chaosblade-exec-os项目的burnio.go文件解读

# 这是第二次执行：调用可执行文件chaos_burnio，但是参数不再有--start，--stop了，总共四个分支执行，只有--start和--stop才会有第二次执行相同可执行命令，故不会在进入到死循环    

cmd := exec.CommandContext(ctx, "/bin/sh", "-c", script+" "+args)
    
output, err := cmd.CombinedOutput()

/*
 * Copyright 1999-2020 Alibaba Group Holding Ltd.
 *
 * 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 (
    "context"
    "flag"
    "fmt"
    "path"
    "strings"
    "time"

    "github.com/chaosblade-io/chaosblade-spec-go/channel"
    "github.com/chaosblade-io/chaosblade-spec-go/util"

    "github.com/chaosblade-io/chaosblade-exec-os/exec"
    "github.com/chaosblade-io/chaosblade-exec-os/exec/bin"
)

const count = 100

var burnIODirectory, burnIOSize string
var burnIORead, burnIOWrite, burnIOStart, burnIOStop, burnIONohup bool

func main() {
    flag.StringVar(&burnIODirectory, "directory", "", "the directory where the disk is burning")
    flag.StringVar(&burnIOSize, "size", "", "block size")
    flag.BoolVar(&burnIOWrite, "write", false, "write io")
    flag.BoolVar(&burnIORead, "read", false, "read io")
    flag.BoolVar(&burnIOStart, "start", false, "start burn io")
    flag.BoolVar(&burnIOStop, "stop", false, "stop burn io")
    flag.BoolVar(&burnIONohup, "nohup", false, "start by nohup")
    bin.ParseFlagAndInitLog()

    if burnIOStart {
        startBurnIO(burnIODirectory, burnIOSize, burnIORead, burnIOWrite)
    } else if burnIOStop {
        stopBurnIO(burnIODirectory, burnIORead, burnIOWrite)
    } else if burnIONohup {
        if burnIORead {
            go burnRead(burnIODirectory, burnIOSize)
        }
        if burnIOWrite {
            go burnWrite(burnIODirectory, burnIOSize)
        }
        select {}
    } else {
        bin.PrintErrAndExit("less --start or --stop flag")
    }
}

var readFile = "chaos_burnio.read"
var writeFile = "chaos_burnio.write"
var burnIOBin = exec.BurnIOBin
var logFile = util.GetNohupOutput(util.Bin, "chaos_burnio.log")

var cl = channel.NewLocalChannel()

var stopBurnIOFunc = stopBurnIO

// start burn io
func startBurnIO(directory, size string, read, write bool) {
    ctx := context.Background()
    response := cl.Run(ctx, "nohup",
        fmt.Sprintf(`%s --directory %s --size %s --read=%t --write=%t --nohup=true > %s 2>&1 &`,
            path.Join(util.GetProgramPath(), burnIOBin), directory, size, read, write, logFile))
    if !response.Success {
        stopBurnIOFunc(directory, read, write)
        bin.PrintErrAndExit(response.Err)
        return
    }
    // check
    time.Sleep(time.Second)
    response = cl.Run(ctx, "grep", fmt.Sprintf("%s %s", bin.ErrPrefix, logFile))
    if response.Success {
        errMsg := strings.TrimSpace(response.Result.(string))
        if errMsg != "" {
            stopBurnIOFunc(directory, read, write)
            bin.PrintErrAndExit(errMsg)
            return
        }
    }
    bin.PrintOutputAndExit("success")
}

// stop burn io,  no need to add os.Exit
func stopBurnIO(directory string, read, write bool) {
    ctx := context.WithValue(context.Background(), channel.ExcludeProcessKey, "--stop")
    if read {
        // dd process
        pids, _ := cl.GetPidsByProcessName(readFile, ctx)
        if pids != nil && len(pids) > 0 {
            cl.Run(ctx, "kill", fmt.Sprintf("-9 %s", strings.Join(pids, " ")))
        }
        // chaos_burnio process
        ctxWithKey := context.WithValue(ctx, channel.ProcessKey, burnIOBin)
        pids, _ = cl.GetPidsByProcessName("--read=true", ctxWithKey)
        if pids != nil && len(pids) > 0 {
            cl.Run(ctx, "kill", fmt.Sprintf("-9 %s", strings.Join(pids, " ")))
        }
        cl.Run(ctx, "rm", fmt.Sprintf("-rf %s*", path.Join(directory, readFile)))
    }
    if write {
        // dd process
        pids, _ := cl.GetPidsByProcessName(writeFile, ctx)
        if pids != nil && len(pids) > 0 {
            cl.Run(ctx, "kill", fmt.Sprintf("-9 %s", strings.Join(pids, " ")))
        }
        ctxWithKey := context.WithValue(ctx, channel.ProcessKey, burnIOBin)
        pids, _ = cl.GetPidsByProcessName("--write=true", ctxWithKey)
        if pids != nil && len(pids) > 0 {
            cl.Run(ctx, "kill", fmt.Sprintf("-9 %s", strings.Join(pids, " ")))
        }
        cl.Run(ctx, "rm", fmt.Sprintf("-rf %s*", path.Join(directory, writeFile)))
    }
}

// write burn
func burnWrite(directory, size string) {
    tmpFileForWrite := path.Join(directory, writeFile)
    for {
        args := fmt.Sprintf(`if=/dev/zero of=%s bs=%sM count=%d oflag=dsync`, tmpFileForWrite, size, count)
        response := cl.Run(context.TODO(), "dd", args)
        if !response.Success {
            bin.PrintAndExitWithErrPrefix(response.Err)
            return
        }
    }
}

// read burn
func burnRead(directory, size string) {
    // create a 600M file under the directory
    tmpFileForRead := path.Join(directory, readFile)
    createArgs := fmt.Sprintf("if=/dev/zero of=%s bs=%dM count=%d oflag=dsync", tmpFileForRead, 6, count)
    response := cl.Run(context.TODO(), "dd", createArgs)
    if !response.Success {
        bin.PrintAndExitWithErrPrefix(
            fmt.Sprintf("using dd command to create a temp file under %s directory for reading error, %s",
                directory, response.Err))
    }
    for {
        args := fmt.Sprintf(`if=%s of=/dev/null bs=%sM count=%d iflag=dsync,direct,fullblock`, tmpFileForRead, size, count)
        response = cl.Run(context.TODO(), "dd", args)
        if !response.Success {
            bin.PrintAndExitWithErrPrefix(fmt.Sprintf("using dd command to burn read io error, %s", response.Err))
            return
        }
    }
}