feat: gossipsub 1.2: IDONTWANT

[wemeetagain]

Add support for gossipsub 1.2, namely, IDONTWANT support.

Behavior

• The first time a message is seen, prevalidation, send IDONTWANT to mesh peers (that aren't the sender and that support 1.2) if the message data is gte idontwantMinDataSize
• Track per-heartbeat count of IDONTWANTs received from peers
• Track IDONTWANTs received from peers, along with the heartbeat tick that the IDONTWANT was received
• Prune IDONTWANT counts in the heartbeat
• Prune tracked IDONTWANTs in the heartbeat, only keep IDONTWANTs for mcacheLength number of heartbeats
• Prune IDONTWANT counts and tracked IDONTWANTs on peer removal
• Prune IDONTWANT counts and tracked IDONTWANTs on stop
• New metrics track sent / received IDONTWANT count and IDONTWANT count of messages we haven't yet received (to track the "savings" of IDONTWANT)

Configuration

• new opts:
  • idontwantMinDataSize - The minimum message size in bytes to be considered for sending IDONTWANT messages. Below this, no IDONTWANT is sent. - default 512
  • idontwantMaxMessages - The maximum number of IDONTWANT messages per heartbeat per peer. IDONTWANTs received beyond this limit are ignored. - default 512
• new metrics
  • gossipsub_rpc_sent_idontwant_total
  • gossipsub_idontwant_rcv_msgids_total
  • gossipsub_idontwant_rcv_dont_have_msgids_total