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//! # Synchronization Tools for no_std environments in Rust
//!
//! ## MCS Lock
//!
//! MCS lock is a fair and scalable mutual lock.
//! This can be used as std::sync::Mutex.
//!
//! ```rust
//! use crate::synctools::mcs;
//! use std::sync::Arc;
//! use std::vec::Vec;
//!
//! const NUM_LOOP: usize = 1000000;
//! const NUM_THREADS: usize = 4;
//!
//! fn main() {
//! // create a MCSLock object
//! let n = Arc::new(mcs::MCSLock::new(0));
//! let mut v = Vec::new();
//!
//! for _ in 0..NUM_THREADS {
//! let n0 = n.clone();
//! let t = std::thread::spawn(move || {
//! let mut node = mcs::MCSNode::new();
//! for _ in 0..NUM_LOOP {
//! // lock and acquire the reference
//! let mut r = n0.lock(&mut node);
//!
//! // increment atomically
//! *r += 1;
//! }
//! });
//!
//! v.push(t);
//! }
//!
//! for t in v {
//! t.join().unwrap();
//! }
//!
//! let mut node = mcs::MCSNode::new();
//! let r = n.lock(&mut node);
//! assert_eq!(NUM_LOOP * NUM_THREADS, *r);
//! }
//! ```
//!
//! ## Readers Writer Lock
//!
//! Spin lock based readers writer lock can be used as std::sync:RwLock.
//!
//! ```rust
//! use crate::synctools::rwlock;
//! use std::sync::Arc;
//! use std::vec::Vec;
//!
//! const NUM_LOOP: usize = 1000000;
//! const NUM_THREADS: usize = 4;
//!
//! fn main() {
//! // create a RwLock object
//! let n = Arc::new(rwlock::RwLock::new(0));
//! let mut v = Vec::new();
//!
//! // reader
//! for _ in 0..(NUM_THREADS - 1) {
//! let n0 = n.clone();
//! let t = std::thread::spawn(move || {
//! for _ in 0..NUM_LOOP {
//! // read lock
//! let r = n0.read();
//! assert_eq!(*r, 0);
//! }
//! });
//!
//! v.push(t);
//! }
//!
//! // writer
//! let n0 = n.clone();
//! let wr = std::thread::spawn(move || {
//! for _ in 0..NUM_LOOP {
//! {
//! // write lock
//! let mut r = n0.write();
//! *r += 1;
//! *r -= 1;
//! }
//! }
//! });
//!
//! v.push(wr);
//!
//! for t in v {
//! t.join().unwrap();
//! }
//! }
//! ```
//!
//! ## Lock Free Stack (AArch64 only)
//!
//! Lock free stack is a concurrent data structure.
//! This can be used only AArch64 and nightly because this
//! uses LL/SC instructions in inline assembly internally.
//!
//! ```rust
//! #[cfg(target_arch = "aarch64")]
//! use crate::synctools::lfstack;
//! use std::sync::Arc;
//! use std::vec::Vec;
//!
//! const NUM_LOOP: usize = 1000000;
//! const NUM_THREADS: usize = 4;
//!
//! #[cfg(target_arch = "aarch64")]
//! fn main() {
//! // create a stack
//! let mut stack = Arc::new(lfstack::LFStack::<usize>::new());
//! let mut v = Vec::new();
//!
//! for i in 0..NUM_THREADS {
//! let mut stack0 = stack.clone();
//! let t = std::thread::spawn(move || {
//! if i & 1 == 0 { // even thread
//! for j in 0..NUM_LOOP {
//! let k = i * NUM_LOOP + j;
//! // push k to the stack
//! stack0.get_mut().push(k);
//! }
//! } else { // odd thread
//! for _ in 0..NUM_LOOP {
//! loop {
//! // pop from the stack
//! if let Some(k) = stack0.get_mut().pop() {
//! break;
//! }
//! }
//! }
//! }
//! });
//! v.push(t);
//! }
//!
//! for t in v {
//! t.join().unwrap();
//! }
//!
//! assert_eq!(stack.get_mut().pop(), None);
//! }
//!
//! #[cfg(not(target_arch = "aarch64"))]
//! fn main() {}
//! ```
#![no_std]
#[cfg(target_arch = "aarch64")]
extern crate alloc;
#[cfg(target_arch = "aarch64")]
pub mod lfstack;
pub mod mcs;
pub mod rwlock;
#[cfg(test)]
#[macro_use]
extern crate std;
#[cfg(test)]
mod tests {
use crate::mcs;
use crate::rwlock;
use std::sync::Arc;
use std::vec::Vec;
const NUM_LOOP: usize = 10000000;
const NUM_THREADS: usize = 8;
#[test]
fn test_mcs() {
let n = Arc::new(mcs::MCSLock::new(0));
let mut v = Vec::new();
for _ in 0..NUM_THREADS {
let n0 = n.clone();
let mut node = mcs::MCSNode::new();
let t = std::thread::spawn(move || {
for _ in 0..NUM_LOOP {
let mut r = n0.lock(&mut node);
*r += 1;
}
});
v.push(t);
}
for t in v {
t.join().unwrap();
}
let mut node = mcs::MCSNode::new();
let r = n.lock(&mut node);
assert_eq!(NUM_LOOP * NUM_THREADS, *r);
}
#[cfg(target_arch = "aarch64")]
#[test]
fn test_lfstack() {
use crate::lfstack;
let mut stack = Arc::new(lfstack::LFStack::<usize>::new());
let mut v = Vec::new();
for i in 0..NUM_THREADS {
let mut stack0 = stack.clone();
let t = std::thread::spawn(move || {
if i & 1 == 0 {
for j in 0..NUM_LOOP {
let k = i * NUM_LOOP + j;
stack0.get_mut().push(k);
}
} else {
for _ in 0..NUM_LOOP {
loop {
if let Some(_) = stack0.get_mut().pop() {
break;
}
}
}
}
});
v.push(t);
}
for t in v {
t.join().unwrap();
}
assert_eq!(stack.get_mut().pop(), None);
}
#[test]
fn test_rwlock() {
let n = Arc::new(rwlock::RwLock::new(0));
let mut v = Vec::new();
for _ in 0..(NUM_THREADS - 1) {
let n0 = n.clone();
let t = std::thread::spawn(move || {
for _ in 0..NUM_LOOP {
let r = n0.read();
assert_eq!(*r, 0);
}
});
v.push(t);
}
let n0 = n.clone();
let wr = std::thread::spawn(move || {
for _ in 0..NUM_LOOP {
{
let mut r = n0.write();
*r += 1;
*r -= 1;
}
}
});
v.push(wr);
for t in v {
t.join().unwrap();
}
}
}