event is a network I/O event notification library for Go. It uses epoll to poll I/O events that is fast and low memory usage. It works in a similar manner as libevent.
The goal of event is to provide a BASIC tool for building high performance network applications.
Note: All development is done on a Raspberry Pi 4B.
- Supports more events
- Flexible timer and ticker
- Supports event priority
- Edge-triggered
- Simple API
- Low memory usage
To start using event, just run go get:
$ go get -u github.com/cheng-zhongliang/eventEvReadfires when the fd is readable.EvWritefires when the fd is writable.EvClosedfires when the connection has closed.EvTimeoutfires when the timeout expires.EvSignalfires when the os signal arrives.EvPersistif not set, the event will be deleted after it is triggered.
When the event is triggered, the callback function will be called.
These events can be used in combination.
base := event.NewBase()
ev := event.New(fd, event.EvRead|event.Timeout|event.EvPersist, callback, arg)
base.AddEvent(ev, 1*time.Second)When the fd is readable or timeout expires, this event will be triggered.
The signal event will be triggered when the os signal arrives.
base := event.NewBase()
ev := event.NewSignal(os.Interrupt, callback, arg)
base.AddEvent(ev, 0)The timer is a one-shot event that will be triggered after the timeout expires.
base := event.NewBase()
ev := event.NewTimer(callback, arg)
base.AddEvent(ev, 1*time.Second)The ticker is a repeating event that will be triggered every time the timeout expires.
base := event.NewBase()
ev := event.NewTicker(callback, arg)
base.AddEvent(ev, 1*time.Second)When events are triggered together, high priority events will be dispatched first.
ev := event.New(fd, event.EvRead|event.EvET, callback, arg)
ev.SetPriority(event.High)The event is level-triggered by default. If you want to use edge-triggered, you can set the EvET flag.
ev := event.New(fd, event.EvRead|event.EvET, callback, arg)Example echo server that binds to port 1246:
package main
import (
"syscall"
"github.com/cheng-zhongliang/event"
)
func main() {
base, err := event.NewBase()
if err != nil {
panic(err)
}
fd := socket()
ev := event.New(fd, event.EvRead|event.EvPersist, accept, base)
if err := base.AddEvent(ev, 0); err != nil {
panic(err)
}
exitEv := event.NewSignal(syscall.SIGINT, exit, base)
if err := base.AddEvent(exitEv, 0); err != nil {
panic(err)
}
if err := base.Dispatch(); err != nil && err != event.ErrBadFileDescriptor {
panic(err)
}
syscall.Close(fd)
}
func socket() int {
addr := syscall.SockaddrInet4{Port: 1246, Addr: [4]byte{0, 0, 0, 0}}
fd, err := syscall.Socket(syscall.AF_INET, syscall.SOCK_STREAM|syscall.SOCK_NONBLOCK, syscall.IPPROTO_TCP)
if err != nil {
panic(err)
}
if err := syscall.Bind(fd, &addr); err != nil {
panic(err)
}
err = syscall.Listen(fd, syscall.SOMAXCONN)
if err != nil {
panic(err)
}
return fd
}
func accept(fd int, events uint32, arg interface{}) {
base := arg.(*event.EventBase)
clientFd, _, err := syscall.Accept(fd)
if err != nil {
panic(err)
}
ev := event.New(clientFd, event.EvRead|event.EvPersist, echo, nil)
if err := base.AddEvent(ev, 0); err != nil {
panic(err)
}
}
func echo(fd int, events uint32, arg interface{}) {
buf := make([]byte, 0xFFF)
n, err := syscall.Read(fd, buf)
if err != nil {
panic(err)
}
if _, err := syscall.Write(fd, buf[:n]); err != nil {
panic(err)
}
}
func exit(fd int, events uint32, arg interface{}) {
base := arg.(*event.EventBase)
if err := base.Exit(); err != nil {
panic(err)
}
}Connect to the echo server:
$ telnet localhost 1246
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