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| 1 | +// NOTE(mia): Currently this is a minimal best-effort bridge that will not |
| 2 | +// scale with higher message rates, yet. Measurements that either the MQTT |
| 3 | +// broker or this bridge can't process will be dropped. |
| 4 | +// refer to https://github.com/RIT-Launch-Initiative/GSW/issues/59 |
| 5 | + |
| 6 | +package main |
| 7 | + |
| 8 | +import ( |
| 9 | + "context" |
| 10 | + "encoding/json" |
| 11 | + "errors" |
| 12 | + "flag" |
| 13 | + "fmt" |
| 14 | + "log" |
| 15 | + "os" |
| 16 | + "os/signal" |
| 17 | + "sync" |
| 18 | + "syscall" |
| 19 | + |
| 20 | + "github.com/AarC10/GSW-V2/lib/tlm" |
| 21 | + "github.com/AarC10/GSW-V2/proc" |
| 22 | + mqtt "github.com/eclipse/paho.mqtt.golang" |
| 23 | +) |
| 24 | + |
| 25 | +var ( |
| 26 | + shmDir = flag.String("shm", "/dev/shm", "directory to use for shared memory") |
| 27 | + brokerURL = flag.String("broker", "tcp://127.0.0.1:1883", "mqtt broker url") |
| 28 | + topicPrefix = flag.String("topic_prefix", "gsw", "mqtt topic prefix") |
| 29 | +) |
| 30 | + |
| 31 | +func main() { |
| 32 | + flag.Parse() |
| 33 | + |
| 34 | + configData, err := proc.ReadTelemetryConfigFromShm(*shmDir) |
| 35 | + if err != nil { |
| 36 | + log.Fatal(err) |
| 37 | + } |
| 38 | + _, err = proc.ParseConfigBytes(configData) |
| 39 | + if err != nil { |
| 40 | + log.Fatal(err) |
| 41 | + } |
| 42 | + |
| 43 | + opts := mqtt.NewClientOptions() |
| 44 | + opts.AddBroker(*brokerURL) |
| 45 | + opts.SetClientID("gsw-mqtt-app") |
| 46 | + opts.SetCleanSession(true) |
| 47 | + |
| 48 | + client := mqtt.NewClient(opts) |
| 49 | + if token := client.Connect(); token.Wait() && token.Error() != nil { |
| 50 | + log.Fatal(token.Error()) |
| 51 | + } |
| 52 | + |
| 53 | + ctx, cancel := context.WithCancel(context.Background()) |
| 54 | + |
| 55 | + var wg sync.WaitGroup |
| 56 | + |
| 57 | + for _, packet := range proc.GswConfig.TelemetryPackets { |
| 58 | + wg.Add(1) |
| 59 | + go func(packet tlm.TelemetryPacket) { |
| 60 | + defer wg.Done() |
| 61 | + err := packetWriter(ctx, packet, client) |
| 62 | + if err != nil && !errors.Is(err, context.Canceled) { |
| 63 | + log.Printf("error in writer: %v", err) |
| 64 | + } |
| 65 | + }(packet) |
| 66 | + } |
| 67 | + |
| 68 | + go func() { |
| 69 | + sigChan := make(chan os.Signal, 1) |
| 70 | + signal.Notify(sigChan, syscall.SIGINT, syscall.SIGTERM) |
| 71 | + <-sigChan |
| 72 | + log.Println("shutting down") |
| 73 | + cancel() |
| 74 | + }() |
| 75 | + |
| 76 | + wg.Wait() |
| 77 | + client.Disconnect(250) |
| 78 | +} |
| 79 | + |
| 80 | +func packetWriter(ctx context.Context, packet tlm.TelemetryPacket, client mqtt.Client) error { |
| 81 | + pLog := log.New(os.Stderr, fmt.Sprintf("[%s] ", packet.Name), log.LstdFlags|log.Lmsgprefix) |
| 82 | + pLog.Println("starting streaming") |
| 83 | + |
| 84 | + reader, err := proc.NewIpcShmReaderForPacket(packet, *shmDir) |
| 85 | + if err != nil { |
| 86 | + return fmt.Errorf("couldn't create reader: %w", err) |
| 87 | + } |
| 88 | + defer reader.Cleanup() |
| 89 | + |
| 90 | + for { |
| 91 | + p, err := reader.Read(ctx) |
| 92 | + if ctx.Err() != nil { |
| 93 | + return ctx.Err() |
| 94 | + } |
| 95 | + if err != nil { |
| 96 | + pLog.Printf("error reading packet: %v\n", err) |
| 97 | + continue |
| 98 | + } |
| 99 | + data := p.Data() |
| 100 | + offset := 0 |
| 101 | + for _, name := range packet.Measurements { |
| 102 | + meas, ok := proc.GswConfig.Measurements[name] |
| 103 | + if !ok || offset+meas.Size > len(data) { |
| 104 | + continue |
| 105 | + } |
| 106 | + val, err := tlm.InterpretMeasurementValue(meas, data[offset:offset+meas.Size]) |
| 107 | + if err != nil { |
| 108 | + pLog.Printf("error interpreting measurement: %v\n", err) |
| 109 | + continue |
| 110 | + } |
| 111 | + jsonStr, err := json.Marshal(val) |
| 112 | + if err != nil { |
| 113 | + pLog.Printf("error marshaling measurement: %v\n", err) |
| 114 | + continue |
| 115 | + } |
| 116 | + // qos=0 delivery not guaranteed |
| 117 | + client.Publish(fmt.Sprintf("%s/%s/%s", *topicPrefix, packet.Name, name), 0, false, jsonStr) |
| 118 | + offset += meas.Size |
| 119 | + } |
| 120 | + } |
| 121 | +} |
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