gst-plugins-rs/plugins/examples/webrtcsink-stats-server.rs

use std::collections::HashMap;
use std::sync::{Arc, Mutex};

use anyhow::Error;

use async_std::net::{TcpListener, TcpStream};
use async_std::task;
use async_tungstenite::tungstenite::Message as WsMessage;
use clap::Parser;
use futures::channel::mpsc;
use futures::prelude::*;
use gst::glib::Type;
use gst::prelude::*;
use tracing::{debug, info, trace};
use tracing_subscriber::prelude::*;

#[derive(Parser, Debug)]
#[clap(about, version, author)]
/// Program arguments
struct Args {
    /// URI of file to serve. Must hold at least one audio and video stream
    uri: String,
    /// Disable Forward Error Correction
    #[clap(long)]
    disable_fec: bool,
    /// Disable retransmission
    #[clap(long)]
    disable_retransmission: bool,
    /// Disable congestion control
    #[clap(long)]
    disable_congestion_control: bool,
}

fn serialize_value(val: &gst::glib::Value) -> Option<serde_json::Value> {
    match val.type_() {
        Type::STRING => Some(val.get::<String>().unwrap().into()),
        Type::BOOL => Some(val.get::<bool>().unwrap().into()),
        Type::I32 => Some(val.get::<i32>().unwrap().into()),
        Type::U32 => Some(val.get::<u32>().unwrap().into()),
        Type::I_LONG | Type::I64 => Some(val.get::<i64>().unwrap().into()),
        Type::U_LONG | Type::U64 => Some(val.get::<u64>().unwrap().into()),
        Type::F32 => Some(val.get::<f32>().unwrap().into()),
        Type::F64 => Some(val.get::<f64>().unwrap().into()),
        _ => {
            if let Ok(s) = val.get::<gst::Structure>() {
                serde_json::to_value(
                    s.iter()
                        .filter_map(|(name, value)| {
                            serialize_value(value).map(|value| (name.to_string(), value))
                        })
                        .collect::<HashMap<String, serde_json::Value>>(),
                )
                .ok()
            } else if let Ok(a) = val.get::<gst::Array>() {
                serde_json::to_value(
                    a.iter()
                        .filter_map(|value| serialize_value(value))
                        .collect::<Vec<serde_json::Value>>(),
                )
                .ok()
            } else if let Some((_klass, values)) = gst::glib::FlagsValue::from_value(val) {
                Some(
                    values
                        .iter()
                        .map(|value| value.nick())
                        .collect::<Vec<&str>>()
                        .join("+")
                        .into(),
                )
            } else if let Ok(value) = val.serialize() {
                Some(value.as_str().into())
            } else {
                None
            }
        }
    }
}

#[derive(Clone)]
struct Listener {
    id: uuid::Uuid,
    sender: mpsc::Sender<WsMessage>,
}

struct State {
    listeners: Vec<Listener>,
}

async fn run(args: Args) -> Result<(), Error> {
    tracing_log::LogTracer::init().expect("Failed to set logger");
    let env_filter = tracing_subscriber::EnvFilter::try_from_env("WEBRTCSINK_STATS_LOG")
        .unwrap_or_else(|_| tracing_subscriber::EnvFilter::new("info"));
    let fmt_layer = tracing_subscriber::fmt::layer()
        .with_thread_ids(true)
        .with_target(true)
        .with_span_events(
            tracing_subscriber::fmt::format::FmtSpan::NEW
                | tracing_subscriber::fmt::format::FmtSpan::CLOSE,
        );
    let subscriber = tracing_subscriber::Registry::default()
        .with(env_filter)
        .with(fmt_layer);
    tracing::subscriber::set_global_default(subscriber).expect("Failed to set subscriber");

    let state = Arc::new(Mutex::new(State { listeners: vec![] }));

    let addr = "127.0.0.1:8484".to_string();

    // Create the event loop and TCP listener we'll accept connections on.
    let try_socket = TcpListener::bind(&addr).await;
    let listener = try_socket.expect("Failed to bind");
    info!("Listening on: {}", addr);

    let pipeline_str = format!(
        "webrtcsink name=ws do-retransmission={} do-fec={} congestion-control={} \
                                uridecodebin name=d uri={} \
                                d. ! video/x-raw ! queue ! ws.video_0 \
                                d. ! audio/x-raw ! queue ! ws.audio_0",
        !args.disable_retransmission,
        !args.disable_fec,
        if args.disable_congestion_control {
            "disabled"
        } else {
            "homegrown"
        },
        args.uri
    );

    let pipeline = gst::parse_launch(&pipeline_str)?;
    let ws = pipeline
        .downcast_ref::<gst::Bin>()
        .unwrap()
        .by_name("ws")
        .unwrap();

    ws.connect("encoder-setup", false, |values| {
        let encoder = values[3].get::<gst::Element>().unwrap();

        info!("Encoder: {}", encoder.factory().unwrap().name());

        let configured = if let Some(factory) = encoder.factory() {
            match factory.name().as_str() {
                "does-not-exist" => {
                    // One could configure a hardware encoder to their liking here,
                    // and return true to make sure webrtcsink does not do any configuration
                    // of its own
                    true
                }
                _ => false,
            }
        } else {
            false
        };

        Some(configured.to_value())
    });

    let ws_clone = ws.downgrade();
    let state_clone = state.clone();
    task::spawn(async move {
        let mut interval = async_std::stream::interval(std::time::Duration::from_millis(100));

        while interval.next().await.is_some() {
            if let Some(ws) = ws_clone.upgrade() {
                let stats = ws.property::<gst::Structure>("stats");
                let stats = serialize_value(&stats.to_value()).unwrap();
                debug!("Stats: {}", serde_json::to_string_pretty(&stats).unwrap());
                let msg = WsMessage::Text(serde_json::to_string(&stats).unwrap());

                let listeners = state_clone.lock().unwrap().listeners.clone();

                for mut listener in listeners {
                    if listener.sender.send(msg.clone()).await.is_err() {
                        let mut state = state_clone.lock().unwrap();
                        let index = state
                            .listeners
                            .iter()
                            .position(|l| l.id == listener.id)
                            .unwrap();
                        state.listeners.remove(index);
                    }
                }
            } else {
                break;
            }
        }
    });

    pipeline.set_state(gst::State::Playing)?;

    while let Ok((stream, _)) = listener.accept().await {
        task::spawn(accept_connection(state.clone(), stream));
    }

    Ok(())
}

async fn accept_connection(state: Arc<Mutex<State>>, stream: TcpStream) {
    let addr = stream
        .peer_addr()
        .expect("connected streams should have a peer address");
    info!("Peer address: {}", addr);

    let mut ws_stream = async_tungstenite::accept_async(stream)
        .await
        .expect("Error during the websocket handshake occurred");

    info!("New WebSocket connection: {}", addr);

    let mut state = state.lock().unwrap();
    let (sender, mut receiver) = mpsc::channel::<WsMessage>(1000);
    state.listeners.push(Listener {
        id: uuid::Uuid::new_v4(),
        sender,
    });
    drop(state);

    task::spawn(async move {
        while let Some(msg) = receiver.next().await {
            trace!("Sending to one listener!");
            if ws_stream.send(msg).await.is_err() {
                info!("Listener errored out");
                receiver.close();
            }
        }
    });
}

fn main() -> Result<(), Error> {
    gst::init()?;

    let args = Args::parse();

    task::block_on(run(args))
}