lookasidechannellb

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

@@ -0,0 +1,68 @@
+/*
+ * Copyright 2019 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.xds;
+
+import static java.util.logging.Level.FINEST;
+
+import io.grpc.LoadBalancer;
+import io.grpc.LoadBalancer.Helper;
+import io.grpc.ManagedChannel;
+import io.grpc.ManagedChannelBuilder;
+import io.grpc.Status;
+import io.grpc.xds.XdsComms.AdsStreamCallback;
+import java.util.logging.Logger;
+
+/** A load balancer that has a lookaside channel. */
+final class LookasideChannelLb extends LoadBalancer {
+
+  LookasideChannelLb(Helper helper, AdsStreamCallback adsCallback, String balancerName) {
+
+  }
+
+  private static ManagedChannel initLbChannel(Helper helper, String balancerName) {
+    ManagedChannel channel;
+    try {
+      channel = helper.createResolvingOobChannel(balancerName);
+    } catch (UnsupportedOperationException uoe) {
+      // Temporary solution until createResolvingOobChannel is implemented
+      // FIXME (https://github.com/grpc/grpc-java/issues/5495)
+      Logger logger = Logger.getLogger(XdsLoadBalancer.class.getName());
+      if (logger.isLoggable(FINEST)) {
+        logger.log(
+            FINEST,
+            "createResolvingOobChannel() not supported by the helper: " + helper,
+            uoe);
+        logger.log(
+            FINEST,
+            "creating oob channel for target {0} using default ManagedChannelBuilder",
+            balancerName);
+      }
+      channel = ManagedChannelBuilder.forTarget(balancerName).build();
+    }
+    return channel;
+  }
+
+  @Override
+  public void handleNameResolutionError(Status error) {
+
+  }
+
+  @Override
+  public void shutdown() {
+
+  }
+}