timer.go

Documentation: github.com/chaos-mesh/chaos-mesh/test/pkg/timer

     1  // Copyright 2020 Chaos Mesh Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // See the License for the specific language governing permissions and
    12  // limitations under the License.
    13  
    14  package timer
    15  
    16  import (
    17  	"bufio"
    18  	"fmt"
    19  	"io"
    20  	"os/exec"
    21  	"strconv"
    22  	"strings"
    23  	"time"
    24  )
    25  
    26  // Timer represents a running timer process
    27  type Timer struct {
    28  	Stdin    io.WriteCloser
    29  	TimeChan chan TimeResult
    30  	process  *exec.Cmd
    31  	pid      int
    32  }
    33  
    34  // Pid returns the pid of timer
    35  func (timer *Timer) Pid() int {
    36  	return timer.pid
    37  }
    38  
    39  // TimeResult represents a get time result with an error
    40  type TimeResult struct {
    41  	Time  *time.Time
    42  	Error error
    43  }
    44  
    45  // StartTimer will start a timer process
    46  func StartTimer() (*Timer, error) {
    47  	process := exec.Command("./bin/test/timer")
    48  
    49  	stdout, err := process.StdoutPipe()
    50  	if err != nil {
    51  		return nil, err
    52  	}
    53  	stdoutScanner := bufio.NewScanner(stdout)
    54  
    55  	output := make(chan TimeResult)
    56  	go func() {
    57  		for stdoutScanner.Scan() {
    58  			line := stdoutScanner.Text()
    59  			sections := strings.Split(line, " ")
    60  
    61  			sec, err := strconv.ParseInt(sections[0], 10, 64)
    62  			if err != nil {
    63  				output <- TimeResult{
    64  					Error: err,
    65  				}
    66  			}
    67  			nsec, err := strconv.ParseInt(sections[1], 10, 64)
    68  			if err != nil {
    69  				output <- TimeResult{
    70  					Error: err,
    71  				}
    72  			}
    73  
    74  			t := time.Unix(sec, nsec)
    75  			output <- TimeResult{
    76  				Time: &t,
    77  			}
    78  		}
    79  		if err := stdoutScanner.Err(); err != nil {
    80  			output <- TimeResult{
    81  				Error: err,
    82  			}
    83  		}
    84  	}()
    85  
    86  	stdin, err := process.StdinPipe()
    87  	if err != nil {
    88  		return nil, err
    89  	}
    90  
    91  	err = process.Start()
    92  	if err != nil {
    93  		return nil, err
    94  	}
    95  
    96  	return &Timer{
    97  		Stdin:    stdin,
    98  		TimeChan: output,
    99  		pid:      process.Process.Pid,
   100  		process:  process,
   101  	}, nil
   102  }
   103  
   104  // GetTime will run `time.Now()` in timer
   105  func (timer *Timer) GetTime() (*time.Time, error) {
   106  	_, err := fmt.Fprintf(timer.Stdin, "\n")
   107  	if err != nil {
   108  		return nil, err
   109  	}
   110  
   111  	result := <-timer.TimeChan
   112  	if result.Error != nil {
   113  		return nil, result.Error
   114  	}
   115  
   116  	return result.Time, nil
   117  }
   118  
   119  // Stop stops the process
   120  func (timer *Timer) Stop() error {
   121  	_, err := fmt.Fprintf(timer.Stdin, "STOP\n")
   122  
   123  	return err
   124  }
   125