net: stop the failover log naming a peer on every re-request

The line was unconditional on the argument that failover firing is the
pathology of #33 and nobody could otherwise see it. That much is right.
Printing a peer address every time it fires is not: a peer decides how
often the line is written, by announcing hashes it will not serve, and
an address is the one thing the .btf transport otherwise takes trouble
not to spread around. Sustained, that was tens of lines a minute, each
naming a peer, driven entirely from outside.

Split it. The per-peer detail -- which block, how long, which peer is
being tried next -- moves behind the net category, where the rest of the
getdata logging already is. What stays unconditional is a count with no
addresses in it, over a window no peer can shorten: the first failover
after a quiet spell still prints immediately, because the change from
"blocks arrive" to "blocks are announced and not served" is the event
worth seeing, and everything after it is summarised once a minute.

Worst case is now one line per minute regardless of what a peer does,
instead of one per re-request.

0 files changed, 0 insertions, 0 deletions