The old Bitcoin alert system has long since been retired.
( See also: https://bitcoin.org/en/alert/2016-11-01-alert-retirement )
This change causes each node to send any old peers that
it connects with a copy of the final alert.
The alert it hardcode cancels all other alerts including
other final alerts.
This command allows a user to increase the fee on a wallet transaction T, creating a "bumper" transaction B.
T must signal that it is BIP-125 replaceable.
T's change output is decremented to pay the additional fee. (B will not add inputs to T.)
T cannot have any descendant transactions.
Once B bumps T, neither T nor B's outputs can be spent until either T or (more likely) B is mined.
Includes code by @jonasschnelli and @ryanofsky
This forces the message handling thread to make another full
iteration of SendMessages prior to going back to sleep, ensuring
we announce the new block to all peers before sleeping.
Technically cs_sendProcessing is entirely useless now because it
is only ever taken on the one MessageHandler thread, but because
there may be multiple of those in the future, it is left in place
cs_vSend is used for two purposes - to lock the datastructures used
to queue messages to place on the wire and to only call
SendMessages once at a time per-node. I believe SendMessages used
to access some of the vSendMsg stuff, but it doesn't anymore, so
these locks do not need to be on the same mutex, and also make
deadlocking much more likely.
This disentangles the script validation skipping from checkpoints.
A new option is introduced "assumevalid" which specifies a block whos
ancestors we assume all have valid scriptsigs and so we do not check
them when they are also burried under the best header by two weeks
worth of work.
Unlike checkpoints this has no influence on consensus unless you set
it to a block with an invalid history. Because of this it can be
easily be updated without risk of influencing the network consensus.
This results in a massive IBD speedup.
This approach was independently recommended by Peter Todd and Luke-Jr
since POW based signature skipping (see PR#9180) does not have the
verifiable properties of a specific hash and may create bad incentives.
The downside is that, like checkpoints, the defaults bitrot and older
releases will sync slower. On the plus side users can provide their
own value here, and if they set it to something crazy all that will
happen is more time will be spend validating signatures.
Checkblocks and checklevel are also moved to the hidden debug options:
Especially now that checkblocks has a low default there is little need
to change these settings, and users frequently misunderstand them as
influencing security or IBD speed. By hiding them we offset the
space added by this new option.
vRecvMsg is now only touched by the socket handler thread.
The accounting vars (nRecvBytes/nLastRecv/mapRecvBytesPerMsgCmd) are also
only used by the socket handler thread, with the exception of queries from
rpc/gui. These accesses are not threadsafe, but they never were. This needs to
be addressed separately.
Also, update comment describing data flow
Similar to the recv flag, but this one indicates whether or not the net's send
buffer is full.
The socket handler checks the send queue when a new message is added and pauses
if necessary, and possibly unpauses after each message is drained from its buffer.
Messages are dumped very quickly from the socket handler to the processor, so
it's the depth of the processing queue that's interesting.
The socket handler checks the process queue's size during the brief message
hand-off and pauses if necessary, and the processor possibly unpauses each time
a message is popped off of its queue.
In order to sleep accurately, the message handler needs to know if _any_ node
has more processing that it should do before the entire thread sleeps.
Rather than returning a value that represents whether ProcessMessages
encountered a message that should trigger a disconnnect, interpret the return
value as whether or not that node has more work to do.
Also, use a global fProcessWake value that can be set by other threads,
which takes precedence (for one cycle) over the messagehandler's decision.
Note that the previous behavior was to only process one message per loop
(except in the case of a bad checksum or invalid header). That was changed in
PR #3180.
The only change here in that regard is that the current node now falls to the
back of the processing queue for the bad checksum/invalid header cases.
Pavel Janík