refactor(bigtable): simplify AdminClient (#8424)

Author: dbolduc

google/cloud/bigtable/admin_client.cc

@@ -13,54 +13,19 @@
 // limitations under the License.
 
 #include "google/cloud/bigtable/admin_client.h"
-#include "google/cloud/bigtable/internal/admin_client_params.h"
 #include "google/cloud/bigtable/internal/defaults.h"
 
 namespace google {
 namespace cloud {
 namespace bigtable {
 GOOGLE_CLOUD_CPP_INLINE_NAMESPACE_BEGIN
 
-namespace {
-
-class DefaultAdminClient : public google::cloud::bigtable::AdminClient {
- public:
-  DefaultAdminClient(std::string project,
-                     bigtable_internal::AdminClientParams params)
-      : project_(std::move(project)),
-        cq_(params.options.get<GrpcCompletionQueueOption>()),
-        background_threads_(std::move(params.background_threads)),
-        connection_(bigtable_admin::MakeBigtableTableAdminConnection(
-            std::move(params.options))) {}
-
-  std::string const& project() const override { return project_; }
-
- private:
-  std::shared_ptr<bigtable_admin::BigtableTableAdminConnection> connection()
-      override {
-    return connection_;
-  }
-
-  CompletionQueue cq() override { return cq_; }
-
-  std::shared_ptr<BackgroundThreads> background_threads() override {
-    return background_threads_;
-  }
-
-  std::string project_;
-  CompletionQueue cq_;
-  std::shared_ptr<BackgroundThreads> background_threads_;
-  std::shared_ptr<bigtable_admin::BigtableTableAdminConnection> connection_;
-};
-
-}  // namespace
-
 std::shared_ptr<AdminClient> MakeAdminClient(std::string project,
                                              Options options) {
   auto params = bigtable_internal::AdminClientParams(
       internal::DefaultTableAdminOptions(std::move(options)));
-  return std::make_shared<DefaultAdminClient>(std::move(project),
-                                              std::move(params));
+  return std::shared_ptr<AdminClient>(
+      new AdminClient(std::move(project), std::move(params)));
 }
 
 std::shared_ptr<AdminClient> CreateDefaultAdminClient(std::string project,

google/cloud/bigtable/admin_client.h

@@ -17,7 +17,9 @@
 
 #include "google/cloud/bigtable/admin/bigtable_table_admin_connection.h"
 #include "google/cloud/bigtable/client_options.h"
+#include "google/cloud/bigtable/internal/admin_client_params.h"
 #include "google/cloud/bigtable/version.h"
+#include "google/cloud/options.h"
 #include <memory>
 #include <string>
 
@@ -37,22 +39,26 @@ GOOGLE_CLOUD_CPP_INLINE_NAMESPACE_BEGIN
  *     configure `bigtable_admin::BigtableTableAdminClient`, instead of using
  *     this class to configure `bigtable::TableAdmin`.
  */
-class AdminClient {
+class AdminClient final {
  public:
-  virtual ~AdminClient() = default;
-
   /// The project id that this AdminClient works on.
-  virtual std::string const& project() const = 0;
+  std::string const& project() { return project_; };
 
  private:
   friend class TableAdmin;
+  friend std::shared_ptr<AdminClient> MakeAdminClient(std::string, Options);
 
-  virtual std::shared_ptr<bigtable_admin::BigtableTableAdminConnection>
-  connection() = 0;
-
-  virtual CompletionQueue cq() = 0;
+  AdminClient(std::string project, bigtable_internal::AdminClientParams params)
+      : project_(std::move(project)),
+        cq_(params.options.get<GrpcCompletionQueueOption>()),
+        background_threads_(std::move(params.background_threads)),
+        connection_(bigtable_admin::MakeBigtableTableAdminConnection(
+            std::move(params.options))) {}
 
-  virtual std::shared_ptr<BackgroundThreads> background_threads() = 0;
+  std::string project_;
+  CompletionQueue cq_;
+  std::shared_ptr<BackgroundThreads> background_threads_;
+  std::shared_ptr<bigtable_admin::BigtableTableAdminConnection> connection_;
 };
 
 /// Create a new table admin client configured via @p options.

google/cloud/bigtable/table_admin.h

@@ -150,9 +150,9 @@ class TableAdmin {
    */
   // NOLINTNEXTLINE(performance-unnecessary-value-param)
   TableAdmin(std::shared_ptr<AdminClient> client, std::string instance_id)
-      : connection_(client->connection()),
-        cq_(client->cq()),
-        background_threads_(client->background_threads()),
+      : connection_(client->connection_),
+        cq_(client->cq_),
+        background_threads_(client->background_threads_),
         project_id_(client->project()),
         instance_id_(std::move(instance_id)),
         instance_name_(InstanceName()),
@@ -195,9 +195,9 @@ class TableAdmin {
   // NOLINTNEXTLINE(performance-unnecessary-value-param)
   TableAdmin(std::shared_ptr<AdminClient> client, std::string instance_id,
              Policies&&... policies)
-      : connection_(client->connection()),
-        cq_(client->cq()),
-        background_threads_(client->background_threads()),
+      : connection_(client->connection_),
+        cq_(client->cq_),
+        background_threads_(client->background_threads_),
         project_id_(client->project()),
         instance_id_(std::move(instance_id)),
         instance_name_(InstanceName()),