It is possible that upon a cold-start, we enqueue a partial file
for deletion that is resumed shortly after startup.
If the file transfer happens to last longer than deleteDelay,
we will delete the partial file, which is unfortunate.
The client spent a long time uploading a file,
only for it to be accidentally deleted.
It's a very rare race, but also a frustrating one
if it happens to manifest.
Fix the code to only delete partial files that
do not have an active puts against it.
We also fix a minor bug in ResumeReader
where we read b[:blockSize] instead of b[:cs.Size].
The former is the fixed size of 64KiB,
while the latter is usually 64KiB,
but may be less for the last block.
Updates tailscale/corp#14772
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
File resumption requires keeping partial files around for some time,
but we must still eventually delete them if never resumed.
Thus, we implement asynchronous file deletion, which could
spawn a background goroutine to delete the files.
We also use the same mechanism for deleting files on Windows,
where a file can't be deleted if there is still an open file handle.
We can enqueue those with the asynchronous file deleter as well.
Updates tailscale/corp#14772
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
We add the following API:
* type FileChecksums
* type Checksum
* func Manager.PartialFiles
* func Manager.HashPartialFile
* func ResumeReader
The Manager methods provide the ability to query for partial files
and retrieve a list of checksums for a given partial file.
The ResumeReader function is a helper that wraps an io.Reader
to discard content that is identical locally and remotely.
The FileChecksums type represents the checksums of a file
and is safe to JSON marshal and send over the wire.
Updates tailscale/corp#14772
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
Co-authored-by: Rhea Ghosh <rhea@tailscale.com>
Changes made:
* Move all HTTP related functionality from taildrop to ipnlocal.
* Add two arguments to taildrop.Manager.PutFile to specify
an opaque client ID and a resume offset (both unused for now).
* Cleanup the logic of taildrop.Manager.PutFile
to be easier to follow.
* Implement file conflict handling where duplicate files are renamed
(e.g., "IMG_1234.jpg" -> "IMG_1234 (2).jpg").
* Implement file de-duplication where "renaming" a partial file
simply deletes it if it already exists with the same contents.
* Detect conflicting active puts where a second concurrent put
results in an error.
Updates tailscale/corp#14772
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
Co-authored-by: Rhea Ghosh <rhea@tailscale.com>
Changes made:
* Unexport declarations specific to internal taildrop functionality.
* Document all exported functionality.
* Move TestRedactErr to the taildrop package.
* Rename and invert Handler.DirectFileDoFinalRename as AvoidFinalRename.
Updates tailscale/corp#14772
Signed-off-by: Joe Tsai <joetsai@digital-static.net>
Over time all taildrop functionality will be contained in the
taildrop package. This will include end to end unit tests. This is
simply the first smallest piece to move over.
There is no functionality change in this commit.
Updates tailscale/corp#14772
Signed-off-by: Rhea Ghosh <rhea@tailscale.com>
Co-authored-by: Joseph Tsai <joetsai@tailscale.com>
Joe Tsai
Rhea Ghosh