Pulp

How would we obtain the total size in a generic way? Maybe we could add a "size" attribute to FileContentUnit, and leave it up to plugins to populate that if/when possible. Would this be optional?

What about on_demand? If a file hasn't been downloaded, should the unit's size be 0? It seems more intuitive that it should be the expected size after download. But what about the size of the repo? I'm not sure why, but my intuition is the opposite: that a repo's size should be 0 if none of its units have been downloaded. Maybe the algorithm would roughly be this:

size = 0
for unit in repo:
  if unit.downloaded is True:
    size += unit.size

For that reason, maybe the repo's attribute would be better-named "disk_use", or something like that.

Presumably the repo's size would have to be updated under any of these circumstances:

• content added (sync/copy/upload)
• content removed (sync/remove)
• unit marked as downloaded

What about "shared content", used by ostree, where multiple units can reference the same files? I wonder if the ostree tooling itself has a standard, "expected" way to represent size of a repo where there may be overlap between branches.

Given the above questions, I wonder if this is complex enough that it should wait for pulp 3.

+1 to making the attribute name 'disk_use' and by that name I only expect it to count the on-disk of already downloaded units (not on_demand units).

+1 to putting it as an attribute on FileContentUnit.

What if we make the pre_save_handler of FileContentUnit calculate the attribute if it is not already set and the file is downloaded locally. It could default to null otherwise to distinguish against empty files. We do this already for important things so doing it for this would work I think [0].

We would also add a property to Repository that contains the algorithm you posted and that field would be summed at runtime and not formally saved on the Repository. Is that what others are thinking?

Also for shared content units I think having a unit be counted against many repositories that share that unit I think is OK. I think of this feature as helping to answer the question: "If I export or download all units for a repo outside of Pulp how much space do I need?"

Also using the FileContentUnit attribute we could have Pulp sum the total space and available space as part of the /status/ API but that is a separate feature answering a different question: "how much space is Pulp using, and how much does it have available before filling up the filesystem".

+0 to waiting for Pulp3 is file. Regardless, I wanted to express my ideas here anyway which could also be translated directly to Pulp3.

[0]: https://github.com/pulp/pulp/blob/91a1e28c9e7d3dee418d5c7680dbf25c3e7adc63/server/pulp/server/db/model/__init__.py#L849-L851