Read Only Directory should be renamed Uncached Directory

[petemoore]

Three different types can be mounted in a task:

• File Mount
• Read Only Directory
• Writable Directory Cache

The name Read Only Directory is misleading, since the directory can be altered by the task. Originally it was thought that we would mount the directory in a read only fashion, so that it could be used for storing e.g. toolchains that should not be altered by tasks, and that would allow the directories to be reused without concern that they may have been tampered with.

As it happens, all read only directories are extracted from an archive file, and that archive file is persisted, and the extracted directories are discarded after the task completes. So it isn't so much a mounting operation, as a copying operation, and therefore any changes are not persisted.

In order to resolve this, two possibilities exist:

1. restricting write access to the read only directories, so that their name is accurate
2. renaming them to something like 'uncached directory' to make it clear that they can be altered, but any changes will not be persisted across tasks

I tend to favour the second option, but note that extracting large archives can be time consuming (e.g. a zip file containing a hundred thousand files) - so if we at some point in the future wished to really mount and unmount an existing directory with read-only permissions in future, it would perhaps be more work to do so.

[SimonSapin]

Is there description field next to the name, in the schema? There could be a sentence explaining that the extracted directory is writable but not persisted across tasks / task runs, each gets a new copy.

“Uncached” is slightly misleading too, because caching the archive (rather than downloading it every time) is the point of this feature.

[petemoore]

Is there description field next to the name, in the schema? There could be a sentence explaining that the extracted directory is writable but not persisted across tasks / task runs, each gets a new copy.

++ We should definitely update description too.

“Uncached” is slightly misleading too, because caching the archive (rather than downloading it every time) is the point of this feature.

Good point! We really need a better name, I'm not happy with "Read Only Directory" either. How about "Preloaded Directory"?