consensus.OnTransaction is a callback, so it can be called at any time.
We need to check whether service (and dBFT) is started before the
subsequent transaction handling like it is done inside the OnPayload
callback.
Notice that it makes the node accept Extensible payloads with any category
which is the same way C# node works. We're trusting Extensible senders,
improper payloads are harmless until they DoS the network, but we have some
protections against that too (and spamming with proper category doesn't differ
a lot).
It was broken somewhere between 2f490a3403 and
85ce207f40 leading to panic on watch only node:
2021-07-21T16:21:39.201+0200 INFO received Commit {"validator": 3}
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x28 pc=0xbcc59e]
goroutine 486 [running]:
github.com/nspcc-dev/neo-go/pkg/consensus.(*service).newBlockFromContext(0xc0001629a0, 0xc000308000, 0xc0010fa000, 0x2cb417800)
github.com/nspcc-dev/neo-go/pkg/consensus/consensus.go:664 +0xbe
github.com/nspcc-dev/dbft.(*Context).MakeHeader(...)
github.com/nspcc-dev/dbft@v0.0.0-20210302103605-cc75991b7cfb/context.go:270
github.com/nspcc-dev/dbft.(*DBFT).onCommit(0xc000308000, 0x138c998, 0xc000115110)
github.com/nspcc-dev/dbft@v0.0.0-20210302103605-cc75991b7cfb/dbft.go:487 +0x575
github.com/nspcc-dev/dbft.(*DBFT).OnReceive(0xc000308000, 0x138c998, 0xc000115110)
github.com/nspcc-dev/dbft@v0.0.0-20210302103605-cc75991b7cfb/dbft.go:251 +0xef5
github.com/nspcc-dev/neo-go/pkg/consensus.(*service).eventLoop(0xc0001629a0)
github.com/nspcc-dev/neo-go/pkg/consensus/consensus.go:312 +0x7d6
created by github.com/nspcc-dev/neo-go/pkg/consensus.(*service).Start
github.com/nspcc-dev/neo-go/pkg/consensus/consensus.go:262 +0xdc
In fact, nonce is correctly provided by dbft library (since Legacy), we just
need to use it here.
It's only used to sign/verify it and is not a part of the structure. It's
still neded in consensus.Payload though because that's the way dbft library
is.
It's not network-tied any more, network is only needed to
sign/verify. Unfortunately we still have to keep network in consensus data
structures because of dbft library interface.
There is a notification pushed into the channel when block is being added,
that notification is read by special goroutine that then forwards it to all
subscribers to that particular event. Consensus goroutine is one of that
subscribers, so for the system to properly function it has to read these
events, but at the same time it can generate new blocks inside, so in some
cases it can generate two blocks without ever reading from the subscription
channel and this will lead to a deadlock.
To avoid that we need to check subscription channel for events on every loop.
NewMerkleTree is a memory hog, we can do better than that:
BenchmarkMerkle/NewMerkleTree-8 13 88434670 ns/op 20828207 B/op 300035 allocs/op
BenchmarkMerkle/CalcMerkleRoot-8 15 69264150 ns/op 0 B/op 0 allocs/op
Now we have VerifyTx() and PoolTx() APIs that either verify transaction in
isolation or verify it against the mempool (either the primary one or the one
given) and then add it there. There is no possibility to check against the
mempool, but not add a transaction to it, but I doubt we really need it.
It allows to remove some duplication between old PoolTx and verifyTx where
they both tried to check transaction against mempool (verifying first and then
adding it). It also saves us utility token balance check because it's done by
the mempool anyway and we no longer need to do that explicitly in verifyTx.
It makes AddBlock() and verifyBlock() transaction's checks more correct,
because previously they could miss that even though sender S has enough
balance to pay for A, B or C, he can't pay for all of them.
Caveats:
* consensus is running concurrently to other processes, so things could
change while verifyBlock() is iterating over transactions, this will be
mitigated in subsequent commits
Improves TPS value for single node by at least 11%.
Fixes#667, fixes#668.
It's cached in dbft for a view anyway, so there is no big difference here
from security POV. Lets us squeeze yet another 4% TPS improvement.
Make the system fail if unable to decrypt the key along the way, which is a
part of #1312.
