Pack files created by interrupted prune runs, appear to consist only of
duplicate blobs on the next run. This caused the previous heuristic to
ignore those pack files. Now, a duplicate blob in a specific pack file
is also selected if that pack file only contains duplicate blobs. This
allows prune to select the already rewritten pack files.
Rewrite implements a streaming rewrite of the index that excludes the
given packs. For this it loads all index files from the repository and
only modifies those that require changes. This will reduce the index
churn when running prune. Rewrite does not require the in-memory index
and thus can drop it to significantly reduce the memory usage.
However, `prune --unsafe-recovery` cannot use this strategy and requires
a separate method to save the whole in-memory index. This is now handled
using SaveFallback.
The toplevel context in restic only canceled if the user interrupts a
restic operation. If the network connection has failed this can require
waiting the full retry duration of 15 minutes which is a bad user
experience for interactive usage. Thus limit the delay to one minute in
this case.
RemoveUnpacked will eventually block removal of all filetypes other than
snapshots. However, getting there requires a major refactor to provide
some components with privileged access.
LoadRaw also includes improved context cancellation handling similar to the
implementation in repository.LoadUnpacked.
The removed cache backend test will be added again later on.
With most cloud providers, traffic is much more expensive than API
calls. Thus slightly bias streamPack towards a bit more API calls in
exchange for slightly less traffic.
Due to the interface of streamPack, we cannot guarantee that operations
progress fast enough that the underlying connections remains open. This
introduces partial failures which massively complicate the error
handling.
Switch to a simpler approach that retrieves the pack in chunks of 32MB.
If a blob is larger than this limit, then it is downloaded separately.
To avoid multiple copies in memory, an auxiliary interface
`discardReader` is introduced that allows directly accessing the
downloaded byte slices, while still supporting the streaming used by the
`check` command.
