// NewSnappyResponseWriter returns a `http.ResponseWriter` wrapper which can encode
// the output with Snappy if requested by the client.
// If snappy isn't enabled, it will act like a regular `http.ResponseWriter`
// `Close` must be call so the `*snappy.Writer` instance can be put back in the `sync.Pool`
func NewSnappyResponseWriter(rw http.ResponseWriter, r *http.Request) *snappyResponseWriter {
var s *snappy.Writer
// Set the necessary `Vary` header
rw.Header().Set("Vary", "Accept-Encoding")
// Disable caching of responses.
rw.Header().Set("Cache-control", "no-cache")
var writer io.Writer
switch r.Header.Get("Accept-Encoding") {
case "snappy":
rw.Header().Set("Content-Encoding", "snappy")
// Try to get a snappy.Writer from the pool
if is := snappyWriterPool.Get(); is != nil {
s = is.(*snappy.Writer)
s.Reset(rw)
} else {
// Creates a new one if the pool is empty
s = snappy.NewWriter(rw)
}
writer = s
default:
// No `Accept-Encoding` header (or unsupported)
// Default to plain-text
writer = rw
}
return &snappyResponseWriter{
snappyWriter: s,
rw: rw,
w: writer,
}
}
func (remote RemoteSnapshotsLoc) SendSnapshot(snapshot Snapshot, parent Timestamp) (err error) {
var sendCmd *exec.Cmd
if parent == "" {
if verbosity > 1 {
log.Println("Performing full send/receive")
}
sendCmd = exec.Command(btrfsBin, "send", snapshot.Path())
} else {
if verbosity > 1 {
log.Println("Performing incremental send/receive")
}
parentPath := path.Join(path.Dir(snapshot.Path()), string(parent))
sendCmd = exec.Command(btrfsBin, "send", "-p", parentPath, snapshot.Path())
}
if verbosity > 1 {
sendCmd.Stderr = os.Stderr
}
sendRd, sendWr := io.Pipe()
defer sendRd.Close()
var recvRunner CmdRunner
var compOut *snappy.Writer
closeComp := false
if remote.Host == "" {
sendCmd.Stdout = sendWr
recvRunner = remote.SnapshotsLoc.ReceiveAndCleanUp(sendRd, snapshot.timestamp)
} else {
if *noCompressionFlag {
sendCmd.Stdout = sendWr
recvRunner = remote.RemoteReceive(sendRd, snapshot.timestamp)
} else {
compOut = snappy.NewBufferedWriter(sendWr)
closeComp = true
sendCmd.Stdout = compOut
recvRunner = remote.RemoteReceive(sendRd, snapshot.timestamp)
}
}
sendRunner := RunCommand(sendCmd)
err = <-recvRunner.Started
if err != nil {
log.Println("Error starting btrfs receive")
return
}
if verbosity > 1 {
printCommand(sendCmd)
}
err = <-sendRunner.Started
if err != nil {
log.Println("Error starting btrfs send")
return
}
select {
case err = <-sendRunner.Done:
if err != nil {
log.Println("Error running btrfs send")
}
if closeComp {
compOut.Close()
}
sendWr.Close()
<-recvRunner.Done
return
case err = <-recvRunner.Done:
if err != nil {
log.Println("Error running btrfs receive")
}
sendRunner.Signal <- os.Kill
<-sendRunner.Done
return
}
}