After reading and chunking all data in a file, the FutureFile still has
to wait until the FutureBlobs are completed. This was done synchronously
which results in blocking the file saver and prevents the next file from
being read.
By replacing the FutureBlob with a callback, it becomes possible to
complete the FutureFile asynchronously.
We always need both values, except in a test, so we don't need to lock
twice and risk scheduling in between.
Also, removed the resetting in Done. This copied a mutex, which isn't
allowed. Static analyzers tend to trip over that.
The channel-based algorithm had grown quite complicated. This is easier
to reason about and likely to be more performant with very many
CompleteBlob calls.
As long as only a small fraction of the data in a repository is
rewritten, the keepBlobs set will be rather small after cleaning it up.
As golang maps do not shrink their memory usage, just copy the contents
over to a new map. However, only copy the map if the cleanup removed at
least half the entries.
The set covers necessary, existing and duplicate blobs. This removes the
duplicate sets used to track whether all necessary blobs also exist.
This reduces the memory usage of prune by about 20-30%.
The RetryBackend tests depend on the mock backend. When the Backend
interface is eventually split from the restic package, this will lead to
a dependency cycle between backend and backend/mock. Thus split the
RetryBackend into a separate package to avoid this problem.
Archiver.Save queries the current time multiple times. This commit
removes one of these calls as they showed up while profiling a backup of
a nearly unchanged dataset containing 3 million files.
There is no need to use a special wildcard `**` to demonstrate negative
patterns. Actually, it is both slower than the simpler variant and seems
to confuse users.
The string form was presumably useful before the introduction of
layouts, but right now it just makes call sequences and garbage
collection more expensive (the latter because every string contains
a pointer to be scanned).
if x { return true } return false => return x
fmt.Sprintf("%v", x) => fmt.Sprint(x) or x.String()
The fmt.Sprintf idiom is still used in the SecretString tests, where it
serves security hardening.
