Failed/incomplete downloads still appear in local data sources

[forman]

Expected behavior

Just got a connection timeout during a download of a large data source (the OZONE one from #374). I expected the failed/incomplete download not to appear in my local data sources next time I start Cate.

Actual behavior

The data source appears.

Note that the *.lock* file could tell that a download is ongoing. It could also contain status incl. progress and error information about the download.

The issue is closely related to #337.

Specifications

Cate 0.9.0.dev7

[mzuehlke]

Hi @kbernat

When the user cancels the download you remove all files, but if an error occurs while downloading all files already downloaded remain on disk. Is this intended?

cate/cate/ds/esa_cci_odp.py

Lines 1009 to 1017 in b519f21

	try:
	self._make_local(local_ds, time_range, region, var_names, monitor=monitor)
	except Cancellation as c:
	local_store.remove_data_source(local_ds)
	raise c
	except Exception as e:
	if local_ds.is_empty:
	local_store.remove_data_source(local_ds)
	raise e

[kbernat]

@mzuehlke yes, it's our "resume" feature :)

[kbernat]

@mzuehlke we may think about asking user if incomplete data should be kept or not..

[forman]

I suggest that a resume should only be possible/required on external errors, e.g. timeout and IOError, not on any (possibly developer) error that might occur in make_local, see #393