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package statsd
import (
"net"
"time"
)
/*
UDSTimeout holds the default timeout for UDS socket writes, as they can get
blocking when the receiving buffer is full.
*/
const defaultUDSTimeout = 1 * time.Millisecond
// udsWriter is an internal class wrapping around management of UDS connection
type udsWriter struct {
// Address to send metrics to, needed to allow reconnection on error
addr net.Addr
// Established connection object, or nil if not connected yet
conn net.Conn
// write timeout
writeTimeout time.Duration
}
// New returns a pointer to a new udsWriter given a socket file path as addr.
func newUdsWriter(addr string) (*udsWriter, error) {
udsAddr, err := net.ResolveUnixAddr("unixgram", addr)
if err != nil {
return nil, err
}
// Defer connection to first Write
writer := &udsWriter{addr: udsAddr, conn: nil, writeTimeout: defaultUDSTimeout}
return writer, nil
}
// SetWriteTimeout allows the user to set a custom write timeout
func (w *udsWriter) SetWriteTimeout(d time.Duration) error {
w.writeTimeout = d
return nil
}
// Write data to the UDS connection with write timeout and minimal error handling:
// create the connection if nil, and destroy it if the statsd server has disconnected
func (w *udsWriter) Write(data []byte) (int, error) {
// Try connecting (first packet or connection lost)
if w.conn == nil {
conn, err := net.Dial(w.addr.Network(), w.addr.String())
if err != nil {
return 0, err
}
w.conn = conn
}
w.conn.SetWriteDeadline(time.Now().Add(w.writeTimeout))
n, e := w.conn.Write(data)
if e != nil {
// Statsd server disconnected, retry connecting at next packet
w.conn = nil
return 0, e
}
return n, e
}
func (w *udsWriter) Close() error {
if w.conn != nil {
return w.conn.Close()
}
return nil
}
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