99 lines
2.3 KiB
Go
99 lines
2.3 KiB
Go
package statsd
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import (
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"net"
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"sync"
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"time"
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)
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/*
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UDSTimeout holds the default timeout for UDS socket writes, as they can get
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blocking when the receiving buffer is full.
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*/
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const defaultUDSTimeout = 1 * time.Millisecond
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// udsWriter is an internal class wrapping around management of UDS connection
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type udsWriter struct {
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// Address to send metrics to, needed to allow reconnection on error
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addr net.Addr
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// Established connection object, or nil if not connected yet
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conn net.Conn
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// write timeout
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writeTimeout time.Duration
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sync.RWMutex // used to lock conn / writer can replace it
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}
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// newUDSWriter returns a pointer to a new udsWriter given a socket file path as addr.
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func newUDSWriter(addr string) (*udsWriter, error) {
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udsAddr, err := net.ResolveUnixAddr("unixgram", addr)
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if err != nil {
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return nil, err
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}
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// Defer connection to first Write
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writer := &udsWriter{addr: udsAddr, conn: nil, writeTimeout: defaultUDSTimeout}
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return writer, nil
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}
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// SetWriteTimeout allows the user to set a custom write timeout
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func (w *udsWriter) SetWriteTimeout(d time.Duration) error {
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w.writeTimeout = d
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return nil
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}
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// Write data to the UDS connection with write timeout and minimal error handling:
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// create the connection if nil, and destroy it if the statsd server has disconnected
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func (w *udsWriter) Write(data []byte) (int, error) {
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conn, err := w.ensureConnection()
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if err != nil {
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return 0, err
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}
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conn.SetWriteDeadline(time.Now().Add(w.writeTimeout))
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n, e := conn.Write(data)
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if err, isNetworkErr := e.(net.Error); !isNetworkErr || !err.Temporary() {
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// Statsd server disconnected, retry connecting at next packet
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w.unsetConnection()
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return 0, e
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}
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return n, e
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}
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func (w *udsWriter) Close() error {
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if w.conn != nil {
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return w.conn.Close()
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}
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return nil
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}
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func (w *udsWriter) ensureConnection() (net.Conn, error) {
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// Check if we've already got a socket we can use
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w.RLock()
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currentConn := w.conn
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w.RUnlock()
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if currentConn != nil {
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return currentConn, nil
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}
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// Looks like we might need to connect - try again with write locking.
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w.Lock()
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defer w.Unlock()
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if w.conn != nil {
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return w.conn, nil
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}
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newConn, err := net.Dial(w.addr.Network(), w.addr.String())
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if err != nil {
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return nil, err
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}
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w.conn = newConn
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return newConn, nil
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}
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func (w *udsWriter) unsetConnection() {
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w.Lock()
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defer w.Unlock()
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w.conn = nil
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}
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