mirror of
https://github.com/fluencelabs/tendermint
synced 2025-04-30 09:12:14 +00:00
123 lines
4.3 KiB
Markdown
123 lines
4.3 KiB
Markdown
# `tendermint/tendermint/p2p`
|
|
|
|
[](https://circleci.com/gh/tendermint/tendermint/p2p)
|
|
|
|
`tendermint/tendermint/p2p` provides an abstraction around peer-to-peer communication.<br/>
|
|
|
|
## MConnection
|
|
|
|
`MConnection` is a multiplex connection:
|
|
|
|
__multiplex__ *noun* a system or signal involving simultaneous transmission of
|
|
several messages along a single channel of communication.
|
|
|
|
Each `MConnection` handles message transmission on multiple abstract communication
|
|
`Channel`s. Each channel has a globally unique byte id.
|
|
The byte id and the relative priorities of each `Channel` are configured upon
|
|
initialization of the connection.
|
|
|
|
The `MConnection` supports three packet types: Ping, Pong, and Msg.
|
|
|
|
### Ping and Pong
|
|
|
|
The ping and pong messages consist of writing a single byte to the connection; 0x1 and 0x2, respectively
|
|
|
|
When we haven't received any messages on an `MConnection` in a time `pingTimeout`, we send a ping message.
|
|
When a ping is received on the `MConnection`, a pong is sent in response.
|
|
|
|
If a pong is not received in sufficient time, the peer's score should be decremented (TODO).
|
|
|
|
### Msg
|
|
|
|
Messages in channels are chopped into smaller msgPackets for multiplexing.
|
|
|
|
```
|
|
type msgPacket struct {
|
|
ChannelID byte
|
|
EOF byte // 1 means message ends here.
|
|
Bytes []byte
|
|
}
|
|
```
|
|
|
|
The msgPacket is serialized using go-wire, and prefixed with a 0x3.
|
|
The received `Bytes` of a sequential set of packets are appended together
|
|
until a packet with `EOF=1` is received, at which point the complete serialized message
|
|
is returned for processing by the corresponding channels `onReceive` function.
|
|
|
|
### Multiplexing
|
|
|
|
Messages are sent from a single `sendRoutine`, which loops over a select statement that results in the sending
|
|
of a ping, a pong, or a batch of data messages. The batch of data messages may include messages from multiple channels.
|
|
Message bytes are queued for sending in their respective channel, with each channel holding one unsent message at a time.
|
|
Messages are chosen for a batch one a time from the channel with the lowest ratio of recently sent bytes to channel priority.
|
|
|
|
## Sending Messages
|
|
|
|
There are two methods for sending messages:
|
|
```go
|
|
func (m MConnection) Send(chID byte, msg interface{}) bool {}
|
|
func (m MConnection) TrySend(chID byte, msg interface{}) bool {}
|
|
```
|
|
|
|
`Send(chID, msg)` is a blocking call that waits until `msg` is successfully queued
|
|
for the channel with the given id byte `chID`. The message `msg` is serialized
|
|
using the `tendermint/wire` submodule's `WriteBinary()` reflection routine.
|
|
|
|
`TrySend(chID, msg)` is a nonblocking call that returns false if the channel's
|
|
queue is full.
|
|
|
|
`Send()` and `TrySend()` are also exposed for each `Peer`.
|
|
|
|
## Peer
|
|
|
|
Each peer has one `MConnection` instance, and includes other information such as whether the connection
|
|
was outbound, whether the connection should be recreated if it closes, various identity information about the node,
|
|
and other higher level thread-safe data used by the reactors.
|
|
|
|
## Switch/Reactor
|
|
|
|
The `Switch` handles peer connections and exposes an API to receive incoming messages
|
|
on `Reactors`. Each `Reactor` is responsible for handling incoming messages of one
|
|
or more `Channels`. So while sending outgoing messages is typically performed on the peer,
|
|
incoming messages are received on the reactor.
|
|
|
|
```go
|
|
// Declare a MyReactor reactor that handles messages on MyChannelID.
|
|
type MyReactor struct{}
|
|
|
|
func (reactor MyReactor) GetChannels() []*ChannelDescriptor {
|
|
return []*ChannelDescriptor{ChannelDescriptor{ID:MyChannelID, Priority: 1}}
|
|
}
|
|
|
|
func (reactor MyReactor) Receive(chID byte, peer *Peer, msgBytes []byte) {
|
|
r, n, err := bytes.NewBuffer(msgBytes), new(int64), new(error)
|
|
msgString := ReadString(r, n, err)
|
|
fmt.Println(msgString)
|
|
}
|
|
|
|
// Other Reactor methods omitted for brevity
|
|
...
|
|
|
|
switch := NewSwitch([]Reactor{MyReactor{}})
|
|
|
|
...
|
|
|
|
// Send a random message to all outbound connections
|
|
for _, peer := range switch.Peers().List() {
|
|
if peer.IsOutbound() {
|
|
peer.Send(MyChannelID, "Here's a random message")
|
|
}
|
|
}
|
|
```
|
|
|
|
### PexReactor/AddrBook
|
|
|
|
A `PEXReactor` reactor implementation is provided to automate peer discovery.
|
|
|
|
```go
|
|
book := p2p.NewAddrBook(addrBookFilePath)
|
|
pexReactor := p2p.NewPEXReactor(book)
|
|
...
|
|
switch := NewSwitch([]Reactor{pexReactor, myReactor, ...})
|
|
```
|