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agent.go
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agent.go
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// Copyright 2018, OpenCensus 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 jaeger
import (
"fmt"
"io"
"net"
"git.apache.org/thrift.git/lib/go/thrift"
gen "go.opencensus.io/exporter/jaeger/internal/gen-go/jaeger"
)
// udpPacketMaxLength is the max size of UDP packet we want to send, synced with jaeger-agent
const udpPacketMaxLength = 65000
// agentClientUDP is a UDP client to Jaeger agent that implements gen.Agent interface.
type agentClientUDP struct {
gen.Agent
io.Closer
connUDP *net.UDPConn
client *gen.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
}
thriftBuffer := thrift.NewTMemoryBufferLen(maxPacketSize)
protocolFactory := thrift.NewTCompactProtocolFactory()
client := gen.NewAgentClientFactory(thriftBuffer, protocolFactory)
destAddr, err := net.ResolveUDPAddr("udp", hostPort)
if 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{
connUDP: connUDP,
client: client,
maxPacketSize: maxPacketSize,
thriftBuffer: thriftBuffer}
return clientUDP, nil
}
// EmitBatch implements EmitBatch() of Agent interface
func (a *agentClientUDP) EmitBatch(batch *gen.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 {
return err
}
if a.thriftBuffer.Len() > a.maxPacketSize {
return fmt.Errorf("Data does not fit within one UDP packet; size %d, max %d, spans %d",
a.thriftBuffer.Len(), a.maxPacketSize, len(batch.Spans))
}
_, err := a.connUDP.Write(a.thriftBuffer.Bytes())
return err
}
// Close implements Close() of io.Closer and closes the underlying UDP connection.
func (a *agentClientUDP) Close() error {
return a.connUDP.Close()
}