distribution/utils/progress.go

   1 package utils
   2
   3 import (
   4         "io"
   5         "net"
   6         "os"
   7         "syscall"
   8
   9         "github.com/Sirupsen/logrus"
  10         "github.com/docker/docker/pkg/progress"
  11         "github.com/docker/docker/pkg/streamformatter"
  12 )
  13
  14 // WriteDistributionProgress is a helper for writing progress from chan to JSON
  15 // stream with an optional cancel function.
  16 func WriteDistributionProgress(cancelFunc func(), outStream io.Writer, progressChan <-chan progress.Progress) {
  17         progressOutput := streamformatter.NewJSONProgressOutput(outStream, false)
  18         operationCancelled := false
  19
  20         for prog := range progressChan {
  21                 if err := progressOutput.WriteProgress(prog); err != nil && !operationCancelled {
  22                         // don't log broken pipe errors as this is the normal case when a client aborts
  23                         if isBrokenPipe(err) {
  24                                 logrus.Info("Pull session cancelled")
  25                         } else {
  26                                 logrus.Errorf("error writing progress to client: %v", err)
  27                         }
  28                         cancelFunc()
  29                         operationCancelled = true
  30                         // Don't return, because we need to continue draining
  31                         // progressChan until it's closed to avoid a deadlock.
  32                 }
  33         }
  34 }
  35
  36 func isBrokenPipe(e error) bool {
  37         if netErr, ok := e.(*net.OpError); ok {
  38                 e = netErr.Err
  39                 if sysErr, ok := netErr.Err.(*os.SyscallError); ok {
  40                         e = sysErr.Err
  41                 }
  42         }
  43         return e == syscall.EPIPE
  44 }