123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189 |
- // 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
- }
|