[BUG] 1965 Split up embedding functions - Redux (chroma-core#2395)

## Description of changes
The original attempt to split up the embedding functions failed because
of python 3.9 and 3.10 incompatibilities with `issubtype`.

Original PR here: chroma-core#2034

Failing tests here:
https://github.com/chroma-core/chroma/actions/runs/9605053108/job/26491923410

The fix is changing `issubtype` to `isinstance`, which has the same
functionality.

## Test plan

Along with CI, tested locally with python 3.9 and 3.10 and confirmed
passing.

## Documentation Changes
N/A

chromadb/api/types.py

@@ -1,7 +1,7 @@
 from typing import Optional, Union, TypeVar, List, Dict, Any, Tuple, cast
 from numpy.typing import NDArray
 import numpy as np
-from typing_extensions import Literal, TypedDict, Protocol
+from typing_extensions import Literal, TypedDict, Protocol, runtime_checkable
 import chromadb.errors as errors
 from chromadb.types import (
     Metadata,
@@ -56,7 +56,7 @@ def maybe_cast_one_to_many_ids(target: OneOrMany[ID]) -> IDs:
 
 
 def maybe_cast_one_to_many_embedding(
-    target: Union[OneOrMany[Embedding], OneOrMany[np.ndarray]]
+    target: Union[OneOrMany[Embedding], OneOrMany[np.ndarray]]  # type: ignore[type-arg]
 ) -> Embeddings:
     if isinstance(target, List):
         # One Embedding
@@ -101,7 +101,7 @@ def maybe_cast_one_to_many_document(target: OneOrMany[Document]) -> Documents:
 
 
 # Images
-ImageDType = Union[np.uint, np.int_, np.float_]
+ImageDType = Union[np.uint, np.int_, np.float_]  # type: ignore[name-defined]
 Image = NDArray[ImageDType]
 Images = List[Image]
 
@@ -184,6 +184,7 @@ class IndexMetadata(TypedDict):
     time_created: float
 
 
+@runtime_checkable
 class EmbeddingFunction(Protocol[D]):
     def __call__(self, input: D) -> Embeddings:
         ...
@@ -199,8 +200,10 @@ def __call__(self: EmbeddingFunction[D], input: D) -> Embeddings:
 
         setattr(cls, "__call__", __call__)
 
-    def embed_with_retries(self, input: D, **retry_kwargs: Dict) -> Embeddings:
-        return retry(**retry_kwargs)(self.__call__)(input)
+    def embed_with_retries(
+        self, input: D, **retry_kwargs: Dict[str, Any]
+    ) -> Embeddings:
+        return cast(Embeddings, retry(**retry_kwargs)(self.__call__)(input))
 
 
 def validate_embedding_function(

chromadb/test/ef/test_default_ef.py

@@ -7,7 +7,10 @@
 import pytest
 from hypothesis import given, settings
 
-from chromadb.utils.embedding_functions import ONNXMiniLM_L6_V2, _verify_sha256
+from chromadb.utils.embedding_functions.onnx_mini_lm_l6_v2 import (
+    ONNXMiniLM_L6_V2,
+    _verify_sha256,
+)
 
 
 def unique_by(x: Hashable) -> Hashable:

chromadb/test/ef/test_ef.py

@@ -0,0 +1,53 @@
+from chromadb.utils import embedding_functions
+from chromadb.api.types import EmbeddingFunction
+
+
+def test_get_builtins_holds() -> None:
+    """
+    Ensure that `get_builtins` is consistent after the ef migration.
+
+    This test is intended to be temporary until the ef migration is complete as
+    these expected builtins are likely to grow as long as users add new
+    embedding functions.
+
+    REMOVE ME ON THE NEXT EF ADDITION
+    """
+    expected_builtins = {
+        "AmazonBedrockEmbeddingFunction",
+        "CohereEmbeddingFunction",
+        "GoogleGenerativeAiEmbeddingFunction",
+        "GooglePalmEmbeddingFunction",
+        "GoogleVertexEmbeddingFunction",
+        "HuggingFaceEmbeddingFunction",
+        "HuggingFaceEmbeddingServer",
+        "InstructorEmbeddingFunction",
+        "JinaEmbeddingFunction",
+        "ONNXMiniLM_L6_V2",
+        "OllamaEmbeddingFunction",
+        "OpenAIEmbeddingFunction",
+        "OpenCLIPEmbeddingFunction",
+        "RoboflowEmbeddingFunction",
+        "SentenceTransformerEmbeddingFunction",
+        "Text2VecEmbeddingFunction",
+        "ChromaLangchainEmbeddingFunction",
+    }
+
+    assert expected_builtins == embedding_functions.get_builtins()
+
+
+def test_default_ef_exists() -> None:
+    assert hasattr(embedding_functions, "DefaultEmbeddingFunction")
+    default_ef = embedding_functions.DefaultEmbeddingFunction()
+
+    assert default_ef is not None
+    assert isinstance(default_ef, EmbeddingFunction)
+
+
+def test_ef_imports() -> None:
+    for ef in embedding_functions.get_builtins():
+        # Langchain embedding function is a special snowflake
+        if ef == "ChromaLangchainEmbeddingFunction":
+            continue
+        assert hasattr(embedding_functions, ef)
+        assert isinstance(getattr(embedding_functions, ef), type)
+        assert issubclass(getattr(embedding_functions, ef), EmbeddingFunction)