m: Update fmt::Debug to produce useful output

cc #86, it's harder to get this info on no_std so I've ignored it for
now

Signed-off-by: John Nunley <[email protected]>

src/lib.rs

@@ -542,7 +542,13 @@ impl<T> Drop for Event<T> {
 
 impl fmt::Debug for Event {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        f.pad("Event { .. }")
+        match self.try_inner() {
+            None => f
+                .debug_tuple("Event")
+                .field(&format_args!("<uninitialized>"))
+                .finish(),
+            Some(inner) => inner.debug_fmt(f),
+        }
     }
 }
 

src/linked_list/lock_free.rs

@@ -5,6 +5,7 @@ use crate::notify::{GenericNotify, Internal, Notification};
 
 use core::cell::{Cell, UnsafeCell};
 use core::cmp::Reverse;
+use core::fmt;
 use core::hint::spin_loop;
 use core::iter;
 use core::marker::PhantomData;
@@ -95,6 +96,12 @@ impl<T> Inner<T> {
         }
     }
 
+    /// Debug output.
+    #[inline]
+    pub(crate) fn debug_fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("Event").finish_non_exhaustive()
+    }
+
     /// We never have enough info to tell this for sure.
     pub(crate) fn notifyable(&self, _limit: usize) -> bool {
         true

src/linked_list/mutex.rs

@@ -5,10 +5,11 @@ use crate::notify::{GenericNotify, Internal, Notification};
 
 use std::boxed::Box;
 use std::cell::{Cell, UnsafeCell};
+use std::fmt;
 use std::mem;
 use std::ops::{Deref, DerefMut};
 use std::ptr::{self, NonNull};
-use std::sync::{Mutex, MutexGuard};
+use std::sync::{Mutex, MutexGuard, TryLockError};
 use std::task::{Context, Poll, Waker};
 use std::thread::{self, Thread};
 use std::time::Instant;
@@ -49,6 +50,28 @@ impl<T> Inner<T> {
         }
     }
 
+    /// Debug output.
+    #[inline]
+    pub(crate) fn debug_fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        let guard = match self.list.try_lock() {
+            Err(TryLockError::WouldBlock) => {
+                return f
+                    .debug_tuple("Event")
+                    .field(&format_args!("<locked>"))
+                    .finish()
+            }
+
+            Err(TryLockError::Poisoned(err)) => err.into_inner(),
+
+            Ok(lock) => lock,
+        };
+
+        f.debug_struct("Event")
+            .field("listeners_notified", &guard.notified)
+            .field("listeners_total", &guard.len)
+            .finish()
+    }
+
     /// Tell whether there is enough room to notify this list.
     #[inline]
     pub(crate) fn notifyable(&self, limit: usize) -> bool {