Update p2p.md

Add explanation on async proc
This commit is contained in:
kdeme 2019-08-20 17:33:43 +02:00 committed by GitHub
parent ece0d7fdbb
commit 843f9c3916
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 8 additions and 5 deletions

View File

@ -177,10 +177,10 @@ The `nextMsg` helper proc can be used to pause the execution of an async
proc until a particular incoming message from a peer arrives:
``` nim
proc helloExample(peer: Peer) {.async.} =
proc helloExample(peer: Peer) =
...
# send a hello message
peer.hello(...)
await peer.hello(...)
# wait for a matching hello response, might want to add a timeout here
let response = await peer.nextMsg(p2p.hello)
@ -205,6 +205,10 @@ place). If there are multiple outstanding calls to `nextMsg`, they will
complete together. Any other messages received in the meantime will still
be dispatched to their respective handlers.
Please also note that the `p2pProtocol` macro will make this `helloExample` proc
`async`. Practically see it as `proc helloExample(peer: Peer) {.async.}`, and
thus never use `waitFor`, but rather `await` inside this proc.
For implementing protocol handshakes with `nextMsg` there are specific helpers
which are explained [below](https://github.com/status-im/nim-eth/blob/master/doc/p2p.md#implementing-handshakes-and-reacting-to-other-events).
@ -254,7 +258,6 @@ peers or misbehaving or disconnecting peers:
``` nim
p2pProtocol foo(version = fooVersion):
onPeerConnected do (peer: Peer):
let m = await peer.status(fooVersion,
timeout = chronos.milliseconds(5000))