(feat): full v2 compat via python fallback

Cargo.toml

@@ -22,6 +22,7 @@ pyo3-stub-gen = "0.6.2"
 opendal = { version = "0.51.0", features = ["services-http"] }
 tokio = { version = "1.41.1", features = ["rt-multi-thread"] }
 zarrs_opendal = "0.5.0"
+zarrs_metadata = "0.3.3" # require recent zarr-python compatibility fixes (remove with zarrs 0.20)
 
 [profile.release]
 lto = true

README.md

@@ -21,7 +21,7 @@ You can then use your `zarr` as normal (with some caveats)!
 
 ## API
 
-We export a `ZarrsCodecPipeline` class so that `zarr-python` can use the class but it is not meant to be instantiated and we do not guarantee the stability of its API beyond what is required so that `zarr-python` can use it.  Therefore, it is not documented here.  We also export two errors, `DiscontiguousArrayError` and `CollapsedDimensionError` that can be thrown in the process of converting to indexers that `zarrs` can understand (see below for more details).
+We export a `ZarrsCodecPipeline` class so that `zarr-python` can use the class but it is not meant to be instantiated and we do not guarantee the stability of its API beyond what is required so that `zarr-python` can use it.  Therefore, it is not documented here.
 
 At the moment, we only support a subset of the `zarr-python` stores:
 
@@ -86,7 +86,7 @@ Chunk concurrency is typically favored because:
 
 ## Supported Indexing Methods
 
-We **do not** officially support the following indexing methods.  Some of these methods may error out, others may not:
+The following methods will trigger use with the old zarr-python pipeline:
 
 1. Any `oindex` or `vindex` integer `np.ndarray` indexing with dimensionality >=3 i.e.,
 
@@ -116,6 +116,9 @@ We **do not** officially support the following indexing methods.  Some of these
    arr[0:10, ..., 0:5]
    ```
 
-Otherwise, we believe that we support your indexing case: slices, ints, and all integer `np.ndarray` indices in 2D for reading, contiguous integer `np.ndarray` indices along one axis for writing etc.  Please file an issue if you believe we have more holes in our coverage than we are aware of or you wish to contribute!  For example, we have an [issue in zarrs for integer-array indexing](https://github.com/LDeakin/zarrs/issues/52) that would unblock a lot of these issues!
 
-That being said, using non-contiguous integer `np.ndarray` indexing for reads may not be as fast as expected given the performance of other supported methods.  Until `zarrs` supports integer indexing, only fetching chunks is done in `rust` while indexing then occurs in `python`.
+Furthermore, using anything except contiguous (i.e., slices or consecutive integer) `np.ndarray` for numeric data will fall back to the default `zarr-python` implementation.
+
+Please file an issue if you believe we have more holes in our coverage than we are aware of or you wish to contribute!  For example, we have an [issue in zarrs for integer-array indexing](https://github.com/LDeakin/zarrs/issues/52) that would unblock a lot the use of the rust pipeline for that use-case (very useful for mini-batch training perhaps!).
+
+Further, any codecs not supported by `zarrs` will also automatically fall back to the python implementation.

docs/index.md

@@ -5,6 +5,5 @@
 :hidden: true
 :maxdepth: 1
 
-api
 contributing
 ```

pyproject.toml

@@ -30,7 +30,7 @@ dependencies = [
     'donfig',
     'pytest',
     'universal_pathlib>=0.2.0',
-    'zarr>=3.0.0',
+    "zarr",
 ]
 
 [project.optional-dependencies]

python/zarrs/_internal.pyi

@@ -4,7 +4,6 @@
 import typing
 from enum import Enum, auto
 
-import numpy
 import numpy.typing
 
 class Basic:
@@ -27,9 +26,6 @@ class CodecPipelineImpl:
         chunk_descriptions: typing.Sequence[WithSubset],
         value: numpy.typing.NDArray[typing.Any],
     ) -> None: ...
-    def retrieve_chunks(
-        self, chunk_descriptions: typing.Sequence[Basic]
-    ) -> list[numpy.typing.NDArray[numpy.uint8]]: ...
     def store_chunks_with_indices(
         self,
         chunk_descriptions: typing.Sequence[WithSubset],

python/zarrs/pipeline.py

@@ -2,15 +2,17 @@
 
 import asyncio
 import json
+import re
 from dataclasses import dataclass
 from typing import TYPE_CHECKING, TypedDict
 
 import numpy as np
 from zarr.abc.codec import Codec, CodecPipeline
+from zarr.core import BatchedCodecPipeline
 from zarr.core.config import config
 
 if TYPE_CHECKING:
-    from collections.abc import Iterable, Iterator
+    from collections.abc import Generator, Iterable, Iterator
     from typing import Any, Self
 
     from zarr.abc.store import ByteGetter, ByteSetter
@@ -20,28 +22,64 @@
     from zarr.core.common import ChunkCoords
     from zarr.core.indexing import SelectorTuple
 
-from ._internal import CodecPipelineImpl
+from ._internal import CodecPipelineImpl, codec_metadata_v2_to_v3
 from .utils import (
     CollapsedDimensionError,
     DiscontiguousArrayError,
-    make_chunk_info_for_rust,
+    FillValueNoneError,
     make_chunk_info_for_rust_with_indices,
 )
 
 
-def get_codec_pipeline_impl(codec_metadata_json: str) -> CodecPipelineImpl:
-    return CodecPipelineImpl(
-        codec_metadata_json,
-        validate_checksums=config.get("codec_pipeline.validate_checksums", None),
-        store_empty_chunks=config.get("array.write_empty_chunks", None),
-        chunk_concurrent_minimum=config.get(
-            "codec_pipeline.chunk_concurrent_minimum", None
-        ),
-        chunk_concurrent_maximum=config.get(
-            "codec_pipeline.chunk_concurrent_maximum", None
-        ),
-        num_threads=config.get("threading.max_workers", None),
-    )
+class UnsupportedDataTypeError(Exception):
+    pass
+
+
+class UnsupportedMetadataError(Exception):
+    pass
+
+
+def get_codec_pipeline_impl(codec_metadata_json: str) -> CodecPipelineImpl | None:
+    try:
+        return CodecPipelineImpl(
+            codec_metadata_json,
+            validate_checksums=config.get("codec_pipeline.validate_checksums", None),
+            store_empty_chunks=config.get("array.write_empty_chunks", None),
+            chunk_concurrent_minimum=config.get(
+                "codec_pipeline.chunk_concurrent_minimum", None
+            ),
+            chunk_concurrent_maximum=config.get(
+                "codec_pipeline.chunk_concurrent_maximum", None
+            ),
+            num_threads=config.get("threading.max_workers", None),
+        )
+    except TypeError as e:
+        if re.match(r"codec (delta|zlib) is not supported", str(e)):
+            return None
+        else:
+            raise e
+
+
+def codecs_to_dict(codecs: Iterable[Codec]) -> Generator[dict[str, Any], None, None]:
+    for codec in codecs:
+        if codec.__class__.__name__ == "V2Codec":
+            codec_dict = codec.to_dict()
+            if codec_dict.get("filters", None) is not None:
+                filters = [
+                    json.dumps(filter.get_config())
+                    for filter in codec_dict.get("filters")
+                ]
+            else:
+                filters = None
+            if codec_dict.get("compressor", None) is not None:
+                compressor = json.dumps(codec_dict.get("compressor").get_config())
+            else:
+                compressor = None
+            codecs_v3 = codec_metadata_v2_to_v3(filters, compressor)
+            for codec in codecs_v3:
+                yield json.loads(codec)
+        else:
+            yield codec.to_dict()
 
 
 class ZarrsCodecPipelineState(TypedDict):
@@ -52,8 +90,9 @@ class ZarrsCodecPipelineState(TypedDict):
 @dataclass
 class ZarrsCodecPipeline(CodecPipeline):
     codecs: tuple[Codec, ...]
-    impl: CodecPipelineImpl
+    impl: CodecPipelineImpl | None
     codec_metadata_json: str
+    python_impl: BatchedCodecPipeline
 
     def __getstate__(self) -> ZarrsCodecPipelineState:
         return {"codec_metadata_json": self.codec_metadata_json, "codecs": self.codecs}
@@ -62,13 +101,14 @@ def __setstate__(self, state: ZarrsCodecPipelineState):
         self.codecs = state["codecs"]
         self.codec_metadata_json = state["codec_metadata_json"]
         self.impl = get_codec_pipeline_impl(self.codec_metadata_json)
+        self.python_impl = BatchedCodecPipeline.from_codecs(self.codecs)
 
     def evolve_from_array_spec(self, array_spec: ArraySpec) -> Self:
         raise NotImplementedError("evolve_from_array_spec")
 
     @classmethod
     def from_codecs(cls, codecs: Iterable[Codec]) -> Self:
-        codec_metadata = [codec.to_dict() for codec in codecs]
+        codec_metadata = list(codecs_to_dict(codecs))
         codec_metadata_json = json.dumps(codec_metadata)
         # TODO: upstream zarr-python has not settled on how to deal with configs yet
         # Should they be checked when an array is created, or when an operation is performed?
@@ -78,6 +118,7 @@ def from_codecs(cls, codecs: Iterable[Codec]) -> Self:
             codec_metadata_json=codec_metadata_json,
             codecs=tuple(codecs),
             impl=get_codec_pipeline_impl(codec_metadata_json),
+            python_impl=BatchedCodecPipeline.from_codecs(codecs),
         )
 
     @property
@@ -120,29 +161,32 @@ async def read(
         drop_axes: tuple[int, ...] = (),  # FIXME: unused
     ) -> None:
         # FIXME: Error if array is not in host memory
-        out: NDArrayLike = out.as_ndarray_like()
         if not out.dtype.isnative:
             raise RuntimeError("Non-native byte order not supported")
         try:
+            if self.impl is None:
+                raise UnsupportedMetadataError()
+            self._raise_error_on_unsupported_batch_dtype(batch_info)
             chunks_desc = make_chunk_info_for_rust_with_indices(
                 batch_info, drop_axes, out.shape
             )
-        except (DiscontiguousArrayError, CollapsedDimensionError):
-            chunks_desc = make_chunk_info_for_rust(batch_info)
+        except (
+            UnsupportedMetadataError,
+            DiscontiguousArrayError,
+            CollapsedDimensionError,
+            UnsupportedDataTypeError,
+            FillValueNoneError,
+        ):
+            await self.python_impl.read(batch_info, out, drop_axes)
+            return None
         else:
+            out: NDArrayLike = out.as_ndarray_like()
             await asyncio.to_thread(
                 self.impl.retrieve_chunks_and_apply_index,
                 chunks_desc,
                 out,
             )
             return None
-        chunks = await asyncio.to_thread(self.impl.retrieve_chunks, chunks_desc)
-        for chunk, (_, spec, selection, out_selection) in zip(chunks, batch_info):
-            chunk_reshaped = chunk.view(spec.dtype).reshape(spec.shape)
-            chunk_selected = chunk_reshaped[selection]
-            if drop_axes:
-                chunk_selected = np.squeeze(chunk_selected, axis=drop_axes)
-            out[out_selection] = chunk_selected
 
     async def write(
         self,
@@ -152,14 +196,46 @@ async def write(
         value: NDBuffer,  # type: ignore
         drop_axes: tuple[int, ...] = (),
     ) -> None:
-        # FIXME: Error if array is not in host memory
-        value: NDArrayLike | np.ndarray = value.as_ndarray_like()
-        if not value.dtype.isnative:
-            value = np.ascontiguousarray(value, dtype=value.dtype.newbyteorder("="))
-        elif not value.flags.c_contiguous:
-            value = np.ascontiguousarray(value)
-        chunks_desc = make_chunk_info_for_rust_with_indices(
-            batch_info, drop_axes, value.shape
-        )
-        await asyncio.to_thread(self.impl.store_chunks_with_indices, chunks_desc, value)
-        return None
+        try:
+            if self.impl is None:
+                raise UnsupportedMetadataError()
+            self._raise_error_on_unsupported_batch_dtype(batch_info)
+            chunks_desc = make_chunk_info_for_rust_with_indices(
+                batch_info, drop_axes, value.shape
+            )
+        except (
+            UnsupportedMetadataError,
+            DiscontiguousArrayError,
+            CollapsedDimensionError,
+            UnsupportedDataTypeError,
+            FillValueNoneError,
+        ):
+            await self.python_impl.write(batch_info, value, drop_axes)
+            return None
+        else:
+            # FIXME: Error if array is not in host memory
+            value_np: NDArrayLike | np.ndarray = value.as_ndarray_like()
+            if not value_np.dtype.isnative:
+                value_np = np.ascontiguousarray(
+                    value_np, dtype=value_np.dtype.newbyteorder("=")
+                )
+            elif not value_np.flags.c_contiguous:
+                value_np = np.ascontiguousarray(value_np)
+            await asyncio.to_thread(
+                self.impl.store_chunks_with_indices, chunks_desc, value_np
+            )
+            return None
+
+    def _raise_error_on_unsupported_batch_dtype(
+        self,
+        batch_info: Iterable[
+            tuple[ByteSetter, ArraySpec, SelectorTuple, SelectorTuple]
+        ],
+    ):
+        # https://github.com/LDeakin/zarrs/blob/0532fe983b7b42b59dbf84e50a2fe5e6f7bad4ce/zarrs_metadata/src/v2_to_v3.rs#L289-L293 for VSUMm
+        # Further, our pipeline does not support variable-length objects due to limitations on decode_into, so object is also out
+        if any(
+            info.dtype.kind in {"V", "S", "U", "M", "m", "O"}
+            for (_, info, _, _) in batch_info
+        ):
+            raise UnsupportedDataTypeError()

python/zarrs/utils.py

@@ -3,10 +3,12 @@
 import operator
 import os
 from functools import reduce
-from typing import TYPE_CHECKING
+from typing import TYPE_CHECKING, Any
 
 import numpy as np
+from zarr.core.array_spec import ArraySpec
 from zarr.core.indexing import SelectorTuple, is_integer
+from zarr.core.metadata.v2 import _default_fill_value
 
 from zarrs._internal import Basic, WithSubset
 
@@ -15,7 +17,6 @@
     from types import EllipsisType
 
     from zarr.abc.store import ByteGetter, ByteSetter
-    from zarr.core.array_spec import ArraySpec
 
 
 # adapted from https://docs.python.org/3/library/concurrent.futures.html#concurrent.futures.ThreadPoolExecutor
@@ -31,6 +32,10 @@ class CollapsedDimensionError(Exception):
     pass
 
 
+class FillValueNoneError(Exception):
+    pass
+
+
 # This is a (mostly) copy of the function from zarr.core.indexing that fixes:
 #   DeprecationWarning: Conversion of an array with ndim > 0 to a scalar is deprecated
 # TODO: Upstream this fix
@@ -134,6 +139,12 @@ def get_shape_for_selector(
     return resulting_shape_from_index(shape, selector_tuple, drop_axes, pad=pad)
 
 
+def get_implicit_fill_value(dtype: np.dtype, fill_value: Any) -> Any:
+    if fill_value is None:
+        fill_value = _default_fill_value(dtype)
+    return fill_value
+
+
 def make_chunk_info_for_rust_with_indices(
     batch_info: Iterable[
         tuple[ByteGetter | ByteSetter, ArraySpec, SelectorTuple, SelectorTuple]
@@ -144,6 +155,14 @@ def make_chunk_info_for_rust_with_indices(
     shape = shape if shape else (1,)  # constant array
     chunk_info_with_indices: list[WithSubset] = []
     for byte_getter, chunk_spec, chunk_selection, out_selection in batch_info:
+        if chunk_spec.fill_value is None:
+            chunk_spec = ArraySpec(
+                chunk_spec.shape,
+                chunk_spec.dtype,
+                get_implicit_fill_value(chunk_spec.dtype, chunk_spec.fill_value),
+                chunk_spec.config,
+                chunk_spec.prototype,
+            )
         chunk_info = Basic(byte_getter, chunk_spec)
         out_selection_as_slices = selector_tuple_to_slice_selection(out_selection)
         chunk_selection_as_slices = selector_tuple_to_slice_selection(chunk_selection)
@@ -169,14 +188,3 @@ def make_chunk_info_for_rust_with_indices(
             )
         )
     return chunk_info_with_indices
-
-
-def make_chunk_info_for_rust(
-    batch_info: Iterable[
-        tuple[ByteGetter | ByteSetter, ArraySpec, SelectorTuple, SelectorTuple]
-    ],
-) -> list[Basic]:
-    return [
-        Basic(byte_interface, chunk_spec)
-        for (byte_interface, chunk_spec, _, _) in batch_info
-    ]