merge(third_party/git): Merge squashed git subtree at v2.23.0

Merge commit '1b593e1ea4' as 'third_party/git'

third_party/git/contrib/persistent-https/proxy.go

@@ -0,0 +1,190 @@
+// Copyright 2012 Google Inc. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package main
+
+import (
+	"fmt"
+	"log"
+	"net"
+	"net/http"
+	"net/http/httputil"
+	"os"
+	"os/exec"
+	"os/signal"
+	"sync"
+	"syscall"
+	"time"
+)
+
+type Proxy struct {
+	BuildLabel         string
+	MaxIdleDuration    time.Duration
+	PollUpdateInterval time.Duration
+
+	ul        net.Listener
+	httpAddr  string
+	httpsAddr string
+}
+
+func (p *Proxy) Run() error {
+	hl, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		return fmt.Errorf("http listen failed: %v", err)
+	}
+	defer hl.Close()
+
+	hsl, err := net.Listen("tcp", "127.0.0.1:0")
+	if err != nil {
+		return fmt.Errorf("https listen failed: %v", err)
+	}
+	defer hsl.Close()
+
+	p.ul, err = DefaultSocket.Listen()
+	if err != nil {
+		c, derr := DefaultSocket.Dial()
+		if derr == nil {
+			c.Close()
+			fmt.Println("OK\nA proxy is already running... exiting")
+			return nil
+		} else if e, ok := derr.(*net.OpError); ok && e.Err == syscall.ECONNREFUSED {
+			// Nothing is listening on the socket, unlink it and try again.
+			syscall.Unlink(DefaultSocket.Path())
+			p.ul, err = DefaultSocket.Listen()
+		}
+		if err != nil {
+			return fmt.Errorf("unix listen failed on %v: %v", DefaultSocket.Path(), err)
+		}
+	}
+	defer p.ul.Close()
+	go p.closeOnSignal()
+	go p.closeOnUpdate()
+
+	p.httpAddr = hl.Addr().String()
+	p.httpsAddr = hsl.Addr().String()
+	fmt.Printf("OK\nListening on unix socket=%v http=%v https=%v\n",
+		p.ul.Addr(), p.httpAddr, p.httpsAddr)
+
+	result := make(chan error, 2)
+	go p.serveUnix(result)
+	go func() {
+		result <- http.Serve(hl, &httputil.ReverseProxy{
+			FlushInterval: 500 * time.Millisecond,
+			Director:      func(r *http.Request) {},
+		})
+	}()
+	go func() {
+		result <- http.Serve(hsl, &httputil.ReverseProxy{
+			FlushInterval: 500 * time.Millisecond,
+			Director: func(r *http.Request) {
+				r.URL.Scheme = "https"
+			},
+		})
+	}()
+	return <-result
+}
+
+type socketContext struct {
+	sync.WaitGroup
+	mutex sync.Mutex
+	last  time.Time
+}
+
+func (sc *socketContext) Done() {
+	sc.mutex.Lock()
+	defer sc.mutex.Unlock()
+	sc.last = time.Now()
+	sc.WaitGroup.Done()
+}
+
+func (p *Proxy) serveUnix(result chan<- error) {
+	sockCtx := &socketContext{}
+	go p.closeOnIdle(sockCtx)
+
+	var err error
+	for {
+		var uconn net.Conn
+		uconn, err = p.ul.Accept()
+		if err != nil {
+			err = fmt.Errorf("accept failed: %v", err)
+			break
+		}
+		sockCtx.Add(1)
+		go p.handleUnixConn(sockCtx, uconn)
+	}
+	sockCtx.Wait()
+	result <- err
+}
+
+func (p *Proxy) handleUnixConn(sockCtx *socketContext, uconn net.Conn) {
+	defer sockCtx.Done()
+	defer uconn.Close()
+	data := []byte(fmt.Sprintf("%v\n%v", p.httpsAddr, p.httpAddr))
+	uconn.SetDeadline(time.Now().Add(5 * time.Second))
+	for i := 0; i < 2; i++ {
+		if n, err := uconn.Write(data); err != nil {
+			log.Printf("error sending http addresses: %+v\n", err)
+			return
+		} else if n != len(data) {
+			log.Printf("sent %d data bytes, wanted %d\n", n, len(data))
+			return
+		}
+		if _, err := uconn.Read([]byte{0, 0, 0, 0}); err != nil {
+			log.Printf("error waiting for Ack: %+v\n", err)
+			return
+		}
+	}
+	// Wait without a deadline for the client to finish via EOF
+	uconn.SetDeadline(time.Time{})
+	uconn.Read([]byte{0, 0, 0, 0})
+}
+
+func (p *Proxy) closeOnIdle(sockCtx *socketContext) {
+	for d := p.MaxIdleDuration; d > 0; {
+		time.Sleep(d)
+		sockCtx.Wait()
+		sockCtx.mutex.Lock()
+		if d = sockCtx.last.Add(p.MaxIdleDuration).Sub(time.Now()); d <= 0 {
+			log.Println("graceful shutdown from idle timeout")
+			p.ul.Close()
+		}
+		sockCtx.mutex.Unlock()
+	}
+}
+
+func (p *Proxy) closeOnUpdate() {
+	for {
+		time.Sleep(p.PollUpdateInterval)
+		if out, err := exec.Command(os.Args[0], "--print_label").Output(); err != nil {
+			log.Printf("error polling for updated binary: %v\n", err)
+		} else if s := string(out[:len(out)-1]); p.BuildLabel != s {
+			log.Printf("graceful shutdown from updated binary: %q --> %q\n", p.BuildLabel, s)
+			p.ul.Close()
+			break
+		}
+	}
+}
+
+func (p *Proxy) closeOnSignal() {
+	ch := make(chan os.Signal, 10)
+	signal.Notify(ch, os.Interrupt, os.Kill, os.Signal(syscall.SIGTERM), os.Signal(syscall.SIGHUP))
+	sig := <-ch
+	p.ul.Close()
+	switch sig {
+	case os.Signal(syscall.SIGHUP):
+		log.Printf("graceful shutdown from signal: %v\n", sig)
+	default:
+		log.Fatalf("exiting from signal: %v\n", sig)
+	}
+}