mirror of
https://github.com/gin-gonic/gin.git
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136 lines
3.5 KiB
Go
136 lines
3.5 KiB
Go
/*
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* MIT License
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*
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* Copyright (c) 2019-present Fenny and Contributors
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*
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* Code Sources In Here Come From: https://github.com/gofiber/fiber/blob/master/prefork.go
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*/
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package gin
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import (
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"fmt"
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"net/http"
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"os"
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"os/exec"
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"runtime"
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"time"
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reuseport "github.com/libp2p/go-reuseport"
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)
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const (
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envPreforkChildKey = "GIN_PREFORK_CHILD"
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envPreforkChildVal = "1"
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)
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// Holds process of childs
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var children = map[int]*exec.Cmd{}
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// IsChild determines if the current process is a child of Prefork
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func IsChild() bool {
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return os.Getenv(envPreforkChildKey) == envPreforkChildVal
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}
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// watchMaster watches child procs
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func watchMaster() {
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if runtime.GOOS == "windows" {
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// finds parent process,
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// and waits for it to exit
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p, err := os.FindProcess(os.Getppid())
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if err == nil {
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_, _ = p.Wait()
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}
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os.Exit(1)
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}
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// if it is equal to 1 (init process ID),
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// it indicates that the master process has exited
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for range time.NewTicker(time.Millisecond * 500).C {
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if os.Getppid() == 1 {
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os.Exit(1)
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}
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}
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}
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// prefork manages child processes to make use of the OS REUSEPORT or REUSEADDR feature
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func prefork(addr string, engine *Engine) (err error) {
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// 👶 child process 👶
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if IsChild() {
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// use 1 cpu core per child process
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runtime.GOMAXPROCS(1)
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// kill current child proc when master exits
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go watchMaster()
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// Run child
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listener, err := reuseport.Listen("tcp", addr)
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if err != nil {
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return err
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}
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defer listener.Close()
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return http.Serve(listener, engine.Handler())
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}
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// child structure to be used in error returning
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type child struct {
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pid int
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err error
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}
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// create variables
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max := runtime.GOMAXPROCS(0)
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channel := make(chan child, max)
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// kill child procs when master exits
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defer func() {
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for _, proc := range children {
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_ = proc.Process.Kill()
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}
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}()
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// launch child procs
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for i := 0; i < max; i++ {
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cmd := exec.Command(os.Args[0], os.Args[1:]...)
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cmd.Stdout = os.Stdout
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cmd.Stderr = os.Stderr
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// Add gin prefork child flag into child proc env
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cmd.Env = append(os.Environ(),
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fmt.Sprintf("%s=%s", envPreforkChildKey, envPreforkChildVal),
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)
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if err = cmd.Start(); err != nil {
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return fmt.Errorf("failed to start a child prefork process, error: %v", err)
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}
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// Store child process ids
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pid := cmd.Process.Pid
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children[pid] = cmd
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// notify master if child crashes
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go func() {
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channel <- child{pid, cmd.Wait()}
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}()
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}
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// return error if child crashes
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return (<-channel).err
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}
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