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/*
* einhyrningsins: graceful restarts for socket-based daemons
* Copyright (C) 2016 Bryan Newbold <bnewbold@robocracy.org>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#[macro_use]
extern crate chan;
extern crate getopts;
extern crate log;
extern crate env_logger;
extern crate nix;
extern crate timer;
extern crate chan_signal;
use std::env;
use std::u64;
use std::str::FromStr;
use std::process::exit;
use std::process::Command;
use std::process::Child;
use std::net::SocketAddr;
use std::net::TcpListener;
use std::net::ToSocketAddrs;
use std::time::{Duration, Instant};
use getopts::Options;
use chan_signal::Signal;
use chan::{Sender, Receiver};
use std::os::unix::io::{RawFd, IntoRawFd};
struct EinConfig {
childhood: Duration,
retries: u64,
count: u64,
bind_fds: Vec<RawFd>,
prog: Command,
//XXX:rpc_ask: Sender<String>,
//XXX:rpc_reply: Receiver<Result<String, String>>,
}
enum OffspringState {
Expectant, // no process exist yet
Infancy, // just started, waiting for ACK
Healthy,
Sick,
Notified, // shutting down
Dead,
}
struct Offspring {
state: OffspringState,
process: Option<Child>,
birthday: Instant, // specifies the generation
attempts: u64,
}
// This is the main event loop
fn shepard(mut cfg: EinConfig, signal_rx: Receiver<Signal>) {
// birth the initial set of offspring
// create timer
let timer = timer::Timer::new();
// XXX: these signatures are bogus
let (timer_tx, timer_rx): (Sender<u64>, Receiver<u64>) = chan::async();
// infinite select() loop over timers, signals, rpc
loop {
chan_select! {
timer_rx.recv() => println!("Timer tick'd"),
signal_rx.recv() => {
println!("Signal received!");
break;
}
}
}
let mut children: Vec<Child> = vec![];
for _ in 0..cfg.count {
println!("Running!");
children.push(cfg.prog.spawn().expect("error spawning"));
}
println!("Waiting for all children to die");
for mut c in children {
c.wait().unwrap();
}
println!("Done.");
}
fn print_usage(opts: Options) {
let brief = "usage:\teinhyrningsins [options] program";
println!("");
print!("{}", opts.usage(&brief));
}
fn main() {
let args: Vec<String> = env::args().collect();
let mut opts = Options::new();
opts.parsing_style(getopts::ParsingStyle::StopAtFirstFree);
opts.optflag("h", "help", "print this help menu");
opts.optflag("v", "verbose", "more debugging messages");
opts.optopt("n", "number", "how many program copies to spawn", "COUNT");
opts.optmulti("b", "bind", "socket(s) to bind to", "ADDR");
let matches = match opts.parse(&args[1..]) {
Ok(m) => { m }
Err(f) => { println!("{}", f.to_string()); print_usage(opts); exit(-1); }
};
if matches.opt_present("h") {
print_usage(opts);
return;
}
//// Parse Configuration
let mut cfg = EinConfig{
count: 1,
childhood: Duration::new(3, 0),
retries: 3,
bind_fds: vec![],
prog: Command::new(""),
};
cfg.count = match matches.opt_str("number") {
Some(n) => u64::from_str(&n).expect("number arg should be an integer"),
None => 1 // XXX: duplicate default
};
//// Bind Sockets
let sock_addrs: Vec<SocketAddr> = matches.opt_strs("bind").iter().map(|b| {
b.to_socket_addrs().unwrap().next().unwrap()
}).collect();
let program_and_args = if !matches.free.is_empty() {
matches.free
} else {
print_usage(opts);
exit(-1);
};
let mut builder = env_logger::LogBuilder::new();
builder.parse("INFO");
if env::var("RUST_LOG").is_ok() {
builder.parse(&env::var("RUST_LOG").unwrap());
}
builder.init().unwrap();
let binds: Vec<TcpListener> = sock_addrs.iter().map(|sa| {
TcpListener::bind(sa).unwrap()
}).collect();
let mut prog = Command::new(&program_and_args[0]);
prog.args(&program_and_args[1..]);
cfg.bind_fds = binds.into_iter().map(|b| {
let orig_fd = b.into_raw_fd();
// Duplicate, which also clears the CLOEXEC flag
let fd = nix::unistd::dup(orig_fd).unwrap();
println!("fd={} FD_CLOEXEC={}", fd, nix::fcntl::fcntl(fd, nix::fcntl::FcntlArg::F_GETFD).unwrap());
fd
}).collect();
prog.env("EINHORN_FD_COUNT", cfg.bind_fds.len().to_string());
// This iterator destroys the TcpListeners
for (i, fd) in cfg.bind_fds.iter().enumerate() {
prog.env(format!("EINHORN_FD_{}", i), fd.to_string());
}
cfg.prog = prog;
//// Listen for signals (before any fork())
println!("Registering signal handlers...");
let signal_rx = chan_signal::notify(&[Signal::INT,
Signal::TERM,
//Signal::CHLD, // XXX: PR has been submitted
Signal::USR2,
Signal::HUP]);
shepard(cfg, signal_rx);
exit(0);
}
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