id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	launchpad_bug
3801	Clarify behavior of overwriting in immutable uploads	itamarst	itamarst	"This is related but not quite the same as #3793.

1. Current interactions from Fooslcap when uploading an immutable basically upload in order. With HTTP, uploads can happen out of order. How to handle holes?
2. Immutables are supposed to be immutable. As such, the data changing between different write attempts to the same in-progress immutable suggests something went very wrong.
3. Current behavior is ""last write wins"". This could potentially lead to unexpected outcomes if there are bugs.

Alternative behaviors to current behavior include:

1. Disallow overlapping writes.
2. Allow overlapping writes so long as data is unchanged.

In either case the need to deal with out-of-order writes remains due to HTTP. Current code might work, but would result in holes that then get overwritten. Policies that explicitly forbid/validate overlapping writes would need to deal with holes."	task	closed	normal	HTTP Storage Protocol	unknown	n/a	fixed