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144 lines
3.6 KiB
144 lines
3.6 KiB
//! Dining philosophers problem
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//!
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//! The code is borrowed from [RustDoc - Dining Philosophers](https://doc.rust-lang.org/1.6.0/book/dining-philosophers.html)
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use crate::sync::Condvar;
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use crate::sync::SleepLock as Mutex;
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use crate::thread;
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use alloc::vec;
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use alloc::{sync::Arc, vec::Vec};
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use core::time::Duration;
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use log::*;
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struct Philosopher {
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name: &'static str,
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left: usize,
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right: usize,
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}
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impl Philosopher {
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fn new(name: &'static str, left: usize, right: usize) -> Philosopher {
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Philosopher { name, left, right }
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}
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fn eat(&self, table: &Arc<Table>) {
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table.eat(self.name, self.left, self.right);
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}
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fn think(&self) {
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println!("{} is thinking.", self.name);
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thread::sleep(Duration::from_secs(1));
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}
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}
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trait Table: Send + Sync {
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fn eat(&self, name: &str, left: usize, right: usize);
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}
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struct MutexTable {
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forks: Vec<Mutex<()>>,
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}
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impl Table for MutexTable {
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fn eat(&self, name: &str, left: usize, right: usize) {
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let _left = self.forks[left].lock();
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let _right = self.forks[right].lock();
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println!("{} is eating.", name);
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thread::sleep(Duration::from_secs(1));
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}
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}
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struct MonitorTable {
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fork_status: Mutex<Vec<bool>>,
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fork_condvar: Vec<Condvar>,
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}
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impl Table for MonitorTable {
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fn eat(&self, name: &str, left: usize, right: usize) {
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{
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let mut fork_status = self.fork_status.lock();
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if fork_status[left] {
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fork_status = self.fork_condvar[left].wait(fork_status);
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}
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fork_status[left] = true;
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if fork_status[right] {
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fork_status = self.fork_condvar[right].wait(fork_status);
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}
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fork_status[right] = true;
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}
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println!("{} is eating.", name);
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thread::sleep(Duration::from_secs(1));
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{
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let mut fork_status = self.fork_status.lock();
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fork_status[left] = false;
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fork_status[right] = false;
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self.fork_condvar[left].notify_one();
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self.fork_condvar[right].notify_one();
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}
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}
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}
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fn philosopher(table: Arc<Table>) {
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let philosophers = vec![
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Philosopher::new("1", 0, 1),
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Philosopher::new("2", 1, 2),
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Philosopher::new("3", 2, 3),
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Philosopher::new("4", 3, 4),
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Philosopher::new("5", 0, 4),
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];
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let handles: Vec<_> = philosophers
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.into_iter()
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.map(|p| {
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let table = table.clone();
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trace!("philosopher start");
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thread::spawn(move || {
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for i in 0..5 {
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p.think();
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p.eat(&table);
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println!("{} iter {} end.", p.name, i);
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}
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})
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})
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.collect();
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trace!("philosopher starting finish");
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for h in handles {
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h.join().expect("handle should not be none");
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}
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println!("philosophers dining end");
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}
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pub fn philosopher_using_mutex() {
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println!("philosophers using mutex");
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let table = Arc::new(MutexTable {
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forks: vec![
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Mutex::new(()),
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Mutex::new(()),
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Mutex::new(()),
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Mutex::new(()),
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Mutex::new(()),
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],
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});
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philosopher(table);
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}
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pub fn philosopher_using_monitor() {
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println!("philosophers using monitor");
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let table = Arc::new(MonitorTable {
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fork_status: Mutex::new(vec![false; 5]),
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fork_condvar: vec![
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Condvar::new(),
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Condvar::new(),
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Condvar::new(),
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Condvar::new(),
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Condvar::new(),
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],
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});
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philosopher(table);
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}
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