/
connection.go
231 lines (185 loc) · 5.13 KB
/
connection.go
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package kafka
import (
"bufio"
"fmt"
"hash/crc32"
"io"
"log"
"net"
)
type SimpleConsumer struct {
conn net.Conn
rw *bufio.ReadWriter
responseQueue chan responseJob
}
const defaultQueueSize = 128
func Dial(addr string) (c *SimpleConsumer, err error) {
conn, err := net.Dial("tcp", addr)
if err != nil {
return nil, err
}
respQueue := make(chan responseJob, defaultQueueSize)
rw := bufio.NewReadWriter(bufio.NewReader(conn), bufio.NewWriter(conn))
c = &SimpleConsumer{
conn: conn,
rw: rw,
responseQueue: respQueue,
}
go c.readWorker()
return c, nil
}
// We are going to reuse the buffers for fetch and multifetch, so don't keep the slices around
// This will yield one per message and close when it's done
func (c *SimpleConsumer) MultiFetch(req MultiFetchRequest) (results FetchResponseChan, err error) {
resp := make(FetchResponseChan)
c.responseQueue <- &multiFetchResponseJob{
ch: resp,
mfr: req,
}
if _, err = c.writeRequest(req); err != nil {
panic(err)
return nil, err
}
results = resp
return
}
// We are going to reuse the buffers for fetch and multifetch, so don't keep the slices around
func (c *SimpleConsumer) Fetch(req FetchRequest) (results FetchResponseChan, err error) {
resp := make(FetchResponseChan)
c.responseQueue <- &fetchResponseJob{
ch: resp,
TopicPartitionOffset: req.TopicPartitionOffset,
}
if _, err = c.writeRequest(&req); err != nil {
return nil, err
}
results = resp
return
}
// We are going to reuse the buffers for fetch and multifetch, so don't keep the slices around
func (c *SimpleConsumer) Offsets(req OffsetsRequest) (results OffsetsResponseChan, err error) {
resp := make(OffsetsResponseChan)
c.responseQueue <- &offsetsResponseJob{
TopicPartition: req.TopicPartition,
ch: resp,
}
if _, err = c.writeRequest(&req); err != nil {
return nil, err
}
results = resp
return
}
func (c *SimpleConsumer) MultiProduce(req MultiProduceRequest) (err error) {
_, err = c.writeRequest(req)
return
}
func (c *SimpleConsumer) Produce(req *ProduceRequest) (err error) {
_, err = c.writeRequest(req)
return
}
func (c *SimpleConsumer) writeRequest(req request) (n int64, err error) {
totalLen := int32(req.Len() + 2) // req, type
if n, err = binwrite(c.rw, totalLen, req.Type()); err != nil {
return -1, err
}
var nn int64
if nn, err = req.WriteTo(c.rw); err != nil {
return -1, err
}
n += nn
if n != int64(totalLen)+4 {
log.Panicln("Did not compute length properly. expected to write", totalLen+4, "but wrote", n)
}
err = c.rw.Flush()
return
}
// This will increment rc's offset
func (c *SimpleConsumer) readMessagesSet(info TopicPartitionOffset, ch FetchResponseChan, messageStream io.Reader) (err error) {
var compression CompressionType
var length int32
var checksum uint32
var magic MagicType
for {
switch err = binread(messageStream, &length); err {
case nil:
case io.EOF:
return nil
default:
return
}
payloadLen := length - messageHeaderSize
// TODO: reuse these. it's not that hard
message := make(Message, payloadLen)
switch err = binread(messageStream, &magic, &compression, &checksum, message); {
case err != nil:
return err
case compression != CompressionTypeNone:
return fmt.Errorf("Only support none compression")
case magic != MagicTypeWithCompression:
return fmt.Errorf("Only support new message format (with magic type of 1)")
case crc32.ChecksumIEEE(message) != checksum:
return fmt.Errorf("Got invalid checksum")
}
info.Offset += Offset(length + 4)
// If we made it here, we have a valid message
ch <- FetchResponse{
Message: message,
TopicPartitionOffset: info,
}
}
return
}
// reads stream and processes puts the response into pr's channel
func (c *SimpleConsumer) failResponses(err error) {
for rc := range c.responseQueue {
rc.Fail(err)
}
}
func (c *SimpleConsumer) doRead() (err error) {
var responseLength int32
var code ErrorCode
if err = binread(c.rw, &responseLength); err != nil {
return
}
remainingResponse := io.LimitReader(c.rw, int64(responseLength))
if err = binread(remainingResponse, &code); err != nil {
return
}
// if the fetch request we sent has an error code, we only fail this one channel
if code != ErrorCodeNoError {
return code
}
var j responseJob
// Just to check for error states
// We should never get response without knowing it
// Also if we're idle, we want to read in case the stream got closed
select {
case j = <-c.responseQueue:
default:
log.Panicln("We received bytes without expecting them")
}
if err = j.ReadResponse(remainingResponse, c); err != nil {
j.Fail(err)
return
} else {
j.Close()
}
// Sanity check to make sure we implemented the protocol correctly
if remainingResponse.(*io.LimitedReader).N != 0 {
log.Panicln(
"Did not read eniter message. we have",
remainingResponse.(*io.LimitedReader).N,
"remaining bytes")
}
return
}
func (c *SimpleConsumer) readWorker() {
defer log.Println("Read worker finishing")
for {
err := c.doRead()
if err != nil {
log.Println("Connection closed with error:", err)
return
}
}
}