flexi_logger 0.22.3

use {
    crate::{primary_writer::PrimaryWriter, writers::LogWriter, FlexiLoggerError},
    std::{
        collections::HashMap,
        sync::{
            mpsc::{channel, Receiver, Sender},
            Arc,
        },
        thread::Builder as ThreadBuilder,
    },
};

#[cfg(any(feature = "specfile", feature = "async"))]
use crate::util::{eprint_err, ERRCODE};

#[cfg(feature = "async")]
use {
    crate::{
        primary_writer::std_stream::StdStream,
        util::{ASYNC_FLUSH, ASYNC_SHUTDOWN},
    },
    crossbeam::{channel::Receiver as CrossbeamReceiver, queue::ArrayQueue},
    std::{sync::Mutex, thread::JoinHandle},
};

// no clue why we get a warning if this allow is omitted; if we omit the use, we get an error
#[allow(unused_imports)]
#[cfg(feature = "async")]
use std::io::Write;

#[cfg(feature = "specfile")]
use {
    crate::{
        logger::log_spec_string_from_file, logger_handle::LogSpecSubscriber, LogSpecification,
    },
    notify::{watcher, DebouncedEvent, RecursiveMode, Watcher},
    std::path::Path,
};

#[cfg(feature = "async")]
const ASYNC_STD_WRITER: &str = "flexi_logger-async_std_writer";
const FLUSHER: &str = "flexi_logger-flusher";
#[cfg(feature = "specfile")]
const SPECFILE_WATCHER: &str = "flexi_logger-specfile-watcher";

// Used in Logger
pub(crate) fn start_flusher_thread(
    primary_writer: Arc<PrimaryWriter>,
    other_writers: Arc<HashMap<String, Box<dyn LogWriter>>>,
    flush_interval: std::time::Duration,
) -> Result<(), FlexiLoggerError> {
    let builder = ThreadBuilder::new().name(FLUSHER.to_string());
    #[cfg(not(feature = "dont_minimize_extra_stacks"))]
    let builder = builder.stack_size(128);

    builder.spawn(move || {
        let (_sender, receiver): (Sender<()>, Receiver<()>) = channel();
        loop {
            receiver.recv_timeout(flush_interval).ok();
            primary_writer.flush().ok();
            for w in other_writers.values() {
                w.flush().ok();
            }
        }
    })?;
    Ok(())
}

// Used in Logger
// Reread the specfile when it was updated
#[cfg(feature = "specfile")]
pub(crate) fn start_specfile_watcher_thread<S: LogSpecSubscriber>(
    specfile: &Path,
    mut subscriber: S,
) -> Result<(), FlexiLoggerError> {
    // Now that the file exists, we can canonicalize the path
    let specfile = specfile
        .canonicalize()
        .map_err(FlexiLoggerError::SpecfileIo)?;

    // Watch the parent folder of the specfile, using debounced events
    let (tx, rx) = std::sync::mpsc::channel();
    let debouncing_delay = std::time::Duration::from_millis(1000);
    let mut watcher = watcher(tx, debouncing_delay)?;
    watcher.watch(
        &specfile.parent().unwrap(/*cannot fail*/),
        RecursiveMode::NonRecursive,
    )?;

    // in a separate thread, reread the specfile when it was updated
    let builder = ThreadBuilder::new().name(SPECFILE_WATCHER.to_string());
    #[cfg(not(feature = "dont_minimize_extra_stacks"))]
    let builder = builder.stack_size(128 * 1024);
    builder.spawn(move || {
        let _anchor_for_watcher = watcher; // keep it alive!
        loop {
            match rx.recv() {
                Ok(debounced_event) => match debounced_event {
                    DebouncedEvent::Create(ref path) | DebouncedEvent::Write(ref path) => {
                        if path.canonicalize().map(|x| x == specfile).unwrap_or(false) {
                            log_spec_string_from_file(&specfile)
                                .map_err(FlexiLoggerError::SpecfileIo)
                                .and_then(|s| LogSpecification::from_toml(&s))
                                .and_then(|spec| subscriber.set_new_spec(spec))
                                .map_err(|e| {
                                    eprint_err(
                                        ERRCODE::LogSpecFile,
                                        "continuing with previous log specification, because \
                                             rereading the log specification file failed",
                                        &e,
                                    );
                                })
                                .ok();
                        }
                    }
                    _event => {}
                },
                Err(e) => {
                    eprint_err(
                        ERRCODE::LogSpecFile,
                        "error while watching the specfile",
                        &e,
                    );
                }
            }
        }
    })?;
    Ok(())
}

#[cfg(feature = "async")]
pub(crate) fn start_async_stdwriter(
    mut std_stream: StdStream,
    receiver: CrossbeamReceiver<std::vec::Vec<u8>>,
    t_pool: Arc<ArrayQueue<Vec<u8>>>,
    msg_capa: usize,
    #[cfg(test)] t_validation_buffer: Arc<Mutex<std::io::Cursor<Vec<u8>>>>,
) -> Mutex<Option<JoinHandle<()>>> {
    Mutex::new(Some(
        ThreadBuilder::new()
            .name(
                ASYNC_STD_WRITER.to_string()
            )
            .spawn(move || {
                loop {
                    match receiver.recv() {
                        Err(_) => break,
                        Ok(mut message) => {
                            match message.as_ref() {
                                ASYNC_FLUSH => {
                                    std_stream
                                        .deref_mut()
                                        .flush()
                                        .unwrap_or_else(
                                            |e| eprint_err(ERRCODE::Flush, "flushing failed", &e)

                                        );
                                }
                                ASYNC_SHUTDOWN => {
                                    break;
                                }
                                _ => {
                                    std_stream
                                        .deref_mut()
                                        .write_all(&message)
                                        .unwrap_or_else(
                                            |e| eprint_err(ERRCODE::Write,"writing failed", &e)

                                        );
                                    #[cfg(test)]
                                    if let Ok(mut guard) = t_validation_buffer.lock() {
                                        (*guard).write_all(&message).ok();
                                    }
                                }
                            }
                            if message.capacity() <= msg_capa {
                                message.clear();
                                t_pool.push(message).ok();
                            }
                        }
                    }
                }
            })
            .unwrap(/* yes, let's panic if the thread can't be spawned */),
    ))
}