[VOL-4291] Rw-core updates for gRPC migration

Change-Id: I8d5a554409115b29318089671ca4e1ab3fa98810
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 0000000..0dffc7f
--- /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
+}
diff --git a/vendor/github.com/uber/jaeger-client-go/utils/udp_client.go b/vendor/github.com/uber/jaeger-client-go/utils/udp_client.go
index fadd73e..4c59ae9 100644
--- a/vendor/github.com/uber/jaeger-client-go/utils/udp_client.go
+++ b/vendor/github.com/uber/jaeger-client-go/utils/udp_client.go
@@ -15,11 +15,14 @@
 package utils
 
 import (
+	"context"
 	"errors"
 	"fmt"
 	"io"
 	"net"
+	"time"
 
+	"github.com/uber/jaeger-client-go/log"
 	"github.com/uber/jaeger-client-go/thrift"
 
 	"github.com/uber/jaeger-client-go/thrift-gen/agent"
@@ -35,53 +38,101 @@
 	agent.Agent
 	io.Closer
 
-	connUDP       *net.UDPConn
+	connUDP       udpConn
 	client        *agent.AgentClient
 	maxPacketSize int                   // max size of datagram in bytes
 	thriftBuffer  *thrift.TMemoryBuffer // buffer used to calculate byte size of a span
 }
 
-// NewAgentClientUDP creates a client that sends spans to Jaeger Agent over UDP.
-func NewAgentClientUDP(hostPort string, maxPacketSize int) (*AgentClientUDP, error) {
-	if maxPacketSize == 0 {
-		maxPacketSize = UDPPacketMaxLength
+type udpConn interface {
+	Write([]byte) (int, error)
+	SetWriteBuffer(int) error
+	Close() error
+}
+
+// AgentClientUDPParams allows specifying options for initializing an AgentClientUDP. An instance of this struct should
+// be passed to NewAgentClientUDPWithParams.
+type AgentClientUDPParams struct {
+	HostPort                   string
+	MaxPacketSize              int
+	Logger                     log.Logger
+	DisableAttemptReconnecting bool
+	AttemptReconnectInterval   time.Duration
+}
+
+// NewAgentClientUDPWithParams creates a client that sends spans to Jaeger Agent over UDP.
+func NewAgentClientUDPWithParams(params AgentClientUDPParams) (*AgentClientUDP, error) {
+	// validate hostport
+	if _, _, err := net.SplitHostPort(params.HostPort); err != nil {
+		return nil, err
 	}
 
-	thriftBuffer := thrift.NewTMemoryBufferLen(maxPacketSize)
+	if params.MaxPacketSize == 0 {
+		params.MaxPacketSize = UDPPacketMaxLength
+	}
+
+	if params.Logger == nil {
+		params.Logger = log.StdLogger
+	}
+
+	if !params.DisableAttemptReconnecting && params.AttemptReconnectInterval == 0 {
+		params.AttemptReconnectInterval = time.Second * 30
+	}
+
+	thriftBuffer := thrift.NewTMemoryBufferLen(params.MaxPacketSize)
 	protocolFactory := thrift.NewTCompactProtocolFactory()
 	client := agent.NewAgentClientFactory(thriftBuffer, protocolFactory)
 
-	destAddr, err := net.ResolveUDPAddr("udp", hostPort)
-	if err != nil {
+	var connUDP udpConn
+	var err error
+
+	if params.DisableAttemptReconnecting {
+		destAddr, err := net.ResolveUDPAddr("udp", params.HostPort)
+		if err != nil {
+			return nil, err
+		}
+
+		connUDP, err = net.DialUDP(destAddr.Network(), nil, destAddr)
+		if err != nil {
+			return nil, err
+		}
+	} else {
+		// host is hostname, setup resolver loop in case host record changes during operation
+		connUDP, err = newReconnectingUDPConn(params.HostPort, params.AttemptReconnectInterval, net.ResolveUDPAddr, net.DialUDP, params.Logger)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	if err := connUDP.SetWriteBuffer(params.MaxPacketSize); err != nil {
 		return nil, err
 	}
 
-	connUDP, err := net.DialUDP(destAddr.Network(), nil, destAddr)
-	if err != nil {
-		return nil, err
-	}
-	if err := connUDP.SetWriteBuffer(maxPacketSize); err != nil {
-		return nil, err
-	}
-
-	clientUDP := &AgentClientUDP{
+	return &AgentClientUDP{
 		connUDP:       connUDP,
 		client:        client,
-		maxPacketSize: maxPacketSize,
-		thriftBuffer:  thriftBuffer}
-	return clientUDP, nil
+		maxPacketSize: params.MaxPacketSize,
+		thriftBuffer:  thriftBuffer,
+	}, nil
+}
+
+// NewAgentClientUDP creates a client that sends spans to Jaeger Agent over UDP.
+func NewAgentClientUDP(hostPort string, maxPacketSize int) (*AgentClientUDP, error) {
+	return NewAgentClientUDPWithParams(AgentClientUDPParams{
+		HostPort:      hostPort,
+		MaxPacketSize: maxPacketSize,
+	})
 }
 
 // EmitZipkinBatch implements EmitZipkinBatch() of Agent interface
-func (a *AgentClientUDP) EmitZipkinBatch(spans []*zipkincore.Span) error {
+func (a *AgentClientUDP) EmitZipkinBatch(context.Context, []*zipkincore.Span) error {
 	return errors.New("Not implemented")
 }
 
 // EmitBatch implements EmitBatch() of Agent interface
-func (a *AgentClientUDP) EmitBatch(batch *jaeger.Batch) error {
+func (a *AgentClientUDP) EmitBatch(ctx context.Context, batch *jaeger.Batch) error {
 	a.thriftBuffer.Reset()
-	a.client.SeqId = 0 // we have no need for distinct SeqIds for our one-way UDP messages
-	if err := a.client.EmitBatch(batch); err != nil {
+	if err := a.client.EmitBatch(ctx, batch); err != nil {
 		return err
 	}
 	if a.thriftBuffer.Len() > a.maxPacketSize {