refactor(port_std): replace try_mutex::TryMutex with spin::Mutex

They are functionally equivalent, but `spin::Mutex` supports no-std
targets. I will need `spin::Mutex` for an upcoming example app, and if
we are going to use `spin::Mutex` in one package, we might as well use
it in all packages to keep the package count in `Cargo.lock` stable.
`spin` is also the most popular of the packages providing similar
functionalities.

Author: yvt

Cargo.lock

@@ -14,7 +14,7 @@ r3 = { version = "0.1.1", path = "../r3" }
 atomic_ref = { version = "0.2.0" }
 env_logger = { version = "0.8.4" }
 once_cell = { version = "1.4.0" }
-try-mutex = { version = "0.3.0" }
+spin = { version = "0.9.2", default-features = false, features = ["spin_mutex"] }
 log = { version = "0.4.8" }
 
 [dev-dependencies.r3_test_suite]

src/r3_port_std/Cargo.toml

@@ -16,12 +16,12 @@ use r3::{
     },
     prelude::*,
 };
+use spin::Mutex as SpinMutex;
 use std::{
     cell::Cell,
     sync::mpsc,
     time::{Duration, Instant},
 };
-use try_mutex::TryMutex;
 
 #[cfg(doc)]
 #[doc = include_str!("../CHANGELOG.md")]
@@ -42,8 +42,6 @@ mod sched;
 mod ums;
 mod utils;
 
-use self::utils::LockConsuming;
-
 /// Used by `use_port!`
 #[doc(hidden)]
 pub extern crate r3;
@@ -89,7 +87,7 @@ pub unsafe trait PortInstance: Kernel + Port<PortTaskState = TaskState> {
 #[doc(hidden)]
 pub struct State {
     thread_group: OnceCell<ums::ThreadGroup<sched::SchedState>>,
-    timer_cmd_send: TryMutex<Option<mpsc::Sender<TimerCmd>>>,
+    timer_cmd_send: SpinMutex<Option<mpsc::Sender<TimerCmd>>>,
     origin: AtomicRef<'static, Instant>,
 }
 
@@ -98,10 +96,10 @@ pub struct TaskState {
     /// The task's state in the task state machine.
     ///
     /// This field is expected to be accessed with CPU Lock or a scheduler lock,
-    /// so `TryMutex` is sufficient (no real mutexes are necessary). It could be
+    /// so `SpinMutex` is sufficient (no real mutexes are necessary). It could be
     /// even `UnsafeCell`, but we'd like to avoid unsafe code whenever possible.
     /// The runtime performance is not a concern in `r3_port_std`.
-    tsm: TryMutex<Tsm>,
+    tsm: SpinMutex<Tsm>,
 }
 
 impl Init for TaskState {
@@ -147,7 +145,7 @@ thread_local! {
 impl TaskState {
     pub const fn new() -> Self {
         Self {
-            tsm: TryMutex::new(Tsm::Uninit),
+            tsm: SpinMutex::new(Tsm::Uninit),
         }
     }
 
@@ -198,7 +196,7 @@ impl State {
     pub const fn new() -> Self {
         Self {
             thread_group: OnceCell::new(),
-            timer_cmd_send: TryMutex::new(None),
+            timer_cmd_send: SpinMutex::new(None),
             origin: AtomicRef::new(None),
         }
     }

src/r3_port_std/src/lib.rs

@@ -48,18 +48,3 @@ impl HasAtomicEquivalent for isize {
 }
 
 pub type Atomic<T> = <T as HasAtomicEquivalent>::AtomicEquivalent;
-
-pub trait LockConsuming {
-    type LockGuard;
-
-    fn lock(self) -> Self::LockGuard;
-}
-
-impl<'a, T> LockConsuming for &'a try_mutex::TryMutex<T> {
-    type LockGuard = try_mutex::TryMutexGuard<'a, T>;
-
-    #[inline]
-    fn lock(self) -> Self::LockGuard {
-        self.try_lock().unwrap()
-    }
-}