using ScopeGuards to increase the readability

Cargo.lock

@@ -184,10 +184,17 @@ dependencies = [
  "num",
  "num-derive",
  "num-traits",
+ "scopeguard",
  "x86",
  "x86_64",
 ]
 
+[[package]]
+name = "scopeguard"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d29ab0c6d3fc0ee92fe66e2d99f700eab17a8d57d1c1d3b748380fb20baa78cd"
+
 [[package]]
 name = "semver"
 version = "0.9.0"

Cargo.toml

@@ -48,6 +48,10 @@ acpi = []
 x86_64 = "0.11.0"
 float-cmp = "0.8.0"
 
+[dependencies.scopeguard]
+version = "1.1"
+default-features = false
+
 [dev-dependencies.num-traits]
 version = "0.2"
 default-features = false

src/lib.rs

@@ -61,6 +61,7 @@ extern crate num;
 #[macro_use]
 extern crate num_derive;
 extern crate num_traits;
+extern crate scopeguard;
 #[cfg(not(target_os = "hermit"))]
 #[macro_use]
 extern crate std;

src/scheduler/task.rs

@@ -547,18 +547,19 @@ impl BlockedTaskQueue {
 		if let Some(wt) = wakeup_time {
 			let mut first_task = true;
 			let mut cursor = self.list.cursor_front_mut();
+			let mut _guard = scopeguard::guard(first_task, |first_task| {
+				// If the task is the new first task in the list, update the one-shot timer
+				// to fire when this task shall be woken up.
+				if first_task {
+					arch::set_oneshot_timer(wakeup_time);
+				}
+			});
 
 			while let Some(node) = cursor.current() {
 				let node_wakeup_time = node.wakeup_time;
 				if node_wakeup_time.is_none() || wt < node_wakeup_time.unwrap() {
 					cursor.insert_before(new_node);
 
-					// If this is the new first task in the list, update the One-Shot Timer
-					// to fire when this task shall be woken up.
-					if first_task {
-						arch::set_oneshot_timer(wakeup_time);
-					}
-
 					return;
 				}
 
@@ -568,12 +569,6 @@ impl BlockedTaskQueue {
 
 			// No, then just insert it at the end of the list.
 			self.list.push_back(new_node);
-
-			// If this is the task with the ealiest deadline (=> first elemen of the list),
-			// update the one-shot timer to fire when this task shall be woken up.
-			if first_task {
-				arch::set_oneshot_timer(wakeup_time);
-			}
 		} else {
 			// No, then just insert it at the end of the list.
 			self.list.push_back(new_node);