rust/chg/src/main.rs

rust: translation of missingancestors

This is as direct as possible a translation of the ancestor.missingancestors
Python class in pure Rust. The goal for this changeset is to make it easy
to compare with the Python version.

We also add to Python tests the cases that helped us develop and debug
this implementation.

Some possible optimizations are marked along the way as TODO comments

Differential Revision: https://phab.mercurial-scm.org/D5416

// Copyright 2018 Yuya Nishihara <[e-mail]>
//
// This software may be used and distributed according to the terms of the
// GNU General Public License version 2 or any later version.

extern crate chg;
extern crate futures;
extern crate log;
extern crate tokio;
extern crate tokio_hglib;

use chg::{ChgClientExt, ChgUiHandler};
use chg::locator;
use chg::procutil;
use futures::sync::oneshot;
use std::env;
use std::io;
use std::process;
use std::time::Instant;
use tokio::prelude::*;
use tokio_hglib::UnixClient;

struct DebugLogger {
    start: Instant,
}

impl DebugLogger {
    pub fn new() -> DebugLogger {
        DebugLogger {
            start: Instant::now(),
        }
    }
}

impl log::Log for DebugLogger {
    fn enabled(&self, metadata: &log::Metadata) -> bool {
        metadata.target().starts_with("chg::")
    }

    fn log(&self, record: &log::Record) {
        if self.enabled(record.metadata()) {
            // just make the output looks similar to chg of C
            let l = format!("{}", record.level()).to_lowercase();
            let t = self.start.elapsed();
            writeln!(io::stderr(), "chg: {}: {}.{:06} {}",
                     l, t.as_secs(), t.subsec_micros(), record.args()).unwrap_or(());
        }
    }

    fn flush(&self) {
    }
}

fn main() {
    if env::var_os("CHGDEBUG").is_some() {
        log::set_boxed_logger(Box::new(DebugLogger::new()))
            .expect("any logger should not be installed yet");
        log::set_max_level(log::LevelFilter::Debug);
    }

    let code = run().unwrap_or_else(|err| {
        writeln!(io::stderr(), "chg: abort: {}", err).unwrap_or(());
        255
    });
    process::exit(code);
}

fn run() -> io::Result<i32> {
    let current_dir = env::current_dir()?;
    let sock_path = locator::prepare_server_socket_path()?;
    let handler = ChgUiHandler::new();
    let (result_tx, result_rx) = oneshot::channel();
    let fut = UnixClient::connect(sock_path)
        .and_then(|client| {
            client.set_current_dir(current_dir)
        })
        .and_then(|client| {
            client.attach_io(io::stdin(), io::stdout(), io::stderr())
        })
        .and_then(|client| {
            let pid = client.server_spec().process_id.unwrap();
            let pgid = client.server_spec().process_group_id;
            procutil::setup_signal_handler_once(pid, pgid)?;
            Ok(client)
        })
        .and_then(|client| {
            client.run_command_chg(handler, env::args_os().skip(1))
        })
        .map(|(_client, _handler, code)| {
            procutil::restore_signal_handler_once()?;
            Ok(code)
        })
        .or_else(|err| Ok(Err(err)))  // pass back error to caller
        .map(|res| result_tx.send(res).unwrap());
    tokio::run(fut);
    result_rx.wait().unwrap_or(Err(io::Error::new(io::ErrorKind::Other,
                                                  "no exit code set")))
}