Use Notify instead of stupid sleep in background worker
Use Semaphore to limit concurrent requests in rpc_client
Make more background tasks cancellable
Issue: RC increases also when the block ref entry is first put by the actual client.
At that point the client is probably already sending us the block content,
so we don't need to do a get...
We should add a delay before the task is added or find something to do.
So, the issues were:
- webpki does not support IP addresses as DNS names in URLs,
so I hacked the HttpsConnector to always provide a fixed string
as the DNS name for server certificate validation
- the certificate requied a SAN section which was complicated to build
but eventually the solution is there in genkeys.sh
So the HTTP client future of Hyper is not Sync, thus the stream
that read blocks wasn't either. However Hyper's default Body type
requires a stream to be Sync for wrap_stream. Solution: reimplement
a custom HTTP body type.
