[DOC] Improve the thread::park and thread::unpark documentation

src/libstd/thread/mod.rs

@@ -585,16 +585,17 @@ pub fn park() {
 /// Blocks unless or until the current thread's token is made available or
 /// the specified duration has been reached (may wake spuriously).
 ///
-/// The semantics of this function are equivalent to `park()` except that the
-/// thread will be blocked for roughly no longer than `ms`. This method
-/// should not be used for precise timing due to anomalies such as
+/// The semantics of this function are equivalent to [`park()`][[park] except
+/// that the thread will be blocked for roughly no longer than `dur`. This
+/// method should not be used for precise timing due to anomalies such as
 /// preemption or platform differences that may not cause the maximum
 /// amount of time waited to be precisely `ms` long.
 ///
 /// See the [module documentation][thread] for more detail.
 ///
 /// [thread]: index.html
 /// [park_timeout]: fn.park_timeout.html
+/// [park]: fn.park.html
 #[stable(feature = "rust1", since = "1.0.0")]
 #[rustc_deprecated(since = "1.6.0", reason = "replaced by `std::thread::park_timeout`")]
 pub fn park_timeout_ms(ms: u32) {
@@ -604,13 +605,13 @@ pub fn park_timeout_ms(ms: u32) {
 /// Blocks unless or until the current thread's token is made available or
 /// the specified duration has been reached (may wake spuriously).
 ///
-/// The semantics of this function are equivalent to `park()` except that the
-/// thread will be blocked for roughly no longer than `dur`. This method
-/// should not be used for precise timing due to anomalies such as
+/// The semantics of this function are equivalent to [`park()`][[park] except
+/// that the thread will be blocked for roughly no longer than `dur`. This
+/// method should not be used for precise timing due to anomalies such as
 /// preemption or platform differences that may not cause the maximum
 /// amount of time waited to be precisely `dur` long.
 ///
-/// See the module doc for more detail.
+/// See the [module doc][thread] for more detail.
 ///
 /// # Platform behavior
 ///
@@ -635,6 +636,9 @@ pub fn park_timeout_ms(ms: u32) {
 ///     park_timeout(timeout);
 /// }
 /// ```
+///
+/// [thread]: index.html
+/// [park]: fn.park.html
 #[stable(feature = "park_timeout", since = "1.4.0")]
 pub fn park_timeout(dur: Duration) {
     let thread = current();
@@ -764,22 +768,36 @@ impl Thread {
 
     /// Atomically makes the handle's token available if it is not already.
     ///
-    /// See the module doc for more detail.
+    /// Every thread is equipped with some basic low-level blocking support, via
+    /// the [`park()`][park] function and the `unpark()` method. These can be
+    /// used as a more CPU-efficient implementation of a spinlock.
+    ///
+    /// See the [module doc][thread] for more detail.
     ///
     /// # Examples
     ///
     /// ```
     /// use std::thread;
     ///
-    /// let handler = thread::Builder::new()
+    /// let parked_thread = thread::Builder::new()
     ///     .spawn(|| {
-    ///         let thread = thread::current();
-    ///         thread.unpark();
+    ///         println!("Parking thread");
+    ///         thread::park();
+    ///         println!("Thread unparked");
     ///     })
     ///     .unwrap();
     ///
-    /// handler.join().unwrap();
+    /// // Let some time pass for the thread to be spawned.
+    /// thread::sleep(Duration::from_millis(10));
+    ///
+    /// println!("Unpark the thread");
+    /// parked_thread.thread().unpark();
+    ///
+    /// parked_thread.join().unwrap();
     /// ```
+    ///
+    /// [thread]: index.html
+    /// [park]: fn.park.html
     #[stable(feature = "rust1", since = "1.0.0")]
     pub fn unpark(&self) {
         let mut guard = self.inner.lock.lock().unwrap();