object config1 = new Object();
+    
+    ResolvedAddresses resolvedAddress = factory.create(config1);
+    
+    assertThat(resolvedAddress.getAddresses()).isEqualTo(addrs);
+    assertThat(resolvedAddress.getAttributes()).isEqualTo(attr);
+    assertThat(resolvedAddress.getLoadBalancingPolicyConfig()).isEqualTo(config1);
+
+    Object config2 = "different object";
+    
+    resolvedAddress = factory.create(config2);
+
+    assertThat(resolvedAddress.getAddresses()).isEqualTo(addrs);
+    assertThat(resolvedAddress.getAttributes()).isEqualTo(attr);
+    assertThat(resolvedAddress.getLoadBalancingPolicyConfig()).isEqualTo(config2);
+  }
+}