Each part of a multipart upload takes 96M of memory, so we make sure
that we don't user more than `--transfers` * 96M of memory buffering
the multipart uploads.
This has the consequence that some uploads may appear to be at 0% for
a while, however they will get going eventually so this won't
re-introduce #731.
This happened when the underlying reader returned io.ErrUnexpectedEOF.
The error handling for the call to io.ReadFull failed to take this
into account.
io.ErrUnexpectedEOF is reasonably common when SSL connections go wrong
when communicating with ACD, so it manifested itself as transfers from
non-encrypted ACD to encrypted ACD getting stuck.
Optional interfaces are becoming more important in rclone,
--track-renames and --backup-dir both rely on them.
Up to this point rclone has used interface upgrades to define optional
behaviour on Fs objects. However when one Fs object wraps another it
is very difficult for this scheme to work accurately. rclone has
relied on specific error messages being returned when the interface
isn't supported - this is unsatisfactory because it means you have to
call the interface to see whether it is supported.
This change enables accurate detection of optional interfaces by use
of a Features struct as returned by an obligatory Fs.Features()
method. The Features struct contains flags and function pointers
which can be tested against nil to see whether they can be used.
As a result crypt and hubic can accurately reflect the capabilities of
the underlying Fs they are wrapping.
This changes `ListFn`'s implementation so that if it encounters a not
found error, instead of sending a fatal error to log, it coordinates the
return of the error between checker goroutines and sends it back to the
caller.
The main impetus here is that it allows an external program compiling
against rclone as a package to handle a not found, where it currently it
cannot.
This does change error output on a not found a little bit, we go from
this:
2017/01/09 21:14:03 directory not found
To this:
2017/01/09 21:13:44 Failed to ls: directory not found
Before this change mount only simulated rmdir & mkdir, now it actually
runs mkdir & rmdir on the underlying remote, using the new parmaeters
to fs.Mkdir and fs.Rmdir.
Fixes#956
