forked from IBM/sarama
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broker.go
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broker.go
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package sarama
import (
"fmt"
"io"
"net"
"strconv"
"sync"
)
// Broker represents a single Kafka broker connection. All operations on this object are entirely concurrency-safe.
type Broker struct {
id int32
addr string
correlationID int32
conn net.Conn
connErr error
lock sync.Mutex
responses chan responsePromise
done chan bool
}
type responsePromise struct {
correlationID int32
packets chan []byte
errors chan error
}
// NewBroker creates and returns a Broker targetting the given host:port address.
// This does not attempt to actually connect, you have to call Open() for that.
func NewBroker(addr string) *Broker {
return &Broker{id: -1, addr: addr}
}
// Open tries to connect to the Broker. It takes the broker lock synchronously, then spawns a goroutine which
// connects and releases the lock. This means any subsequent operations on the broker will block waiting for
// the connection to finish. To get the effect of a fully synchronous Open call, follow it by a call to Connected().
// The only error Open will return directly is AlreadyConnected. The maxOpenRequests parameter determines how many
// requests can be issued concurrently before future requests block. You generally will want at least one for each
// topic-partition the broker will be interacting with concurrently.
func (b *Broker) Open(maxOpenRequests int) error {
b.lock.Lock()
if b.conn != nil {
b.lock.Unlock()
Logger.Printf("Failed to connect to broker %s\n", b.addr)
Logger.Println(AlreadyConnected)
return AlreadyConnected
}
go withRecover(func() {
defer b.lock.Unlock()
b.conn, b.connErr = net.Dial("tcp", b.addr)
if b.connErr != nil {
Logger.Printf("Failed to connect to broker %s\n", b.addr)
Logger.Println(b.connErr)
return
}
b.done = make(chan bool)
// permit a few outstanding requests before we block waiting for responses
b.responses = make(chan responsePromise, maxOpenRequests)
Logger.Printf("Connected to broker %s\n", b.addr)
go withRecover(b.responseReceiver)
})
return nil
}
// Connected returns true if the broker is connected and false otherwise. If the broker is not
// connected but it had tried to connect, the error from that connection attempt is also returned.
func (b *Broker) Connected() (bool, error) {
b.lock.Lock()
defer b.lock.Unlock()
return b.conn != nil, b.connErr
}
func (b *Broker) Close() (err error) {
b.lock.Lock()
defer b.lock.Unlock()
defer func() {
if err == nil {
Logger.Printf("Closed connection to broker %s\n", b.addr)
} else {
Logger.Printf("Failed to close connection to broker %s.\n", b.addr)
Logger.Println(err)
}
}()
if b.conn == nil {
return NotConnected
}
close(b.responses)
<-b.done
err = b.conn.Close()
b.conn = nil
b.connErr = nil
b.done = nil
b.responses = nil
return
}
// ID returns the broker ID retrieved from Kafka's metadata, or -1 if that is not known.
func (b *Broker) ID() int32 {
return b.id
}
// Addr returns the broker address as either retrieved from Kafka's metadata or passed to NewBroker.
func (b *Broker) Addr() string {
return b.addr
}
func (b *Broker) GetMetadata(clientID string, request *MetadataRequest) (*MetadataResponse, error) {
response := new(MetadataResponse)
err := b.sendAndReceive(clientID, request, response)
if err != nil {
return nil, err
}
return response, nil
}
func (b *Broker) GetConsumerMetadata(clientID string, request *ConsumerMetadataRequest) (*ConsumerMetadataResponse, error) {
response := new(ConsumerMetadataResponse)
err := b.sendAndReceive(clientID, request, response)
if err != nil {
return nil, err
}
return response, nil
}
func (b *Broker) GetAvailableOffsets(clientID string, request *OffsetRequest) (*OffsetResponse, error) {
response := new(OffsetResponse)
err := b.sendAndReceive(clientID, request, response)
if err != nil {
return nil, err
}
return response, nil
}
func (b *Broker) Produce(clientID string, request *ProduceRequest) (*ProduceResponse, error) {
var response *ProduceResponse
var err error
if request.RequiredAcks == NoResponse {
err = b.sendAndReceive(clientID, request, nil)
} else {
response = new(ProduceResponse)
err = b.sendAndReceive(clientID, request, response)
}
if err != nil {
return nil, err
}
return response, nil
}
func (b *Broker) Fetch(clientID string, request *FetchRequest) (*FetchResponse, error) {
response := new(FetchResponse)
err := b.sendAndReceive(clientID, request, response)
if err != nil {
return nil, err
}
return response, nil
}
func (b *Broker) CommitOffset(clientID string, request *OffsetCommitRequest) (*OffsetCommitResponse, error) {
response := new(OffsetCommitResponse)
err := b.sendAndReceive(clientID, request, response)
if err != nil {
return nil, err
}
return response, nil
}
func (b *Broker) FetchOffset(clientID string, request *OffsetFetchRequest) (*OffsetFetchResponse, error) {
response := new(OffsetFetchResponse)
err := b.sendAndReceive(clientID, request, response)
if err != nil {
return nil, err
}
return response, nil
}
func (b *Broker) send(clientID string, req requestEncoder, promiseResponse bool) (*responsePromise, error) {
b.lock.Lock()
defer b.lock.Unlock()
if b.conn == nil {
if b.connErr != nil {
return nil, b.connErr
}
return nil, NotConnected
}
fullRequest := request{b.correlationID, clientID, req}
buf, err := encode(&fullRequest)
if err != nil {
return nil, err
}
_, err = b.conn.Write(buf)
if err != nil {
return nil, err
}
b.correlationID++
if !promiseResponse {
return nil, nil
}
promise := responsePromise{fullRequest.correlationID, make(chan []byte), make(chan error)}
b.responses <- promise
return &promise, nil
}
func (b *Broker) sendAndReceive(clientID string, req requestEncoder, res decoder) error {
promise, err := b.send(clientID, req, res != nil)
if err != nil {
return err
}
if promise == nil {
return nil
}
select {
case buf := <-promise.packets:
return decode(buf, res)
case err = <-promise.errors:
return err
}
}
func (b *Broker) decode(pd packetDecoder) (err error) {
b.id, err = pd.getInt32()
if err != nil {
return err
}
host, err := pd.getString()
if err != nil {
return err
}
port, err := pd.getInt32()
if err != nil {
return err
}
b.addr = fmt.Sprint(host, ":", port)
return nil
}
func (b *Broker) encode(pe packetEncoder) (err error) {
host, portstr, err := net.SplitHostPort(b.addr)
if err != nil {
return err
}
port, err := strconv.Atoi(portstr)
if err != nil {
return err
}
pe.putInt32(b.id)
err = pe.putString(host)
if err != nil {
return err
}
pe.putInt32(int32(port))
return nil
}
func (b *Broker) responseReceiver() {
header := make([]byte, 8)
for response := range b.responses {
_, err := io.ReadFull(b.conn, header)
if err != nil {
response.errors <- err
continue
}
decodedHeader := responseHeader{}
err = decode(header, &decodedHeader)
if err != nil {
response.errors <- err
continue
}
if decodedHeader.correlationID != response.correlationID {
response.errors <- DecodingError{Info: "CorrelationID didn't match"}
continue
}
buf := make([]byte, decodedHeader.length-4)
_, err = io.ReadFull(b.conn, buf)
if err != nil {
response.errors <- err
continue
}
response.packets <- buf
}
close(b.done)
}