91 lines
2.0 KiB
Go
91 lines
2.0 KiB
Go
package bitcoin
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import (
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"encoding/binary"
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"log"
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zmq "github.com/pebbe/zmq4"
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)
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// MQ is message queue listener handle
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type MQ struct {
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context *zmq.Context
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socket *zmq.Socket
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isRunning bool
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finished chan bool
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}
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// MQMessage contains data received from Bitcoind message queue
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type MQMessage struct {
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Topic string
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Sequence uint32
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Body []byte
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}
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// New creates new Bitcoind ZeroMQ listener
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// callback function receives messages
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func New(binding string, callback func(*MQMessage)) (*MQ, error) {
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context, err := zmq.NewContext()
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if err != nil {
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return nil, err
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}
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socket, err := context.NewSocket(zmq.SUB)
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if err != nil {
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return nil, err
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}
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socket.SetSubscribe("hashblock")
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socket.SetSubscribe("hashtx")
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socket.SetSubscribe("rawblock")
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socket.SetSubscribe("rawtx")
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socket.Connect(binding)
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log.Printf("MQ listening to %s", binding)
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mq := &MQ{context, socket, true, make(chan bool)}
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go mq.run(callback)
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return mq, nil
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}
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func (mq *MQ) run(callback func(*MQMessage)) {
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mq.isRunning = true
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for {
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msg, err := mq.socket.RecvMessageBytes(0)
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if err != nil {
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if zmq.AsErrno(err) == zmq.Errno(zmq.ETERM) {
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close(mq.finished)
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log.Print("MQ loop terminated")
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break
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}
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log.Printf("MQ RecvMessageBytes error %v", err)
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}
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if msg != nil && len(msg) >= 3 {
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sequence := uint32(0)
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if len(msg[len(msg)-1]) == 4 {
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sequence = binary.LittleEndian.Uint32(msg[len(msg)-1])
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}
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m := &MQMessage{
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Topic: string(msg[0]),
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Sequence: sequence,
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Body: msg[1],
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}
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callback(m)
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}
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}
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mq.isRunning = false
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}
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// Shutdown stops listening to the ZeroMQ and closes the connection
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func (mq *MQ) Shutdown() error {
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log.Printf("MQ server shutdown")
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if mq.isRunning {
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// if errors in socket.Close or context.Term, let it close ungracefully
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if err := mq.socket.Close(); err != nil {
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return err
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}
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if err := mq.context.Term(); err != nil {
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return err
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}
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_, _ = <-mq.finished
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log.Printf("MQ server shutdown finished")
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}
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return nil
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}
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