feat: add Feature Store: Streaming Ingestion (write_feature_values()) and introduce Preview namespace to Vertex SDK

PiperOrigin-RevId: 489080135

Author: vertex-sdk-bot

google/cloud/aiplatform/base.py

@@ -35,6 +35,7 @@
     Sequence,
     Tuple,
     Type,
+    TypeVar,
     Union,
 )
 
@@ -1391,3 +1392,33 @@ def done(self) -> bool:
             return super().done()
 
         return False
+
+
+# PreviewClass type variable
+PreviewClass = TypeVar("PreviewClass", bound=VertexAiResourceNoun)
+
+
+class PreviewMixin(abc.ABC):
+    """An abstract class for adding preview functionality to certain classes.
+    A child class that inherits from both this Mixin and another parent
+    class allows the child class to introduce preview features.
+    """
+
+    @classmethod
+    @property
+    @abc.abstractmethod
+    def _preview_class(cls: Type[PreviewClass]) -> Type[PreviewClass]:
+        """Class that is currently in preview or has a preview feature.
+        Class must have `resource_name` and `credentials` attributes.
+        """
+        pass
+
+    @property
+    def preview(self) -> PreviewClass:
+        """Exposes features available in preview for this class."""
+        if not hasattr(self, "_preview_instance"):
+            self._preview_instance = self._preview_class(
+                self.resource_name, credentials=self.credentials
+            )
+
+        return self._preview_instance