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@ -9,6 +9,7 @@ extern crate core;
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use user_lib::{thread_create, waittid, exit, sleep};
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use alloc::vec::Vec;
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use core::sync::atomic::{AtomicUsize, Ordering};
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const N: usize = 2;
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const THREAD_NUM: usize = 10;
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@ -21,19 +22,33 @@ enum FlagState {
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static mut TURN: usize = 0;
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static mut FLAG: [FlagState; THREAD_NUM] = [FlagState::Out; THREAD_NUM];
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static GUARD: AtomicUsize = AtomicUsize::new(0);
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fn critical_test_enter() {
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assert_eq!(GUARD.fetch_add(1, Ordering::SeqCst), 0);
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}
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fn critical_test_claim() {
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assert_eq!(GUARD.load(Ordering::SeqCst), 1);
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}
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fn critical_test_exit() {
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assert_eq!(GUARD.fetch_sub(1, Ordering::SeqCst), 1);
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}
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fn eisenberg_enter_critical(id: usize) {
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/* announce that we want to enter */
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loop {
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println!("Thread[{}] try enter", id);
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store!(&FLAG[id], FlagState::Want);
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vstore!(&FLAG[id], FlagState::Want);
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loop {
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/* check if any with higher priority is `Want` or `In` */
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let mut prior_thread:Option<usize> = None;
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let turn = load!(&TURN);
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let turn = vload!(&TURN);
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let ring_id = if id < turn { id + THREAD_NUM } else { id };
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// FLAG.iter() may lead to some errors, use for-loop instead
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for i in turn..ring_id {
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if load!(&FLAG[i % THREAD_NUM]) != FlagState::Out {
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if vload!(&FLAG[i % THREAD_NUM]) != FlagState::Out {
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prior_thread = Some(i % THREAD_NUM);
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break;
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}
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@ -46,13 +61,13 @@ fn eisenberg_enter_critical(id: usize) {
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sleep(1);
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}
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/* now tentatively claim the resource */
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store!(&FLAG[id], FlagState::In);
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vstore!(&FLAG[id], FlagState::In);
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/* enforce the order of `claim` and `conflict check`*/
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memory_fence!();
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/* check if anthor thread is also `In`, which imply a conflict*/
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let mut conflict = false;
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for i in 0..THREAD_NUM {
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if i != id && load!(&FLAG[i]) == FlagState::In {
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if i != id && vload!(&FLAG[i]) == FlagState::In {
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conflict = true;
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}
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}
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@ -63,7 +78,7 @@ fn eisenberg_enter_critical(id: usize) {
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/* no need to sleep */
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}
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/* clain the trun */
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store!(&TURN, id);
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vstore!(&TURN, id);
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println!("Thread[{}] enter", id);
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}
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@ -73,14 +88,14 @@ fn eisenberg_exit_critical(id: usize) {
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let ring_id = id + THREAD_NUM;
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for i in (id+1)..ring_id {
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let idx = i % THREAD_NUM;
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if load!(&FLAG[idx]) == FlagState::Want {
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if vload!(&FLAG[idx]) == FlagState::Want {
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next = idx;
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break;
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}
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}
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store!(&TURN, next);
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vstore!(&TURN, next);
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/* All done */
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store!(&FLAG[id], FlagState::Out);
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vstore!(&FLAG[id], FlagState::Out);
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println!("Thread[{}] exit, give turn to {}", id, next);
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}
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@ -88,9 +103,12 @@ pub fn thread_fn(id: usize) -> ! {
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println!("Thread[{}] init.", id);
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for _ in 0..N {
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eisenberg_enter_critical(id);
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critical_test_enter();
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for _ in 0..3 {
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critical_test_claim();
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sleep(2);
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}
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critical_test_exit();
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eisenberg_exit_critical(id);
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}
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exit(0)
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@ -107,6 +125,7 @@ pub fn main() -> i32 {
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}
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for tid in v.iter() {
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let exit_code = waittid(*tid as usize);
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assert_eq!(exit_code, 0, "thread conflict happened!");
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println!("thread#{} exited with code {}", tid, exit_code);
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}
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println!("main thread exited.");
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