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use std::io::{self, Read, Write};
use std::net::{SocketAddr, TcpStream};
use std::time::Duration;
const MAGIC: [u8; 4] = [0x32, 0x7f, 0xfe, 0x4c];
const RESP_OK: [u8; 5] = [0x32, 0x7f, 0xfe, 0x4c, 0x00];
const RESP_NORMAL: [u8; 5] = [0x32, 0x7f, 0xfe, 0x4c, 0x01];
const PING_INTERVAL: Duration = Duration::from_secs(12);
const TCP_TIMEOUT: Duration = Duration::from_secs(8);
const MAX_RETRY: i32 = 30;
const EXIT_SUCCESS: i32 = 0;
const EXIT_USAGE: i32 = 1;
const EXIT_PING: i32 = 2;
const EXIT_BUG: i32 = 3;
const EXIT_IO: i32 = 4;
fn main() {
let mut args = std::env::args().skip(1);
let addr = match args.next() {
Some(addr) => addr,
None => {
eprintln!("Usage: rsdsl_healthping host:port");
std::process::exit(EXIT_USAGE);
}
};
let addr: SocketAddr = match addr.parse() {
Ok(addr) => addr,
Err(e) => {
eprintln!("invalid address: {}", e);
std::process::exit(EXIT_USAGE);
}
};
let mut lasterr = None;
print!("Pinging");
for _ in 0..MAX_RETRY {
print!(".");
match io::stdout().flush() {
Ok(_) => {}
Err(e) => {
eprintln!("flush stdout: {}", e);
std::thread::sleep(PING_INTERVAL);
std::process::exit(EXIT_IO);
}
}
let mut conn = match TcpStream::connect_timeout(&addr, TCP_TIMEOUT) {
Ok(conn) => conn,
Err(e) => {
lasterr = Some(e);
std::thread::sleep(PING_INTERVAL);
continue;
}
};
match conn.write_all(&MAGIC) {
Ok(_) => {}
Err(e) => {
lasterr = Some(e);
std::thread::sleep(PING_INTERVAL);
continue;
}
}
let mut buf = [0; 5];
match conn.read_exact(&mut buf) {
Ok(_) => {}
Err(e) => {
lasterr = Some(e);
std::thread::sleep(PING_INTERVAL);
continue;
}
}
match buf {
RESP_OK => success(),
RESP_NORMAL => success_unexpected(),
_ => eprintln!("got invalid response {:?}", buf),
}
std::thread::sleep(PING_INTERVAL);
}
println!();
match lasterr {
Some(e) => {
eprintln!("{}", e);
std::process::exit(EXIT_PING)
}
None => {
eprintln!("max retries exceeded without error");
std::process::exit(EXIT_BUG)
}
}
}
fn success() {
println!();
println!("Success");
std::process::exit(EXIT_SUCCESS);
}
fn success_unexpected() {
println!();
println!("Host is not waiting for healthcheck ping");
std::process::exit(EXIT_SUCCESS);
}
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