Improve API using new Rust 1.50 feature

.github/workflows/ci.yml

@@ -8,6 +8,12 @@ jobs:
 
     steps:
     - uses: actions/checkout@master
+    - uses: actions-rs/toolchain@v1
+      name: Install Rust
+      with:
+        profile: minimal
+        toolchain: stable
+        override: true
     - name: Build
       run: cargo build --verbose
     - name: Run tests

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "interchange"
-version = "0.1.1"
+version = "0.1.2"
 authors = ["Nicolas Stalder <[email protected]>"]
 edition = "2018"
 description = "Request/response mechanism for embedded development, using atomics"

src/lib.rs

@@ -167,7 +167,7 @@ pub trait Interchange: Sized {
     fn claim() -> Option<(Requester<Self>, Responder<Self>)>;
 
     /// Method for debugging: how many allocated clients have not been claimed.
-    fn available_clients() -> usize;
+    fn unclaimed_clients() -> usize;
 
     /// Method purely for testing - do not use in production
     ///

src/macros.rs

@@ -29,10 +29,10 @@
 #[macro_export]
 macro_rules! interchange {
     ($Name:ident: ($REQUEST:ty, $RESPONSE:ty)) => {
-        $crate::interchange!($Name: ($REQUEST, $RESPONSE, 1, [None]));
+        $crate::interchange!($Name: ($REQUEST, $RESPONSE, 1));
     };
 
-    ($Name:ident: ($REQUEST:ty, $RESPONSE:ty, $N:expr, $Nones:expr)) => {
+    ($Name:ident: ($REQUEST:ty, $RESPONSE:ty, $N:expr)) => {
 
         // TODO: figure out how to implement, e.g., Clone iff REQUEST
         // and RESPONSE are clone (do not introduce Clone, Debug, etc. trait bounds).
@@ -49,8 +49,10 @@ macro_rules! interchange {
                 use core::cell::UnsafeCell;
 
                 // TODO(nickray): This turns up in .data section, fix this.
-                // static mut INTERCHANGES: [Option<$Name>; $N] = [None; $N];
-                static mut INTERCHANGES: [Option<$Name>; $N] = $Nones;
+
+                // yay Rust 1.50
+                const NONE: Option<$Name> = None;
+                static mut INTERCHANGES: [Option<$Name>; $N] = [NONE; $N];
                 static mut STATES: [u8; $N] = [0u8; $N];
                 unsafe {
                     let mut cell: MaybeUninit<UnsafeCell<&'static mut Option<$Name>>> = MaybeUninit::uninit();
@@ -110,7 +112,7 @@ macro_rules! interchange {
                 }
             }
 
-            fn available_clients() -> usize {
+            fn unclaimed_clients() -> usize {
                 Self::CLIENT_CAPACITY - Self::last_claimed().load(core::sync::atomic::Ordering::SeqCst)
             }