watchexec/src/main.rs

#[macro_use]
extern crate clap;
extern crate globset;
extern crate env_logger;
extern crate libc;
#[macro_use]
extern crate log;
#[macro_use]
extern crate lazy_static;
extern crate notify;

#[cfg(unix)]
extern crate nix;
#[cfg(windows)]
extern crate winapi;
#[cfg(windows)]
extern crate kernel32;

#[cfg(test)]
extern crate mktemp;

mod cli;
mod gitignore;
mod notification_filter;
mod process;
mod signal;
mod watcher;

use std::collections::HashMap;
use std::path::{Path, PathBuf};
use std::sync::{Arc, RwLock};
use std::sync::mpsc::{channel, Receiver};
use std::time::Duration;

use notification_filter::NotificationFilter;
use process::Process;
use watcher::{Event, Watcher};
use nix::sys::signal::Signal;

fn init_logger(debug: bool) {
    let mut log_builder = env_logger::LogBuilder::new();
    let level = if debug {
        log::LogLevelFilter::Debug
    } else {
        log::LogLevelFilter::Warn
    };

    log_builder.format(|r| format!("*** {}", r.args()))
        .filter(None, level);
    log_builder.init().expect("unable to initialize logger");
}

fn main() {
    let args = cli::get_args();
    let child_process: Arc<RwLock<Option<Process>>> = Arc::new(RwLock::new(None));
    let weak_child = Arc::downgrade(&child_process);

    // Convert signal string to the corresponding integer
    let signal = signal::new(&*args.signal);

    signal::install_handler(move |sig: Signal| {
        if let Some(lock) = weak_child.upgrade() {
            let strong = lock.read().unwrap();
            if let Some(ref child) = *strong {
                match sig {
                    // TODO: This should be generalized to use new --signal flag
                    // TODO: Not sure what this is doing tbh :(
                    Signal::SIGTERM => {
                        // TODO: Removed kill variable for now
                        child.terminate();
                    }
                    Signal::SIGSTOP => child.pause(),
                    Signal::SIGCONT => child.resume(),
                    Signal::SIGCHLD => child.reap(),
                    _ => debug!("Unhandled signal: {:?}", sig),
                }
            }
        }
    });

    init_logger(args.debug);

    let paths: Vec<PathBuf> = args.paths
        .iter()
        .map(|p| {
            Path::new(&p)
                .canonicalize()
                .expect(&format!("unable to canonicalize \"{}\"", &p))
                .to_owned()
        })
        .collect();

    let gitignore = if !args.no_vcs_ignore {
        gitignore::load(&paths)
    } else {
        gitignore::load(&[])
    };

    let filter = NotificationFilter::new(args.filters, args.ignores, gitignore)
        .expect("unable to create notification filter");

    let (tx, rx) = channel();
    let watcher = Watcher::new(tx, &paths, args.poll, args.poll_interval)
        .expect("unable to create watcher");

    if watcher.is_polling() {
        warn!("Polling for changes every {} ms", args.poll_interval);
    }

    // Start child process initially, if necessary
    if args.run_initially && !args.once {
        if args.clear_screen {
            cli::clear_screen();
        }

        let mut guard = child_process.write().unwrap();
        *guard = Some(process::spawn(&args.cmd, vec![]));
    }

    loop {
        debug!("Waiting for filesystem activity");
        let paths = wait_fs(&rx, &filter);
        if let Some(path) = paths.get(0) {
            debug!("Path updated: {:?}", path);
        }

        // Wait for current child process to exit
        // Note: signal is cloned here automatically
        wait_process(&child_process, signal, args.restart);

        // Launch child process
        if args.clear_screen {
            cli::clear_screen();
        }

        debug!("Launching child process");
        {
            let mut guard = child_process.write().unwrap();
            *guard = Some(process::spawn(&args.cmd, paths));
        }

        // Handle once option for integration testing
        if args.once {
            // Note: signal is cloned here automatically
            wait_process(&child_process, signal, false);
            break;
        }
    }
}

fn wait_fs(rx: &Receiver<Event>, filter: &NotificationFilter) -> Vec<PathBuf> {
    let mut paths = vec![];
    let mut cache = HashMap::new();

    loop {
        let e = rx.recv().expect("error when reading event");

        if let Some(ref path) = e.path {
            // Ignore cache for the initial file. Otherwise, in
            // debug mode it's hard to track what's going on
            let excluded = filter.is_excluded(path);
            if !cache.contains_key(path) {
                cache.insert(path.to_owned(), excluded);
            }

            if !excluded {
                paths.push(path.to_owned());
                break;
            }
        }
    }

    // Wait for filesystem activity to cool off
    let timeout = Duration::from_millis(500);
    while let Ok(e) = rx.recv_timeout(timeout) {
        if let Some(ref path) = e.path {
            if cache.contains_key(path) {
                continue;
            }

            let excluded = filter.is_excluded(path);

            let p = path.to_owned();
            cache.insert(p.clone(), excluded);

            if !excluded {
                paths.push(p);
            }
        }
    }

    paths
}

fn wait_process(process: &RwLock<Option<Process>>, signal: Signal, restart: bool) {
    let guard = process.read().unwrap();

    if let Some(ref child) = *guard {
        if restart {
            debug!("Stopping child process with {:?} signal", signal);
            child.signal(signal);
        }

        debug!("Waiting for process to exit...");
        child.wait();
    }
}