This should be essentially no-op change for hGetContentsMetered, since it
always gets the entire contents. So the only difference is that each chunk
of the lazy bytestring will always be the full chunk size. So, I'm pretty
sure this is safe. Also, the only current users of hGetContentsMetered are
reading files, so the stream won't block for long in the middle.
The improvement is that hGetUntilMetered will always get some multiple of
the defaultChunkSize. This will allow the S3 multipart code to pick a fixed
size and know that hGetUntilMetered will really get that size.
(cherry picked from commit bd09046291)
This only performs some basic tests so far; no testing of chunking or
resuming. Also, the existing encryption type of the remote is used; it
would be good later to derive an encrypted and a non-encrypted version of
the remote and test them both.
This commit was sponsored by Joseph Liu.
Leverage the new chunked remotes to automatically resume downloads.
Sort of like rsync, although of course not as efficient since this
needs to start at a chunk boundry.
But, unlike rsync, this method will work for S3, WebDAV, external
special remotes, etc, etc. Only directory special remotes so far,
but many more soon!
This implementation will also properly handle starting a download
from one remote, interrupting, and resuming from another one, and so on.
(Resuming interrupted chunked uploads is similarly doable, although
slightly more expensive.)
This commit was sponsored by Thomas Djärv.
Not yet used by any special remotes, but should not be too hard to add it
to most of them.
storeChunks is the hairy bit! It's loosely based on
Remote.Directory.storeLegacyChunked. The object is read in using a lazy
bytestring, which is streamed though, creating chunks as needed, without
ever buffering more than 1 chunk in memory.
Getting the progress meter update to work right was also fun, since
progress meter values are absolute. Finessed by constructing an offset
meter.
This commit was sponsored by Richard Collins.
This has not been tested at all. It compiles!
The only known missing things are support for encryption, and for get/set
of special remote configuration, and of key state. (The latter needs
separate work to add a new per-key log file to store that state.)
Only thing I don't much like is that initremote needs to be passed both
type=external and externaltype=foo. It would be better to have just
type=foo
Most of this is quite straightforward code, that largely wrote itself given
the types. The only tricky parts were:
* Need to lock the remote when using it to eg make a request, because
in theory git-annex could have multiple threads that each try to use
a remote at the same time. I don't think that git-annex ever does
that currently, but better safe than sorry.
* Rather than starting up every external special remote program when
git-annex starts, they are started only on demand, when first used.
This will avoid slowdown, especially when running fast git-annex query
commands. Once started, they keep running until git-annex stops, currently,
which may not be ideal, but it's hard to know a better time to stop them.
* Bit of a chicken and egg problem with caching the cost of the remote,
because setting annex-cost in the git config needs the remote to already
be set up. Managed to finesse that.
This commit was sponsored by Lukas Anzinger.
There was confusion in different parts of the progress bar code about
whether an update contained the total number of bytes transferred, or the
number of bytes transferred since the last update. One way this bug
showed up was progress bars that seemed to stick at zero for a long time.
In order to fix it comprehensively, I add a new BytesProcessed data type,
that is explicitly a total quantity of bytes, not a delta.
Note that this doesn't necessarily fix every problem with progress bars.
Particularly, buffering can now cause progress bars to seem to run ahead
of transfers, reaching 100% when data is still being uploaded.
