schematics/src/setup/util.rs

use crate::async_utils::join;
use crate::resources::Resource;
use crate::to_artifact::ToArtifact;
use async_trait::async_trait;
use slog::{Drain, Filter, Logger, OwnedKVList, Record};
use slog_async::AsyncRecord;
use std::cell::RefCell;
use std::error::Error;
use std::fmt::Debug;
use std::io::{self, Write};
use std::rc::Rc;
use std::sync::{Arc, Mutex};

pub trait AddableResource: 'static + Resource + Debug {}
impl<R> AddableResource for R where R: 'static + Resource + Debug {}

pub type AddResult<R> = Result<(<R as ToArtifact>::Artifact, bool), Box<dyn Error>>;

#[async_trait(?Send)]
pub trait Add<R: AddableResource> {
  async fn add(&self, logger: &Rc<Logger>, resource: Rc<R>, force_run: bool) -> AddResult<R>;
}

#[async_trait(?Send)]
pub trait AddGeneric<X: ToArtifact> {
  async fn add_generic(&self, logger: &Rc<Logger>, x: X, force_run: bool) -> AddResult<X>;
}

macro_rules! add_generic {
  ( $($name:ident)* ) => (
    #[async_trait(?Send)]
    #[allow(non_snake_case)]
    impl<_S, $($name: AddableResource,)*>
      AddGeneric<($($name,)*)> for _S
      where
      $(
        _S: AddGeneric<$name>
      ),*
    {
      #[allow(unused, clippy::shadow_unrelated)]
      async fn add_generic(&self, logger: &Rc<Logger>, ($($name,)*): ($($name,)*), force_run: bool) -> AddResult<($($name,)*)>
      {
        let ($($name,)*) = join!($(self.add_generic(logger, $name, force_run),)*);
        let mut did_run_any = false;
        $(
        let (artifact, did_run) = $name?;
        did_run_any = did_run_any || did_run;
        let $name = artifact;
        )*
        Ok((($($name,)*), did_run_any))
      }
    }
  );
}

for_each_tuple!(add_generic);

#[async_trait(?Send)]
impl<R: AddableResource + Debug, S: Add<R>> AddGeneric<R> for S {
  async fn add_generic(&self, logger: &Rc<Logger>, r: R, force_run: bool) -> AddResult<R> {
    self.add(logger, Rc::new(r), force_run).await
  }
}

// From https://users.rust-lang.org/t/how-to-send-a-writer-into-a-thread/4965/10
#[derive(Clone)]
struct Output<W>(Rc<RefCell<W>>);

impl<W: Write> Output<W> {
  pub fn new(w: W) -> Self {
    Self(Rc::new(RefCell::new(w)))
  }
}

impl<W: Write> Write for Output<W> {
  fn write(&mut self, buf: &[u8]) -> io::Result<usize> {
    self.0.borrow_mut().write(buf)
  }

  fn flush(&mut self) -> io::Result<()> {
    self.0.borrow_mut().flush()
  }
}

#[derive(Clone, Default)]
pub struct Recorder(Arc<Mutex<Vec<AsyncRecord>>>);

impl Drain for Recorder {
  type Ok = ();
  type Err = slog::Never;

  fn log(&self, record: &Record<'_>, logger_values: &OwnedKVList) -> Result<Self::Ok, Self::Err> {
    self
      .0
      .lock()
      .unwrap()
      .push(AsyncRecord::from(record, logger_values));
    Ok(())
  }
}

impl Recorder {
  pub fn into_string(self, filter_level: slog::Level) -> String {
    let output = Output::new(vec![]);
    {
      let decorator = slog_term::PlainDecorator::new(output.clone());
      let drain = Filter::new(
        slog_term::CompactFormat::new(decorator).build(),
        move |record| record.level().is_at_least(filter_level),
      );
      let Ok(mutex) = Arc::try_unwrap(self.0) else { panic!("cannot unwrap Arc") }; // AsyncRecord does not implement Debug, so we cannot unwrap
      for record in mutex.into_inner().unwrap() {
        record.log_to(&drain).unwrap();
      }
    }
    String::from_utf8(Rc::try_unwrap(output.0).unwrap().into_inner())
      .expect("Record output should be valid UTF-8")
  }
}

#[cfg(test)]
mod test {
  use super::Recorder;
  use slog::Level;

  #[test]
  fn records_no_output() {
    let recorder = Recorder::default();
    assert_eq!(recorder.into_string(Level::Trace), "");
  }
}