package nsqd
import (
"encoding/binary"
"fmt"
"io"
"net"
"time"
"github.com/nsqio/go-nsq"
)
// lookupPeer is a low-level type for connecting/reading/writing to nsqlookupd
//
// A lookupPeer instance is designed to connect lazily to nsqlookupd and reconnect
// gracefully (i.e. it is all handled by the library). Clients can simply use the
// Command interface to perform a round-trip.
type lookupPeer struct { l Logger
addr string
conn net.Conn
state int32
connectCallback func(*lookupPeer)
maxBodySize int64
Info peerInfo
}
// peerInfo contains metadata for a lookupPeer instance (and is JSON marshalable)
type peerInfo struct { TCPPort int `json:"tcp_port"`
HTTPPort int `json:"http_port"`
Version string `json:"version"`
BroadcastAddress string `json:"broadcast_address"`
}
// newLookupPeer creates a new lookupPeer instance connecting to the supplied address.
//
// The supplied connectCallback will be called *every* time the instance connects.
func newLookupPeer(addr string, maxBodySize int64, l Logger, connectCallback func(*lookupPeer)) *lookupPeer { return &lookupPeer{ l: l,
addr: addr,
state: stateDisconnected,
maxBodySize: maxBodySize,
connectCallback: connectCallback,
}
}
// Connect will Dial the specified address, with timeouts
func (lp *lookupPeer) Connect() error { lp.l.Output(2, fmt.Sprintf("LOOKUP connecting to %s", lp.addr)) conn, err := net.DialTimeout("tcp", lp.addr, time.Second) if err != nil { return err
}
lp.conn = conn
return nil
}
// String returns the specified address
func (lp *lookupPeer) String() string { return lp.addr
}
// Read implements the io.Reader interface, adding deadlines
func (lp *lookupPeer) Read(data []byte) (int, error) { lp.conn.SetReadDeadline(time.Now().Add(time.Second))
return lp.conn.Read(data)
}
// Write implements the io.Writer interface, adding deadlines
func (lp *lookupPeer) Write(data []byte) (int, error) { lp.conn.SetWriteDeadline(time.Now().Add(time.Second))
return lp.conn.Write(data)
}
// Close implements the io.Closer interface
func (lp *lookupPeer) Close() error { lp.state = stateDisconnected
if lp.conn != nil { return lp.conn.Close()
}
return nil
}
// Command performs a round-trip for the specified Command.
//
// It will lazily connect to nsqlookupd and gracefully handle
// reconnecting in the event of a failure.
//
// It returns the response from nsqlookupd as []byte
func (lp *lookupPeer) Command(cmd *nsq.Command) ([]byte, error) { initialState := lp.state
if lp.state != stateConnected { err := lp.Connect()
if err != nil { return nil, err
}
lp.state = stateConnected
lp.Write(nsq.MagicV1)
if initialState == stateDisconnected { lp.connectCallback(lp)
}
}
if cmd == nil { return nil, nil
}
_, err := cmd.WriteTo(lp)
if err != nil { lp.Close()
return nil, err
}
resp, err := readResponseBounded(lp, lp.maxBodySize)
if err != nil { lp.Close()
return nil, err
}
return resp, nil
}
func readResponseBounded(r io.Reader, limit int64) ([]byte, error) { var msgSize int32
// message size
err := binary.Read(r, binary.BigEndian, &msgSize)
if err != nil { return nil, err
}
if int64(msgSize) > limit { return nil, fmt.Errorf("response body size (%d) is greater than limit (%d)", msgSize, limit)
}
// message binary data
buf := make([]byte, msgSize)
_, err = io.ReadFull(r, buf)
if err != nil { return nil, err
}
return buf, nil
}