fork.go

/*
 * Copyright (c) 2021. Lorem ipsum dolor sit amet, consectetur adipiscing elit.
 * Morbi non lorem porttitor neque feugiat blandit. Ut vitae ipsum eget quam lacinia accumsan.
 * Etiam sed turpis ac ipsum condimentum fringilla. Maecenas magna.
 * Proin dapibus sapien vel ante. Aliquam erat volutpat. Pellentesque sagittis ligula eget metus.
 * Vestibulum commodo. Ut rhoncus gravida arcu.
 */

package process_master

import (
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"os"
	"syscall"
	"time"

	"github.com/eolinker/eosc/env"
	"github.com/eolinker/eosc/traffic"
	"github.com/eolinker/eosc/utils"

	"github.com/eolinker/eosc"

	"github.com/eolinker/eosc/log"
	"github.com/eolinker/eosc/pidfile"
	"github.com/eolinker/eosc/process"
)

var runningMasterForked = new(ForkStatus)

// Fork Master fork 子进程，入参为子进程需要的内容
func (m *Master) Fork(pFile *pidfile.PidFile) error {
	if !runningMasterForked.Start() {
		return errors.New("Another process already forked. Ignoring this one.")
	}

	err := pFile.TryFork()
	if err != nil {
		return err
	}

	tfMaster, filesMaster := traffic.Export(m.adminTraffic, 3)

	dataMasterTraffic, err := json.Marshal(&traffic.PbTraffics{Traffic: tfMaster})
	if err != nil {
		return err
	}

	dataMasterTraffic = utils.EncodeFrame(dataMasterTraffic)

	tfWorker, filesWorker := traffic.Export(m.workerTraffic, len(filesMaster)+3)
	dataWorkerTraffic, err := json.Marshal(&traffic.PbTraffics{Traffic: tfWorker})

	if err != nil {
		return err
	}
	dataWorkerTraffic = utils.EncodeFrame(dataWorkerTraffic)

	data := make([]byte, len(dataMasterTraffic)+len(dataWorkerTraffic))
	copy(data, dataMasterTraffic)
	copy(data[len(dataMasterTraffic):], dataWorkerTraffic)

	cmd, err := process.Cmd(eosc.ProcessMaster, os.Args[1:])
	if err != nil {
		return err
	}
	cmd.Stdout = os.Stdout
	cmd.Stderr = os.Stderr
	cmd.Stdin = bytes.NewReader(data)
	cmd.SysProcAttr = &syscall.SysProcAttr{
		Setsid: true,
	}
	cmd.ExtraFiles = append(filesMaster, filesWorker...)
	// 子进程的环境变量加入MASTER_CONTINUE字段，用于新的Master启动后给父Master传送中断信号
	cmd.Env = append(os.Environ(), env.GenEnv("MASTER_CONTINUE", "1"))

	err = cmd.Start()
	if err != nil {
		log.Fatalf("Restart: Failed to launch, error: %v", err)
		return err
	}
	log.Debug("fork new process: ", cmd.Process.Pid, ":", cmd.String())
	// check cmd
	go waitFork(m.ctx, pFile, cmd.Process.Pid)

	return nil
}

func waitFork(ctx context.Context, pFile *pidfile.PidFile, pid int) {
	t := time.NewTicker(time.Millisecond * 100)
	defer t.Stop()
	for {
		select {
		case <-ctx.Done():
			return
		case <-t.C:
			if !pidfile.ProcessExists(pid) {
				pFile.UnFork()
				runningMasterForked.Stop()
				return
			}
		}
	}

}