github.com/livekit/protocol@v1.16.1-0.20240517185851-47e4c6bba773/utils/messaging.go (about)

     1  // Copyright 2023 LiveKit, Inc.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package utils
    16  
    17  import (
    18  	"context"
    19  	"crypto/sha256"
    20  	"encoding/base64"
    21  	"math/rand"
    22  	"time"
    23  
    24  	"github.com/eapache/channels"
    25  	"github.com/prometheus/client_golang/prometheus"
    26  	"github.com/redis/go-redis/v9"
    27  	"google.golang.org/protobuf/proto"
    28  )
    29  
    30  const lockExpiration = time.Second * 5
    31  
    32  var (
    33  	PromMessageBusCounter = prometheus.NewCounterVec(
    34  		prometheus.CounterOpts{
    35  			Namespace: "livekit",
    36  			Subsystem: "messagebus",
    37  			Name:      "messages",
    38  		},
    39  		[]string{"type", "status"},
    40  	)
    41  )
    42  
    43  func init() {
    44  	prometheus.MustRegister(PromMessageBusCounter)
    45  }
    46  
    47  type MessageBus interface {
    48  	Subscribe(ctx context.Context, channel string) (PubSub, error)
    49  	// SubscribeQueue is like subscribe, but ensuring only a single instance gets to process the message
    50  	SubscribeQueue(ctx context.Context, channel string) (PubSub, error)
    51  	Publish(ctx context.Context, channel string, msg proto.Message) error
    52  }
    53  
    54  type PubSub interface {
    55  	Channel() <-chan interface{}
    56  	Payload(msg interface{}) []byte
    57  	Close() error
    58  }
    59  
    60  type RedisMessageBus struct {
    61  	rc redis.UniversalClient
    62  }
    63  
    64  func NewRedisMessageBus(rc redis.UniversalClient) MessageBus {
    65  	return &RedisMessageBus{rc: rc}
    66  }
    67  
    68  func (r *RedisMessageBus) Lock(ctx context.Context, key string, expiration time.Duration) (bool, error) {
    69  	return r.rc.SetNX(ctx, key, rand.Int(), expiration).Result()
    70  }
    71  
    72  func (r *RedisMessageBus) Subscribe(ctx context.Context, channel string) (PubSub, error) {
    73  	ps := r.rc.Subscribe(ctx, channel)
    74  	return &RedisPubSub{
    75  		ps:   ps,
    76  		c:    channels.Wrap(ps.Channel()).Out(),
    77  		done: make(chan struct{}, 1),
    78  	}, nil
    79  }
    80  
    81  func (r *RedisMessageBus) SubscribeQueue(ctx context.Context, channel string) (PubSub, error) {
    82  	sub := r.rc.Subscribe(ctx, channel)
    83  	c := make(chan *redis.Message, 100) // same chan size as redis pubsub
    84  	ps := &RedisPubSub{
    85  		ps:   sub,
    86  		c:    channels.Wrap(c).Out(),
    87  		done: make(chan struct{}, 1),
    88  	}
    89  
    90  	go func() {
    91  		for {
    92  			select {
    93  			case <-ps.done:
    94  				return
    95  			case msg := <-sub.Channel():
    96  				sha := sha256.Sum256([]byte(msg.Payload))
    97  				hash := base64.StdEncoding.EncodeToString(sha[:])
    98  				acquired, _ := r.Lock(ctx, hash, lockExpiration)
    99  				if acquired {
   100  					PromMessageBusCounter.WithLabelValues("in", "success").Add(1)
   101  					c <- msg
   102  				}
   103  			}
   104  		}
   105  	}()
   106  
   107  	return ps, nil
   108  }
   109  
   110  func (r *RedisMessageBus) Publish(ctx context.Context, channel string, msg proto.Message) error {
   111  	b, err := proto.Marshal(msg)
   112  	if err != nil {
   113  		PromMessageBusCounter.WithLabelValues("out", "failure").Add(1)
   114  		return err
   115  	}
   116  
   117  	err = r.rc.Publish(ctx, channel, b).Err()
   118  	if err == nil {
   119  		PromMessageBusCounter.WithLabelValues("out", "success").Add(1)
   120  	} else {
   121  		PromMessageBusCounter.WithLabelValues("out", "failure").Add(1)
   122  	}
   123  
   124  	return err
   125  }
   126  
   127  type RedisPubSub struct {
   128  	ps   *redis.PubSub
   129  	c    <-chan interface{}
   130  	done chan struct{}
   131  }
   132  
   133  func (r *RedisPubSub) Channel() <-chan interface{} {
   134  	return r.c
   135  }
   136  
   137  func (r *RedisPubSub) Payload(msg interface{}) []byte {
   138  	return []byte(msg.(*redis.Message).Payload)
   139  }
   140  
   141  func (r *RedisPubSub) Close() error {
   142  	r.done <- struct{}{}
   143  	return r.ps.Close()
   144  }