Lack of generics support is blocking various dependency upgrades,
so this unblocks that.
Temporarily disabled `checklocks` linter until it is fixed upstream.
* Unify sparse and normal IO output
This commit refactors the code paths that excercise normal and sparse
writing of restored content. The goal is to expose sparsefile.Copy()
and iocopy.Copy() to be interchangeable, thereby allowing us to wrap
or transform their behavior more easily in the future.
* Introduce getStreamCopier()
* Pull ioCopy() into getStreamCopier()
* Fix small nit in E2E test
We should be getting the block size of the destination file, not
the source file.
* Call stat.GetBlockSize() once per FilesystemOutput
A tiny refactor to pull this call out of the generated stream copier,
as the block size should not change from one file to the next within
a restore entry.
NOTE: as a side effect, if block size could not be found (an error
is returned), we will return the default stream copier instead of
letting the sparse copier fail. A warning will be logged, but this
error will not cause the restore to fail; it will proceed silently.
This removes big shared lock held for for the duration of each request
and replaces it with trivially short lock to capture the current
state of the server/repository before passing it to handlers.
Handlers are now limited to only accessing a small subset of Server
functionality to be able to better reason about them.
