134 lines
2.7 KiB
Go
134 lines
2.7 KiB
Go
package respond
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import (
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"encoding/json"
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"log"
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"net"
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"reflect"
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"time"
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)
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//Collector for a specificle respond messages
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type Collector struct {
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CollectType string
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connection *net.UDPConn // UDP socket
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queue chan *Response // received responses
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onReceive OnReceive
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msgType reflect.Type
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// Ticker and stopper
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ticker *time.Ticker
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stop chan interface{}
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}
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type OnReceive func(net.UDPAddr, interface{})
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//NewCollector creates a Collector struct
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func NewCollector(CollectType string, initialDelay time.Duration, interval time.Duration, msgStruct interface{}, onReceive OnReceive) *Collector {
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// Parse address
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addr, err := net.ResolveUDPAddr("udp", "[::]:0")
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if err != nil {
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log.Panic(err)
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}
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// Open socket
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conn, err := net.ListenUDP("udp", addr)
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if err != nil {
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log.Panic(err)
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}
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conn.SetReadBuffer(maxDataGramSize)
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collector := &Collector{
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CollectType: CollectType,
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connection: conn,
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queue: make(chan *Response, 400),
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ticker: time.NewTicker(interval),
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stop: make(chan interface{}, 1),
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msgType: reflect.TypeOf(msgStruct),
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onReceive: onReceive,
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}
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go collector.receiver()
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go collector.parser()
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// Run senders
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go func() {
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time.Sleep(initialDelay)
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collector.sendOnce() // immediately
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collector.sender() // periodically
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}()
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return collector
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}
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// Close Collector
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func (coll *Collector) Close() {
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// stop ticker
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coll.ticker.Stop()
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coll.stop <- nil
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coll.connection.Close()
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close(coll.queue)
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}
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func (coll *Collector) sendOnce() {
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coll.sendPacket(net.JoinHostPort(multiCastGroup, port))
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log.Println("request", coll.CollectType)
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}
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func (coll *Collector) sendPacket(address string) {
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addr, err := net.ResolveUDPAddr("udp", address)
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if err != nil {
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log.Panic(err)
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}
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if _, err := coll.connection.WriteToUDP([]byte(coll.CollectType), addr); err != nil {
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log.Println("WriteToUDP failed:", err)
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}
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}
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// send packets continously
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func (coll *Collector) sender() {
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for {
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select {
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case <-coll.stop:
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return
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case <-coll.ticker.C:
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coll.sendOnce()
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}
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}
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}
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func (coll *Collector) parser() {
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for obj := range coll.queue {
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// create new struct instance
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data := reflect.New(coll.msgType).Interface()
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if err := json.Unmarshal(obj.Raw, data); err == nil {
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coll.onReceive(obj.Address, data)
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} else {
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log.Println("unable to decode response from", obj.Address.String(), err, "\n", string(obj.Raw))
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}
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}
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}
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func (coll *Collector) receiver() {
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buf := make([]byte, maxDataGramSize)
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for {
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n, src, err := coll.connection.ReadFromUDP(buf)
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if err != nil {
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log.Println("ReadFromUDP failed:", err)
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return
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}
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raw := make([]byte, n)
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copy(raw, buf)
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coll.queue <- &Response{
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Address: *src,
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Raw: raw,
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}
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}
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}
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