When the network is big enough, MinPeers may be suboptimal for good network
connectivity, but if we know the network size we can do some estimation on the
number of sufficient peers.
We have a number of queues for different purposes:
* regular broadcast queue
* direct p2p queue
* high-priority queue
And two basic egress scenarios:
* direct p2p messages (replies to requests in Server's handle* methods)
* broadcasted messages
Low priority broadcasted messages:
* transaction inventories
* block inventories
* notary inventories
* non-consensus extensibles
High-priority broadcasted messages:
* consensus extensibles
* getdata transaction requests from consensus process
* getaddr requests
P2P messages are a bit more complicated, most of the time they use p2p queue,
but extensible message requests/replies use HP queue.
Server's handle* code is run from Peer's handleIncoming, every peer has this
thread that handles incoming messages. When working with the peer it's
important to reply to requests and blocking this thread until we send (queue)
a reply is fine, if the peer is slow we just won't get anything new from
it. The queue used is irrelevant wrt this issue.
Broadcasted messages are radically different, we want them to be delivered to
many peers, but we don't care about specific ones. If it's delivered to 2/3 of
the peers we're fine, if it's delivered to more of them --- it's not an
issue. But doing this fairly is not an easy thing, current code tries performing
unblocked sends and if this doesn't yield enough results it then blocks (but
has a timeout, we can't wait indefinitely). But it does so in sequential
manner, once the peer is chosen the code will wait for it (and only it) until
timeout happens.
What can be done instead is an attempt to push the message to all of the peers
simultaneously (or close to that). If they all deliver --- OK, if some block
and wait then we can wait until _any_ of them pushes the message through (or
global timeout happens, we still can't wait forever). If we have enough
deliveries then we can cancel pending ones and it's again not an error if
these canceled threads still do their job.
This makes the system more dynamic and adds some substantial processing
overhead, but it's a networking code, any of this overhead is much lower than
the actual packet delivery time. It also allows to spread the load more
fairly, if there is any spare queue it'll get the packet and release the
broadcaster. On the next broadcast iteration another peer is more likely to be
chosen just because it didn't get a message previously (and had some time to
deliver already queued messages).
It works perfectly in tests, with optimal networking conditions we have much
better block times and TPS increases by 5-25%% depending on the scenario.
I'd go as far as to say that it fixes the original problem of #2678, because
in this particular scenario we have empty queues in ~100% of the cases and
this new logic will likely lead to 100% fan out in this case (cancelation just
won't happen fast enough). But when the load grows and there is some waiting
in the queue it will optimize out the slowest links.
Value of PublicKey parameter always stores public key bytes, not the
deserialized representation. All other code (CLI parameters parsing with
its NewParameterFromString, Parameter unmarshaller, etc.) is based on
the idea that value of PublicKey is []byte.
Peers can be slow, very slow, slow enough to affect node's regular
operation. We can't wait for them indefinitely, there has to be a timeout for
send operations.
This patch uses TimePerBlock as a reference for its timeout. It's relatively
big and it doesn't affect tests much, 4+1 scenarios tend to perform a little
worse with while 7+2 scenarios work a little better. The difference is in some
percents, but all of these tests easily have 10-15% variations from run to
run.
It's an important step in making our gossip better because we can't have any
behavior where neighbors directly block the node forever, refs. #2678 and
Refs. #2379, but not completely solves it, one package seriously outweights
others:
? github.com/nspcc-dev/neo-go/cli [no test files]
ok github.com/nspcc-dev/neo-go/cli/app 0.036s coverage: 100.0% of statements
ok github.com/nspcc-dev/neo-go/cli/cmdargs 0.011s coverage: 60.8% of statements
ok github.com/nspcc-dev/neo-go/cli/flags 0.009s coverage: 97.7% of statements
? github.com/nspcc-dev/neo-go/cli/input [no test files]
ok github.com/nspcc-dev/neo-go/cli/options 0.033s coverage: 50.0% of statements
? github.com/nspcc-dev/neo-go/cli/paramcontext [no test files]
ok github.com/nspcc-dev/neo-go/cli/query 2.155s coverage: 45.3% of statements
ok github.com/nspcc-dev/neo-go/cli/server 1.373s coverage: 67.8% of statements
ok github.com/nspcc-dev/neo-go/cli/smartcontract 8.819s coverage: 94.3% of statements
ok github.com/nspcc-dev/neo-go/cli/util 0.006s coverage: 10.9% of statements
? github.com/nspcc-dev/neo-go/cli/vm [no test files]
ok github.com/nspcc-dev/neo-go/cli/wallet 72.103s coverage: 88.2% of statements
Still a nice thing to have.
In case of ellipsis usage compiler defines argument type as ArrayT
(which is correct, because it's a natural representation of the last
argument, it represents the array of interface{}).
Here goes the problem:
```
=== RUN TestEventWarnings/variadic_event_args_via_ellipsis
compiler_test.go:251:
Error Trace: compiler_test.go:251
Error: Received unexpected error:
event 'Event' should have 'Integer' as type of 1 parameter, got: Array
Test: TestEventWarnings/variadic_event_args_via_ellipsis
```
Parsing the last argument in this case is a separate complicated problem
due to the fact that we need to grab types of elements of []interface{} inside the
fully qualified ast node which may looks like:
```
runtime.Notify("Event", (append([]interface{}{1, 2}, (([]interface{}{someVar, 4}))...))...)
```
Temporary solution is to exclude such notifications from analysis until we're
able to properly resolve element types of []interface{}.
It's possible that declared manifest event has parameter of AnyT for
those cases when parameter type differs from method to method. If so,
then we don't need to enforce type check after compilation.
