v1.13.5 made some proxies angry with its massive chunklists
when stitching chunks, only list the first chunk hash in full,
and include a truncated hash for the consecutive chunks
should be enough for logfiles to make sense
and to smoketest that clients are behaving
rather than sending each file chunk as a separate HTTP request,
sibling chunks will now be fused together into larger HTTP POSTs
which results in unreasonably huge speed boosts on some routes
( `2.6x` from Norway to US-East, `1.6x` from US-West to Finland )
the `x-up2k-hash` request header now takes a comma-separated list
of chunk hashes, which must all be sibling chunks, resulting in
one large consecutive range of file data as the post body
a new global-option `--u2sz`, default `1,64,96`, sets the target
request size as 64 MiB, allowing the settings ui to specify any
value between 1 and 96 MiB, which is cloudflare's max value
this does not cause any issues for resumable uploads; thanks to the
streaming HTTP POST parser, each chunk will be verified and written
to disk as they arrive, meaning only the untransmitted chunks will
have to be resent in the event of a connection drop -- of course
assuming there are no misconfigured WAFs or caching-proxies
the previous up2k approach of uploading each chunk in a separate HTTP
POST was inefficient in many real-world scenarios, mainly due to TCP
window-scaling behaving erratically in some IXPs / along some routes
a particular link from Norway to Virginia,US is unusably slow for
the first 4 MiB, only reaching optimal speeds after 100 MiB, and
then immediately resets the scale when the request has been sent;
connection reuse does not help in this case
on this route, the basic-uploader was somehow faster than up2k
with 6 parallel uploads; only time i've seen this
use sigmasks to block SIGINT, SIGTERM, SIGUSR1 from all other threads
also initiate shutdown by calling sighandler directly,
in case this misses anything and that is still unreliable
(discovered by `--exit=idx` being noop once in a blue moon)
* mention cloudflare-specific nginx config
versus.md:
* seafile has a size limit on zip downloads
* seafile and nextcloud are slow at uploading many small files
u2c: improve error message in funky environments
