func realHandleGet(cmd common.GetRequest, dataOut chan common.GetResponse, errorOut chan error, rw *bufio.ReadWriter) {
// read index
// make buf
// for numChunks do
// read chunk directly into buffer
// send response
defer close(errorOut)
defer close(dataOut)
outer:
for idx, key := range cmd.Keys {
missResponse := common.GetResponse{
Miss: true,
Quiet: cmd.Quiet[idx],
Opaque: cmd.Opaques[idx],
Flags: 0,
Key: key,
Data: nil,
}
_, metaData, err := getMetadata(rw, key)
if err != nil {
if err == common.ErrKeyNotFound {
metrics.IncCounter(MetricCmdGetMissesMeta)
dataOut <- missResponse
continue outer
}
errorOut <- err
return
}
missResponse.Flags = metaData.OrigFlags
cmdSize := int(metaData.NumChunks)*(len(key)+4 /* key suffix */ +binprot.ReqHeaderLen) + binprot.ReqHeaderLen /* for the noop */
cmdbuf := bytes.NewBuffer(make([]byte, 0, cmdSize))
// Write all the get commands before reading
for i := 0; i < int(metaData.NumChunks); i++ {
chunkKey := chunkKey(key, i)
// bytes.Buffer doesn't error
binprot.WriteGetQCmd(cmdbuf, chunkKey)
}
// The final command must be Get or Noop to guarantee a response
// We use Noop to make coding easier, but it's (very) slightly less efficient
// since we send 24 extra bytes in each direction
// bytes.Buffer doesn't error
binprot.WriteNoopCmd(cmdbuf)
// bufio's ReadFrom will end up doing an io.Copy(cmdbuf, socket), which is more
// efficient than writing directly into the bufio or using cmdbuf.WriteTo(rw)
if _, err := rw.ReadFrom(cmdbuf); err != nil {
errorOut <- err
return
}
// Flush to make sure all the get commands are sent to the server.
if err := rw.Flush(); err != nil {
errorOut <- err
return
}
dataBuf := make([]byte, metaData.Length)
tokenBuf := make([]byte, tokenSize)
// Now that all the headers are sent, start reading in the data chunks. We read until the
// header for the Noop command comes back, keeping track of how many chunks are read. This
// means that there is no fast fail when a chunk is missing, but at least all the data is
// read in so there's no problem with unread, buffered data that should have been discarded.
// If the number of chunks doesn't match, we throw away the data and call it a miss.
chunk := 0
miss := false
var lastErr error
for {
opcodeNoop, err := getLocalIntoBuf(rw.Reader, metaData, tokenBuf, dataBuf, chunk, int(metaData.ChunkSize))
if err != nil {
if err == common.ErrKeyNotFound {
if !miss {
metrics.IncCounter(MetricCmdGetMissesChunk)
miss = true
}
continue
} else {
lastErr = err
}
}
if opcodeNoop {
break
}
if !bytes.Equal(metaData.Token[:], tokenBuf) {
//fmt.Println(id, "Get miss because of invalid chunk token. Cmd:", cmd)
//fmt.Printf("Expected: %v\n", metaData.Token)
//fmt.Printf("Got: %v\n", tokenBuf)
if !miss {
metrics.IncCounter(MetricCmdGetMissesToken)
miss = true
}
}
chunk++
}
if lastErr != nil {
errorOut <- lastErr
return
}
if miss {
//fmt.Println("Get miss because of missing chunk")
dataOut <- missResponse
continue outer
}
dataOut <- common.GetResponse{
Miss: false,
Quiet: cmd.Quiet[idx],
Opaque: cmd.Opaques[idx],
Flags: metaData.OrigFlags,
Key: key,
Data: dataBuf,
}
}
}