refactor(bigtable): encapsulate V2 callable creation inside V2 client

Author: jinseopkim0

java-bigtable/google-cloud-bigtable/src/main/java/com/google/cloud/bigtable/admin/v2/BigtableTableAdminClient.java

@@ -70,7 +70,6 @@
 import com.google.cloud.bigtable.admin.v2.models.UpdateBackupRequest;
 import com.google.cloud.bigtable.admin.v2.models.UpdateSchemaBundleRequest;
 import com.google.cloud.bigtable.admin.v2.models.UpdateTableRequest;
-import com.google.cloud.bigtable.admin.v2.stub.AwaitConsistencyCallableV2;
 import com.google.cloud.bigtable.admin.v2.stub.EnhancedBigtableTableAdminStub;
 import com.google.cloud.bigtable.data.v2.internal.TableAdminRequestContext;
 import com.google.common.base.Preconditions;
@@ -234,17 +233,17 @@ public synchronized BigtableTableAdminClientV2 getBaseClient() {
       boolean shouldAutoClose =
           stub.getSettings().getBackgroundExecutorProvider().shouldAutoClose();
 
-      AwaitConsistencyCallableV2 awaitConsistencyCallable =
-          BigtableTableAdminClientV2.createAwaitConsistencyCallable(
-              stub, stub.getSettings(), stub.getClientContext().getClock(), backgroundExecutor);
-
-      v2Client =
-          new BigtableTableAdminClientV2(
-              stub,
-              backgroundExecutor,
-              shouldAutoClose,
-              awaitConsistencyCallable,
-              stub.awaitOptimizeRestoredTableCallable());
+      try {
+        v2Client =
+            BigtableTableAdminClientV2.create(
+                stub,
+                stub.getSettings(),
+                stub.getClientContext().getClock(),
+                backgroundExecutor,
+                shouldAutoClose);
+      } catch (IOException e) {
+        throw new IllegalStateException("Failed to initialize modern V2 table admin client", e);
+      }
     }
     return v2Client;
   }

java-bigtable/google-cloud-bigtable/src/main/java/com/google/cloud/bigtable/admin/v2/BigtableTableAdminClientV2.java

@@ -108,7 +108,8 @@ public static final BigtableTableAdminClientV2 create(BaseBigtableTableAdminSett
 
     OperationCallable<Void, Empty, OptimizeRestoredTableMetadata>
         optimizeRestoredTableOperationBaseCallable =
-            createOptimizeRestoredTableOperationBaseCallable(stub, settings, backgroundExecutor);
+            createOptimizeRestoredTableOperationBaseCallable(
+                stub, settings.getStubSettings().getClock(), backgroundExecutor);
 
     return new BigtableTableAdminClientV2(
         stub,
@@ -118,6 +119,34 @@ public static final BigtableTableAdminClientV2 create(BaseBigtableTableAdminSett
         optimizeRestoredTableOperationBaseCallable);
   }
 
+  /**
+   * Package-private factory method to construct an instance of {@link BigtableTableAdminClientV2}
+   * by reusing an existing stub, settings, clock, and background executor.
+   *
+   * <p>This is used by the legacy {@code BigtableTableAdminClient}'s escape hatch ({@code
+   * getBaseClient()}) to wrap the legacy client's active stub, ensuring the underlying gRPC channel
+   * and resources are shared rather than recreated.
+   */
+  static BigtableTableAdminClientV2 create(
+      GrpcBigtableTableAdminStub stub,
+      BigtableTableAdminStubSettings settings,
+      ApiClock clock,
+      ScheduledExecutorService backgroundExecutor,
+      boolean shouldAutoClose)
+      throws IOException {
+    AwaitConsistencyCallableV2 awaitConsistencyCallable =
+        createAwaitConsistencyCallable(stub, settings, clock, backgroundExecutor);
+    OperationCallable<Void, Empty, OptimizeRestoredTableMetadata>
+        optimizeRestoredTableOperationBaseCallable =
+            createOptimizeRestoredTableOperationBaseCallable(stub, clock, backgroundExecutor);
+    return new BigtableTableAdminClientV2(
+        stub,
+        backgroundExecutor,
+        shouldAutoClose,
+        awaitConsistencyCallable,
+        optimizeRestoredTableOperationBaseCallable);
+  }
+
   protected BigtableTableAdminClientV2(
       GrpcBigtableTableAdminStub stub,
       @Nullable ScheduledExecutorService backgroundExecutor,
@@ -133,7 +162,7 @@ protected BigtableTableAdminClientV2(
     this.optimizeRestoredTableOperationBaseCallable = optimizeRestoredTableOperationBaseCallable;
   }
 
-  static AwaitConsistencyCallableV2 createAwaitConsistencyCallable(
+  private static AwaitConsistencyCallableV2 createAwaitConsistencyCallable(
       GrpcBigtableTableAdminStub stub,
       BigtableTableAdminStubSettings settings,
       ApiClock clock,
@@ -156,7 +185,7 @@ static AwaitConsistencyCallableV2 createAwaitConsistencyCallable(
   private static OperationCallable<Void, Empty, OptimizeRestoredTableMetadata>
       createOptimizeRestoredTableOperationBaseCallable(
           GrpcBigtableTableAdminStub stub,
-          BaseBigtableTableAdminSettings settings,
+          ApiClock clock,
           ScheduledExecutorService backgroundExecutor)
           throws IOException {
 
@@ -229,7 +258,7 @@ public Empty apply(OperationSnapshot input) {
     // (including channels, credentials, and headers) for executing the polling RPCs.
     ClientContext clientContext =
         ClientContext.newBuilder()
-            .setClock(settings.getStubSettings().getClock())
+            .setClock(clock)
             .setExecutor(backgroundExecutor)
             .setDefaultCallContext(GrpcCallContext.createDefault())
             .build();