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package recording
import (
"bilibili-livestream-archiver/common"
"bilibili-livestream-archiver/danmaku"
"bilibili-livestream-archiver/danmaku/dmpkg"
"context"
"encoding/json"
"fmt"
"log"
"time"
)
type WatcherEvent int
const (
WatcherLiveStart WatcherEvent = 0
WatcherLiveStop WatcherEvent = 1
)
type liveCommand string
const (
CommandLiveStart = "LIVE"
CommandStreamPreparing = "PREPARING"
)
type liveInfo struct {
Command liveCommand `json:"cmd"`
}
type ErrorReason int
const (
ErrSuccess ErrorReason = iota // no error happens, normally closed
ErrTransport // I/O error, safe to retry
ErrProtocol // application protocol logic error, do not retry
)
const (
kHeartBeatInterval = 30 * time.Second
)
// watch monitors live room status by subscribing messages from Bilibili danmaku server,
// which talks to the client via a WebSocket or TCP connection.
// In our implementation, we use WebSocket over SSL/TLS.
func watch(
ctx context.Context,
url string,
authKey string,
roomId common.RoomId,
liveStatusChecker func() (bool, error),
chEvent chan<- WatcherEvent,
) (error, ErrorReason) {
logger := log.Default()
var err error
dm := danmaku.NewDanmakuClient()
defer func() { _ = dm.Disconnect() }()
// connect to danmaku server for live online/offline notifications
err = dm.Connect(ctx, url)
if err != nil {
return fmt.Errorf("failed to connect to danmaku server: %w", err), ErrTransport
}
defer func() { _ = dm.Disconnect() }()
// the danmaku server requires an auth token and room id when connected
logger.Println("ws connected. Authenticating...")
err = dm.Authenticate(roomId, authKey)
if err != nil {
return fmt.Errorf("auth failed: %w", err), ErrProtocol
}
// the danmaku server requires heartbeat messages every 30 seconds
heartbeat := func() error {
err := dm.Heartbeat()
return err
}
// send initial heartbeat immediately
err = heartbeat()
if err != nil {
return err, ErrTransport
}
// create heartbeat timer
heartBeatTimer := time.NewTicker(kHeartBeatInterval)
defer func() { heartBeatTimer.Stop() }()
logger.Println("Checking initial live status...")
isLiving, err := liveStatusChecker()
if err != nil {
return fmt.Errorf("check initial live status failed: %w", err), ErrTransport
}
if isLiving {
logger.Println("The live is already started. Start recording immediately.")
chEvent <- WatcherLiveStart
} else {
logger.Println("The live is not started yet. Waiting...")
}
for {
select {
case <-ctx.Done():
return nil, ErrSuccess
case <-heartBeatTimer.C:
err = heartbeat()
if err != nil {
return fmt.Errorf("heartbeat failed: %w", err), ErrTransport
}
default:
var msg dmpkg.DanmakuExchange
msg, err = dm.ReadExchange()
if err != nil {
return fmt.Errorf("exchange read failed: %w", err), ErrTransport
}
// the exchange may be compressed
msg, err = msg.Inflate()
if err != nil {
return fmt.Errorf("inflate server message failed: %v", err), ErrProtocol
}
switch msg.Operation {
case dmpkg.OpLayer7Data:
logger.Printf("server message: op %v, body %v\n", msg.Operation, string(msg.Body))
var info liveInfo
err := json.Unmarshal(msg.Body, &info)
if err != nil {
logger.Printf("ERROR: invalid JSON: \"%v\", exchange: %v", string(msg.Body), msg)
return fmt.Errorf("decode server message body JSON failed: %w", err), ErrProtocol
}
switch info.Command {
case CommandLiveStart:
if !isLiving {
chEvent <- WatcherLiveStart
isLiving = true
}
case CommandStreamPreparing:
if isLiving {
chEvent <- WatcherLiveStop
}
default:
logger.Printf("Ignoring server message %v %v %v\n",
info.Command, msg.Operation, string(msg.Body))
}
default:
logger.Printf("Server message: %v\n", msg.String())
}
}
}
}
|
