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server.go
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server.go
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package socket
import (
"context"
"errors"
"net"
"sync"
"sync/atomic"
"time"
"github.com/cenkalti/backoff/v4"
)
var ErrServerClosed = errors.New("socket: Server closed")
type Context struct {
net.Conn // by conn
context.Context // by Serve
}
type Handler func(*Context) //close socket when return
type Server struct {
BaseContext func(net.Listener) context.Context
ErrorHandler func(*Context, ...interface{})
m sync.Mutex
listeners map[*net.Listener]struct{}
open int32
closed int32
}
func (server *Server) trackListener(listener *net.Listener, track bool) bool {
server.m.Lock()
defer server.m.Unlock()
if track {
if server.isClosed() {
return false
}
if server.listeners == nil {
server.listeners = make(map[*net.Listener]struct{})
}
server.listeners[listener] = struct{}{}
} else {
delete(server.listeners, listener)
(*listener).Close()
}
return true
}
func (server *Server) Serve(listener net.Listener, handler Handler) (err error) {
// listener = onceCloseListener{Listener: listener}
if !server.trackListener(&listener, true) {
return ErrServerClosed
}
defer server.trackListener(&listener, false)
baseCtx := context.Background()
if server.BaseContext != nil {
baseCtx = server.BaseContext(listener)
if baseCtx == nil {
panic("ServeContext returned a nil context")
}
}
atomic.AddInt32(&server.open, 1)
defer atomic.AddInt32(&server.open, -1)
var conn net.Conn
for {
conn, err = listener.Accept()
if err != nil {
if netErr, ok := err.(net.Error); ok && netErr.Temporary() {
time.Sleep(time.Second)
continue
}
if server.isClosed() {
err = ErrServerClosed
return
}
return
}
go server.serve(baseCtx, conn, handler)
}
}
func (server *Server) serve(ctx context.Context, conn net.Conn, handler Handler) {
atomic.AddInt32(&server.open, 1)
defer atomic.AddInt32(&server.open, -1)
defer conn.Close()
// var cancel context.CancelFunc
// ctx, cancel = context.WithCancel(ctx)
// defer cancel()
socket := &Context{conn, ctx}
defer func() {
if server.ErrorHandler != nil {
if err := recover(); err != nil {
server.ErrorHandler(socket, err)
}
}
}()
if handler != nil {
handler(socket)
}
}
func (server *Server) isClosed() bool {
return atomic.LoadInt32(&server.closed) != 0
}
func (server *Server) Close() (err error) {
atomic.StoreInt32(&server.closed, 1)
server.m.Lock()
defer server.m.Unlock()
for listener := range server.listeners {
if cerr := (*listener).Close(); cerr != nil && err == nil {
err = cerr
}
}
server.listeners = nil
return
}
func (server *Server) Shutdown(ctx context.Context) (err error) {
if err = server.Close(); err != nil {
return
}
ticker := backoff.NewTicker(NewNeverStopBackOff())
for range ticker.C {
if open := atomic.LoadInt32(&server.open); open == 0 {
break
}
if err = ctx.Err(); err != nil {
break
}
}
ticker.Stop()
return
}
func NewNeverStopBackOff() *backoff.ExponentialBackOff {
b := &backoff.ExponentialBackOff{
InitialInterval: backoff.DefaultInitialInterval,
RandomizationFactor: backoff.DefaultRandomizationFactor,
Multiplier: backoff.DefaultMultiplier,
MaxInterval: backoff.DefaultMaxInterval,
MaxElapsedTime: 0,
Stop: backoff.Stop,
Clock: backoff.SystemClock,
}
b.Reset()
return b
}
// type onceCloseListener struct {
// net.Listener
// once sync.Once
// closeErr error
// }
// func (oc *onceCloseListener) Close() error {
// oc.once.Do(oc.close)
// return oc.closeErr
// }
// func (oc *onceCloseListener) close() { oc.closeErr = oc.Listener.Close() }