server_windows.go

// Copyright 2019 Andy Pan. All rights reserved.
// Copyright 2018 Joshua J Baker. All rights reserved.
// Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file.

// +build windows

package gnet

import (
	"errors"
	"os"
	"os/signal"
	"runtime"
	"sync"
	"syscall"
	"time"
)

// commandBufferSize represents the buffer size of event-loop command channel on Windows.
const (
	commandBufferSize = 512
)

type server struct {
	ln           *listener          // all the listeners
	cond         *sync.Cond         // shutdown signaler
	opts         *Options           // options with server
	serr         error              // signal error
	once         sync.Once          // make sure only signalShutdown once
	codec        ICodec             // codec for TCP stream
	loopWG       sync.WaitGroup     // loop close WaitGroup
	logger       Logger             // customized logger for logging info
	ticktock     chan time.Duration // ticker channel
	listenerWG   sync.WaitGroup     // listener close WaitGroup
	eventHandler EventHandler       // user eventHandler
	subLoopGroup IEventLoopGroup    // loops for handling events
}

// waitForShutdown waits for a signal to shutdown.
func (svr *server) waitForShutdown() error {
	svr.cond.L.Lock()
	svr.cond.Wait()
	err := svr.serr
	svr.cond.L.Unlock()
	return err
}

// signalShutdown signals a shutdown an begins server closing.
func (svr *server) signalShutdown(err error) {
	svr.once.Do(func() {
		svr.cond.L.Lock()
		svr.serr = err
		svr.cond.Signal()
		svr.cond.L.Unlock()
	})
}

func (svr *server) startListener() {
	svr.listenerWG.Add(1)
	go func() {
		svr.listenerRun()
		svr.listenerWG.Done()
	}()
}

func (svr *server) startLoops(numEventLoop int) {
	for i := 0; i < numEventLoop; i++ {
		el := &eventloop{
			ch:           make(chan interface{}, commandBufferSize),
			idx:          i,
			svr:          svr,
			codec:        svr.codec,
			connections:  make(map[*stdConn]struct{}),
			eventHandler: svr.eventHandler,
		}
		svr.subLoopGroup.register(el)
	}
	svr.loopWG.Add(svr.subLoopGroup.len())
	svr.subLoopGroup.iterate(func(i int, el *eventloop) bool {
		go el.loopRun()
		return true
	})
}

func (svr *server) stop() {
	// Wait on a signal for shutdown.
	svr.logger.Printf("server is being shutdown with err: %v\n", svr.waitForShutdown())

	// Close listener.
	svr.ln.close()
	svr.listenerWG.Wait()

	// Notify all loops to close.
	svr.subLoopGroup.iterate(func(i int, el *eventloop) bool {
		el.ch <- errServerShutdown
		return true
	})

	// Wait on all loops to close.
	svr.loopWG.Wait()

	// Close all connections.
	svr.loopWG.Add(svr.subLoopGroup.len())
	svr.subLoopGroup.iterate(func(i int, el *eventloop) bool {
		el.ch <- errServerShutdown
		return true
	})
	svr.loopWG.Wait()
}

func serve(eventHandler EventHandler, listener *listener, options *Options) (err error) {
	// Figure out the correct number of loops/goroutines to use.
	numEventLoop := 1
	if options.Multicore {
		numEventLoop = runtime.NumCPU()
	}
	if options.NumEventLoop > 0 {
		numEventLoop = options.NumEventLoop
	}

	svr := new(server)
	svr.opts = options
	svr.eventHandler = eventHandler
	svr.ln = listener

	switch options.LB {
	case RoundRobin:
		svr.subLoopGroup = new(roundRobinEventLoopGroup)
	case LeastConnections:
		svr.subLoopGroup = new(leastConnectionsEventLoopGroup)
	case SourceAddrHash:
		svr.subLoopGroup = new(sourceAddrHashEventLoopGroup)
	}

	svr.ticktock = make(chan time.Duration, 1)
	svr.cond = sync.NewCond(&sync.Mutex{})
	svr.logger = func() Logger {
		if options.Logger == nil {
			return defaultLogger
		}
		return options.Logger
	}()
	svr.codec = func() ICodec {
		if options.Codec == nil {
			return new(BuiltInFrameCodec)
		}
		return options.Codec
	}()

	server := Server{
		svr:          svr,
		Multicore:    options.Multicore,
		Addr:         listener.lnaddr,
		NumEventLoop: numEventLoop,
		ReusePort:    options.ReusePort,
		TCPKeepAlive: options.TCPKeepAlive,
	}
	switch svr.eventHandler.OnInitComplete(server) {
	case None:
	case Shutdown:
		return
	}
	defer svr.eventHandler.OnShutdown(server)

	shutdown := make(chan os.Signal, 1)
	signal.Notify(shutdown, os.Interrupt, syscall.SIGINT, syscall.SIGTERM)
	defer close(shutdown)

	go func() {
		if <-shutdown == nil {
			return
		}
		svr.signalShutdown(errors.New("caught OS signal"))
	}()

	// Start all loops.
	svr.startLoops(numEventLoop)
	// Start listener.
	svr.startListener()
	defer svr.stop()

	return
}