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client.go
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client.go
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package amqprpc
import (
"errors"
"net/rpc"
"strconv"
"github.com/streadway/amqp"
)
type codec struct {
conn *amqp.Connection
channel *amqp.Channel
routing string //routing key
codec EncodingCodec
curDelivery amqp.Delivery
message <-chan amqp.Delivery
}
type clientCodec struct {
*codec
serverRouting string //server routing key
}
func (client *clientCodec) WriteRequest(r *rpc.Request, v interface{}) error {
//TODO(vibhavp): Set ContentType, ContentEncoding
body, err := client.codec.codec.Marshal(v)
if err != nil {
return err
}
publishing := amqp.Publishing{
ReplyTo: r.ServiceMethod,
CorrelationId: client.routing,
MessageId: strconv.FormatUint(r.Seq, 10),
Body: body,
}
return client.channel.Publish("", client.serverRouting, false, false, publishing)
}
func (client *clientCodec) ReadResponseHeader(r *rpc.Response) error {
client.curDelivery = <-client.message
var err error
if err = client.curDelivery.Headers.Validate(); err != nil {
return errors.New("error while reading body: " + err.Error())
}
if err, ok := client.curDelivery.Headers["error"]; ok {
errStr, ok := err.(string)
if !ok {
return errors.New("error header not a string")
}
r.Error = errStr
}
r.ServiceMethod = client.curDelivery.ReplyTo
r.Seq, err = strconv.ParseUint(client.curDelivery.MessageId, 10, 64)
if err != nil {
return err
}
return nil
}
func (client *clientCodec) ReadResponseBody(v interface{}) error {
if v == nil {
return nil
}
return client.codec.codec.Unmarshal(client.curDelivery.Body, v)
}
func (client *clientCodec) Close() error {
return client.conn.Close()
}
var ErrNoConsumers = errors.New("amqprpc: No consumers in queue")
//NewClientCodec returns a new rpc.ClientCodec using AMQP on conn. serverRouting is the routing
//key with with RPC calls are sent, it should be the same routing key used with NewServerCodec.
//encodingCodec is an EncodingCoding implementation. This package provdes JSONCodec and GobCodec
//for the JSON and Gob encodings respectively.
func NewClientCodec(conn *amqp.Connection, serverRouting string, encodingCodec EncodingCodec) (rpc.ClientCodec, error) {
channel, err := conn.Channel()
if err != nil {
return nil, err
}
queue, err := channel.QueueDeclare("", false, true, false, false, nil)
if err != nil {
return nil, err
}
serverQueue, err := channel.QueueDeclare(serverRouting, false, false, false, false, nil)
if err != nil {
return nil, err
}
if serverQueue.Consumers == 0 {
return nil, ErrNoConsumers
}
message, err := channel.Consume(queue.Name, "", true, false, false, false, nil)
client := &clientCodec{
codec: &codec{
conn: conn,
channel: channel,
routing: queue.Name,
codec: encodingCodec,
message: message,
},
serverRouting: serverRouting,
}
return client, err
}