v0.1: fix guard forget + organisation stuff

CHANGELOG.md

···
+# Changelog
+
+## [0.1.0] - Date
+- Initial Release

LICENSES/Apache-2.0.txt

···
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README.md

···
 If the writer thread is the non realtime thread and reading should be nonblocking take a look at my other library
 [simple-left-right](https://crates.io/crates/simple-left-right). The implementation is similar, but the roles are reversed.
 
+Hosted on [tangled](https://tangled.org/did:plc:54jgbo4psy24qu2bk4njtpc4/rt-write-lock/), [codeberg](https://codeberg.org/increasing/rt-write-lock)
+and [github](https://github.com/luca3s/rt-write-lock). Open a PR or issue on any platform you like.
+
+## std::mem::forget
+The library tries to detect if a Read/Write guard is forgotten and panics. Without this detection this could lead to UB.

src/lib.rs

···
+// std::mem::forget creates issues because you can run a lock function without running the unlock function
+// i deal with this by tracking for Reader and Writer if they are locked currently. If a new locked is aquired
+// while it's still locked it panics. If Reader or Writer are dropped while locked it also panics.
+//
+// This could be circumvented by leaking Reader or Writer, but this doesn't lead to issues as then it's impossible
+// to aquire a new Reader or Writer, because then the count also wasn't decremented.
+//
+// This panics more often than UB would occur without this detection, but this exact specs is a implementation detail
+// and users just shouldn't forget the Guards.
+
 #![no_std]
 
 extern crate alloc;
···
 
 pub struct Reader<T> {
     shared: NonNull<Shared<T>>,
+    locked: bool,
     _owned: PhantomData<T>,
 }
 
 impl<T> Reader<T> {
-    pub fn try_read(&mut self) -> Option<ReadLock<'_, T>> {
+    pub fn try_read(&mut self) -> Option<ReadGuard<'_, T>> {
+        if self.locked {
+            self.locked = false; // don't also panic in the destructor
+            panic!("ReadGuard was forgotten");
+        }
         let shared = self.get_shared();
         let value = shared.try_read();
-        value.map(|value| ReadLock { shared, value })
+        // SAFETY: try_read returned Some to allowed to get a shared ref
+        let value = value.map(|v| unsafe { &*v.get() });
+        if let Some(value) = value {
+            // only set locked if locking actually was successful
+            self.locked = true;
+            Some(ReadGuard {
+                reader: self,
+                value,
+            })
+        } else {
+            None
+        }
     }
 
     fn get_shared(&self) -> &Shared<T> {
···
         Self {
             shared: Shared::new(value),
             _owned: PhantomData,
+            locked: false,
         }
     }
 }
···
         Self {
             shared: Shared::new_default(),
             _owned: PhantomData,
+            locked: false,
         }
     }
 }
···
         unsafe {
             Shared::drop(self.shared);
         }
+        assert!(!self.locked, "ReadGuard was forgotten")
     }
 }
 
-pub struct ReadLock<'a, T> {
-    shared: &'a Shared<T>,
+pub struct ReadGuard<'a, T> {
+    reader: &'a mut Reader<T>,
     value: &'a T,
 }
 
-impl<T> Deref for ReadLock<'_, T> {
+impl<T> Deref for ReadGuard<'_, T> {
     type Target = T;
 
     fn deref(&self) -> &Self::Target {
···
     }
 }
 
-impl<T> Drop for ReadLock<'_, T> {
+impl<T> Drop for ReadGuard<'_, T> {
     fn drop(&mut self) {
-        self.shared.remove_current_read();
+        self.reader.locked = false;
+        self.reader.get_shared().remove_current_read();
     }
 }
 
···
         unsafe { self.shared.as_ref() }
     }
 
-    pub fn write(&mut self) -> WriteLock<'_, T> {
-        assert!(
-            !self.locked,
-            "writelock destructor wasn't run. Create a new writer to "
-        );
+    pub fn write(&mut self) -> WriteGuard<'_, T> {
+        if self.locked {
+            self.locked = false; // don't also panic in the destructor
+            panic!("WriteGuard was forgotten");
+        }
+        // locking here is always successfull, so we set it unconditionally
+        self.locked = true;
         let shared = self.get_shared();
         // SAFETY: won't be called again while the mut ref is still live, as the write method needs a mut ref
         let pre_res = unsafe { shared.write() };
         // SAFETY: was just locked
         let value = unsafe { &mut *pre_res.0.get() };
         let ptr = pre_res.1;
-        self.locked = true;
 
-        WriteLock {
+        WriteGuard {
             writer: self,
             value,
             next_read: ptr,
···
         unsafe {
             Shared::drop(self.shared);
         }
+        assert!(!self.locked, "WriteGuard was forgotten")
     }
 }
 
···
 ///
 /// I still offer DerefMut instead of just taking a new T, because this allows reusing allocations inside of T instead of
 /// dropping and reallocing. This is important for realtime usecases.
-pub struct WriteLock<'a, T> {
+pub struct WriteGuard<'a, T> {
     writer: &'a mut Writer<T>,
     value: &'a mut T,
     // if some: set the next_read bit to the ptr value for unlocking
···
 
 // i don't really want this. I would prefer to only write, but i need a mut ref to be able to write rt-safe.
 // and for DerefMut i need Deref.
-impl<T> Deref for WriteLock<'_, T> {
+impl<T> Deref for WriteGuard<'_, T> {
     type Target = T;
 
     fn deref(&self) -> &Self::Target {
···
     }
 }
 
-impl<T> DerefMut for WriteLock<'_, T> {
+impl<T> DerefMut for WriteGuard<'_, T> {
     fn deref_mut(&mut self) -> &mut Self::Target {
         self.value
     }
 }
 
-impl<T> Drop for WriteLock<'_, T> {
+impl<T> Drop for WriteGuard<'_, T> {
     fn drop(&mut self) {
         self.writer.get_shared().unlock_write(self.next_read);
         self.writer.locked = false;

src/shared.rs

···
 }
 
 impl<T> Shared<T> {
-    pub fn try_read(&self) -> Option<&T> {
+    // returns a unsafecell to allow some lifetime stuff
+    pub fn try_read(&self) -> Option<&UnsafeCell<T>> {
         let result = self
             .state
             .fetch_update(Ordering::Acquire, Ordering::Relaxed, |value| {
···
                 let ptr = State::new(v).get_next_read().unwrap();
                 // SAFETY: atomic was just locked and the read state was set.
                 Some(match ptr {
-                    Ptr::Value1 => unsafe { &*self.value_1.get() },
-                    Ptr::Value2 => unsafe { &*self.value_2.get() },
+                    Ptr::Value1 => &self.value_1,
+                    Ptr::Value2 => &self.value_2,
                 })
             }
             // read isn't allowed
···
             .fetch_update(Ordering::Acquire, Ordering::Acquire, |v| {
                 let state = State::new(v);
                 let current_read = state.get_current_read();
-                // this can be None if WriteLock was forgotten instead of dropped. The state of the library is completely
-                // broken at this point.
-                let next_read = state
-                    .get_next_read()
-                    .expect("Destructor of WriteLock didn't run");
+                // this can't be None because if WriteLock was forgotten instead of dropped the outer API layer panics,
+                // before calling this function
+                let next_read = unsafe { state.get_next_read().unwrap_unchecked() };
 
                 match (current_read, next_read) {
                     (Some(c), n) if c != n => Some(state.disallow_read().0),

tests/tests.rs

···
     }
 
     #[test]
-    #[ignore = "need to find a complete design for preventing forgetting locks"]
+    #[should_panic]
     fn double_write() {
         let mut reader: Reader<u32> = Reader::default();
         let mut writer = reader.get_writer().unwrap();
 
         let write = writer.write();
         core::mem::forget(write);
-        let write = writer.write();
+        writer.write();
     }
 
     #[test]