1 files changed, 189 insertions, 0 deletions
diff --git a/vendor/github.com/uber/jaeger-client-go/utils/reconnecting_udp_conn.go b/vendor/github.com/uber/jaeger-client-go/utils/reconnecting_udp_conn.go
new file mode 100644
index 000000000..0dffc7fa2
--- /dev/null
+++ b/vendor/github.com/uber/jaeger-client-go/utils/reconnecting_udp_conn.go
@@ -0,0 +1,189 @@
+// Copyright (c) 2020 The Jaeger Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package utils
+
+import (
+	"fmt"
+	"net"
+	"sync"
+	"sync/atomic"
+	"time"
+
+	"github.com/uber/jaeger-client-go/log"
+)
+
+// reconnectingUDPConn is an implementation of udpConn that resolves hostPort every resolveTimeout, if the resolved address is
+// different than the current conn then the new address is dialed and the conn is swapped.
+type reconnectingUDPConn struct {
+	hostPort    string
+	resolveFunc resolveFunc
+	dialFunc    dialFunc
+	logger      log.Logger
+	bufferBytes int64
+
+	connMtx   sync.RWMutex
+	conn      *net.UDPConn
+	destAddr  *net.UDPAddr
+	closeChan chan struct{}
+}
+
+type resolveFunc func(network string, hostPort string) (*net.UDPAddr, error)
+type dialFunc func(network string, laddr, raddr *net.UDPAddr) (*net.UDPConn, error)
+
+// newReconnectingUDPConn returns a new udpConn that resolves hostPort every resolveTimeout, if the resolved address is
+// different than the current conn then the new address is dialed and the conn is swapped.
+func newReconnectingUDPConn(hostPort string, resolveTimeout time.Duration, resolveFunc resolveFunc, dialFunc dialFunc, logger log.Logger) (*reconnectingUDPConn, error) {
+	conn := &reconnectingUDPConn{
+		hostPort:    hostPort,
+		resolveFunc: resolveFunc,
+		dialFunc:    dialFunc,
+		logger:      logger,
+		closeChan:   make(chan struct{}),
+	}
+
+	if err := conn.attemptResolveAndDial(); err != nil {
+		logger.Error(fmt.Sprintf("failed resolving destination address on connection startup, with err: %q. retrying in %s", err.Error(), resolveTimeout))
+	}
+
+	go conn.reconnectLoop(resolveTimeout)
+
+	return conn, nil
+}
+
+func (c *reconnectingUDPConn) reconnectLoop(resolveTimeout time.Duration) {
+	ticker := time.NewTicker(resolveTimeout)
+	defer ticker.Stop()
+
+	for {
+		select {
+		case <-c.closeChan:
+			return
+		case <-ticker.C:
+			if err := c.attemptResolveAndDial(); err != nil {
+				c.logger.Error(err.Error())
+			}
+		}
+	}
+}
+
+func (c *reconnectingUDPConn) attemptResolveAndDial() error {
+	newAddr, err := c.resolveFunc("udp", c.hostPort)
+	if err != nil {
+		return fmt.Errorf("failed to resolve new addr for host %q, with err: %w", c.hostPort, err)
+	}
+
+	c.connMtx.RLock()
+	curAddr := c.destAddr
+	c.connMtx.RUnlock()
+
+	// dont attempt dial if an addr was successfully dialed previously and, resolved addr is the same as current conn
+	if curAddr != nil && newAddr.String() == curAddr.String() {
+		return nil
+	}
+
+	if err := c.attemptDialNewAddr(newAddr); err != nil {
+		return fmt.Errorf("failed to dial newly resolved addr '%s', with err: %w", newAddr, err)
+	}
+
+	return nil
+}
+
+func (c *reconnectingUDPConn) attemptDialNewAddr(newAddr *net.UDPAddr) error {
+	connUDP, err := c.dialFunc(newAddr.Network(), nil, newAddr)
+	if err != nil {
+		return err
+	}
+
+	if bufferBytes := int(atomic.LoadInt64(&c.bufferBytes)); bufferBytes != 0 {
+		if err = connUDP.SetWriteBuffer(bufferBytes); err != nil {
+			return err
+		}
+	}
+
+	c.connMtx.Lock()
+	c.destAddr = newAddr
+	// store prev to close later
+	prevConn := c.conn
+	c.conn = connUDP
+	c.connMtx.Unlock()
+
+	if prevConn != nil {
+		return prevConn.Close()
+	}
+
+	return nil
+}
+
+// Write calls net.udpConn.Write, if it fails an attempt is made to connect to a new addr, if that succeeds the write is retried before returning
+func (c *reconnectingUDPConn) Write(b []byte) (int, error) {
+	var bytesWritten int
+	var err error
+
+	c.connMtx.RLock()
+	if c.conn == nil {
+		// if connection is not initialized indicate this with err in order to hook into retry logic
+		err = fmt.Errorf("UDP connection not yet initialized, an address has not been resolved")
+	} else {
+		bytesWritten, err = c.conn.Write(b)
+	}
+	c.connMtx.RUnlock()
+
+	if err == nil {
+		return bytesWritten, nil
+	}
+
+	// attempt to resolve and dial new address in case that's the problem, if resolve and dial succeeds, try write again
+	if reconnErr := c.attemptResolveAndDial(); reconnErr == nil {
+		c.connMtx.RLock()
+		defer c.connMtx.RUnlock()
+		return c.conn.Write(b)
+	}
+
+	// return original error if reconn fails
+	return bytesWritten, err
+}
+
+// Close stops the reconnectLoop, then closes the connection via net.udpConn 's implementation
+func (c *reconnectingUDPConn) Close() error {
+	close(c.closeChan)
+
+	// acquire rw lock before closing conn to ensure calls to Write drain
+	c.connMtx.Lock()
+	defer c.connMtx.Unlock()
+
+	if c.conn != nil {
+		return c.conn.Close()
+	}
+
+	return nil
+}
+
+// SetWriteBuffer defers to the net.udpConn SetWriteBuffer implementation wrapped with a RLock. if no conn is currently held
+// and SetWriteBuffer is called store bufferBytes to be set for new conns
+func (c *reconnectingUDPConn) SetWriteBuffer(bytes int) error {
+	var err error
+
+	c.connMtx.RLock()
+	if c.conn != nil {
+		err = c.conn.SetWriteBuffer(bytes)
+	}
+	c.connMtx.RUnlock()
+
+	if err == nil {
+		atomic.StoreInt64(&c.bufferBytes, int64(bytes))
+	}
+
+	return err
+}