dora_daemon/

lib.rs

use aligned_vec::{AVec, ConstAlign};
use coordinator::CoordinatorEvent;
use crossbeam::queue::ArrayQueue;
use dora_core::{
    build::{self, BuildInfo, GitManager, PrevGitSource},
    config::{DataId, Input, InputMapping, NodeId, NodeRunConfig, OperatorId},
    descriptor::{
        CoreNodeKind, DYNAMIC_SOURCE, Descriptor, DescriptorExt, ResolvedNode, RuntimeNode,
        read_as_descriptor,
    },
    topics::{
        DORA_DAEMON_LOCAL_LISTEN_PORT_DEFAULT, LOCALHOST, open_zenoh_session,
        zenoh_output_publish_topic,
    },
    uhlc::{self, HLC},
};
use dora_message::{
    BuildId, DataflowId, SessionId,
    common::{
        DaemonId, DataMessage, DropToken, GitSource, LogLevel, NodeError, NodeErrorCause,
        NodeExitStatus,
    },
    coordinator_to_cli::DataflowResult,
    coordinator_to_daemon::{BuildDataflowNodes, DaemonCoordinatorEvent, SpawnDataflowNodes},
    daemon_to_coordinator::{
        CoordinatorRequest, DaemonCoordinatorReply, DaemonEvent, DataflowDaemonResult,
    },
    daemon_to_daemon::InterDaemonEvent,
    daemon_to_node::{DaemonReply, NodeConfig, NodeDropEvent, NodeEvent},
    descriptor::{NodeSource, RestartPolicy},
    metadata::{self, ArrowTypeInfo},
    node_to_daemon::{DynamicNodeEvent, Timestamped},
};
use dora_node_api::{Parameter, arrow::datatypes::DataType};
use eyre::{Context, ContextCompat, Result, bail, eyre};
use futures::{FutureExt, TryFutureExt, future, stream};
use futures_concurrency::stream::Merge;
use local_listener::DynamicNodeEventWrapper;
use log::{DaemonLogger, DataflowLogger, Logger};
use pending::PendingNodes;
use process_wrap::tokio::TokioChildWrapper;
use shared_memory_server::ShmemConf;
use socket_stream_utils::socket_stream_send;
use spawn::Spawner;
use std::{
    collections::{BTreeMap, BTreeSet, HashMap, VecDeque},
    env::current_dir,
    future::Future,
    io,
    net::SocketAddr,
    path::{Path, PathBuf},
    pin::pin,
    sync::{
        Arc,
        atomic::{self, AtomicBool, AtomicU32},
    },
    time::{Duration, Instant},
};
use tokio::{
    fs::File,
    io::{AsyncReadExt, AsyncSeekExt},
    net::TcpStream,
    sync::{
        broadcast,
        mpsc::{self, UnboundedSender},
        oneshot::{self, Sender},
    },
};
use tokio_stream::{Stream, StreamExt, wrappers::ReceiverStream};
use tracing::{error, warn};
use uuid::{NoContext, Timestamp, Uuid};

pub use flume;
pub use log::LogDestination;

mod coordinator;
mod local_listener;
mod log;
mod node_communication;
mod pending;
mod socket_stream_utils;
mod spawn;

#[cfg(feature = "telemetry")]
use dora_tracing::telemetry::serialize_context;
#[cfg(feature = "telemetry")]
use tracing_opentelemetry::OpenTelemetrySpanExt;

use crate::pending::DataflowStatus;

const STDERR_LOG_LINES: usize = 10;

pub struct Daemon {
    running: HashMap<DataflowId, RunningDataflow>,
    working_dir: HashMap<DataflowId, PathBuf>,

    events_tx: mpsc::Sender<Timestamped<Event>>,

    coordinator_connection: Option<TcpStream>,
    last_coordinator_heartbeat: Instant,
    daemon_id: DaemonId,

    /// used for testing and examples
    exit_when_done: Option<BTreeSet<(Uuid, NodeId)>>,
    /// set on ctrl-c
    exit_when_all_finished: bool,
    /// used to record results of local nodes
    dataflow_node_results: BTreeMap<Uuid, BTreeMap<NodeId, Result<(), NodeError>>>,

    clock: Arc<uhlc::HLC>,

    zenoh_session: zenoh::Session,
    remote_daemon_events_tx: Option<flume::Sender<eyre::Result<Timestamped<InterDaemonEvent>>>>,

    logger: DaemonLogger,

    sessions: BTreeMap<SessionId, BuildId>,
    builds: BTreeMap<BuildId, BuildInfo>,
    git_manager: GitManager,
    /// System instance for metrics collection (reused across calls)
    metrics_system: sysinfo::System,
}

type DaemonRunResult = BTreeMap<Uuid, BTreeMap<NodeId, Result<(), NodeError>>>;

struct NodeBuildTask<F> {
    node_id: NodeId,
    dynamic_node: bool,
    task: F,
}

impl Daemon {
    pub async fn run(
        coordinator_addr: SocketAddr,
        machine_id: Option<String>,
        local_listen_port: u16,
    ) -> eyre::Result<()> {
        let clock = Arc::new(HLC::default());

        let mut ctrlc_events = set_up_ctrlc_handler(clock.clone())?;
        let (remote_daemon_events_tx, remote_daemon_events_rx) = flume::bounded(10);
        let (daemon_id, incoming_events) = {
            let incoming_events = set_up_event_stream(
                coordinator_addr,
                &machine_id,
                &clock,
                remote_daemon_events_rx,
                local_listen_port,
            );

            // finish early if ctrl-c is is pressed during event stream setup
            let ctrl_c = pin!(ctrlc_events.recv());
            match futures::future::select(ctrl_c, pin!(incoming_events)).await {
                future::Either::Left((_ctrl_c, _)) => {
                    tracing::info!("received ctrl-c signal -> stopping daemon");
                    return Ok(());
                }
                future::Either::Right((events, _)) => events?,
            }
        };

        let log_destination = {
            // additional connection for logging
            let stream = TcpStream::connect(coordinator_addr)
                .await
                .wrap_err("failed to connect log to dora-coordinator")?;
            stream
                .set_nodelay(true)
                .wrap_err("failed to set TCP_NODELAY")?;
            LogDestination::Coordinator {
                coordinator_connection: stream,
            }
        };

        Self::run_general(
            (ReceiverStream::new(ctrlc_events), incoming_events).merge(),
            Some(coordinator_addr),
            daemon_id,
            None,
            clock.clone(),
            Some(remote_daemon_events_tx),
            Default::default(),
            log_destination,
        )
        .await
        .map(|_| ())
    }

    pub async fn run_dataflow(
        dataflow_path: &Path,
        build_id: Option<BuildId>,
        local_build: Option<BuildInfo>,
        session_id: SessionId,
        uv: bool,
        log_destination: LogDestination,
        write_events_to: Option<PathBuf>,
    ) -> eyre::Result<DataflowResult> {
        let working_dir = dataflow_path
            .canonicalize()
            .context("failed to canonicalize dataflow path")?
            .parent()
            .ok_or_else(|| eyre::eyre!("canonicalized dataflow path has no parent"))?
            .to_owned();

        let descriptor = read_as_descriptor(dataflow_path).await?;
        if let Some(node) = descriptor.nodes.iter().find(|n| n.deploy.is_some()) {
            eyre::bail!(
                "node {} has a `deploy` section, which is not supported in `dora run`\n\n
                Instead, you need to spawn a `dora coordinator` and one or more `dora daemon`
                instances and then use `dora start`.",
                node.id
            )
        }

        descriptor.check(&working_dir)?;
        let nodes = descriptor.resolve_aliases_and_set_defaults()?;

        let (events_tx, events_rx) = flume::bounded(10);
        if nodes
            .iter()
            .find(|(_n, resolved_nodes)| resolved_nodes.kind.dynamic())
            .is_some()
        {
            // Spawn local listener for dynamic nodes
            let _listen_port = local_listener::spawn_listener_loop(
                (LOCALHOST, DORA_DAEMON_LOCAL_LISTEN_PORT_DEFAULT).into(),
                events_tx,
            )
            .await?;
        }
        let dynamic_node_events = events_rx.into_stream().map(|e| Timestamped {
            inner: Event::DynamicNode(e.inner),
            timestamp: e.timestamp,
        });

        let dataflow_id = Uuid::new_v7(Timestamp::now(NoContext));
        let spawn_command = SpawnDataflowNodes {
            build_id,
            session_id,
            dataflow_id,
            local_working_dir: Some(working_dir),
            spawn_nodes: nodes.keys().cloned().collect(),
            nodes,
            dataflow_descriptor: descriptor,
            uv,
            write_events_to,
        };

        let clock = Arc::new(HLC::default());

        let ctrlc_events = ReceiverStream::new(set_up_ctrlc_handler(clock.clone())?);

        let exit_when_done = spawn_command
            .nodes
            .values()
            .map(|n| (spawn_command.dataflow_id, n.id.clone()))
            .collect();
        let (reply_tx, reply_rx) = oneshot::channel();
        let timestamp = clock.new_timestamp();
        let coordinator_events = stream::once(async move {
            Timestamped {
                inner: Event::Coordinator(CoordinatorEvent {
                    event: DaemonCoordinatorEvent::Spawn(spawn_command),
                    reply_tx,
                }),
                timestamp,
            }
        });
        let events = (coordinator_events, ctrlc_events, dynamic_node_events).merge();
        let run_result = Self::run_general(
            Box::pin(events),
            None,
            DaemonId::new(None),
            Some(exit_when_done),
            clock.clone(),
            None,
            if let Some(local_build) = local_build {
                let Some(build_id) = build_id else {
                    bail!("no build_id, but local_build set")
                };
                let mut builds = BTreeMap::new();
                builds.insert(build_id, local_build);
                builds
            } else {
                Default::default()
            },
            log_destination,
        );

        let spawn_result = reply_rx
            .map_err(|err| eyre!("failed to receive spawn result: {err}"))
            .and_then(|r| async {
                match r {
                    Some(DaemonCoordinatorReply::TriggerSpawnResult(result)) => {
                        result.map_err(|err| eyre!(err))
                    }
                    _ => Err(eyre!("unexpected spawn reply")),
                }
            });

        let (mut dataflow_results, ()) = future::try_join(run_result, spawn_result).await?;

        Ok(DataflowResult {
            uuid: dataflow_id,
            timestamp: clock.new_timestamp(),
            node_results: dataflow_results
                .remove(&dataflow_id)
                .context("no node results for dataflow_id")?,
        })
    }

    #[allow(clippy::too_many_arguments)]
    async fn run_general(
        external_events: impl Stream<Item = Timestamped<Event>> + Unpin,
        coordinator_addr: Option<SocketAddr>,
        daemon_id: DaemonId,
        exit_when_done: Option<BTreeSet<(Uuid, NodeId)>>,
        clock: Arc<HLC>,
        remote_daemon_events_tx: Option<flume::Sender<eyre::Result<Timestamped<InterDaemonEvent>>>>,
        builds: BTreeMap<BuildId, BuildInfo>,
        log_destination: LogDestination,
    ) -> eyre::Result<DaemonRunResult> {
        let coordinator_connection = match coordinator_addr {
            Some(addr) => {
                let stream = TcpStream::connect(addr)
                    .await
                    .wrap_err("failed to connect to dora-coordinator")?;
                stream
                    .set_nodelay(true)
                    .wrap_err("failed to set TCP_NODELAY")?;
                Some(stream)
            }
            None => None,
        };

        let zenoh_session = open_zenoh_session(coordinator_addr.map(|addr| addr.ip()))
            .await
            .wrap_err("failed to open zenoh session")?;
        let (dora_events_tx, dora_events_rx) = mpsc::channel(5);
        let daemon = Self {
            logger: Logger {
                destination: log_destination,
                daemon_id: daemon_id.clone(),
                clock: clock.clone(),
            }
            .for_daemon(daemon_id.clone()),
            running: HashMap::new(),
            working_dir: HashMap::new(),
            events_tx: dora_events_tx,
            coordinator_connection,
            last_coordinator_heartbeat: Instant::now(),
            daemon_id,
            exit_when_done,
            exit_when_all_finished: false,
            dataflow_node_results: BTreeMap::new(),
            clock,
            zenoh_session,
            remote_daemon_events_tx,
            git_manager: Default::default(),
            builds,
            sessions: Default::default(),
            metrics_system: sysinfo::System::new(),
        };

        let dora_events = ReceiverStream::new(dora_events_rx);
        let watchdog_clock = daemon.clock.clone();
        let watchdog_interval = tokio_stream::wrappers::IntervalStream::new(tokio::time::interval(
            Duration::from_secs(5),
        ))
        .map(|_| Timestamped {
            inner: Event::HeartbeatInterval,
            timestamp: watchdog_clock.new_timestamp(),
        });

        let metrics_clock = daemon.clock.clone();
        let metrics_interval = tokio_stream::wrappers::IntervalStream::new(tokio::time::interval(
            Duration::from_secs(2), // Collect metrics every 2 seconds
        ))
        .map(|_| Timestamped {
            inner: Event::MetricsInterval,
            timestamp: metrics_clock.new_timestamp(),
        });

        let events = (
            external_events,
            dora_events,
            watchdog_interval,
            metrics_interval,
        )
            .merge();
        daemon.run_inner(events).await
    }

    #[tracing::instrument(skip(incoming_events, self), fields(?self.daemon_id))]
    async fn run_inner(
        mut self,
        incoming_events: impl Stream<Item = Timestamped<Event>> + Unpin,
    ) -> eyre::Result<DaemonRunResult> {
        let mut events = incoming_events;

        while let Some(event) = events.next().await {
            let Timestamped { inner, timestamp } = event;
            if let Err(err) = self.clock.update_with_timestamp(&timestamp) {
                tracing::warn!("failed to update HLC with incoming event timestamp: {err}");
            }

            // used below for checking the duration of event handling
            let start = Instant::now();
            let event_kind = inner.kind();

            match inner {
                Event::Coordinator(CoordinatorEvent { event, reply_tx }) => {
                    let status = self.handle_coordinator_event(event, reply_tx).await?;

                    match status {
                        RunStatus::Continue => {}
                        RunStatus::Exit => break,
                    }
                }
                Event::Daemon(event) => {
                    self.handle_inter_daemon_event(event).await?;
                }
                Event::Node {
                    dataflow_id: dataflow,
                    node_id,
                    event,
                } => self.handle_node_event(event, dataflow, node_id).await?,
                Event::Dora(event) => self.handle_dora_event(event).await?,
                Event::DynamicNode(event) => self.handle_dynamic_node_event(event).await?,
                Event::HeartbeatInterval => {
                    if let Some(connection) = &mut self.coordinator_connection {
                        let msg = serde_json::to_vec(&Timestamped {
                            inner: CoordinatorRequest::Event {
                                daemon_id: self.daemon_id.clone(),
                                event: DaemonEvent::Heartbeat,
                            },
                            timestamp: self.clock.new_timestamp(),
                        })?;
                        socket_stream_send(connection, &msg)
                            .await
                            .wrap_err("failed to send watchdog message to dora-coordinator")?;

                        if self.last_coordinator_heartbeat.elapsed() > Duration::from_secs(20) {
                            bail!("lost connection to coordinator")
                        }
                    }
                }
                Event::MetricsInterval => {
                    self.collect_and_send_metrics().await?;
                }
                Event::CtrlC => {
                    tracing::info!("received ctrlc signal -> stopping all dataflows");
                    for dataflow in self.running.values_mut() {
                        let mut logger = self.logger.for_dataflow(dataflow.id);
                        dataflow
                            .stop_all(
                                &mut self.coordinator_connection,
                                &self.clock,
                                None,
                                false,
                                &mut logger,
                            )
                            .await?;
                    }
                    self.exit_when_all_finished = true;
                    if self.running.is_empty() {
                        break;
                    }
                }
                Event::SecondCtrlC => {
                    tracing::warn!("received second ctrlc signal -> exit immediately");
                    bail!("received second ctrl-c signal");
                }
                Event::DaemonError(err) => {
                    tracing::error!("Daemon error: {err:?}");
                }
                Event::SpawnNodeResult {
                    dataflow_id,
                    node_id,
                    dynamic_node,
                    result,
                } => match result {
                    Ok(running_node) => {
                        if let Some(dataflow) = self.running.get_mut(&dataflow_id) {
                            dataflow.running_nodes.insert(node_id, running_node);
                        } else {
                            tracing::error!(
                                "failed to handle SpawnNodeResult: no running dataflow with ID {dataflow_id}"
                            );
                        }
                    }
                    Err(error) => {
                        self.dataflow_node_results
                            .entry(dataflow_id)
                            .or_default()
                            .insert(node_id.clone(), Err(error));
                        self.handle_node_stop(dataflow_id, &node_id, dynamic_node)
                            .await?;
                    }
                },
                Event::BuildDataflowResult {
                    build_id,
                    session_id,
                    result,
                } => {
                    let (build_info, result) = match result {
                        Ok(build_info) => (Some(build_info), Ok(())),
                        Err(err) => (None, Err(err)),
                    };
                    if let Some(build_info) = build_info {
                        self.builds.insert(build_id, build_info);
                        if let Some(old_build_id) = self.sessions.insert(session_id, build_id) {
                            self.builds.remove(&old_build_id);
                        }
                    }
                    if let Some(connection) = &mut self.coordinator_connection {
                        let msg = serde_json::to_vec(&Timestamped {
                            inner: CoordinatorRequest::Event {
                                daemon_id: self.daemon_id.clone(),
                                event: DaemonEvent::BuildResult {
                                    build_id,
                                    result: result.map_err(|err| format!("{err:?}")),
                                },
                            },
                            timestamp: self.clock.new_timestamp(),
                        })?;
                        socket_stream_send(connection, &msg).await.wrap_err(
                            "failed to send BuildDataflowResult message to dora-coordinator",
                        )?;
                    }
                }
                Event::SpawnDataflowResult {
                    dataflow_id,
                    result,
                } => {
                    if let Some(connection) = &mut self.coordinator_connection {
                        let msg = serde_json::to_vec(&Timestamped {
                            inner: CoordinatorRequest::Event {
                                daemon_id: self.daemon_id.clone(),
                                event: DaemonEvent::SpawnResult {
                                    dataflow_id,
                                    result: result.map_err(|err| format!("{err:?}")),
                                },
                            },
                            timestamp: self.clock.new_timestamp(),
                        })?;
                        socket_stream_send(connection, &msg).await.wrap_err(
                            "failed to send SpawnDataflowResult message to dora-coordinator",
                        )?;
                    }
                }
                Event::NodeStopped {
                    dataflow_id,
                    node_id,
                } => {
                    if let Some(exit_when_done) = &mut self.exit_when_done {
                        exit_when_done.remove(&(dataflow_id, node_id));
                        if exit_when_done.is_empty() {
                            tracing::info!(
                                "exiting daemon because all required dataflows are finished"
                            );
                            break;
                        }
                    }
                    if self.exit_when_all_finished && self.running.is_empty() {
                        break;
                    }
                }
            }

            // warn if event handling took too long -> the main loop should never be blocked for too long
            let elapsed = start.elapsed();
            if elapsed > Duration::from_millis(100) {
                tracing::warn!(
                    "Daemon took {}ms for handling event: {event_kind}",
                    elapsed.as_millis()
                );
            }
        }

        if let Some(mut connection) = self.coordinator_connection.take() {
            let msg = serde_json::to_vec(&Timestamped {
                inner: CoordinatorRequest::Event {
                    daemon_id: self.daemon_id.clone(),
                    event: DaemonEvent::Exit,
                },
                timestamp: self.clock.new_timestamp(),
            })?;
            socket_stream_send(&mut connection, &msg)
                .await
                .wrap_err("failed to send Exit message to dora-coordinator")?;
        }

        Ok(self.dataflow_node_results)
    }

    async fn handle_coordinator_event(
        &mut self,
        event: DaemonCoordinatorEvent,
        reply_tx: Sender<Option<DaemonCoordinatorReply>>,
    ) -> eyre::Result<RunStatus> {
        let status = match event {
            DaemonCoordinatorEvent::Build(BuildDataflowNodes {
                build_id,
                session_id,
                local_working_dir,
                git_sources,
                prev_git_sources,
                dataflow_descriptor,
                nodes_on_machine,
                uv,
            }) => {
                match dataflow_descriptor.communication.remote {
                    dora_core::config::RemoteCommunicationConfig::Tcp => {}
                }

                let base_working_dir = self.base_working_dir(local_working_dir, session_id)?;

                let result = self
                    .build_dataflow(
                        build_id,
                        session_id,
                        base_working_dir,
                        git_sources,
                        prev_git_sources,
                        dataflow_descriptor,
                        nodes_on_machine,
                        uv,
                    )
                    .await;
                let (trigger_result, result_task) = match result {
                    Ok(result_task) => (Ok(()), Some(result_task)),
                    Err(err) => (Err(format!("{err:?}")), None),
                };
                let reply = DaemonCoordinatorReply::TriggerBuildResult(trigger_result);
                let _ = reply_tx.send(Some(reply)).map_err(|_| {
                    error!("could not send `TriggerBuildResult` reply from daemon to coordinator")
                });

                let result_tx = self.events_tx.clone();
                let clock = self.clock.clone();
                if let Some(result_task) = result_task {
                    tokio::spawn(async move {
                        let message = Timestamped {
                            inner: Event::BuildDataflowResult {
                                build_id,
                                session_id,
                                result: result_task.await,
                            },
                            timestamp: clock.new_timestamp(),
                        };
                        let _ = result_tx
                            .send(message)
                            .map_err(|_| {
                                error!(
                                    "could not send `BuildResult` reply from daemon to coordinator"
                                )
                            })
                            .await;
                    });
                }

                RunStatus::Continue
            }
            DaemonCoordinatorEvent::Spawn(SpawnDataflowNodes {
                build_id,
                session_id,
                dataflow_id,
                local_working_dir,
                nodes,
                dataflow_descriptor,
                spawn_nodes,
                uv,
                write_events_to,
            }) => {
                match dataflow_descriptor.communication.remote {
                    dora_core::config::RemoteCommunicationConfig::Tcp => {}
                }

                let base_working_dir = self.base_working_dir(local_working_dir, session_id)?;

                let result = self
                    .spawn_dataflow(
                        build_id,
                        dataflow_id,
                        base_working_dir,
                        nodes,
                        dataflow_descriptor,
                        spawn_nodes,
                        uv,
                        write_events_to,
                    )
                    .await;
                let (trigger_result, result_task) = match result {
                    Ok(result_task) => (Ok(()), Some(result_task)),
                    Err(err) => (Err(format!("{err:?}")), None),
                };
                let reply = DaemonCoordinatorReply::TriggerSpawnResult(trigger_result);
                let _ = reply_tx.send(Some(reply)).map_err(|_| {
                    error!("could not send `TriggerSpawnResult` reply from daemon to coordinator")
                });

                let result_tx = self.events_tx.clone();
                let clock = self.clock.clone();
                if let Some(result_task) = result_task {
                    tokio::spawn(async move {
                        let message = Timestamped {
                            inner: Event::SpawnDataflowResult {
                                dataflow_id,
                                result: result_task.await,
                            },
                            timestamp: clock.new_timestamp(),
                        };
                        let _ = result_tx
                            .send(message)
                            .map_err(|_| {
                                error!(
                                    "could not send `SpawnResult` reply from daemon to coordinator"
                                )
                            })
                            .await;
                    });
                }

                RunStatus::Continue
            }
            DaemonCoordinatorEvent::AllNodesReady {
                dataflow_id,
                exited_before_subscribe,
            } => {
                let mut logger = self.logger.for_dataflow(dataflow_id);
                logger.log(LogLevel::Debug, None,
                    Some("daemon".into()),
                    format!("received AllNodesReady (exited_before_subscribe: {exited_before_subscribe:?})"
                )).await;
                match self.running.get_mut(&dataflow_id) {
                    Some(dataflow) => {
                        let ready = exited_before_subscribe.is_empty();
                        dataflow
                            .pending_nodes
                            .handle_external_all_nodes_ready(
                                exited_before_subscribe,
                                &mut dataflow.cascading_error_causes,
                            )
                            .await?;
                        if ready {
                            logger.log(LogLevel::Info, None,
                                Some("daemon".into()),
                                "coordinator reported that all nodes are ready, starting dataflow",
                            ).await;
                            dataflow.start(&self.events_tx, &self.clock).await?;
                        }
                    }
                    None => {
                        tracing::warn!(
                            "received AllNodesReady for unknown dataflow (ID `{dataflow_id}`)"
                        );
                    }
                }
                let _ = reply_tx.send(None).map_err(|_| {
                    error!("could not send `AllNodesReady` reply from daemon to coordinator")
                });
                RunStatus::Continue
            }
            DaemonCoordinatorEvent::Logs {
                dataflow_id,
                node_id,
                tail,
            } => {
                match self.working_dir.get(&dataflow_id) {
                    Some(working_dir) => {
                        let working_dir = working_dir.clone();
                        tokio::spawn(async move {
                            let logs = async {
                                let mut file =
                                    File::open(log::log_path(&working_dir, &dataflow_id, &node_id))
                                        .await
                                        .wrap_err(format!(
                                            "Could not open log file: {:#?}",
                                            log::log_path(&working_dir, &dataflow_id, &node_id)
                                        ))?;

                                let mut contents = match tail {
                                    None | Some(0) => {
                                        let mut contents = vec![];
                                        file.read_to_end(&mut contents).await.map(|_| contents)
                                    }
                                    Some(tail) => read_last_n_lines(&mut file, tail).await,
                                }
                                .wrap_err("Could not read last n lines of log file")?;
                                if !contents.ends_with(b"\n") {
                                    // Append newline for better readability
                                    contents.push(b'\n');
                                }
                                Result::<Vec<u8>, eyre::Report>::Ok(contents)
                            }
                            .await
                            .map_err(|err| format!("{err:?}"));
                            let _ = reply_tx
                                .send(Some(DaemonCoordinatorReply::Logs(logs)))
                                .map_err(|_| {
                                    error!("could not send logs reply from daemon to coordinator")
                                });
                        });
                    }
                    None => {
                        tracing::warn!("received Logs for unknown dataflow (ID `{dataflow_id}`)");
                        let _ = reply_tx.send(None).map_err(|_| {
                            error!(
                                "could not send `AllNodesReady` reply from daemon to coordinator"
                            )
                        });
                    }
                }
                RunStatus::Continue
            }
            DaemonCoordinatorEvent::ReloadDataflow {
                dataflow_id,
                node_id,
                operator_id,
            } => {
                let result = self.send_reload(dataflow_id, node_id, operator_id).await;
                let reply =
                    DaemonCoordinatorReply::ReloadResult(result.map_err(|err| format!("{err:?}")));
                let _ = reply_tx
                    .send(Some(reply))
                    .map_err(|_| error!("could not send reload reply from daemon to coordinator"));
                RunStatus::Continue
            }
            DaemonCoordinatorEvent::StopDataflow {
                dataflow_id,
                grace_duration,
                force,
            } => {
                let mut logger = self.logger.for_dataflow(dataflow_id);
                let dataflow = self
                    .running
                    .get_mut(&dataflow_id)
                    .wrap_err_with(|| format!("no running dataflow with ID `{dataflow_id}`"));
                let (reply, future) = match dataflow {
                    Ok(dataflow) => {
                        let future = dataflow.stop_all(
                            &mut self.coordinator_connection,
                            &self.clock,
                            grace_duration,
                            force,
                            &mut logger,
                        );
                        (Ok(()), Some(future))
                    }
                    Err(err) => (Err(err.to_string()), None),
                };

                let _ = reply_tx
                    .send(Some(DaemonCoordinatorReply::StopResult(reply)))
                    .map_err(|_| error!("could not send stop reply from daemon to coordinator"));

                if let Some(future) = future {
                    future.await?;
                }

                RunStatus::Continue
            }
            DaemonCoordinatorEvent::Destroy => {
                tracing::info!("received destroy command -> exiting");
                let (notify_tx, notify_rx) = oneshot::channel();
                let reply = DaemonCoordinatorReply::DestroyResult {
                    result: Ok(()),
                    notify: Some(notify_tx),
                };
                let _ = reply_tx
                    .send(Some(reply))
                    .map_err(|_| error!("could not send destroy reply from daemon to coordinator"));
                // wait until the reply is sent out
                if notify_rx.await.is_err() {
                    tracing::warn!("no confirmation received for DestroyReply");
                }
                RunStatus::Exit
            }
            DaemonCoordinatorEvent::Heartbeat => {
                self.last_coordinator_heartbeat = Instant::now();
                let _ = reply_tx.send(None);
                RunStatus::Continue
            }
        };
        Ok(status)
    }

    async fn collect_and_send_metrics(&mut self) -> eyre::Result<()> {
        use dora_message::daemon_to_coordinator::NodeMetrics;
        use sysinfo::{Pid, ProcessRefreshKind, ProcessesToUpdate};

        if self.coordinator_connection.is_none() {
            return Ok(());
        }

        // Reuse system instance for metrics collection
        let system = &mut self.metrics_system;

        // Metrics are collected every 2 seconds (metrics_interval)
        const METRICS_INTERVAL_SECS: f64 = 2.0;

        // Collect metrics for all running dataflows
        for (dataflow_id, dataflow) in &self.running {
            let mut metrics = BTreeMap::new();

            // Collect all PIDs for this dataflow
            let pids: Vec<Pid> = dataflow
                .running_nodes
                .values()
                .filter_map(|node| {
                    node.pid
                        .as_ref()
                        .map(|pid| Pid::from_u32(pid.load(atomic::Ordering::Acquire)))
                })
                .collect();

            if !pids.is_empty() {
                // Refresh process metrics (cpu, memory, disk)
                let refresh_kind = ProcessRefreshKind::nothing()
                    .with_cpu()
                    .with_memory()
                    .with_disk_usage();
                system.refresh_processes_specifics(
                    ProcessesToUpdate::Some(&pids),
                    true,
                    refresh_kind,
                );

                // Collect metrics for each node
                for (node_id, running_node) in &dataflow.running_nodes {
                    if let Some(pid) = running_node.pid.as_ref() {
                        let pid = pid.load(atomic::Ordering::Acquire);
                        let sys_pid = Pid::from_u32(pid);
                        if let Some(process) = system.process(sys_pid) {
                            let disk_usage = process.disk_usage();
                            // Divide by metrics_interval to get per-second averages
                            metrics.insert(
                                node_id.clone(),
                                NodeMetrics {
                                    pid,
                                    cpu_usage: process.cpu_usage(),
                                    memory_bytes: process.memory(),
                                    disk_read_bytes: Some(
                                        (disk_usage.read_bytes as f64 / METRICS_INTERVAL_SECS)
                                            as u64,
                                    ),
                                    disk_write_bytes: Some(
                                        (disk_usage.written_bytes as f64 / METRICS_INTERVAL_SECS)
                                            as u64,
                                    ),
                                },
                            );
                        }
                    }
                }
            }

            // Send metrics to coordinator if we have any
            if !metrics.is_empty() {
                if let Some(connection) = &mut self.coordinator_connection {
                    let msg = serde_json::to_vec(&Timestamped {
                        inner: CoordinatorRequest::Event {
                            daemon_id: self.daemon_id.clone(),
                            event: DaemonEvent::NodeMetrics {
                                dataflow_id: *dataflow_id,
                                metrics,
                            },
                        },
                        timestamp: self.clock.new_timestamp(),
                    })?;
                    socket_stream_send(connection, &msg)
                        .await
                        .wrap_err("failed to send metrics to coordinator")?;
                }
            }
        }

        Ok(())
    }

    async fn handle_inter_daemon_event(&mut self, event: InterDaemonEvent) -> eyre::Result<()> {
        match event {
            InterDaemonEvent::Output {
                dataflow_id,
                node_id,
                output_id,
                metadata,
                data,
            } => {
                let inner = async {
                    let dataflow = self.running.get_mut(&dataflow_id).wrap_err_with(|| {
                        format!("send out failed: no running dataflow with ID `{dataflow_id}`")
                    })?;
                    send_output_to_local_receivers(
                        node_id.clone(),
                        output_id.clone(),
                        dataflow,
                        &metadata,
                        data.map(DataMessage::Vec),
                        &self.clock,
                    )
                    .await?;
                    Result::<_, eyre::Report>::Ok(())
                };
                if let Err(err) = inner
                    .await
                    .wrap_err("failed to forward remote output to local receivers")
                {
                    let mut logger = self.logger.for_dataflow(dataflow_id).for_node(node_id);
                    logger
                        .log(LogLevel::Warn, Some("daemon".into()), format!("{err:?}"))
                        .await;
                }
                Ok(())
            }
            InterDaemonEvent::OutputClosed {
                dataflow_id,
                node_id,
                output_id,
            } => {
                let output_id = OutputId(node_id.clone(), output_id);
                let mut logger = self
                    .logger
                    .for_dataflow(dataflow_id)
                    .for_node(node_id.clone());
                logger
                    .log(
                        LogLevel::Debug,
                        Some("daemon".into()),
                        format!("received OutputClosed event for output {output_id:?}"),
                    )
                    .await;

                let inner = async {
                    let dataflow = self.running.get_mut(&dataflow_id).wrap_err_with(|| {
                        format!("send out failed: no running dataflow with ID `{dataflow_id}`")
                    })?;

                    if let Some(inputs) = dataflow.mappings.get(&output_id).cloned() {
                        for (receiver_id, input_id) in &inputs {
                            close_input(dataflow, receiver_id, input_id, &self.clock);
                        }
                    }
                    Result::<(), eyre::Report>::Ok(())
                };
                if let Err(err) = inner
                    .await
                    .wrap_err("failed to handle InputsClosed event sent by coordinator")
                {
                    logger
                        .log(LogLevel::Warn, Some("daemon".into()), format!("{err:?}"))
                        .await;
                }
                Ok(())
            }
        }
    }

    #[allow(clippy::too_many_arguments)]
    async fn build_dataflow(
        &mut self,
        build_id: BuildId,
        session_id: SessionId,
        base_working_dir: PathBuf,
        git_sources: BTreeMap<NodeId, GitSource>,
        prev_git_sources: BTreeMap<NodeId, GitSource>,
        dataflow_descriptor: Descriptor,
        local_nodes: BTreeSet<NodeId>,
        uv: bool,
    ) -> eyre::Result<impl Future<Output = eyre::Result<BuildInfo>> + use<>> {
        let builder = build::Builder {
            session_id,
            base_working_dir,
            uv,
        };
        self.git_manager.clear_planned_builds(session_id);

        let nodes = dataflow_descriptor.resolve_aliases_and_set_defaults()?;

        let mut tasks = Vec::new();

        // build nodes
        for node in nodes.into_values().filter(|n| local_nodes.contains(&n.id)) {
            let dynamic_node = node.kind.dynamic();

            let node_id = node.id.clone();
            let mut logger = self.logger.for_node_build(build_id, node_id.clone());
            logger.log(LogLevel::Debug, "building").await;
            let git_source = git_sources.get(&node_id).cloned();
            let prev_git_source = prev_git_sources.get(&node_id).cloned();
            let prev_git = prev_git_source.map(|prev_source| PrevGitSource {
                still_needed_for_this_build: git_sources.values().any(|s| s == &prev_source),
                git_source: prev_source,
            });

            let logger_cloned = logger
                .try_clone_impl()
                .await
                .wrap_err("failed to clone logger")?;

            let mut builder = builder.clone();
            if let Some(node_working_dir) =
                node.deploy.as_ref().and_then(|d| d.working_dir.as_deref())
            {
                builder.base_working_dir = builder.base_working_dir.join(node_working_dir);
            }

            match builder
                .build_node(
                    node,
                    git_source,
                    prev_git,
                    logger_cloned,
                    &mut self.git_manager,
                )
                .await
                .wrap_err_with(|| format!("failed to build node `{node_id}`"))
            {
                Ok(result) => {
                    tasks.push(NodeBuildTask {
                        node_id,
                        task: result,
                        dynamic_node,
                    });
                }
                Err(err) => {
                    logger.log(LogLevel::Error, format!("{err:?}")).await;
                    return Err(err);
                }
            }
        }

        let task = async move {
            let mut info = BuildInfo {
                node_working_dirs: Default::default(),
            };
            for task in tasks {
                let NodeBuildTask {
                    node_id,
                    dynamic_node: _,
                    task,
                } = task;
                let node = task
                    .await
                    .with_context(|| format!("failed to build node `{node_id}`"))?;
                info.node_working_dirs
                    .insert(node_id, node.node_working_dir);
            }
            Ok(info)
        };

        Ok(task)
    }

    #[allow(clippy::too_many_arguments)]
    async fn spawn_dataflow(
        &mut self,
        build_id: Option<BuildId>,
        dataflow_id: DataflowId,
        base_working_dir: PathBuf,
        nodes: BTreeMap<NodeId, ResolvedNode>,
        dataflow_descriptor: Descriptor,
        spawn_nodes: BTreeSet<NodeId>,
        uv: bool,
        write_events_to: Option<PathBuf>,
    ) -> eyre::Result<impl Future<Output = eyre::Result<()>> + use<>> {
        let mut logger = self
            .logger
            .for_dataflow(dataflow_id)
            .try_clone()
            .await
            .context("failed to clone logger")?;
        let dataflow =
            RunningDataflow::new(dataflow_id, self.daemon_id.clone(), &dataflow_descriptor);
        let dataflow = match self.running.entry(dataflow_id) {
            std::collections::hash_map::Entry::Vacant(entry) => {
                self.working_dir
                    .insert(dataflow_id, base_working_dir.clone());
                entry.insert(dataflow)
            }
            std::collections::hash_map::Entry::Occupied(_) => {
                bail!("there is already a running dataflow with ID `{dataflow_id}`")
            }
        };

        let mut stopped = Vec::new();

        let build_info = build_id.and_then(|build_id| self.builds.get(&build_id));
        let node_with_git_source = nodes.values().find(|n| n.has_git_source());
        if let Some(git_node) = node_with_git_source {
            if build_info.is_none() {
                eyre::bail!(
                    "node {} has git source, but no `dora build` was run yet\n\n\
                    nodes with a `git` field must be built using `dora build` before starting the \
                    dataflow",
                    git_node.id
                )
            }
        }
        let node_working_dirs = build_info
            .map(|info| info.node_working_dirs.clone())
            .unwrap_or_default();

        // calculate info about mappings
        for node in nodes.values() {
            let local = spawn_nodes.contains(&node.id);

            let inputs = node_inputs(node);
            for (input_id, input) in inputs {
                if local {
                    dataflow
                        .open_inputs
                        .entry(node.id.clone())
                        .or_default()
                        .insert(input_id.clone());
                    match input.mapping {
                        InputMapping::User(mapping) => {
                            dataflow
                                .mappings
                                .entry(OutputId(mapping.source, mapping.output))
                                .or_default()
                                .insert((node.id.clone(), input_id));
                        }
                        InputMapping::Timer { interval } => {
                            dataflow
                                .timers
                                .entry(interval)
                                .or_default()
                                .insert((node.id.clone(), input_id));
                        }
                    }
                } else if let InputMapping::User(mapping) = input.mapping {
                    dataflow
                        .open_external_mappings
                        .insert(OutputId(mapping.source, mapping.output));
                }
            }
        }

        let spawner = Spawner {
            dataflow_id,
            daemon_tx: self.events_tx.clone(),
            dataflow_descriptor,
            clock: self.clock.clone(),
            uv,
        };

        let mut tasks = Vec::new();

        // spawn nodes and set up subscriptions
        for node in nodes.into_values() {
            let mut logger = logger.reborrow().for_node(node.id.clone());
            let local = spawn_nodes.contains(&node.id);
            if local {
                let dynamic_node = node.kind.dynamic();
                if dynamic_node {
                    dataflow.dynamic_nodes.insert(node.id.clone());
                } else {
                    dataflow.pending_nodes.insert(node.id.clone());
                }

                let node_id = node.id.clone();
                let node_stderr_most_recent = dataflow
                    .node_stderr_most_recent
                    .entry(node.id.clone())
                    .or_insert_with(|| Arc::new(ArrayQueue::new(STDERR_LOG_LINES)))
                    .clone();

                let configured_node_working_dir = node_working_dirs.get(&node_id).cloned();
                if configured_node_working_dir.is_none() && node.has_git_source() {
                    eyre::bail!(
                        "node {} has git source, but no git clone directory was found for it\n\n\
                        try running `dora build` again",
                        node.id
                    )
                }
                let node_working_dir = configured_node_working_dir
                    .or_else(|| {
                        node.deploy
                            .as_ref()
                            .and_then(|d| d.working_dir.as_ref().map(|d| base_working_dir.join(d)))
                    })
                    .unwrap_or(base_working_dir.clone())
                    .clone();
                let node_write_events_to = write_events_to
                    .as_ref()
                    .map(|p| p.join(format!("inputs-{}.json", node.id)));
                match spawner
                    .clone()
                    .spawn_node(
                        node,
                        node_working_dir,
                        node_stderr_most_recent,
                        node_write_events_to,
                        &mut logger,
                    )
                    .await
                    .wrap_err_with(|| format!("failed to spawn node `{node_id}`"))
                {
                    Ok(result) => {
                        tasks.push(NodeBuildTask {
                            node_id,
                            task: result,
                            dynamic_node,
                        });
                    }
                    Err(err) => {
                        logger
                            .log(LogLevel::Error, Some("daemon".into()), format!("{err:?}"))
                            .await;
                        self.dataflow_node_results
                            .entry(dataflow_id)
                            .or_default()
                            .insert(
                                node_id.clone(),
                                Err(NodeError {
                                    timestamp: self.clock.new_timestamp(),
                                    cause: NodeErrorCause::FailedToSpawn(format!("{err:?}")),
                                    exit_status: NodeExitStatus::Unknown,
                                }),
                            );
                        stopped.push((node_id.clone(), dynamic_node));
                    }
                }
            } else {
                // wait until node is ready before starting
                dataflow.pending_nodes.set_external_nodes(true);

                // subscribe to all node outputs that are mapped to some local inputs
                for output_id in dataflow.mappings.keys().filter(|o| o.0 == node.id) {
                    let tx = self
                        .remote_daemon_events_tx
                        .clone()
                        .wrap_err("no remote_daemon_events_tx channel")?;
                    let mut finished_rx = dataflow.finished_tx.subscribe();
                    let subscribe_topic =
                        zenoh_output_publish_topic(dataflow.id, &output_id.0, &output_id.1);
                    tracing::debug!("declaring subscriber on {subscribe_topic}");
                    let subscriber = self
                        .zenoh_session
                        .declare_subscriber(subscribe_topic)
                        .await
                        .map_err(|e| eyre!(e))
                        .wrap_err_with(|| format!("failed to subscribe to {output_id:?}"))?;
                    tokio::spawn(async move {
                        let mut finished = pin!(finished_rx.recv());
                        loop {
                            let finished_or_next =
                                futures::future::select(finished, subscriber.recv_async());
                            match finished_or_next.await {
                                future::Either::Left((finished, _)) => match finished {
                                    Err(broadcast::error::RecvError::Closed) => {
                                        tracing::debug!(
                                            "dataflow finished, breaking from zenoh subscribe task"
                                        );
                                        break;
                                    }
                                    other => {
                                        tracing::warn!(
                                            "unexpected return value of dataflow finished_rx channel: {other:?}"
                                        );
                                        break;
                                    }
                                },
                                future::Either::Right((sample, f)) => {
                                    finished = f;
                                    let event = sample.map_err(|e| eyre!(e)).and_then(|s| {
                                        Timestamped::deserialize_inter_daemon_event(
                                            &s.payload().to_bytes(),
                                        )
                                    });
                                    if tx.send_async(event).await.is_err() {
                                        // daemon finished
                                        break;
                                    }
                                }
                            }
                        }
                    });
                }
            }
        }
        for (node_id, dynamic) in stopped {
            self.handle_node_stop(dataflow_id, &node_id, dynamic)
                .await?;
        }

        let spawn_result = Self::spawn_prepared_nodes(
            dataflow_id,
            logger,
            tasks,
            self.events_tx.clone(),
            self.clock.clone(),
        );

        Ok(spawn_result)
    }

    async fn spawn_prepared_nodes(
        dataflow_id: Uuid,
        mut logger: DataflowLogger<'_>,
        tasks: Vec<NodeBuildTask<impl Future<Output = eyre::Result<spawn::PreparedNode>>>>,
        events_tx: mpsc::Sender<Timestamped<Event>>,
        clock: Arc<HLC>,
    ) -> eyre::Result<()> {
        let node_result = |node_id, dynamic_node, result| Timestamped {
            inner: Event::SpawnNodeResult {
                dataflow_id,
                node_id,
                dynamic_node,
                result,
            },
            timestamp: clock.new_timestamp(),
        };
        let mut failed_to_prepare = None;
        let mut prepared_nodes = Vec::new();
        for task in tasks {
            let NodeBuildTask {
                node_id,
                dynamic_node,
                task,
            } = task;
            match task.await {
                Ok(node) => prepared_nodes.push(node),
                Err(err) => {
                    if failed_to_prepare.is_none() {
                        failed_to_prepare = Some(node_id.clone());
                    }
                    let node_err: NodeError = NodeError {
                        timestamp: clock.new_timestamp(),
                        cause: NodeErrorCause::FailedToSpawn(format!(
                            "preparing for spawn failed: {err:?}"
                        )),
                        exit_status: NodeExitStatus::Unknown,
                    };
                    let send_result = events_tx
                        .send(node_result(node_id, dynamic_node, Err(node_err)))
                        .await;
                    if send_result.is_err() {
                        tracing::error!("failed to send SpawnNodeResult to main daemon task")
                    }
                }
            }
        }

        // once all nodes are prepared, do the actual spawning
        if let Some(failed_node) = failed_to_prepare {
            // don't spawn any nodes when an error occurred before
            for node in prepared_nodes {
                let err = NodeError {
                    timestamp: clock.new_timestamp(),
                    cause: NodeErrorCause::Cascading {
                        caused_by_node: failed_node.clone(),
                    },
                    exit_status: NodeExitStatus::Unknown,
                };
                let send_result = events_tx
                    .send(node_result(
                        node.node_id().clone(),
                        node.dynamic(),
                        Err(err),
                    ))
                    .await;
                if send_result.is_err() {
                    tracing::error!("failed to send SpawnNodeResult to main daemon task")
                }
            }
            Err(eyre!("failed to prepare node {failed_node}"))
        } else {
            let mut spawn_result = Ok(());

            logger
                .log(
                    LogLevel::Info,
                    None,
                    Some("dora daemon".into()),
                    "finished building nodes, spawning...",
                )
                .await;

            // spawn the nodes
            for node in prepared_nodes {
                let node_id = node.node_id().clone();
                let dynamic_node = node.dynamic();
                let logger = logger
                    .reborrow()
                    .for_node(node_id.clone())
                    .try_clone()
                    .await
                    .context("failed to clone NodeLogger")?;
                let result = node.spawn(logger).await;
                let node_spawn_result = match result {
                    Ok(node) => Ok(node),
                    Err(err) => {
                        let node_err = NodeError {
                            timestamp: clock.new_timestamp(),
                            cause: NodeErrorCause::FailedToSpawn(format!("spawn failed: {err:?}")),
                            exit_status: NodeExitStatus::Unknown,
                        };
                        if spawn_result.is_ok() {
                            spawn_result = Err(err.wrap_err(format!("failed to spawn {node_id}")));
                        }
                        Err(node_err)
                    }
                };
                let send_result = events_tx
                    .send(node_result(node_id, dynamic_node, node_spawn_result))
                    .await;
                if send_result.is_err() {
                    tracing::error!("failed to send SpawnNodeResult to main daemon task")
                }
            }
            spawn_result
        }
    }

    async fn handle_dynamic_node_event(
        &mut self,
        event: DynamicNodeEventWrapper,
    ) -> eyre::Result<()> {
        match event {
            DynamicNodeEventWrapper {
                event: DynamicNodeEvent::NodeConfig { node_id },
                reply_tx,
            } => {
                let number_node_id = self
                    .running
                    .iter()
                    .filter(|(_id, dataflow)| dataflow.running_nodes.contains_key(&node_id))
                    .count();

                let node_config = match number_node_id {
                    2.. => Err(format!(
                        "multiple dataflows contain dynamic node id {node_id}. \
                        Please only have one running dataflow with the specified \
                        node id if you want to use dynamic node",
                    )),
                    1 => self
                        .running
                        .iter()
                        .filter(|(_id, dataflow)| dataflow.running_nodes.contains_key(&node_id))
                        .map(|(id, dataflow)| -> Result<NodeConfig> {
                            let node_config = dataflow
                                .running_nodes
                                .get(&node_id)
                                .with_context(|| {
                                    format!("no node with ID `{node_id}` within the given dataflow")
                                })?
                                .node_config
                                .clone();
                            if !node_config.dynamic {
                                bail!("node with ID `{node_id}` in {id} is not dynamic");
                            }
                            Ok(node_config)
                        })
                        .next()
                        .ok_or_else(|| eyre!("no node with ID `{node_id}`"))
                        .and_then(|r| r)
                        .map_err(|err| {
                            format!(
                                "failed to get dynamic node config within given dataflow: {err}"
                            )
                        }),
                    0 => Err(format!("no node with ID `{node_id}`")),
                };

                let reply = DaemonReply::NodeConfig {
                    result: node_config,
                };
                let _ = reply_tx.send(Some(reply)).map_err(|_| {
                    error!("could not send node info reply from daemon to coordinator")
                });
                Ok(())
            }
        }
    }

    async fn handle_node_event(
        &mut self,
        event: DaemonNodeEvent,
        dataflow_id: DataflowId,
        node_id: NodeId,
    ) -> eyre::Result<()> {
        let might_restart = || {
            let dataflow = self.running.get(&dataflow_id)?;
            let node = dataflow.running_nodes.get(&node_id)?;
            Some(match node.restart_policy {
                RestartPolicy::Never => false,
                _ if node.restarts_disabled() => false,
                RestartPolicy::OnFailure | RestartPolicy::Always => true,
            })
        };
        match event {
            DaemonNodeEvent::Subscribe {
                event_sender,
                reply_sender,
            } => {
                let mut logger = self.logger.for_dataflow(dataflow_id);
                logger
                    .log(
                        LogLevel::Info,
                        Some(node_id.clone()),
                        Some("daemon".into()),
                        "node is ready",
                    )
                    .await;

                let dataflow = self.running.get_mut(&dataflow_id).ok_or_else(|| {
                    format!("subscribe failed: no running dataflow with ID `{dataflow_id}`")
                });

                match dataflow {
                    Err(err) => {
                        let _ = reply_sender.send(DaemonReply::Result(Err(err)));
                    }
                    Ok(dataflow) => {
                        Self::subscribe(dataflow, node_id.clone(), event_sender, &self.clock).await;

                        let status = dataflow
                            .pending_nodes
                            .handle_node_subscription(
                                node_id.clone(),
                                reply_sender,
                                &mut self.coordinator_connection,
                                &self.clock,
                                &mut dataflow.cascading_error_causes,
                                &mut logger,
                            )
                            .await?;
                        match status {
                            DataflowStatus::AllNodesReady if !dataflow.dataflow_started => {
                                logger
                                    .log(
                                        LogLevel::Info,
                                        None,
                                        Some("daemon".into()),
                                        "all nodes are ready, starting dataflow",
                                    )
                                    .await;
                                dataflow.start(&self.events_tx, &self.clock).await?;
                                dataflow.dataflow_started = true;
                            }
                            _ => {}
                        }
                    }
                }
            }
            DaemonNodeEvent::SubscribeDrop {
                event_sender,
                reply_sender,
            } => {
                let dataflow = self.running.get_mut(&dataflow_id).wrap_err_with(|| {
                    format!("failed to subscribe: no running dataflow with ID `{dataflow_id}`")
                });
                let result = match dataflow {
                    Ok(dataflow) => {
                        dataflow.drop_channels.insert(node_id, event_sender);
                        Ok(())
                    }
                    Err(err) => Err(err.to_string()),
                };
                let _ = reply_sender.send(DaemonReply::Result(result));
            }
            DaemonNodeEvent::CloseOutputs {
                outputs,
                reply_sender,
            } => {
                let reply = if might_restart().unwrap_or(false) {
                    self.logger
                        .for_dataflow(dataflow_id)
                        .for_node(node_id.clone())
                        .log(
                            LogLevel::Debug,
                            Some("daemon".into()),
                            "skipping CloseOutputs because node might restart",
                        )
                        .await;
                    Ok(())
                } else {
                    // notify downstream nodes
                    let inner = async {
                        self.send_output_closed_events(dataflow_id, node_id, outputs)
                            .await
                    };

                    inner.await.map_err(|err| format!("{err:?}"))
                };
                let _ = reply_sender.send(DaemonReply::Result(reply));
            }
            DaemonNodeEvent::OutputsDone { reply_sender } => {
                let result = self
                    .handle_outputs_done(dataflow_id, &node_id, might_restart().unwrap_or(false))
                    .await;

                let _ = reply_sender.send(DaemonReply::Result(
                    result.map_err(|err| format!("{err:?}")),
                ));
            }
            DaemonNodeEvent::SendOut {
                output_id,
                metadata,
                data,
            } => self
                .send_out(dataflow_id, node_id, output_id, metadata, data)
                .await
                .context("failed to send out")?,
            DaemonNodeEvent::ReportDrop { tokens } => {
                let dataflow = self.running.get_mut(&dataflow_id).wrap_err_with(|| {
                    format!(
                        "failed to get handle drop tokens: \
                        no running dataflow with ID `{dataflow_id}`"
                    )
                });

                match dataflow {
                    Ok(dataflow) => {
                        for token in tokens {
                            match dataflow.pending_drop_tokens.get_mut(&token) {
                                Some(info) => {
                                    if info.pending_nodes.remove(&node_id) {
                                        dataflow.check_drop_token(token, &self.clock).await?;
                                    } else {
                                        tracing::warn!(
                                            "node `{node_id}` is not pending for drop token `{token:?}`"
                                        );
                                    }
                                }
                                None => tracing::warn!("unknown drop token `{token:?}`"),
                            }
                        }
                    }
                    Err(err) => tracing::warn!("{err:?}"),
                }
            }
            DaemonNodeEvent::EventStreamDropped { reply_sender } => {
                let inner = async {
                    let dataflow = self
                        .running
                        .get_mut(&dataflow_id)
                        .wrap_err_with(|| format!("no running dataflow with ID `{dataflow_id}`"))?;
                    dataflow.subscribe_channels.remove(&node_id);
                    Result::<_, eyre::Error>::Ok(())
                };

                let reply = inner.await.map_err(|err| format!("{err:?}"));
                let _ = reply_sender.send(DaemonReply::Result(reply));
            }
        }
        Ok(())
    }

    async fn send_reload(
        &mut self,
        dataflow_id: Uuid,
        node_id: NodeId,
        operator_id: Option<OperatorId>,
    ) -> Result<(), eyre::ErrReport> {
        let dataflow = self.running.get_mut(&dataflow_id).wrap_err_with(|| {
            format!("Reload failed: no running dataflow with ID `{dataflow_id}`")
        })?;
        if let Some(channel) = dataflow.subscribe_channels.get(&node_id) {
            match send_with_timestamp(channel, NodeEvent::Reload { operator_id }, &self.clock) {
                Ok(()) => {}
                Err(_) => {
                    dataflow.subscribe_channels.remove(&node_id);
                }
            }
        }
        Ok(())
    }

    async fn send_out(
        &mut self,
        dataflow_id: Uuid,
        node_id: NodeId,
        output_id: DataId,
        metadata: dora_message::metadata::Metadata,
        data: Option<DataMessage>,
    ) -> Result<(), eyre::ErrReport> {
        let dataflow = self.running.get_mut(&dataflow_id).wrap_err_with(|| {
            format!("send out failed: no running dataflow with ID `{dataflow_id}`")
        })?;
        let data_bytes = send_output_to_local_receivers(
            node_id.clone(),
            output_id.clone(),
            dataflow,
            &metadata,
            data,
            &self.clock,
        )
        .await?;

        let output_id = OutputId(node_id, output_id);
        let remote_receivers = dataflow.open_external_mappings.contains(&output_id)
            || dataflow.publish_all_messages_to_zenoh;
        if remote_receivers {
            let event = InterDaemonEvent::Output {
                dataflow_id,
                node_id: output_id.0.clone(),
                output_id: output_id.1.clone(),
                metadata,
                data: data_bytes,
            };
            self.send_to_remote_receivers(dataflow_id, &output_id, event)
                .await?;
        }

        Ok(())
    }

    async fn send_to_remote_receivers(
        &mut self,
        dataflow_id: Uuid,
        output_id: &OutputId,
        event: InterDaemonEvent,
    ) -> Result<(), eyre::Error> {
        let dataflow = self.running.get_mut(&dataflow_id).wrap_err_with(|| {
            format!("send out failed: no running dataflow with ID `{dataflow_id}`")
        })?;

        // publish via zenoh
        let publisher = match dataflow.publishers.get(output_id) {
            Some(publisher) => publisher,
            None => {
                let publish_topic =
                    zenoh_output_publish_topic(dataflow.id, &output_id.0, &output_id.1);
                tracing::debug!("declaring publisher on {publish_topic}");
                let publisher = self
                    .zenoh_session
                    .declare_publisher(publish_topic)
                    .await
                    .map_err(|e| eyre!(e))
                    .context("failed to create zenoh publisher")?;
                dataflow.publishers.insert(output_id.clone(), publisher);
                dataflow.publishers.get(output_id).unwrap()
            }
        };

        let serialized_event = Timestamped {
            inner: event,
            timestamp: self.clock.new_timestamp(),
        }
        .serialize();
        publisher
            .put(serialized_event)
            .await
            .map_err(|e| eyre!(e))
            .context("zenoh put failed")?;
        Ok(())
    }

    async fn send_output_closed_events(
        &mut self,
        dataflow_id: DataflowId,
        node_id: NodeId,
        outputs: Vec<DataId>,
    ) -> eyre::Result<()> {
        let dataflow = self
            .running
            .get_mut(&dataflow_id)
            .wrap_err_with(|| format!("no running dataflow with ID `{dataflow_id}`"))?;
        let local_node_inputs: BTreeSet<_> = dataflow
            .mappings
            .iter()
            .filter(|(k, _)| k.0 == node_id && outputs.contains(&k.1))
            .flat_map(|(_, v)| v)
            .cloned()
            .collect();
        for (receiver_id, input_id) in &local_node_inputs {
            close_input(dataflow, receiver_id, input_id, &self.clock);
        }

        let mut closed = Vec::new();
        for output_id in &dataflow.open_external_mappings {
            if output_id.0 == node_id && outputs.contains(&output_id.1) {
                closed.push(output_id.clone());
            }
        }

        for output_id in closed {
            let event = InterDaemonEvent::OutputClosed {
                dataflow_id,
                node_id: output_id.0.clone(),
                output_id: output_id.1.clone(),
            };
            self.send_to_remote_receivers(dataflow_id, &output_id, event)
                .await?;
        }

        Ok(())
    }

    async fn subscribe(
        dataflow: &mut RunningDataflow,
        node_id: NodeId,
        event_sender: UnboundedSender<Timestamped<NodeEvent>>,
        clock: &HLC,
    ) {
        // some inputs might have been closed already -> report those events
        let closed_inputs = dataflow
            .mappings
            .values()
            .flatten()
            .filter(|(node, _)| node == &node_id)
            .map(|(_, input)| input)
            .filter(|input| {
                dataflow
                    .open_inputs
                    .get(&node_id)
                    .map(|open_inputs| !open_inputs.contains(*input))
                    .unwrap_or(true)
            });
        for input_id in closed_inputs {
            let _ = send_with_timestamp(
                &event_sender,
                NodeEvent::InputClosed {
                    id: input_id.clone(),
                },
                clock,
            );
        }
        if dataflow.open_inputs(&node_id).is_empty() {
            if let Some(node) = dataflow.running_nodes.get_mut(&node_id) {
                node.disable_restart();
            }
            let _ = send_with_timestamp(&event_sender, NodeEvent::AllInputsClosed, clock);
        }

        // if a stop event was already sent for the dataflow, send it to
        // the newly connected node too
        if dataflow.stop_sent {
            if let Some(node) = dataflow.running_nodes.get_mut(&node_id) {
                node.disable_restart();
            }
            let _ = send_with_timestamp(&event_sender, NodeEvent::Stop, clock);
        }

        dataflow.subscribe_channels.insert(node_id, event_sender);
    }

    #[tracing::instrument(skip(self), level = "trace")]
    async fn handle_outputs_done(
        &mut self,
        dataflow_id: DataflowId,
        node_id: &NodeId,
        might_restart: bool,
    ) -> eyre::Result<()> {
        let dataflow = self
            .running
            .get_mut(&dataflow_id)
            .ok_or_else(|| eyre!("no running dataflow with ID `{dataflow_id}`"))?;

        let outputs = dataflow
            .mappings
            .keys()
            .filter(|m| &m.0 == node_id)
            .map(|m| &m.1)
            .cloned()
            .collect();

        if might_restart {
            self.logger
                .for_dataflow(dataflow_id)
                .for_node(node_id.clone())
                .log(
                    LogLevel::Debug,
                    Some("daemon".into()),
                    "keeping outputs open because node might restart",
                )
                .await;
        } else {
            self.send_output_closed_events(dataflow_id, node_id.clone(), outputs)
                .await?;
        }

        let dataflow = self
            .running
            .get_mut(&dataflow_id)
            .ok_or_else(|| eyre!("no running dataflow with ID `{dataflow_id}`"))?;
        dataflow.drop_channels.remove(node_id);
        Ok(())
    }

    async fn handle_node_stop(
        &mut self,
        dataflow_id: Uuid,
        node_id: &NodeId,
        dynamic_node: bool,
    ) -> eyre::Result<()> {
        let result = self
            .handle_node_stop_inner(dataflow_id, node_id, dynamic_node)
            .await;
        let _ = self
            .events_tx
            .send(Timestamped {
                inner: Event::NodeStopped {
                    dataflow_id,
                    node_id: node_id.clone(),
                },
                timestamp: self.clock.new_timestamp(),
            })
            .await;
        result
    }

    async fn handle_node_stop_inner(
        &mut self,
        dataflow_id: Uuid,
        node_id: &NodeId,
        dynamic_node: bool,
    ) -> eyre::Result<()> {
        let mut logger = self.logger.for_dataflow(dataflow_id);
        let dataflow = match self.running.get_mut(&dataflow_id) {
            Some(dataflow) => dataflow,
            None if dynamic_node => {
                // The dataflow might be done already as we don't wait for dynamic nodes. In this
                // case, we don't need to do anything to handle the node stop.
                tracing::debug!(
                    "dynamic node {dataflow_id}/{node_id} stopped after dataflow was done"
                );
                return Ok(());
            }
            None => eyre::bail!(
                "failed to get downstream nodes: no running dataflow with ID `{dataflow_id}`"
            ),
        };

        dataflow
            .pending_nodes
            .handle_node_stop(
                node_id,
                &mut self.coordinator_connection,
                &self.clock,
                &mut dataflow.cascading_error_causes,
                &mut logger,
            )
            .await?;

        // node only reaches here if it will not be restarted
        let might_restart = false;

        self.handle_outputs_done(dataflow_id, node_id, might_restart)
            .await?;

        let mut logger = self.logger.for_dataflow(dataflow_id);
        let dataflow = self.running.get_mut(&dataflow_id).wrap_err_with(|| {
            format!("failed to get downstream nodes: no running dataflow with ID `{dataflow_id}`")
        })?;
        dataflow.running_nodes.remove(node_id);
        if !dataflow.pending_nodes.local_nodes_pending()
            && dataflow
                .running_nodes
                .iter()
                .all(|(_id, n)| n.node_config.dynamic)
        {
            let result = DataflowDaemonResult {
                timestamp: self.clock.new_timestamp(),
                node_results: self
                    .dataflow_node_results
                    .get(&dataflow.id)
                    .context("failed to get dataflow node results")?
                    .clone(),
            };

            self.git_manager
                .clones_in_use
                .values_mut()
                .for_each(|dataflows| {
                    dataflows.remove(&dataflow_id);
                });

            logger
                .log(
                    LogLevel::Info,
                    None,
                    Some("daemon".into()),
                    format!("dataflow finished on machine `{}`", self.daemon_id),
                )
                .await;
            if let Some(connection) = &mut self.coordinator_connection {
                let msg = serde_json::to_vec(&Timestamped {
                    inner: CoordinatorRequest::Event {
                        daemon_id: self.daemon_id.clone(),
                        event: DaemonEvent::AllNodesFinished {
                            dataflow_id,
                            result,
                        },
                    },
                    timestamp: self.clock.new_timestamp(),
                })?;
                socket_stream_send(connection, &msg)
                    .await
                    .wrap_err("failed to report dataflow finish to dora-coordinator")?;
            }
            self.running.remove(&dataflow_id);
        }

        Ok(())
    }

    async fn handle_dora_event(&mut self, event: DoraEvent) -> eyre::Result<()> {
        match event {
            DoraEvent::Timer {
                dataflow_id,
                interval,
                metadata,
            } => {
                let Some(dataflow) = self.running.get_mut(&dataflow_id) else {
                    tracing::warn!("Timer event for unknown dataflow `{dataflow_id}`");
                    return Ok(());
                };

                let Some(subscribers) = dataflow.timers.get(&interval) else {
                    return Ok(());
                };

                let mut closed = Vec::new();
                for (receiver_id, input_id) in subscribers {
                    let Some(channel) = dataflow.subscribe_channels.get(receiver_id) else {
                        continue;
                    };

                    let send_result = send_with_timestamp(
                        channel,
                        NodeEvent::Input {
                            id: input_id.clone(),
                            metadata: metadata.clone(),
                            data: None,
                        },
                        &self.clock,
                    );
                    match send_result {
                        Ok(()) => {}
                        Err(_) => {
                            closed.push(receiver_id);
                        }
                    }
                }
                for id in closed {
                    dataflow.subscribe_channels.remove(id);
                }
            }
            DoraEvent::Logs {
                dataflow_id,
                output_id,
                message,
                metadata,
            } => {
                let Some(dataflow) = self.running.get_mut(&dataflow_id) else {
                    tracing::warn!("Logs event for unknown dataflow `{dataflow_id}`");
                    return Ok(());
                };

                let Some(subscribers) = dataflow.mappings.get(&output_id) else {
                    tracing::warn!(
                        "No subscribers found for {:?} in {:?}",
                        output_id,
                        dataflow.mappings
                    );
                    return Ok(());
                };

                let mut closed = Vec::new();
                for (receiver_id, input_id) in subscribers {
                    let Some(channel) = dataflow.subscribe_channels.get(receiver_id) else {
                        tracing::warn!("No subscriber channel found for {:?}", output_id);
                        continue;
                    };

                    let send_result = send_with_timestamp(
                        channel,
                        NodeEvent::Input {
                            id: input_id.clone(),
                            metadata: metadata.clone(),
                            data: Some(message.clone()),
                        },
                        &self.clock,
                    );
                    match send_result {
                        Ok(()) => {}
                        Err(_) => {
                            closed.push(receiver_id);
                        }
                    }
                }
                for id in closed {
                    dataflow.subscribe_channels.remove(id);
                }
            }
            DoraEvent::SpawnedNodeResult {
                dataflow_id,
                node_id,
                dynamic_node,
                exit_status,
                restart,
            } => {
                let mut logger = self
                    .logger
                    .for_dataflow(dataflow_id)
                    .for_node(node_id.clone());
                logger
                    .log(
                        LogLevel::Debug,
                        Some("daemon".into()),
                        format!("handling node stop with exit status {exit_status:?} (restart: {restart})"),
                    )
                    .await;

                let node_result = match exit_status {
                    NodeExitStatus::Success => Ok(()),
                    exit_status => {
                        let dataflow = self.running.get(&dataflow_id);
                        let caused_by_node = dataflow
                            .and_then(|dataflow| {
                                dataflow.cascading_error_causes.error_caused_by(&node_id)
                            })
                            .cloned();
                        let grace_duration_kill = dataflow
                            .map(|d| d.grace_duration_kills.contains(&node_id))
                            .unwrap_or_default();

                        let cause = match caused_by_node {
                            Some(caused_by_node) => {
                                logger
                                    .log(
                                        LogLevel::Info,
                                        Some("daemon".into()),
                                        format!("marking `{node_id}` as cascading error caused by `{caused_by_node}`")
                                    )
                                    .await;

                                NodeErrorCause::Cascading { caused_by_node }
                            }
                            None if grace_duration_kill => NodeErrorCause::GraceDuration,
                            None => {
                                let cause = dataflow
                                    .and_then(|d| d.node_stderr_most_recent.get(&node_id))
                                    .map(|queue| {
                                        let mut s = if queue.is_full() {
                                            "[...]".into()
                                        } else {
                                            String::new()
                                        };
                                        while let Some(line) = queue.pop() {
                                            s += &line;
                                        }
                                        s
                                    })
                                    .unwrap_or_default();

                                NodeErrorCause::Other { stderr: cause }
                            }
                        };
                        Err(NodeError {
                            timestamp: self.clock.new_timestamp(),
                            cause,
                            exit_status,
                        })
                    }
                };

                logger
                    .log(
                        if node_result.is_ok() {
                            LogLevel::Info
                        } else {
                            LogLevel::Error
                        },
                        Some("daemon".into()),
                        match &node_result {
                            Ok(()) => format!("{node_id} finished successfully"),
                            Err(err) => format!("{err}"),
                        },
                    )
                    .await;

                if restart {
                    logger
                        .log(
                            LogLevel::Info,
                            Some("daemon".into()),
                            "node will be restarted",
                        )
                        .await;
                } else {
                    self.dataflow_node_results
                        .entry(dataflow_id)
                        .or_default()
                        .insert(node_id.clone(), node_result);

                    self.handle_node_stop(dataflow_id, &node_id, dynamic_node)
                        .await?;
                }
            }
        }
        Ok(())
    }

    fn base_working_dir(
        &self,
        local_working_dir: Option<PathBuf>,
        session_id: SessionId,
    ) -> eyre::Result<PathBuf> {
        match local_working_dir {
            Some(working_dir) => {
                // check that working directory exists
                if working_dir.exists() {
                    Ok(working_dir)
                } else {
                    bail!(
                        "working directory does not exist: {}",
                        working_dir.display(),
                    )
                }
            }
            None => {
                // use subfolder of daemon working dir
                let daemon_working_dir =
                    current_dir().context("failed to get daemon working dir")?;
                Ok(daemon_working_dir
                    .join("_work")
                    .join(session_id.uuid().to_string()))
            }
        }
    }
}

async fn read_last_n_lines(file: &mut File, mut tail: usize) -> io::Result<Vec<u8>> {
    let mut pos = file.seek(io::SeekFrom::End(0)).await?;

    let mut output = VecDeque::<u8>::new();
    let mut extend_slice_to_start = |slice: &[u8]| {
        output.extend(slice);
        output.rotate_right(slice.len());
    };

    let mut buffer = vec![0; 2048];
    let mut estimated_line_length = 0;
    let mut at_end = true;
    'main: while tail > 0 && pos > 0 {
        let new_pos = pos.saturating_sub(buffer.len() as u64);
        file.seek(io::SeekFrom::Start(new_pos)).await?;
        let read_len = (pos - new_pos) as usize;
        pos = new_pos;

        file.read_exact(&mut buffer[..read_len]).await?;
        let read_buf = if at_end {
            at_end = false;
            &buffer[..read_len].trim_ascii_end()
        } else {
            &buffer[..read_len]
        };

        let mut iter = memchr::memrchr_iter(b'\n', read_buf);
        let mut lines = 1;
        loop {
            let Some(pos) = iter.next() else {
                extend_slice_to_start(read_buf);
                break;
            };
            lines += 1;
            tail -= 1;
            if tail == 0 {
                extend_slice_to_start(&read_buf[(pos + 1)..]);
                break 'main;
            }
        }

        estimated_line_length = estimated_line_length.max((read_buf.len() + 1).div_ceil(lines));
        let estimated_buffer_length = estimated_line_length * tail;
        if estimated_buffer_length >= buffer.len() * 2 {
            buffer.resize(buffer.len() * 2, 0);
        }
    }

    Ok(output.into())
}

async fn set_up_event_stream(
    coordinator_addr: SocketAddr,
    machine_id: &Option<String>,
    clock: &Arc<HLC>,
    remote_daemon_events_rx: flume::Receiver<eyre::Result<Timestamped<InterDaemonEvent>>>,
    // used for dynamic nodes
    local_listen_port: u16,
) -> eyre::Result<(DaemonId, impl Stream<Item = Timestamped<Event>> + Unpin)> {
    let clock_cloned = clock.clone();
    let remote_daemon_events = remote_daemon_events_rx.into_stream().map(move |e| match e {
        Ok(e) => Timestamped {
            inner: Event::Daemon(e.inner),
            timestamp: e.timestamp,
        },
        Err(err) => Timestamped {
            inner: Event::DaemonError(err),
            timestamp: clock_cloned.new_timestamp(),
        },
    });
    let (daemon_id, coordinator_events) =
        coordinator::register(coordinator_addr, machine_id.clone(), clock)
            .await
            .wrap_err("failed to connect to dora-coordinator")?;
    let coordinator_events = coordinator_events.map(
        |Timestamped {
             inner: event,
             timestamp,
         }| Timestamped {
            inner: Event::Coordinator(event),
            timestamp,
        },
    );
    let (events_tx, events_rx) = flume::bounded(10);
    let _listen_port =
        local_listener::spawn_listener_loop((LOCALHOST, local_listen_port).into(), events_tx)
            .await?;
    let dynamic_node_events = events_rx.into_stream().map(|e| Timestamped {
        inner: Event::DynamicNode(e.inner),
        timestamp: e.timestamp,
    });
    let incoming = (
        coordinator_events,
        remote_daemon_events,
        dynamic_node_events,
    )
        .merge();
    Ok((daemon_id, incoming))
}

async fn send_output_to_local_receivers(
    node_id: NodeId,
    output_id: DataId,
    dataflow: &mut RunningDataflow,
    metadata: &metadata::Metadata,
    data: Option<DataMessage>,
    clock: &HLC,
) -> Result<Option<AVec<u8, ConstAlign<128>>>, eyre::ErrReport> {
    let timestamp = metadata.timestamp();
    let empty_set = BTreeSet::new();
    let output_id = OutputId(node_id, output_id);
    let local_receivers = dataflow.mappings.get(&output_id).unwrap_or(&empty_set);
    let OutputId(node_id, _) = output_id;
    let mut closed = Vec::new();
    for (receiver_id, input_id) in local_receivers {
        if let Some(channel) = dataflow.subscribe_channels.get(receiver_id) {
            let item = NodeEvent::Input {
                id: input_id.clone(),
                metadata: metadata.clone(),
                data: data.clone(),
            };
            match channel.send(Timestamped {
                inner: item,
                timestamp,
            }) {
                Ok(()) => {
                    if let Some(token) = data.as_ref().and_then(|d| d.drop_token()) {
                        dataflow
                            .pending_drop_tokens
                            .entry(token)
                            .or_insert_with(|| DropTokenInformation {
                                owner: node_id.clone(),
                                pending_nodes: Default::default(),
                            })
                            .pending_nodes
                            .insert(receiver_id.clone());
                    }
                }
                Err(_) => {
                    closed.push(receiver_id);
                }
            }
        }
    }
    for id in closed {
        dataflow.subscribe_channels.remove(id);
    }
    let (data_bytes, drop_token) = match data {
        None => (None, None),
        Some(DataMessage::SharedMemory {
            shared_memory_id,
            len,
            drop_token,
        }) => {
            let memory = ShmemConf::new()
                .os_id(shared_memory_id)
                .open()
                .wrap_err("failed to map shared memory output")?;
            let data = Some(AVec::from_slice(1, &unsafe { memory.as_slice() }[..len]));
            (data, Some(drop_token))
        }
        Some(DataMessage::Vec(v)) => (Some(v), None),
    };
    if let Some(token) = drop_token {
        // insert token into `pending_drop_tokens` even if there are no local subscribers
        dataflow
            .pending_drop_tokens
            .entry(token)
            .or_insert_with(|| DropTokenInformation {
                owner: node_id.clone(),
                pending_nodes: Default::default(),
            });
        // check if all local subscribers are finished with the token
        dataflow.check_drop_token(token, clock).await?;
    }
    Ok(data_bytes)
}

fn node_inputs(node: &ResolvedNode) -> BTreeMap<DataId, Input> {
    match &node.kind {
        CoreNodeKind::Custom(n) => n.run_config.inputs.clone(),
        CoreNodeKind::Runtime(n) => runtime_node_inputs(n),
    }
}

fn close_input(
    dataflow: &mut RunningDataflow,
    receiver_id: &NodeId,
    input_id: &DataId,
    clock: &HLC,
) {
    if let Some(open_inputs) = dataflow.open_inputs.get_mut(receiver_id) {
        if !open_inputs.remove(input_id) {
            return;
        }
    }
    if let Some(channel) = dataflow.subscribe_channels.get(receiver_id) {
        let _ = send_with_timestamp(
            channel,
            NodeEvent::InputClosed {
                id: input_id.clone(),
            },
            clock,
        );

        if dataflow.open_inputs(receiver_id).is_empty() {
            if let Some(node) = dataflow.running_nodes.get_mut(receiver_id) {
                node.disable_restart();
            }
            let _ = send_with_timestamp(channel, NodeEvent::AllInputsClosed, clock);
        }
    }
}

#[derive(Debug)]
pub struct RunningNode {
    process: Option<ProcessHandle>,
    node_config: NodeConfig,
    pid: Option<Arc<AtomicU32>>,
    restart_policy: RestartPolicy,
    /// Don't restart the node even if the restart policy says so.
    ///
    /// This flag is set when all inputs of the node were closed and when a manual stop command
    /// was sent.
    disable_restart: Arc<AtomicBool>,
}

impl RunningNode {
    pub fn restarts_disabled(&self) -> bool {
        self.disable_restart.load(atomic::Ordering::Acquire)
    }

    pub fn disable_restart(&mut self) {
        self.disable_restart.store(true, atomic::Ordering::Release);
    }
}

#[derive(Debug)]
enum ProcessOperation {
    SoftKill,
    Kill,
}

impl ProcessOperation {
    pub fn execute(&self, child: &mut dyn TokioChildWrapper) {
        match self {
            Self::SoftKill => {
                #[cfg(unix)]
                {
                    // Send SIGTERM
                    if let Err(err) = child.signal(15) {
                        warn!("failed to send SIGTERM to process {:?}: {err}", child.id());
                    }
                }

                #[cfg(windows)]
                unsafe {
                    let Some(pid) = child.id() else {
                        warn!("failed to get child process id");
                        return;
                    };
                    if let Err(err) = windows::Win32::System::Console::GenerateConsoleCtrlEvent(
                        windows::Win32::System::Console::CTRL_BREAK_EVENT,
                        pid,
                    ) {
                        warn!("failed to send CTRL_BREAK_EVENT to process {pid}: {err}");
                    }
                }

                #[cfg(not(any(unix, windows)))]
                {
                    warn!("killing process is not implemented on this platform");
                }
            }
            Self::Kill => {
                if let Err(err) = child.start_kill() {
                    warn!("failed to kill child process: {err}");
                }
            }
        }
    }
}

#[derive(Debug)]
struct ProcessHandle {
    op_tx: flume::Sender<ProcessOperation>,
}

impl ProcessHandle {
    pub fn new(op_tx: flume::Sender<ProcessOperation>) -> Self {
        Self { op_tx }
    }

    /// Returns true if the process is not finished yet and the operation is
    /// delivered.
    pub fn submit(&self, operation: ProcessOperation) -> bool {
        self.op_tx.send(operation).is_ok()
    }
}

impl Drop for ProcessHandle {
    fn drop(&mut self) {
        if self.submit(ProcessOperation::Kill) {
            warn!("process was killed on drop because it was still running");
        }
    }
}

pub struct RunningDataflow {
    id: Uuid,
    /// Local nodes that are not started yet
    pending_nodes: PendingNodes,

    dataflow_started: bool,

    subscribe_channels: HashMap<NodeId, UnboundedSender<Timestamped<NodeEvent>>>,
    drop_channels: HashMap<NodeId, UnboundedSender<Timestamped<NodeDropEvent>>>,
    mappings: HashMap<OutputId, BTreeSet<InputId>>,
    timers: BTreeMap<Duration, BTreeSet<InputId>>,
    open_inputs: BTreeMap<NodeId, BTreeSet<DataId>>,
    running_nodes: BTreeMap<NodeId, RunningNode>,

    /// List of all dynamic node IDs.
    ///
    /// We want to treat dynamic nodes differently in some cases, so we need
    /// to know which nodes are dynamic.
    dynamic_nodes: BTreeSet<NodeId>,

    open_external_mappings: BTreeSet<OutputId>,

    pending_drop_tokens: HashMap<DropToken, DropTokenInformation>,

    /// Keep handles to all timer tasks of this dataflow to cancel them on drop.
    _timer_handles: BTreeMap<Duration, futures::future::RemoteHandle<()>>,
    stop_sent: bool,

    /// Used in `open_inputs`.
    ///
    /// TODO: replace this with a constant once `BTreeSet::new` is `const` on stable.
    empty_set: BTreeSet<DataId>,

    /// Contains the node that caused the error for nodes that experienced a cascading error.
    cascading_error_causes: CascadingErrorCauses,
    grace_duration_kills: Arc<crossbeam_skiplist::SkipSet<NodeId>>,

    node_stderr_most_recent: BTreeMap<NodeId, Arc<ArrayQueue<String>>>,

    publishers: BTreeMap<OutputId, zenoh::pubsub::Publisher<'static>>,

    finished_tx: broadcast::Sender<()>,

    publish_all_messages_to_zenoh: bool,
}

impl RunningDataflow {
    fn new(
        dataflow_id: Uuid,
        daemon_id: DaemonId,
        dataflow_descriptor: &Descriptor,
    ) -> RunningDataflow {
        let (finished_tx, _) = broadcast::channel(1);
        Self {
            id: dataflow_id,
            pending_nodes: PendingNodes::new(dataflow_id, daemon_id),
            dataflow_started: false,
            subscribe_channels: HashMap::new(),
            drop_channels: HashMap::new(),
            mappings: HashMap::new(),
            timers: BTreeMap::new(),
            open_inputs: BTreeMap::new(),
            running_nodes: BTreeMap::new(),
            dynamic_nodes: BTreeSet::new(),
            open_external_mappings: Default::default(),
            pending_drop_tokens: HashMap::new(),
            _timer_handles: BTreeMap::new(),
            stop_sent: false,
            empty_set: BTreeSet::new(),
            cascading_error_causes: Default::default(),
            grace_duration_kills: Default::default(),
            node_stderr_most_recent: BTreeMap::new(),
            publishers: Default::default(),
            finished_tx,
            publish_all_messages_to_zenoh: dataflow_descriptor.debug.publish_all_messages_to_zenoh,
        }
    }

    async fn start(
        &mut self,
        events_tx: &mpsc::Sender<Timestamped<Event>>,
        clock: &Arc<HLC>,
    ) -> eyre::Result<()> {
        for interval in self.timers.keys().copied() {
            if self._timer_handles.get(&interval).is_some() {
                continue;
            }
            let events_tx = events_tx.clone();
            let dataflow_id = self.id;
            let clock = clock.clone();
            let task = async move {
                let mut interval_stream = tokio::time::interval(interval);
                let hlc = HLC::default();
                loop {
                    interval_stream.tick().await;

                    let span = tracing::span!(tracing::Level::TRACE, "tick");
                    let _ = span.enter();

                    let mut parameters = BTreeMap::new();
                    parameters.insert(
                        "open_telemetry_context".to_string(),
                        #[cfg(feature = "telemetry")]
                        Parameter::String(serialize_context(&span.context())),
                        #[cfg(not(feature = "telemetry"))]
                        Parameter::String("".into()),
                    );

                    let metadata = metadata::Metadata::from_parameters(
                        hlc.new_timestamp(),
                        empty_type_info(),
                        parameters,
                    );

                    let event = Timestamped {
                        inner: DoraEvent::Timer {
                            dataflow_id,
                            interval,
                            metadata,
                        }
                        .into(),
                        timestamp: clock.new_timestamp(),
                    };
                    if events_tx.send(event).await.is_err() {
                        break;
                    }
                }
            };
            let (task, handle) = task.remote_handle();
            tokio::spawn(task);
            self._timer_handles.insert(interval, handle);
        }

        Ok(())
    }

    async fn stop_all(
        &mut self,
        coordinator_connection: &mut Option<TcpStream>,
        clock: &HLC,
        grace_duration: Option<Duration>,
        force: bool,
        logger: &mut DataflowLogger<'_>,
    ) -> eyre::Result<()> {
        self.pending_nodes
            .handle_dataflow_stop(
                coordinator_connection,
                clock,
                &mut self.cascading_error_causes,
                &self.dynamic_nodes,
                logger,
            )
            .await?;

        for node in self.running_nodes.values_mut() {
            node.disable_restart();
        }

        for (_node_id, channel) in self.subscribe_channels.drain() {
            let _ = send_with_timestamp(&channel, NodeEvent::Stop, clock);
        }

        let running_processes: Vec<_> = self
            .running_nodes
            .iter_mut()
            .map(|(id, n)| (id.clone(), n.process.take()))
            .collect();
        if force {
            for (_, proc) in &running_processes {
                if let Some(proc) = proc {
                    proc.submit(crate::ProcessOperation::Kill);
                }
            }
        } else {
            let grace_duration_kills = self.grace_duration_kills.clone();
            tokio::spawn(async move {
                let duration = grace_duration.unwrap_or(Duration::from_millis(10000));
                tokio::time::sleep(duration).await;

                for (node, proc) in &running_processes {
                    if let Some(proc) = proc {
                        if proc.submit(crate::ProcessOperation::SoftKill) {
                            grace_duration_kills.insert(node.clone());
                        }
                    }
                }

                let kill_duration = duration / 2;
                tokio::time::sleep(kill_duration).await;

                for (node, proc) in &running_processes {
                    if let Some(proc) = proc {
                        if proc.submit(crate::ProcessOperation::Kill) {
                            grace_duration_kills.insert(node.clone());
                            warn!(
                                "{node} was killed due to not stopping within the {:#?} grace period",
                                duration + kill_duration
                            );
                        }
                    }
                }
            });
        }
        self.stop_sent = true;
        Ok(())
    }

    fn open_inputs(&self, node_id: &NodeId) -> &BTreeSet<DataId> {
        self.open_inputs.get(node_id).unwrap_or(&self.empty_set)
    }

    async fn check_drop_token(&mut self, token: DropToken, clock: &HLC) -> eyre::Result<()> {
        match self.pending_drop_tokens.entry(token) {
            std::collections::hash_map::Entry::Occupied(entry) => {
                if entry.get().pending_nodes.is_empty() {
                    let (drop_token, info) = entry.remove_entry();
                    let result = match self.drop_channels.get_mut(&info.owner) {
                        Some(channel) => send_with_timestamp(
                            channel,
                            NodeDropEvent::OutputDropped { drop_token },
                            clock,
                        )
                        .wrap_err("send failed"),
                        None => Err(eyre!("no subscribe channel for node `{}`", &info.owner)),
                    };
                    if let Err(err) = result.wrap_err_with(|| {
                        format!(
                            "failed to report drop token `{drop_token:?}` to owner `{}`",
                            &info.owner
                        )
                    }) {
                        tracing::warn!("{err:?}");
                    }
                }
            }
            std::collections::hash_map::Entry::Vacant(_) => {
                tracing::warn!("check_drop_token called with already closed token")
            }
        }

        Ok(())
    }
}

fn empty_type_info() -> ArrowTypeInfo {
    ArrowTypeInfo {
        data_type: DataType::Null,
        len: 0,
        null_count: 0,
        validity: None,
        offset: 0,
        buffer_offsets: Vec::new(),
        child_data: Vec::new(),
    }
}

#[derive(Debug, Clone, PartialEq, Eq, Hash, PartialOrd, Ord)]
pub struct OutputId(NodeId, DataId);
type InputId = (NodeId, DataId);

struct DropTokenInformation {
    /// The node that created the associated drop token.
    owner: NodeId,
    /// Contains the set of pending nodes that still have access to the input
    /// associated with a drop token.
    pending_nodes: BTreeSet<NodeId>,
}

#[derive(Debug)]
pub enum Event {
    Node {
        dataflow_id: DataflowId,
        node_id: NodeId,
        event: DaemonNodeEvent,
    },
    Coordinator(CoordinatorEvent),
    Daemon(InterDaemonEvent),
    Dora(DoraEvent),
    DynamicNode(DynamicNodeEventWrapper),
    HeartbeatInterval,
    MetricsInterval,
    CtrlC,
    SecondCtrlC,
    DaemonError(eyre::Report),
    SpawnNodeResult {
        dataflow_id: DataflowId,
        node_id: NodeId,
        dynamic_node: bool,
        result: Result<RunningNode, NodeError>,
    },
    BuildDataflowResult {
        build_id: BuildId,
        session_id: SessionId,
        result: eyre::Result<BuildInfo>,
    },
    SpawnDataflowResult {
        dataflow_id: Uuid,
        result: eyre::Result<()>,
    },
    NodeStopped {
        dataflow_id: Uuid,
        node_id: NodeId,
    },
}

impl From<DoraEvent> for Event {
    fn from(event: DoraEvent) -> Self {
        Event::Dora(event)
    }
}

impl Event {
    pub fn kind(&self) -> &'static str {
        match self {
            Event::Node { .. } => "Node",
            Event::Coordinator(_) => "Coordinator",
            Event::Daemon(_) => "Daemon",
            Event::Dora(_) => "Dora",
            Event::DynamicNode(_) => "DynamicNode",
            Event::HeartbeatInterval => "HeartbeatInterval",
            Event::MetricsInterval => "MetricsInterval",
            Event::CtrlC => "CtrlC",
            Event::SecondCtrlC => "SecondCtrlC",
            Event::DaemonError(_) => "DaemonError",
            Event::SpawnNodeResult { .. } => "SpawnNodeResult",
            Event::BuildDataflowResult { .. } => "BuildDataflowResult",
            Event::SpawnDataflowResult { .. } => "SpawnDataflowResult",
            Event::NodeStopped { .. } => "NodeStopped",
        }
    }
}

#[derive(Debug)]
#[allow(clippy::large_enum_variant)]
pub enum DaemonNodeEvent {
    OutputsDone {
        reply_sender: oneshot::Sender<DaemonReply>,
    },
    Subscribe {
        event_sender: UnboundedSender<Timestamped<NodeEvent>>,
        reply_sender: oneshot::Sender<DaemonReply>,
    },
    SubscribeDrop {
        event_sender: UnboundedSender<Timestamped<NodeDropEvent>>,
        reply_sender: oneshot::Sender<DaemonReply>,
    },
    CloseOutputs {
        outputs: Vec<dora_core::config::DataId>,
        reply_sender: oneshot::Sender<DaemonReply>,
    },
    SendOut {
        output_id: DataId,
        metadata: metadata::Metadata,
        data: Option<DataMessage>,
    },
    ReportDrop {
        tokens: Vec<DropToken>,
    },
    EventStreamDropped {
        reply_sender: oneshot::Sender<DaemonReply>,
    },
}

#[derive(Debug)]
pub enum DoraEvent {
    Timer {
        dataflow_id: DataflowId,
        interval: Duration,
        metadata: metadata::Metadata,
    },
    Logs {
        dataflow_id: DataflowId,
        output_id: OutputId,
        message: DataMessage,
        metadata: metadata::Metadata,
    },
    SpawnedNodeResult {
        dataflow_id: DataflowId,
        node_id: NodeId,
        dynamic_node: bool,
        exit_status: NodeExitStatus,
        /// Whether the node will be restarted
        restart: bool,
    },
}

#[must_use]
enum RunStatus {
    Continue,
    Exit,
}

fn send_with_timestamp<T>(
    sender: &UnboundedSender<Timestamped<T>>,
    event: T,
    clock: &HLC,
) -> Result<(), mpsc::error::SendError<Timestamped<T>>> {
    sender.send(Timestamped {
        inner: event,
        timestamp: clock.new_timestamp(),
    })
}

fn set_up_ctrlc_handler(
    clock: Arc<HLC>,
) -> eyre::Result<tokio::sync::mpsc::Receiver<Timestamped<Event>>> {
    let (ctrlc_tx, ctrlc_rx) = mpsc::channel(1);

    let mut ctrlc_sent = 0;
    ctrlc::set_handler(move || {
        let event = match ctrlc_sent {
            0 => Event::CtrlC,
            1 => Event::SecondCtrlC,
            _ => {
                tracing::warn!("received 3rd ctrlc signal -> aborting immediately");
                std::process::abort();
            }
        };
        if ctrlc_tx
            .blocking_send(Timestamped {
                inner: event,
                timestamp: clock.new_timestamp(),
            })
            .is_err()
        {
            tracing::error!("failed to report ctrl-c event to dora-coordinator");
        }

        ctrlc_sent += 1;
    })
    .wrap_err("failed to set ctrl-c handler")?;

    Ok(ctrlc_rx)
}

#[derive(Debug, Default, Clone, PartialEq, Eq)]
pub struct CascadingErrorCauses {
    caused_by: BTreeMap<NodeId, NodeId>,
}

impl CascadingErrorCauses {
    pub fn experienced_cascading_error(&self, node: &NodeId) -> bool {
        self.caused_by.contains_key(node)
    }

    /// Return the ID of the node that caused a cascading error for the given node, if any.
    pub fn error_caused_by(&self, node: &NodeId) -> Option<&NodeId> {
        self.caused_by.get(node)
    }

    pub fn report_cascading_error(&mut self, causing_node: NodeId, affected_node: NodeId) {
        self.caused_by.entry(affected_node).or_insert(causing_node);
    }
}

fn runtime_node_inputs(n: &RuntimeNode) -> BTreeMap<DataId, Input> {
    n.operators
        .iter()
        .flat_map(|operator| {
            operator.config.inputs.iter().map(|(input_id, mapping)| {
                (
                    DataId::from(format!("{}/{input_id}", operator.id)),
                    mapping.clone(),
                )
            })
        })
        .collect()
}

fn runtime_node_outputs(n: &RuntimeNode) -> BTreeSet<DataId> {
    n.operators
        .iter()
        .flat_map(|operator| {
            operator
                .config
                .outputs
                .iter()
                .map(|output_id| DataId::from(format!("{}/{output_id}", operator.id)))
        })
        .collect()
}

trait CoreNodeKindExt {
    fn run_config(&self) -> NodeRunConfig;
    fn dynamic(&self) -> bool;
}

impl CoreNodeKindExt for CoreNodeKind {
    fn run_config(&self) -> NodeRunConfig {
        match self {
            CoreNodeKind::Runtime(n) => NodeRunConfig {
                inputs: runtime_node_inputs(n),
                outputs: runtime_node_outputs(n),
            },
            CoreNodeKind::Custom(n) => n.run_config.clone(),
        }
    }

    fn dynamic(&self) -> bool {
        match self {
            CoreNodeKind::Runtime(_n) => false,
            CoreNodeKind::Custom(n) => {
                matches!(&n.source, NodeSource::Local) && n.path == DYNAMIC_SOURCE
            }
        }
    }
}