There was a deadlock while trying to finalize transaction during
PostBlock:
1) (*Notary).PostBlock is called under the blockchain lock
2) (*Notary).onTransaction is called inside the PostBlock
3) (*Notary).onTransaction needs to RLock the blockchain to add
completed transaction to the memory pool (and the blockchain is Lock'ed
by this moment)
The problem is fixed by using notifications subsistem, because it's not
required to call (*Notary).PostBlock under the blockchain lock.
And stop dropping connections if we're to receive them. Proper handling is
subject of #1701, but we need at least some connection-level stability for
now.
Node receiving extensible payload from the future is confused and drops
connection. Note that this can still happen if the node is to loose its
synchrony.
Calling `IsInSync()` is quite expensive, so we stop doing that once synchrony
is reached (hence bool flag).
1. Initialization is performed via `Blockchain` methods.
2. Native Oracle contract updates list of oracle nodes
and in-fly requests in `PostPersist`.
3. RPC uses Oracle module directly.
It could be the case that checks are performed simultaneosly and
peers connections goes down from 2 to 0. We must take such case into
account and register address as good in discovery.
Right now a single slow peer can slow down whole network.
Do broadcast in 2 parts:
1. Perform non-blocking send to all peers if possible.
2. Perform blocking sends until message is sent to 2/3 of good peers.
If the node is to start with seeds unavailable it will try connecting to each
of them three times, blacklist them and then sit forever waiting for
something. It's not a good behavior, it should always try connecting to seeds
if nothing else works.
GetBlockByIndex handler starts sending blocks right from the start index and
if that index is s.chain.BlockHeight() then we're requesting and receiving a
block we already have.
Turns out, C# node no longer broadcasts an Inv when it's creating a block,
instead it sends a ping and if we're not paying attention to the height
specified there we're technically missing a new block. Of course we'll get it
later after ping timer expiration and regular ping/pong sequence, but that's
delaying it for no good reason.
Closes#1192
1. We now have CMDGetBlockByIndex, so there's no need to request headers
first when we can just ask for blocks.
2. We don't ask for headers (i.e. we don't send CMDGetHeaders),
consequently, we shouldn't react on CMDHeaders.
3. But we still keep on reacting on CMDGetHeaders command as
there could be a node which needs headers.
It returned an error in case if block wasn't found (it might be when our
chain is lower). Fixed. It also should return all requested blocks, not
the first one.
We can't lock them (or there will be a deadlock), but we need to fix this:
fatal error: concurrent map iteration and map write
goroutine 1 [running]:
runtime.throw(0xdec086, 0x26)
/usr/lib64/go/1.12/src/runtime/panic.go:617 +0x72 fp=0xc02fec2bf8 sp=0xc02fec2bc8 pc=0x42d932
runtime.mapiternext(0xc02fec2d40)
/usr/lib64/go/1.12/src/runtime/map.go:860 +0x597 fp=0xc02fec2c80 sp=0xc02fec2bf8 pc=0x40efe7
github.com/nspcc-dev/neo-go/pkg/network.(*Server).Shutdown(0xc0000fc160)
/home/rik/dev/neo-go2/pkg/network/server.go:194 +0x238 fp=0xc02fec2db0 sp=0xc02fec2c80 pc=0xa89da8
github.com/nspcc-dev/neo-go/cli/server.startServer(0xc0000fcc60, 0x0, 0x0)
/home/rik/dev/neo-go2/cli/server/server.go:399 +0x7a9 fp=0xc02fec3820 sp=0xc02fec2db0 pc=0xae2079
...
We make it explicit in the appropriate Block/Transaction structures, not via a
singleton as C# node does. I think this approach has a bit more potential and
allows better packages reuse for different purposes.
Get new blocks directly from the Blockchain. It may lead to some duplications
(as we'll also receive our own blocks), but at the same time it's more
correct, because technically we can also get blocks via other means besides
network server like RPC (submitblock call). And it simplifies network server
at the same time.
