Support for new fsspec-style caching

[ian-r-rose]

As far as I can tell, this driver doesn't support fsspec-style caching at the moment:

import intake_parquet

path = "https://github.com/apache/parquet-testing/raw/master/data/alltypes_plain.parquet"
intake_parquet.ParquetSource(urlpath=path, engine="pyarrow").read()  # works
intake_parquet.ParquetSource(urlpath="simplecache::"+path, engine="pyarrow").read()  # fails

Unsure if this is more appropriate to be fixed at the dask layer or here. Is there a roadmap for rolling out fsspec caching to various drivers?

[martindurant]

Huff, OK. I'm not entirely sure why, but the latter is doing an extra isdir somewhere, and regex can't find any links (which is reasonable). The following works, but I wonder what would happen if there was by chance a link in the binary data.

--- a/fsspec/implementations/http.py
+++ b/fsspec/implementations/http.py
@@ -12,8 +12,8 @@ from fsspec.asyn import sync_wrapper, sync, AsyncFileSystem, maybe_sync
 from ..caching import AllBytes

 # https://stackoverflow.com/a/15926317/3821154
-ex = re.compile(r"""<a\s+(?:[^>]*?\s+)?href=(["'])(.*?)\1""")
-ex2 = re.compile(r"""(http[s]?://[-a-zA-Z0-9@:%_+.~#?&/=]+)""")
+ex = re.compile(b"""<a\\s+(?:[^>]*?\s+)?href=(["'])(.*?)\1""")
+ex2 = re.compile(b"""(http[s]?://[-a-zA-Z0-9@:%_+.~#?&/=]+)""")

 async def get_client():
@@ -98,7 +98,7 @@ class HTTPFileSystem(AsyncFileSystem):
         kw.update(kwargs)
         async with self.session.get(url, **self.kwargs) as r:
             r.raise_for_status()
-            text = await r.text()
+            text = await r.read()
         if self.simple_links:
             links = ex2.findall(text) + ex.findall(text)
         else:
@@ -108,6 +108,7 @@ class HTTPFileSystem(AsyncFileSystem):
         for l in links:
             if isinstance(l, tuple):
                 l = l[1]
+            l = l.decode()
             if l.startswith("/") and len(l) > 1:
                 # absolute URL on this server
                 l = parts.scheme + "://" + parts.netloc + l

[martindurant]

(PS: the parquet driver should not really be calling isdir, but isfile - and in HTTP, and sometimes s3/gcs, the same path can be both)

[zaneselvans]

Lest anybody else be confused by this issue, fsspec based simplecache caching does seem to work now, and can be enabled by passing the right storage_option to dask.dataframe.read_parquet(). See @martindurant's comment on an issue of ours over here: https://github.com/catalyst-cooperative/pudl/issues/1496#issuecomment-1085033950