Catch some allowed exceptions

[maxrjones]

zarr.create_array works with this PR. Here are a couple open questions:

1. Should allowed exceptions be constant or configurable as in the fsspec store?
2. What's the best way to catch any exceptions returned during get_partial_values?

Work torwards zarr-developers#1661

[kylebarron]

1. Should allowed exceptions be constant or configurable as in the fsspec store?

I'm happy to make it configurable. Perhaps we should provide a default but make it configurable?

2. What's the best way to catch any exceptions returned during get_partial_values?

I think as you have is probably fine?

[maxrjones]

Should allowed exceptions be constant or configurable as in the fsspec store?

I'm happy to make it configurable. Perhaps we should provide a default but make it configurable?

This is the approach that fsspec takes. I think it's necessary to provide a default because FileNotFoundErrors need to be caught for determining groups/arrays/nothing.

What's the best way to catch any exceptions returned during get_partial_values?

I think as you have is probably fine?

I could test this, but I thought that there may be an issue in

zarr-python/src/zarr/storage/object_store.py

Lines 355 to 359 in 72c9b30

	# TODO: this gather a list of list of Response; not sure if there's a way to
	# unpack these lists inside of an `asyncio.gather`?
	for responses in await asyncio.gather(*futs):
	for resp in responses:
	buffers[resp["original_request_index"]] = resp["buffer"]

with the 'buffer' key not existing in the responses if there was a 'FileNotFoundError'.

[kylebarron]

This is the approach that fsspec takes. I think it's necessary to provide a default because FileNotFoundErrors need to be caught for determining groups/arrays/nothing.

So in that case we should always catch FileNotFound, and if the user desires we can catch additional errors?

[kylebarron]

I could test this, but I thought that there may be an issue in

zarr-python/src/zarr/storage/object_store.py

Lines 355 to 359 in 72c9b30

	# TODO: this gather a list of list of Response; not sure if there's a way to
	# unpack these lists inside of an `asyncio.gather`?
	for responses in await asyncio.gather(*futs):
	for resp in responses:
	buffers[resp["original_request_index"]] = resp["buffer"]

with the 'buffer' key not existing in the responses if there was a 'FileNotFoundError'.

Oh perhaps; maybe just use get instead of []?

[kylebarron]

Perhaps you're right that this snippet needs to be updated in more ways than just replacing [] with get(). I haven't spent time thinking about it yet.