v0.2.0 (on Bitcoin Core 0.19.1)

UDP Multicast Tx

• Refactor the UDP Tx packet scheduler implementation on udpnet.cpp.
• Implement a standalone ring buffer class and use it on the new scheduler.
• Add a class to handle throttling in the UDP packet scheduler and reuse it to
  implement the throttling of txns sent over UDP multicast.
• Remove the tracking of block Tx window cycles (with debug=udpmulticast) due
  to inaccuracies that derive from the chunk interleaving approach.
• Fix checksum initialization on the UDP message header.
• Fix the computation of physical and logical UDP multicast stream indexes.
• Configure option udpmulticasttx based on an independent configuration file
  instead of using comma-separated arguments.
• Support the independent enabling of the block and txn streams composing each
  UDP multicast Tx instance.
• Support control of FEC overhead applied to block repetition loops via the new
  udpmulticasttx configuration file.
• Fix rounding of variable overhead used on FEC encoding.

UDP Multicast Rx

• Fix the UDP multicast Rx bitrate measurements that were not considering the
  variable-length UDP packets used for txns.

FEC

• Add unit tests covering fec.cpp.
• Support FEC decoding in both memory and mmap modes. Use the memory mode for
  new blocks and the mmap approach for historic (repeated) blocks.
• Optimize the fetching of wirehair-decoded FEC objects that are not pre-filled
  (i.e., historic blocks and large mempool txns).
• Update the naming format adopted for memory-mapped files storing partial
  FEC-encoded block data.
• Support persistence of partially-received FEC-encoded blocks across
  sessions. Keep the partial block files on disk until they are entirely decoded
  and reload partially-received block files on startup.

RPCs

Tx RPCs

• Add RPC gettxqueueinfo to fetch information from the transmit queues active
  in the UDP Tx packet scheduler.
• Add RPC gettxwindowinfo to fetch the UDP multicast Tx block window status
  and remove this information from the previous periodic debug logs.
• Add RPC gettxntxinfo for monitoring of mempool txn transmissions.
• Add RPC txblock for re-transmission of any arbitrary block (specified by
  height) over the UDP multicast Tx instances.

Rx RPCs

• Add RPC getfechitratio to fetch the txn and FEC chunk hit ratios
  corresponding to the txn/chunk pre-filling mechanism.
• Add RPC getudpmulticastinfo to read UDP multicast Rx information, including
  the measured bit rates.
• Add RPC getoooblocks to obtain information regarding out-of-order blocks.

Debug options

• Drop the previous optional debug printing of FEC chunk stats, deprecated in
  favor of debugging using the getchunkstats RPC.