caddy/caddyhttp/httpserver/graceful.go at master · digideskio/caddy · GitHub

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package httpserver

import (

"net"

"sync"

"syscall"

)

// TODO: Should this be a generic graceful listener available in its own package or something?

// Also, passing in a WaitGroup is a little awkward. Why can't this listener just keep

// the waitgroup internal to itself?

// newGracefulListener returns a gracefulListener that wraps l and

// uses wg (stored in the host server) to count connections.

func newGracefulListener(l net.Listener, wg *sync.WaitGroup) *gracefulListener {

gl := &gracefulListener{Listener: l, stop: make(chan error), connWg: wg}

go func() {

<-gl.stop

gl.Lock()

gl.stopped = true

gl.Unlock()

gl.stop <- gl.Listener.Close()

}()

return gl

}

// gracefuListener is a net.Listener which can

// count the number of connections on it. Its

// methods mainly wrap net.Listener to be graceful.

type gracefulListener struct {

net.Listener

stop chan error

stopped bool

sync.Mutex // protects the stopped flag

connWg *sync.WaitGroup // pointer to the host's wg used for counting connections

}

// Accept accepts a connection.

func (gl *gracefulListener) Accept() (c net.Conn, err error) {

c, err = gl.Listener.Accept()

if err != nil {

return

}

c = gracefulConn{Conn: c, connWg: gl.connWg}

gl.connWg.Add(1)

return

}

// Close immediately closes the listener.

func (gl *gracefulListener) Close() error {

gl.Lock()

if gl.stopped {

gl.Unlock()

return syscall.EINVAL

}

gl.Unlock()

gl.stop <- nil

return <-gl.stop

}

// gracefulConn represents a connection on a

// gracefulListener so that we can keep track

// of the number of connections, thus facilitating

// a graceful shutdown.

type gracefulConn struct {

net.Conn

connWg *sync.WaitGroup // pointer to the host server's connection waitgroup

}

// Close closes c's underlying connection while updating the wg count.

func (c gracefulConn) Close() error {

err := c.Conn.Close()

if err != nil {

return err

}

// close can fail on http2 connections (as of Oct. 2015, before http2 in std lib)

// so don't decrement count unless close succeeds

c.connWg.Done()

return nil

}

caddy/caddyhttp/httpserver/graceful.go at master · digideskio/caddy · GitHub

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