forked from optiopay/kafka
/
connection.go
325 lines (294 loc) · 7.77 KB
/
connection.go
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package kafka
import (
"bufio"
"bytes"
"errors"
"fmt"
"io"
"log"
"math"
"net"
"sync"
"time"
"github.com/optiopay/kafka/proto"
)
// ErrClosed is returned as result of any request made using closed connection.
var ErrClosed = errors.New("closed")
// Low level abstraction over connection to Kafka.
type connection struct {
rw io.ReadWriteCloser
stop chan struct{}
nextID chan int32
mu sync.Mutex
respc map[int32]chan []byte
stopErr error
}
// newConnection returns new, initialized connection or error
func newTCPConnection(address string, timeout time.Duration) (*connection, error) {
conn, err := net.DialTimeout("tcp", address, timeout)
if err != nil {
return nil, err
}
c := &connection{
stop: make(chan struct{}),
nextID: make(chan int32),
rw: conn,
respc: make(map[int32]chan []byte),
}
go c.nextIDLoop()
go c.readRespLoop()
return c, nil
}
// nextIDLoop generates correlation IDs, making sure they are always in order
// and within the scope of request-response mapping array.
func (c *connection) nextIDLoop() {
var id int32 = 1
for {
select {
case <-c.stop:
close(c.nextID)
return
case c.nextID <- id:
id++
if id == math.MaxInt32 {
id = 1
}
}
}
}
// readRespLoop constantly reading response messages from the socket and after
// partial parsing, sends byte representation of the whole message to request
// sending process.
func (c *connection) readRespLoop() {
defer func() {
c.mu.Lock()
for _, cc := range c.respc {
close(cc)
}
c.respc = make(map[int32]chan []byte)
c.mu.Unlock()
}()
rd := bufio.NewReader(c.rw)
for {
correlationID, b, err := proto.ReadResp(rd)
if err != nil {
c.mu.Lock()
if c.stopErr == nil {
c.stopErr = err
close(c.stop)
}
c.mu.Unlock()
return
}
c.mu.Lock()
rc, ok := c.respc[correlationID]
delete(c.respc, correlationID)
c.mu.Unlock()
if !ok {
log.Printf("response to unknown request: %d", correlationID)
continue
}
select {
case <-c.stop:
c.mu.Lock()
if c.stopErr == nil {
c.stopErr = ErrClosed
}
c.mu.Unlock()
case rc <- b:
}
close(rc)
}
}
// respWaiter register listener to response message with given correlationID
// and return channel that single response message will be pushed to once it
// will arrive.
// After pushing response message, channel is closed.
//
// Upon connection close, all unconsumed channels are closed.
func (c *connection) respWaiter(correlationID int32) (respc chan []byte, err error) {
c.mu.Lock()
defer c.mu.Unlock()
if c.stopErr != nil {
return nil, c.stopErr
}
if _, ok := c.respc[correlationID]; ok {
return nil, fmt.Errorf("correlation conflict: %d", correlationID)
}
respc = make(chan []byte)
c.respc[correlationID] = respc
return respc, nil
}
// releaseWaiter removes response channel from waiters pool and close it.
// Calling this method for unknown correlationID has no effect.
func (c *connection) releaseWaiter(correlationID int32) {
c.mu.Lock()
rc, ok := c.respc[correlationID]
if ok {
delete(c.respc, correlationID)
close(rc)
}
c.mu.Unlock()
}
// Close close underlying transport connection and cancel all pending response
// waiters.
func (c *connection) Close() error {
c.mu.Lock()
if c.stopErr == nil {
c.stopErr = ErrClosed
close(c.stop)
}
c.mu.Unlock()
return c.rw.Close()
}
// Metadata sends given metadata request to kafka node and returns related
// metadata response.
// Calling this method on closed connection will always return ErrClosed.
func (c *connection) Metadata(req *proto.MetadataReq) (*proto.MetadataResp, error) {
var ok bool
if req.CorrelationID, ok = <-c.nextID; !ok {
return nil, c.stopErr
}
respc, err := c.respWaiter(req.CorrelationID)
if err != nil {
return nil, fmt.Errorf("wait for response: %s", err)
}
if _, err := req.WriteTo(c.rw); err != nil {
c.releaseWaiter(req.CorrelationID)
return nil, err
}
b, ok := <-respc
if !ok {
return nil, c.stopErr
}
return proto.ReadMetadataResp(bytes.NewReader(b))
}
// Produce sends given produce request to kafka node and returns related
// response. Sending request with no ACKs flag will result with returning nil
// right after sending request, without waiting for response.
// Calling this method on closed connection will always return ErrClosed.
func (c *connection) Produce(req *proto.ProduceReq) (*proto.ProduceResp, error) {
var ok bool
if req.CorrelationID, ok = <-c.nextID; !ok {
return nil, c.stopErr
}
if req.RequiredAcks == proto.RequiredAcksNone {
_, err := req.WriteTo(c.rw)
return nil, err
}
respc, err := c.respWaiter(req.CorrelationID)
if err != nil {
return nil, fmt.Errorf("wait for response: %s", err)
}
if _, err := req.WriteTo(c.rw); err != nil {
c.releaseWaiter(req.CorrelationID)
return nil, err
}
b, ok := <-respc
if !ok {
return nil, c.stopErr
}
return proto.ReadProduceResp(bytes.NewReader(b))
}
// Fetch sends given fetch request to kafka node and returns related response.
// Calling this method on closed connection will always return ErrClosed.
func (c *connection) Fetch(req *proto.FetchReq) (*proto.FetchResp, error) {
var ok bool
if req.CorrelationID, ok = <-c.nextID; !ok {
return nil, c.stopErr
}
respc, err := c.respWaiter(req.CorrelationID)
if err != nil {
return nil, fmt.Errorf("wait for response: %s", err)
}
if _, err := req.WriteTo(c.rw); err != nil {
c.releaseWaiter(req.CorrelationID)
return nil, err
}
b, ok := <-respc
if !ok {
return nil, c.stopErr
}
return proto.ReadFetchResp(bytes.NewReader(b))
}
// Offset sends given offset request to kafka node and returns related response.
// Calling this method on closed connection will always return ErrClosed.
func (c *connection) Offset(req *proto.OffsetReq) (*proto.OffsetResp, error) {
var ok bool
if req.CorrelationID, ok = <-c.nextID; !ok {
return nil, c.stopErr
}
respc, err := c.respWaiter(req.CorrelationID)
if err != nil {
return nil, fmt.Errorf("wait for response: %s", err)
}
// TODO(husio) documentation is not mentioning this directly, but I assume
// -1 is for non node clients
req.ReplicaID = -1
if _, err := req.WriteTo(c.rw); err != nil {
c.releaseWaiter(req.CorrelationID)
return nil, err
}
b, ok := <-respc
if !ok {
return nil, c.stopErr
}
return proto.ReadOffsetResp(bytes.NewReader(b))
}
func (c *connection) ConsumerMetadata(req *proto.ConsumerMetadataReq) (*proto.ConsumerMetadataResp, error) {
var ok bool
if req.CorrelationID, ok = <-c.nextID; !ok {
return nil, c.stopErr
}
respc, err := c.respWaiter(req.CorrelationID)
if err != nil {
return nil, fmt.Errorf("wait for response: %s", err)
}
if _, err := req.WriteTo(c.rw); err != nil {
c.releaseWaiter(req.CorrelationID)
return nil, err
}
b, ok := <-respc
if !ok {
return nil, c.stopErr
}
return proto.ReadConsumerMetadataResp(bytes.NewReader(b))
}
func (c *connection) OffsetCommit(req *proto.OffsetCommitReq) (*proto.OffsetCommitResp, error) {
var ok bool
if req.CorrelationID, ok = <-c.nextID; !ok {
return nil, c.stopErr
}
respc, err := c.respWaiter(req.CorrelationID)
if err != nil {
return nil, fmt.Errorf("wait for response: %s", err)
}
if _, err := req.WriteTo(c.rw); err != nil {
c.releaseWaiter(req.CorrelationID)
return nil, err
}
b, ok := <-respc
if !ok {
return nil, c.stopErr
}
return proto.ReadOffsetCommitResp(bytes.NewReader(b))
}
func (c *connection) OffsetFetch(req *proto.OffsetFetchReq) (*proto.OffsetFetchResp, error) {
var ok bool
if req.CorrelationID, ok = <-c.nextID; !ok {
return nil, c.stopErr
}
respc, err := c.respWaiter(req.CorrelationID)
if err != nil {
return nil, fmt.Errorf("wait for response: %s", err)
}
if _, err := req.WriteTo(c.rw); err != nil {
c.releaseWaiter(req.CorrelationID)
return nil, err
}
b, ok := <-respc
if !ok {
return nil, c.stopErr
}
return proto.ReadOffsetFetchResp(bytes.NewReader(b))
}