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//! # Multiple orderings on an example with two threads and two values
//! Modelling a scenario with two values, a and b. Both a and b are incremented only on a writer thread
//! and and read on a reader thread.
//! Invariants
//! At t0: num_a > num_b
//! On each iteration, increment (store) a, with a value larger than the one used in b.
//! On each iteration of the loop, read b before reading a
//!
//! Expected logic:
//! num_a should be >= than num_b
//!
//! Notes:
//! whenever the reader uses `Relaxed` on both operations, then the test fails.
//!
//!
//! ```rust
//! use std::sync::atomic::Ordering::{Acquire, Relaxed, Release, SeqCst};
//!
//! use std::sync::atomic::Ordering;
//!
//! use loom::{
//! sync::{atomic::AtomicUsize, Arc},
//! thread,
//! };
//!
//!fn two_numbers_with_a_dependency(
//! read_ordering_a: Ordering,
//! read_ordering_b: Ordering,
//! write_ordering_a: Ordering,
//! write_ordering_b: Ordering,
//!) {
//! loom::model(move || {
//! let num_a = Arc::new(AtomicUsize::new(1));
//! let num_b = Arc::new(AtomicUsize::new(0));
//!
//! let num_a2 = num_a.clone();
//! let num_b2 = num_b.clone();
//! let tb = thread::spawn(move || {
//! for idx in 1..4 {
//! num_a2.store(idx + 1, read_ordering_a);
//! num_b2.store(idx, read_ordering_b);
//! }
//! });
//!
//! let _ = thread::spawn(move || {
//! for _ in 1..4 {
//! let nb = num_b.load(write_ordering_b);
//! let na = num_a.load(write_ordering_a);
//! assert!(na >= nb);
//! }
//! });
//! tb.join().unwrap();
//! });
//!}
//!
//!#[test]
//!#[should_panic]
//!fn atomics_relaxed_failing() {
//! two_numbers_with_a_dependency(Relaxed, Relaxed, Relaxed, Relaxed);
//!}
//!
//!#[test]
//!#[should_panic]
//!fn atomics_writer_release_reader_relaxed_failing() {
//! two_numbers_with_a_dependency(Release, Release, Relaxed, Relaxed);
//!
//!}
//!
//!#[test]
//!fn atomics_writer_release_reader_seqcst_and_relaxed() {
//! two_numbers_with_a_dependency(Release, Release, Relaxed, SeqCst);
//!}
//!
//!#[test]
//!fn atomics_seq_cst_does_not_fail() {
//! two_numbers_with_a_dependency(SeqCst, SeqCst, SeqCst, SeqCst);
//!}
//!
//!#[test]
//!fn atomics_acquire_release_does_not_fail() {
//! two_numbers_with_a_dependency(Release, Release, Acquire, Acquire);
//!}
//! ```