digital_io: test: use thread local storage instead of global line list

Cargo test runs test in parallel using one thread per test.
Usually parallelism in rust is safe enough to not make this an issue
but here we built something intentionally hacky (to keep the non-test/
mock code simple) in the form of a global index of mock GPIO lines whos
values can be read out in test code.

The next commit will introduce a second dut_power thread that uses the
same GPIO lines as the first test.
As all tests run in the same process this means that they share the
same list of mock GPIO lines, resulting in havoc when the tests run in
parallel.

This time we can get around this issue by using a list of mock GPIO
lines per thread so we do not have to complicate the non-test code.

Signed-off-by: Leonard Göhrs <[email protected]>

Author: hnez

src/digital_io/gpio/test.rs

@@ -15,17 +15,19 @@
 // with this program; if not, write to the Free Software Foundation, Inc.,
 // 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 
+use std::cell::RefCell;
 use std::iter::Iterator;
 use std::ops::BitOr;
 use std::sync::atomic::{AtomicU8, Ordering};
 use std::thread::sleep;
 use std::time::Duration;
 
 use anyhow::Result;
-use async_std::sync::{Arc, Mutex};
-use async_std::task::block_on;
+use async_std::sync::Arc;
 
-static LINES: Mutex<Vec<(String, Arc<AtomicU8>)>> = Mutex::new(Vec::new());
+std::thread_local! {
+    static LINES: RefCell<Vec<(String, Arc<AtomicU8>)>> = RefCell::new(Vec::new());
+}
 
 pub struct LineHandle {
     name: String,
@@ -115,17 +117,15 @@ impl FindDecoy {
 }
 
 pub fn find_line(name: &str) -> Option<FindDecoy> {
-    let val = {
-        let mut lines = block_on(LINES.lock());
-
+    let val = LINES.with_borrow_mut(|lines| {
         if let Some((_, v)) = lines.iter().find(|(n, _)| n == name) {
             v.clone()
         } else {
             let v = Arc::new(AtomicU8::new(0));
             lines.push((name.to_string(), v.clone()));
             v
         }
-    };
+    });
 
     Some(FindDecoy {
         name: name.to_string(),