This threw an unusual exception w/o an error message when probing to see if
the bucket exists yet. So rather than relying on tryS3, catch all
exceptions.
This does mean that it might get an exception for some transient network
error, think this means the bucket DNE yet, and try to create it, and then
fail when it already exists.
When uploading the last part of a file, which was 640229 bytes, S3 rejected
that part: "Your proposed upload is smaller than the minimum allowed size"
I don't know what the minimum is, but the fix is just to include the last
part into the previous part. Since this can result in a part that's
double-sized, use half-sized parts normally.
Unfortunately, I don't fully understand why it was leaking using the old
method of a lazy bytestring. I just know that it was leaking, despite
neither hGetUntilMetered nor byteStringPopper seeming to leak by
themselves.
The new method avoids the lazy bytestring, and simply reads chunks from the
handle and streams them out to the http socket.
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.
Untested and not even compiled yet.
Testing should include checks that file content streams through without
buffering in memory.
Note that CL.consume causes all the etags to be buffered in memory.
This is probably nearly unavoidable, since a request has to be constructed
that contains the list of etags in its body. (While it might be possible to
stream generation of the body, that would entail making a http request that
dribbles out parts of the body as the multipart uploads complete, which is
not likely to work well..
To limit this being a problem, it's best for partsize to be set to some
suitably large value, like 1gb. Then a full terabyte file will need only
1024 etags to be stored, which will probably use around 1 mb of memory.
