gistfile1.go

package main                                                                                                                                                                                                                                                                     
                                                                               
import (                                                                       
    "time"                                                                     
    "net/http"                                                                 
    "net/smtp"                                                                 
    "fmt"                                                                      
) 

func sendMail(body string) error{                                              
    // Set up authentication information.                                      
    // Connect to the server, authenticate, set the sender and recipient,         
    // and send the email all in one step.                                     
    addr := "smtp.gmail.com:587"                                               
    c, err := smtp.Dial(addr)                                                  
    if err != nil {                                                            
        return err                                                             
    }                                                                          
    ///////////////////////                                                    
    // Not present in std pkg. Bug ??                                          
    defer c.Quit()                                                             
    ///////////////////////                                                    
    if err := c.Hello(""); err != nil {                                        
        return err                                                             
    }                                                                          
    if ok, _ := c.Extension("STARTTLS"); ok {                                  
        if err = c.StartTLS(nil); err != nil {                                 
            return err                                                         
        }                                                                      
    }                                                                          
    a := smtp.PlainAuth(                                                       
            "",                                                                
            "x@x.com",                                         
            "password",                                                     
            "smtp.gmail.com",                                                  
        )                                                                      
    if err = c.Auth(a); err != nil {                                           
        return err                                                             
    }                                                                          
    from := "x@x.com"                                          
    to := []string{"x@x.com"}                             
    subject := body                                                            
                                                                               
    msg := fmt.Sprint("Subject: ", subject, "\r\n\r\n", body)                  
                                                                               
    if err = c.Mail(from); err != nil {                                        
        return err                                                             
    }                                                                          
    for _, addr := range to {                                                  
        if err = c.Rcpt(addr); err != nil {                                    
            return err                                                         
        }                                                                      
    }                                                                          
    w, err := c.Data()                                                         
    if err != nil {                                                            
        return err                                                             
    }                                                                          
    _, err = w.Write([]byte(msg))                                              
    if err != nil {                                                            
        return err                                                             
    }                                                                          
    err = w.Close()                                                            
    if err != nil {                                                            
        return err                                                             
    }                                                                          
    fmt.Println("Send mail")                                                   
    return nil                                                                 
}         


func ping(url string, c chan *http.Response, start_pinging, exit chan bool){   
    for _ = range(start_pinging){                                              
        fmt.Println("Pinging ", url)                                           
        start := time.Now()                                                    
        resp, err := http.Get(url)                                             
        stop := time.Now()                                                     
        if stop.Sub(start) < time.Millisecond{                                 
            exit <- true                                                       
        }                                                                      
        fmt.Println("Received ", url, stop.Sub(start))                         
        if err != nil{                                                         
            err = sendMail(fmt.Sprint("Error fetching ", url, " error: ", err))
            if err != nil{                                                     
                fmt.Println("Error sending mail", err)                         
            }                                                                  
        }else{                                                                 
            select{                                                            
            case c<-resp:                                                      
            default:                                                           
            }                                                                  
        }                                                                      
    }                                                                          
}                                                                              
                                                                               
func main(){                                                                   
    responses := make(chan *http.Response)                                     
    exit := make(chan bool)                                                    
    url := "SOME URL"                                                    
    err := sendMail(fmt.Sprint("Starting pinging :", url))                     
    if err != nil{                                                             
        fmt.Println("Error sending mail", err)                                 
    }                                                                          
    start_pinging := make(chan bool)                                           
    go ping(url, responses, start_pinging, exit)                               
    for _ = range time.Tick(60 * time.Second) {                                
        fmt.Println("Tick")                                                    
        start_pinging<-true                                                    
        select {                                                               
        case resp := <-responses:                                              
            if resp.StatusCode != 200{                                         
                err = sendMail(fmt.Sprint("Error fetching ", url, " (non 200 code, actual:", resp.StatusCode, ")"))
                if err != nil{                                                 
                    fmt.Println("Error sending mail", err)                     
                }                                                              
            }else{                                                             
                fmt.Print(".")                                                 
            }                                                                  
        case <-time.After(2 * time.Second):                                    
            err = sendMail(fmt.Sprint("Error fetching ", url, " (timeout)"))   
            if err != nil{                                                     
                fmt.Println("Error sending mail", err)                                                                                                                                                                                                                           
            }                                                                  
        case <- exit:                                                          
            return        
        }
    }
}