81 lines
1.6 KiB
Go
81 lines
1.6 KiB
Go
//
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// Copyright (c) 2018
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// Mainflux
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//
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// SPDX-License-Identifier: Apache-2.0
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//
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// Package nats contains NATS message publisher implementation.
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package nats
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import (
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"fmt"
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"github.com/sony/gobreaker"
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"github.com/gogo/protobuf/proto"
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"github.com/mainflux/mainflux"
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"github.com/mainflux/mainflux/ws"
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broker "github.com/nats-io/go-nats"
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)
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const (
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prefix = "channel"
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maxFailedReqs = 3
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maxFailureRatio = 0.6
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)
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var _ ws.Service = (*natsPubSub)(nil)
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type natsPubSub struct {
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nc *broker.Conn
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cb *gobreaker.CircuitBreaker
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}
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// New instantiates NATS message publisher.
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func New(nc *broker.Conn) ws.Service {
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st := gobreaker.Settings{
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Name: "NATS",
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ReadyToTrip: func(counts gobreaker.Counts) bool {
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fr := float64(counts.TotalFailures) / float64(counts.Requests)
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return counts.Requests >= maxFailedReqs && fr >= maxFailureRatio
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},
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}
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cb := gobreaker.NewCircuitBreaker(st)
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return &natsPubSub{nc, cb}
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}
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func (pubsub *natsPubSub) Publish(msg mainflux.RawMessage) error {
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data, err := proto.Marshal(&msg)
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if err != nil {
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return err
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}
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return pubsub.nc.Publish(fmt.Sprintf("%s.%s", prefix, msg.Channel), data)
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}
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func (pubsub *natsPubSub) Subscribe(chanID string, channel *ws.Channel) error {
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var sub *broker.Subscription
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sub, err := pubsub.nc.Subscribe(fmt.Sprintf("%s.%s", prefix, chanID), func(msg *broker.Msg) {
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if msg == nil {
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return
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}
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var rawMsg mainflux.RawMessage
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if err := proto.Unmarshal(msg.Data, &rawMsg); err != nil {
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return
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}
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// Sends message to messages channel
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channel.Send(rawMsg)
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})
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// Check if subscription should be closed
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go func() {
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<-channel.Closed
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sub.Unsubscribe()
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}()
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return err
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}
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