This commit fixes a bunch of issues at the same time, as they are all
related to path handling:
- `pathlib.Path.resolve()` or `.absolute()` are replaced by
`bpathlib.make_absolute()`. The latter does NOT follow symlinks and does
NOT network mounts from a drive letter to UNC notation. This also has
advantages on non-Windows sytems, as it allows BAT-packing a directory
structure with symlinked files (such as a Shaman checkout).
- Better handling of drive letters, and of paths that cross drive
boundaries.
- Better testing of Windows-specific cases when running the tests on
Windows, and of POSIX-specific cases on other platforms.
Thanks to @wisaac for starting this patch in D6676.
Thanks to @jbakker for pointing out the drive letter issue. This fixes
T70655.
The Shaman server is a file storage system that identifies files by
SHA256sum and file length. BAT can send packs there by only uploading
changed/new files. The BAT pack is reproduced at the Shaman server's
checkout directory by creating symlinks to the files in its file
storage.
Retrying sending files:
When we can defer uploading a file (that is, when we have other files to
upload as well, and we could send the current file at a later moment) we
send an `X-Shaman-Can-Defer-Upload: true` header in the file upload
request. In that case, when someone else is already uploading that file,
a `208 Already Reported` response is sent and the connection is closed.
Python's Requests library unfortunately won't give us that response if
we're still streaming the request, and raise a ConnectionError exception
instead. This exception can mean two things:
- If the `X-Shaman-Can-Defer-Upload: true` header was sent: someone else
is currently uploading that file, so defer it.
- If that header was not sent: that file is already completely uploaded
and does not need to be uploaded again.
Instead of retrying each failed file, after a few failures we now just
resend the definition file to get a new list of files to upload, then
send those. This should considerably reduce the number of HTTP calls
when multiple clients are uploading the same set of files.
The target path is just read as string from the CLI now, to allow more
complex targets (such as URLs) that don't directly map to a path.
The Packer subclass now handles the conversion from that string to a
`pathlib.PurePath`, and specific subclasses & transfer classes can convert
those to a `pathlib.Path` to perform actual filesystem operations when
necessary.
This makes BAT skip assets that are referred to with an absolute path.
It is assumed that the receiver of the BAT pack can access those assets
at the same path.
For this to work well I also had to remove the sorting of blocks in
trace.deps(). The sorting caused the first `yield` to be executed only
after each blend file was opened, which means that the consuming for-loop
takes a long time to hit its first iteration. As a result, it would respond
slowly to abort requests. By not sorting the first `yield` is much sooner,
resolving this issue.
Both the dependency Tracer class and the Packer class now support a
callback object, where the latter is a subclass of the former.
For file transfers running in a separate thread, there is a thread-safe
wrapper for progress callbacks. This wrapper can be called from any thread,
and calls the wrapped callback object from the main thread. This way the
callback implementation itself doesn't have to worry about threading
issues.
