I have small code which reads 100 MB file from Google cloud storage and then return output.
Code works fine for 1MB file but fails for 100 mb file.
Below is the code which is not working
rc, err := client.Bucket("mabucket").Object(gcpurl).NewReader(ctx)
if err != nil {
fmt.Println(err)
return
}
defer rc.Close()
w.Header().Set("Content-Length", strconv.Itoa(int(rc.Size())))
w.Header().Set("Cache-Control", "max-age=2592000")
w.Header().Set("Content-Type", rc.ContentType())
spew.Dump(rc.ContentType())
if rc.ContentType() == "audio/wav" || rc.ContentType() == "audio/wave" {
w.Header().Set("Accept-Ranges", "bytes")
tilrange := rc.Size() - 1
newRangeString := "bytes 0-" + strconv.Itoa(int(tilrange)) + "/" + strconv.Itoa(int(rc.Size()))
w.Header().Set("Content-Range", newRangeString)
w.WriteHeader(206)
}
//spew.Dump(rc.Attrs)
io.Copy(w, rc)
I have written another code which is able to download same file and create a local file of 100 mb.
this time I am using ioutil.ReadAll. what can be problem with io.copy when receiving large date from GCP?
func main() {
ctx := context.Background()
client, _ := storage.NewClient(ctx)
data, err := downloadFile(client, "mabucket", "606ff2b71a916907409a953f/606ff2ed1a916907409a9540/60a38a967b291f7b44488824/123/audio/210415164000M29713363.wav")
//210415164000M29713363.wav
if err != nil {
log.Fatalf("Cannot read object: %v", err)
}
fmt.Printf("Object contents: %d\n", len(data))
f, err := os.Create("a.wav")
check(err)
defer f.Close()
n2, err := f.Write(data)
check(err)
fmt.Printf("wrote %d bytes\n", n2)
}
// downloadFile downloads an object.
func downloadFile(client *storage.Client, bucket, object string) ([]byte, error) {
// [START download_file]
ctx := context.Background()
ctx, cancel := context.WithTimeout(ctx, time.Second*50)
defer cancel()
rc, err := client.Bucket(bucket).Object(object).NewReader(ctx)
if err != nil {
return nil, err
}
defer rc.Close()
data, err := ioutil.ReadAll(rc)
if err != nil {
return nil, err
}
return data, nil
// [END download_file]
}
io.copy was trying to copy the details but OS was not allowing it. it was throwing error as (*net.OpError)(0xc0003302d0)(write tcp [::1]:80->[::1]:63014: wsasend: An established connection was aborted by the software in your host machine
Related
I'm trying to make a music app that sends file through tcp protocol using go and microservice architecture. Now I'm creating a player service that should:
Get user token and get claims from it
Check is user exists using claims and user_service microservice
Get song from redis
Check is song exists using music_service
Read file by chunks and send it to client using tcp
Redis data looks like this:
{
"user_id": [{
"song_id": "<song_id>"
}]
}
But I faced with a small problem. My music files stored in a flac format and when I receive it on the client, my player doesn't play it. I don't really know what can be the problem. So here's my code:
SERVER
service_setup.go
//this function is called in main function
func setService() {
ln, err := net.Listen("tcp", config.TCPAddress)
if err != nil {
panic("couldn't start tcp server")
}
defer ln.Close()
for {
conn, err := ln.Accept()
if err != nil {
logger.ErrorLog(fmt.Sprintf("Error: couldn't accept connection. Details: %v", err))
return
}
service.DownloadSong(conn)
}
}
downloader_service.go
func DownloadSong(conn net.Conn) {
token, err := bufio.NewReader(conn).ReadString('\n')
if err != nil {
logger.ErrorLog(fmt.Sprintf("Error: couldn't get token. Details: %v", token))
conn.Close()
return
}
claims, err := jwt_funcs.DecodeJwt(token)
if err != nil {
conn.Close()
return
}
songs, err := redis_repo.Get(claims.Id)
if err != nil {
conn.Close()
return
}
for _, song := range songs {
download(song, conn)
}
}
func download(song models.SongsModel, conn net.Conn) {
filePath, err := filepath.Abs(fmt.Sprintf("./songs/%s.flac", song.SongId))
if err != nil {
logger.ErrorLog(fmt.Sprintf("Errror: couldn't create filepath. Details: %v", err))
conn.Close()
return
}
file, err := os.Open(filePath)
defer file.Close()
if err != nil {
logger.ErrorLog(fmt.Sprintf("Errror: couldn't open file. Details: %v", err))
conn.Close()
return
}
read(file, conn)
}
func read(file *os.File, conn net.Conn) {
reader := bufio.NewReader(file)
buf := make([]byte, 15)
defer conn.Close()
for {
_, err := reader.Read(buf)
if err != nil && err == io.EOF {
logger.InfoLog(fmt.Sprintf("Details: %v", err))
fmt.Println()
return
}
conn.Write(buf)
}
}
CLIENT
main.go
func main() {
conn, _ := net.Dial("tcp", "127.0.0.1:6060")
var glMessage []byte
text := "eyJhbGciOiJFUzI1NiIsInR5cCI6IkpXVCJ9.eyJpZCI6IjYzYzlhNmE1OWI3ZmQyNTQ2ZjA4ZWEyYSIsInVzZXJuYW1lIjoiMTIiLCJleHAiOjE2NzQyMTE5ODl9.aarSDhrFF1df3i2pIRyjNxTfSHKObqLU3kHJiPreredIhLNCzs7z7jMgRHQIcLaIvCOECN7bX0OaSvKdW7VKsQ\n"
fmt.Fprint(conn, text)
reader := bufio.NewReader(conn)
b := make([]byte, 15)
c := 0
for i, _ := reader.Read(b); int(i) != 0; i, _ = reader.Read(b) {
c += i
glMessage = append(glMessage, b...)
}
os.WriteFile("./test.flac", glMessage, 0644)
}
If you know what can be the problem, please tell me. I'd really appreciate it!
It looks like you're trying to send the music file over the network in 15 byte chunks, which is likely not enough to play the song on the client side.
You can try increasing the chunk size, for example, to 8192 bytes. To do this, replace buf := make([]byte, 15) with buf := make([]byte, 8192).
Also, it's better to write the received data directly to the file rather than storing it in memory. You can do this by creating a file and using os.Create to write the received data to it:
file, err := os.Create("./test.flac")
if err != nil {
fmt.Println("Error: couldn't create file")
return
}
defer file.Close()
for {
i, err := reader.Read(buf)
if err != nil && err == io.EOF {
break
}
file.Write(buf[:i])
}
I believe that this can solve the issue.
I write simple example code, it worked, but size of file that recived is not compressed
My client (for connect to server and send file):
// connect to server
conn, err := net.Dial("tcp", serverAddr)
CheckError(err)
defer conn.Close()
in, err := os.Open(srcFile)
if err != nil {
log.Fatal(err)
}
pr, pw := io.Pipe()
gw, err := gzip.NewWriterLevel(pw, 7)
CheckError(err)
go func() {
n, err := io.Copy(gw, in)
gw.Close()
pw.Close()
log.Printf("copied %v %v", n, err)
}()
//maybe error some next?
_, err = io.Copy(conn, pr)
Please, help, how right to use pipe with copy
As I already said in the comment, your code works. I created a little example to test or see if I can solve your problem. So I guess you can close this question.
package main
import (
"compress/gzip"
"io"
"log"
"net"
"os"
)
func main() {
// Create a listener on a random port.
listener, err := net.Listen("tcp", "127.0.0.1:")
if err != nil {
log.Fatal(err)
}
log.Println("Server listening on: " + listener.Addr().String())
done := make(chan struct{})
go func() {
defer func() { done <- struct{}{} }()
for {
conn, err := listener.Accept()
if err != nil {
log.Println(err)
return
}
go func(c net.Conn) {
defer func() {
c.Close()
done <- struct{}{}
}()
buf := make([]byte, 1024)
for {
n, err := c.Read(buf)
if err != nil {
if err != io.EOF {
log.Println(err)
}
return
}
log.Printf("received: %q", buf[:n])
log.Printf("bytes: %d", n)
}
}(conn)
}
}()
conn, err := net.Dial("tcp", listener.Addr().String())
if err != nil {
log.Fatal(err)
}
log.Println("Connected to server.")
file, err := os.Open("./file.txt")
if err != nil {
log.Fatal(err)
}
pr, pw := io.Pipe()
w, err := gzip.NewWriterLevel(pw, 7)
if err != nil {
log.Fatal(err)
}
go func() {
n, err := io.Copy(w, file)
if err != nil {
log.Fatal(err)
}
w.Close()
pw.Close()
log.Printf("copied to piped writer via the compressed writer: %d", n)
}()
n, err := io.Copy(conn, pr)
if err != nil {
log.Fatal(err)
}
log.Printf("copied to connection: %d", n)
conn.Close()
<-done
listener.Close()
<-done
}
The output of that program with a simple text file with many repeated characters in it, to have something to compress: The file is 153 bytes and I send/received 46 bytes
2022/04/04 11:23:58 Server listening on: 127.0.0.1:58250
2022/04/04 11:23:58 Connected to server.
2022/04/04 11:23:58 received: "\x1f\x8b\b\x00\x00\x00\x00\x00\x00\xff"
2022/04/04 11:23:58 bytes: 10
2022/04/04 11:23:58 copied to piped writer via the compressed writer: 153
2022/04/04 11:23:58 copied to connection: 46
2022/04/04 11:23:58 received: "*I-.I,NI,N\xc1\x01\x8aS\x8a\x13i\bx\xb9pX \r\b\x00\x00\xff\xff\xc7\xfe\xa6c\x99\x00\x00\x00"
2022/04/04 11:23:58 bytes: 36
2022/04/04 11:23:58 accept tcp 127.0.0.1:58250: use of closed network connection
I am able to zip a file using logic similar to the zip writer seen here.
This results in an array of bytes ([]byte) being created within the bytes.Buffer object that is returned. I would just like to know if there is there any way I can upload this 'zipped' array of bytes to an API endpoint that expects a 'multipart/form-data' request body (without having to save it locally).
Supplementary information:
I have code that utilizes this when compressing a folder. I am able to successfully execute an HTTP POST request with the zip file to the endpoint with this logic.
However, this unfortunately saves zipped files in a user's local file system. I would like to try to avoid this :)
You can create multipart writer and write []byte zipped data into field with field name you like and file name like below.
func addZipFileToReq(zipped []byte) (*http.Request, error){
body := bytes.NewBuffer(nil)
writer := multipart.NewWriter(body)
part, err := writer.CreateFormFile(`fileField`, `filename`)
if err != nil {
return nil, err
}
_, err = part.Write(zipped)
if err != nil {
return nil, err
}
err = writer.Close()
if err != nil {
return nil, err
}
r, err := http.NewRequest(http.MethodPost, "https://example.com", body)
if err != nil {
return nil, err
}
r.Header.Set("Content-Type", writer.FormDataContentType())
return r, nil
}
If you want to stream-upload the zip, you should be able to do so with io.Pipe. The following is an incomplete and untested example to demonstrate the general idea. To make it work you'll need to modify it and potentially fix whatever bugs you encounter.
func UploadReader(r io.Reader) error {
req, err := http.NewRequest("POST", "<UPLOAD_URL>", r)
if err != nil {
return err
}
// TODO set necessary headers (content type, auth, etc)
res, err := http.DefaultClient.Do(req)
if err != nil {
return err
} else if res.StatusCode != 200 {
return errors.New("not ok")
}
return nil
}
func ZipDir(dir string, w io.Writer) error {
zw := zip.NewWriter(w)
defer zw.Close()
return filepath.Walk(dir, func(path string, fi os.FileInfo, err error) error {
if err != nil {
return err
}
if !fi.Mode().IsRegular() {
return nil
}
header, err := zip.FileInfoHeader(fi)
if err != nil {
return err
}
header.Name = path
header.Method = zip.Deflate
w, err := zw.CreateHeader(header)
if err != nil {
return err
}
f, err := os.Open(path)
if err != nil {
return err
}
defer f.Close()
if _, err := io.Copy(w, f); err != nil {
return err
}
return nil
})
}
func UploadDir(dir string) error {
r, w := io.Pipe()
ch := make(chan error)
wg := sync.WaitGroup{}
wg.Add(1)
go func() {
defer wg.Done()
defer w.Close()
if err := ZipDir(dir, w); err != nil {
ch <- err
}
}()
wg.Add(1)
go func() {
defer wg.Done()
defer r.Close()
if err := UploadReader(r); err != nil {
ch <- err
}
}()
go func() {
wg.Wait()
close(ch)
}()
return <-ch
}
I'm trying to download a remote file over ssh
The following approach works fine on shell
ssh hostname "tar cz /opt/local/folder" > folder.tar.gz
However the same approach on golang giving some difference in output artifact size. For example the same folders with pure shell produce artifact gz file 179B and same with go script 178B.
I assume that something has been missed from io.Reader or session got closed earlier. Kindly ask you guys to help.
Here is the example of my script:
func executeCmd(cmd, hostname string, config *ssh.ClientConfig, path string) error {
conn, _ := ssh.Dial("tcp", hostname+":22", config)
session, err := conn.NewSession()
if err != nil {
panic("Failed to create session: " + err.Error())
}
r, _ := session.StdoutPipe()
scanner := bufio.NewScanner(r)
go func() {
defer session.Close()
name := fmt.Sprintf("%s/backup_folder_%v.tar.gz", path, time.Now().Unix())
file, err := os.OpenFile(name, os.O_APPEND|os.O_WRONLY|os.O_CREATE, 0644)
if err != nil {
panic(err)
}
defer file.Close()
for scanner.Scan() {
fmt.Println(scanner.Bytes())
if err := scanner.Err(); err != nil {
fmt.Println(err)
}
if _, err = file.Write(scanner.Bytes()); err != nil {
log.Fatal(err)
}
}
}()
if err := session.Run(cmd); err != nil {
fmt.Println(err.Error())
panic("Failed to run: " + err.Error())
}
return nil
}
Thanks!
bufio.Scanner is for newline delimited text. According to the documentation, the scanner will remove the newline characters, stripping any 10s out of your binary file.
You don't need a goroutine to do the copy, because you can use session.Start to start the process asynchronously.
You probably don't need to use bufio either. You should be using io.Copy to copy the file, which has an internal buffer already on top of any buffering already done in the ssh client itself. If an additional buffer is needed for performance, wrap the session output in a bufio.Reader
Finally, you return an error value, so use it rather than panic'ing on regular error conditions.
conn, err := ssh.Dial("tcp", hostname+":22", config)
if err != nil {
return err
}
session, err := conn.NewSession()
if err != nil {
return err
}
defer session.Close()
r, err := session.StdoutPipe()
if err != nil {
return err
}
name := fmt.Sprintf("%s/backup_folder_%v.tar.gz", path, time.Now().Unix())
file, err := os.OpenFile(name, os.O_APPEND|os.O_WRONLY|os.O_CREATE, 0644)
if err != nil {
return err
}
defer file.Close()
if err := session.Start(cmd); err != nil {
return err
}
n, err := io.Copy(file, r)
if err != nil {
return err
}
if err := session.Wait(); err != nil {
return err
}
return nil
You can try doing something like this:
r, _ := session.StdoutPipe()
reader := bufio.NewReader(r)
go func() {
defer session.Close()
// open file etc
// 10 is the number of bytes you'd like to copy in one write operation
p := make([]byte, 10)
for {
n, err := reader.Read(p)
if err == io.EOF {
break
}
if err != nil {
log.Fatal("err", err)
}
if _, err = file.Write(p[:n]); err != nil {
log.Fatal(err)
}
}
}()
Make sure your goroutines are synchronized properly so output is completeky written to the file.
Is there a way to download a large file using Go that will store the content directly into a file instead of storing it all in memory before writing it to a file? Because the file is so big, storing it all in memory before writing it to a file is going to use up all the memory.
I'll assume you mean download via http (error checks omitted for brevity):
import ("net/http"; "io"; "os")
...
out, err := os.Create("output.txt")
defer out.Close()
...
resp, err := http.Get("http://example.com/")
defer resp.Body.Close()
...
n, err := io.Copy(out, resp.Body)
The http.Response's Body is a Reader, so you can use any functions that take a Reader, to, e.g. read a chunk at a time rather than all at once. In this specific case, io.Copy() does the gruntwork for you.
A more descriptive version of Steve M's answer.
import (
"os"
"net/http"
"io"
)
func downloadFile(filepath string, url string) (err error) {
// Create the file
out, err := os.Create(filepath)
if err != nil {
return err
}
defer out.Close()
// Get the data
resp, err := http.Get(url)
if err != nil {
return err
}
defer resp.Body.Close()
// Check server response
if resp.StatusCode != http.StatusOK {
return fmt.Errorf("bad status: %s", resp.Status)
}
// Writer the body to file
_, err = io.Copy(out, resp.Body)
if err != nil {
return err
}
return nil
}
The answer selected above using io.Copy is exactly what you need, but if you are interested in additional features like resuming broken downloads, auto-naming files, checksum validation or monitoring progress of multiple downloads, checkout the grab package.
Here is a sample. https://github.com/thbar/golang-playground/blob/master/download-files.go
Also I give u some codes might help you.
code:
func HTTPDownload(uri string) ([]byte, error) {
fmt.Printf("HTTPDownload From: %s.\n", uri)
res, err := http.Get(uri)
if err != nil {
log.Fatal(err)
}
defer res.Body.Close()
d, err := ioutil.ReadAll(res.Body)
if err != nil {
log.Fatal(err)
}
fmt.Printf("ReadFile: Size of download: %d\n", len(d))
return d, err
}
func WriteFile(dst string, d []byte) error {
fmt.Printf("WriteFile: Size of download: %d\n", len(d))
err := ioutil.WriteFile(dst, d, 0444)
if err != nil {
log.Fatal(err)
}
return err
}
func DownloadToFile(uri string, dst string) {
fmt.Printf("DownloadToFile From: %s.\n", uri)
if d, err := HTTPDownload(uri); err == nil {
fmt.Printf("downloaded %s.\n", uri)
if WriteFile(dst, d) == nil {
fmt.Printf("saved %s as %s\n", uri, dst)
}
}
}