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[1]: https://godoc.org/github.com/xtaci/smux?status.svg
[2]: https://godoc.org/github.com/xtaci/smux
[3]: https://img.shields.io/badge/license-MIT-blue.svg
[4]: LICENSE
[5]: https://travis-ci.org/xtaci/smux.svg?branch=master
[6]: https://travis-ci.org/xtaci/smux
[7]: https://goreportcard.com/badge/github.com/xtaci/smux
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[9]: https://codecov.io/gh/xtaci/smux/branch/master/graph/badge.svg
[10]: https://codecov.io/gh/xtaci/smux
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[12]: https://sourcegraph.com/github.com/xtaci/smux?badge
## Introduction
Smux ( **S**imple **MU**ltiple**X**ing) is a multiplexing library for Golang. It relies on an underlying connection to provide reliability and ordering, such as TCP or [KCP](https://github.com/xtaci/kcp-go), and provides stream-oriented multiplexing. The original intention of this library is to power the connection management for [kcp-go](https://github.com/xtaci/kcp-go).
## Features
1. ***Token bucket*** controlled receiving, which provides smoother bandwidth graph(see picture below).
2. Session-wide receive buffer, shared among streams, **fully controlled** overall memory usage.
3. Minimized header(8Bytes), maximized payload.
4. Well-tested on millions of devices in [kcptun](https://github.com/xtaci/kcptun).
5. Builtin fair queue traffic shaping.
6. Per-stream sliding window to control congestion.(protocol version 2+).
## Documentation
For complete documentation, see the associated [Godoc](https://godoc.org/github.com/xtaci/smux).
## Benchmark
```
$ go test -v -run=^$ -bench .
goos: darwin
goarch: amd64
pkg: github.com/xtaci/smux
BenchmarkMSB-4 30000000 51.8 ns/op
BenchmarkAcceptClose-4 50000 36783 ns/op
BenchmarkConnSmux-4 30000 58335 ns/op 2246.88 MB/s 1208 B/op 19 allocs/op
BenchmarkConnTCP-4 50000 25579 ns/op 5124.04 MB/s 0 B/op 0 allocs/op
PASS
ok github.com/xtaci/smux 7.811s
```
## Specification
```
VERSION(1B) | CMD(1B) | LENGTH(2B) | STREAMID(4B) | DATA(LENGTH)
VALUES FOR LATEST VERSION:
VERSION:
1/2
CMD:
cmdSYN(0)
cmdFIN(1)
cmdPSH(2)
cmdNOP(3)
cmdUPD(4) // only supported on version 2
STREAMID:
client use odd numbers starts from 1
server use even numbers starts from 0
cmdUPD:
| CONSUMED(4B) | WINDOW(4B) |
```
## Usage
```go
func client() {
// Get a TCP connection
conn, err := net.Dial(...)
if err != nil {
panic(err)
}
// Setup client side of smux
session, err := smux.Client(conn, nil)
if err != nil {
panic(err)
}
// Open a new stream
stream, err := session.OpenStream()
if err != nil {
panic(err)
}
// Stream implements io.ReadWriteCloser
stream.Write([]byte("ping"))
stream.Close()
session.Close()
}
func server() {
// Accept a TCP connection
conn, err := listener.Accept()
if err != nil {
panic(err)
}
// Setup server side of smux
session, err := smux.Server(conn, nil)
if err != nil {
panic(err)
}
// Accept a stream
stream, err := session.AcceptStream()
if err != nil {
panic(err)
}
// Listen for a message
buf := make([]byte, 4)
stream.Read(buf)
stream.Close()
session.Close()
}
```
## Status
Stable