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endless.go
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package endless
import (
"crypto/tls"
"errors"
"fmt"
"log"
"net"
"net/http"
"os"
"os/exec"
"os/signal"
"runtime"
"strings"
"sync"
"syscall"
"time"
// "github.com/fvbock/uds-go/introspect"
)
const (
PRE_SIGNAL = iota
POST_SIGNAL
STATE_INIT
STATE_RUNNING
STATE_SHUTTING_DOWN
STATE_TERMINATE
)
var (
runningServerReg sync.RWMutex
runningServers map[string]*endlessServer
runningServersOrder []string
socketPtrOffsetMap map[string]uint
runningServersForked bool
DefaultReadTimeOut time.Duration
DefaultWriteTimeOut time.Duration
DefaultMaxHeaderBytes int
DefaultHammerTime time.Duration
isChild bool
socketOrder string
hookableSignals []os.Signal
)
func init() {
runningServerReg = sync.RWMutex{}
runningServers = make(map[string]*endlessServer)
runningServersOrder = []string{}
socketPtrOffsetMap = make(map[string]uint)
DefaultMaxHeaderBytes = 0 // use http.DefaultMaxHeaderBytes - which currently is 1 << 20 (1MB)
// after a restart the parent will finish ongoing requests before
// shutting down. set to a negative value to disable
DefaultHammerTime = 60 * time.Second
hookableSignals = []os.Signal{
syscall.SIGHUP,
syscall.SIGUSR1,
syscall.SIGUSR2,
syscall.SIGINT,
syscall.SIGTERM,
syscall.SIGTSTP,
}
}
type endlessServer struct {
http.Server
EndlessListener net.Listener
SignalHooks map[int]map[os.Signal][]func()
tlsInnerListener *endlessListener
wg sync.WaitGroup
sigChan chan os.Signal
isChild bool
state uint8
lock *sync.RWMutex
BeforeBegin func(add string)
}
/*
NewServer returns an intialized endlessServer Object. Calling Serve on it will
actually "start" the server.
*/
func NewServer(addr string, handler http.Handler) (srv *endlessServer) {
runningServerReg.Lock()
defer runningServerReg.Unlock()
socketOrder = os.Getenv("ENDLESS_SOCKET_ORDER")
isChild = os.Getenv("ENDLESS_CONTINUE") != ""
if len(socketOrder) > 0 {
for i, addr := range strings.Split(socketOrder, ",") {
socketPtrOffsetMap[addr] = uint(i)
}
} else {
socketPtrOffsetMap[addr] = uint(len(runningServersOrder))
}
srv = &endlessServer{
wg: sync.WaitGroup{},
sigChan: make(chan os.Signal),
isChild: isChild,
SignalHooks: map[int]map[os.Signal][]func(){
PRE_SIGNAL: {
syscall.SIGHUP: []func(){},
syscall.SIGUSR1: []func(){},
syscall.SIGUSR2: []func(){},
syscall.SIGINT: []func(){},
syscall.SIGTERM: []func(){},
syscall.SIGTSTP: []func(){},
},
POST_SIGNAL: {
syscall.SIGHUP: []func(){},
syscall.SIGUSR1: []func(){},
syscall.SIGUSR2: []func(){},
syscall.SIGINT: []func(){},
syscall.SIGTERM: []func(){},
syscall.SIGTSTP: []func(){},
},
},
state: STATE_INIT,
lock: &sync.RWMutex{},
}
srv.Server.Addr = addr
srv.Server.ReadTimeout = DefaultReadTimeOut
srv.Server.WriteTimeout = DefaultWriteTimeOut
srv.Server.MaxHeaderBytes = DefaultMaxHeaderBytes
srv.Server.Handler = handler
srv.BeforeBegin = func(addr string) {
log.Println(syscall.Getpid(), addr)
}
runningServersOrder = append(runningServersOrder, addr)
runningServers[addr] = srv
return
}
/*
ListenAndServe listens on the TCP network address addr and then calls Serve
with handler to handle requests on incoming connections. Handler is typically
nil, in which case the DefaultServeMux is used.
*/
func ListenAndServe(addr string, handler http.Handler) error {
server := NewServer(addr, handler)
return server.ListenAndServe()
}
/*
ListenAndServeTLS acts identically to ListenAndServe, except that it expects
HTTPS connections. Additionally, files containing a certificate and matching
private key for the server must be provided. If the certificate is signed by a
certificate authority, the certFile should be the concatenation of the server's
certificate followed by the CA's certificate.
*/
func ListenAndServeTLS(addr string, certFile string, keyFile string, handler http.Handler) error {
server := NewServer(addr, handler)
return server.ListenAndServeTLS(certFile, keyFile)
}
func (srv *endlessServer) getState() uint8 {
srv.lock.RLock()
defer srv.lock.RUnlock()
return srv.state
}
func (srv *endlessServer) setState(st uint8) {
srv.lock.Lock()
defer srv.lock.Unlock()
srv.state = st
}
/*
Serve accepts incoming HTTP connections on the listener l, creating a new
service goroutine for each. The service goroutines read requests and then call
handler to reply to them. Handler is typically nil, in which case the
DefaultServeMux is used.
In addition to the stl Serve behaviour each connection is added to a
sync.Waitgroup so that all outstanding connections can be served before shutting
down the server.
*/
func (srv *endlessServer) Serve() (err error) {
defer log.Println(syscall.Getpid(), "Serve() returning...")
srv.setState(STATE_RUNNING)
err = srv.Server.Serve(srv.EndlessListener)
log.Println(syscall.Getpid(), "Waiting for connections to finish...")
srv.wg.Wait()
srv.setState(STATE_TERMINATE)
return
}
/*
ListenAndServe listens on the TCP network address srv.Addr and then calls Serve
to handle requests on incoming connections. If srv.Addr is blank, ":http" is
used.
*/
func (srv *endlessServer) ListenAndServe() (err error) {
addr := srv.Addr
if addr == "" {
addr = ":http"
}
go srv.handleSignals()
l, err := srv.getListener(addr)
if err != nil {
log.Println(err)
return
}
srv.EndlessListener = newEndlessListener(l, srv)
if srv.isChild {
err = syscall.Kill(syscall.Getppid(), syscall.SIGTERM)
if err != nil {
log.Printf("endless: error killing child: %v", err)
}
}
srv.BeforeBegin(srv.Addr)
return srv.Serve()
}
/*
ListenAndServeTLS listens on the TCP network address srv.Addr and then calls
Serve to handle requests on incoming TLS connections.
Filenames containing a certificate and matching private key for the server must
be provided. If the certificate is signed by a certificate authority, the
certFile should be the concatenation of the server's certificate followed by the
CA's certificate.
If srv.Addr is blank, ":https" is used.
*/
func (srv *endlessServer) ListenAndServeTLS(certFile, keyFile string) (err error) {
addr := srv.Addr
if addr == "" {
addr = ":https"
}
var config *tls.Config
if srv.TLSConfig != nil {
config = srv.TLSConfig
} else {
config = &tls.Config{}
}
if config.NextProtos == nil {
config.NextProtos = []string{"http/1.1"}
}
configHasCert := len(config.Certificates) > 0 || config.GetCertificate != nil
if !configHasCert || certFile != "" || keyFile != "" {
var err error
config.Certificates = make([]tls.Certificate, 1)
config.Certificates[0], err = tls.LoadX509KeyPair(certFile, keyFile)
if err != nil {
return err
}
}
go srv.handleSignals()
l, err := srv.getListener(addr)
if err != nil {
log.Println(err)
return
}
srv.tlsInnerListener = newEndlessListener(l, srv)
srv.EndlessListener = tls.NewListener(srv.tlsInnerListener, config)
if srv.isChild {
err = syscall.Kill(syscall.Getppid(), syscall.SIGTERM)
if err != nil {
log.Printf("endless: error killing child: %v", err)
}
}
log.Println(syscall.Getpid(), srv.Addr)
return srv.Serve()
}
/*
getListener either opens a new socket to listen on, or takes the acceptor socket
it got passed when restarted.
*/
func (srv *endlessServer) getListener(laddr string) (l net.Listener, err error) {
if srv.isChild {
var ptrOffset uint = 0
runningServerReg.RLock()
defer runningServerReg.RUnlock()
if len(socketPtrOffsetMap) > 0 {
ptrOffset = socketPtrOffsetMap[laddr]
// log.Println("laddr", laddr, "ptr offset", socketPtrOffsetMap[laddr])
}
f := os.NewFile(uintptr(3+ptrOffset), "")
l, err = net.FileListener(f)
if err != nil {
err = fmt.Errorf("net.FileListener error: %v", err)
return
}
} else {
l, err = net.Listen("tcp", laddr)
if err != nil {
err = fmt.Errorf("net.Listen error: %v", err)
return
}
}
return
}
/*
handleSignals listens for os Signals and calls any hooked in function that the
user had registered with the signal.
*/
func (srv *endlessServer) handleSignals() {
var sig os.Signal
signal.Notify(
srv.sigChan,
hookableSignals...,
)
pid := syscall.Getpid()
for {
sig = <-srv.sigChan
srv.signalHooks(PRE_SIGNAL, sig)
switch sig {
case syscall.SIGHUP:
log.Println(pid, "Received SIGHUP. forking.")
err := srv.fork()
if err != nil {
log.Println("Fork err:", err)
}
case syscall.SIGUSR1:
log.Println(pid, "Received SIGUSR1.")
case syscall.SIGUSR2:
log.Println(pid, "Received SIGUSR2.")
srv.hammerTime(0 * time.Second)
case syscall.SIGINT:
log.Println(pid, "Received SIGINT.")
srv.shutdown()
case syscall.SIGTERM:
log.Println(pid, "Received SIGTERM.")
srv.shutdown()
case syscall.SIGTSTP:
log.Println(pid, "Received SIGTSTP.")
default:
log.Printf("Received %v: nothing i care about...\n", sig)
}
srv.signalHooks(POST_SIGNAL, sig)
}
}
func (srv *endlessServer) signalHooks(ppFlag int, sig os.Signal) {
if _, notSet := srv.SignalHooks[ppFlag][sig]; !notSet {
return
}
for _, f := range srv.SignalHooks[ppFlag][sig] {
f()
}
return
}
/*
shutdown closes the listener so that no new connections are accepted. it also
starts a goroutine that will hammer (stop all running requests) the server
after DefaultHammerTime.
*/
func (srv *endlessServer) shutdown() {
if srv.getState() != STATE_RUNNING {
return
}
srv.setState(STATE_SHUTTING_DOWN)
if DefaultHammerTime >= 0 {
go srv.hammerTime(DefaultHammerTime)
}
// disable keep-alives on existing connections
srv.SetKeepAlivesEnabled(false)
err := srv.EndlessListener.Close()
if err != nil {
log.Println(syscall.Getpid(), "Listener.Close() error:", err)
} else {
log.Println(syscall.Getpid(), srv.EndlessListener.Addr(), "Listener closed.")
}
}
/*
hammerTime forces the server to shutdown in a given timeout - whether it
finished outstanding requests or not. if Read/WriteTimeout are not set or the
max header size is very big a connection could hang...
srv.Serve() will not return until all connections are served. this will
unblock the srv.wg.Wait() in Serve() thus causing ListenAndServe(TLS) to
return.
*/
func (srv *endlessServer) hammerTime(d time.Duration) {
defer func() {
// we are calling srv.wg.Done() until it panics which means we called
// Done() when the counter was already at 0 and we're done.
// (and thus Serve() will return and the parent will exit)
if r := recover(); r != nil {
log.Println("WaitGroup at 0", r)
}
}()
if srv.getState() != STATE_SHUTTING_DOWN {
return
}
time.Sleep(d)
log.Println("[STOP - Hammer Time] Forcefully shutting down parent")
for {
if srv.getState() == STATE_TERMINATE {
break
}
srv.wg.Done()
runtime.Gosched()
}
}
func (srv *endlessServer) fork() (err error) {
runningServerReg.Lock()
defer runningServerReg.Unlock()
// only one server instance should fork!
if runningServersForked {
return errors.New("Another process already forked. Ignoring this one.")
}
runningServersForked = true
var files = make([]*os.File, len(runningServers))
var orderArgs = make([]string, len(runningServers))
// get the accessor socket fds for _all_ server instances
for _, srvPtr := range runningServers {
// introspect.PrintTypeDump(srvPtr.EndlessListener)
switch srvPtr.EndlessListener.(type) {
case *endlessListener:
// normal listener
files[socketPtrOffsetMap[srvPtr.Server.Addr]] = srvPtr.EndlessListener.(*endlessListener).File()
default:
// tls listener
files[socketPtrOffsetMap[srvPtr.Server.Addr]] = srvPtr.tlsInnerListener.File()
}
orderArgs[socketPtrOffsetMap[srvPtr.Server.Addr]] = srvPtr.Server.Addr
}
env := append(
os.Environ(),
"ENDLESS_CONTINUE=1",
)
if len(runningServers) > 1 {
env = append(env, fmt.Sprintf(`ENDLESS_SOCKET_ORDER=%s`, strings.Join(orderArgs, ",")))
}
// log.Println(files)
path := os.Args[0]
var args []string
if len(os.Args) > 1 {
args = os.Args[1:]
}
cmd := exec.Command(path, args...)
cmd.Stdout = os.Stdout
cmd.Stderr = os.Stderr
cmd.ExtraFiles = files
cmd.Env = env
// cmd.SysProcAttr = &syscall.SysProcAttr{
// Setsid: true,
// Setctty: true,
// Ctty: ,
// }
err = cmd.Start()
if err != nil {
log.Fatalf("Restart: Failed to launch, error: %v", err)
}
return
}
type endlessListener struct {
net.Listener
stopped bool
server *endlessServer
}
func (el *endlessListener) Accept() (c net.Conn, err error) {
tc, err := el.Listener.(*net.TCPListener).AcceptTCP()
if err != nil {
return nil, err
}
err = tc.SetKeepAlive(true) // see http.tcpKeepAliveListener
if err != nil {
return nil, err
}
err = tc.SetKeepAlivePeriod(3 * time.Minute) // see http.tcpKeepAliveListener
if err != nil {
return nil, err
}
c = endlessConn{
Conn: tc,
server: el.server,
}
el.server.wg.Add(1)
return
}
func newEndlessListener(l net.Listener, srv *endlessServer) (el *endlessListener) {
el = &endlessListener{
Listener: l,
server: srv,
}
return
}
func (el *endlessListener) Close() error {
if el.stopped {
return syscall.EINVAL
}
el.stopped = true
return el.Listener.Close()
}
func (el *endlessListener) File() *os.File {
// returns a dup(2) - FD_CLOEXEC flag *not* set
tl := el.Listener.(*net.TCPListener)
fl, _ := tl.File()
return fl
}
type endlessConn struct {
net.Conn
server *endlessServer
}
func (w endlessConn) Close() error {
err := w.Conn.Close()
if err == nil {
w.server.wg.Done()
}
return err
}
/*
RegisterSignalHook registers a function to be run PRE_SIGNAL or POST_SIGNAL for
a given signal. PRE or POST in this case means before or after the signal
related code endless itself runs
*/
func (srv *endlessServer) RegisterSignalHook(prePost int, sig os.Signal, f func()) (err error) {
if prePost != PRE_SIGNAL && prePost != POST_SIGNAL {
err = fmt.Errorf("Cannot use %v for prePost arg. Must be endless.PRE_SIGNAL or endless.POST_SIGNAL.", sig)
return
}
for _, s := range hookableSignals {
if s == sig {
srv.SignalHooks[prePost][sig] = append(srv.SignalHooks[prePost][sig], f)
return
}
}
err = fmt.Errorf("Signal %v is not supported.", sig)
return
}