1 files changed, 162 insertions, 65 deletions
diff --git a/ecs/src/lock.rs b/ecs/src/lock.rs
index fbc6842..fe4e08b 100644
--- a/ecs/src/lock.rs
+++ b/ecs/src/lock.rs
@@ -1,105 +1,120 @@
-use std::mem::transmute;
+use std::any::type_name;
+use std::mem::forget;
 use std::ops::{Deref, DerefMut};
-use std::sync::{PoisonError, RwLock, RwLockReadGuard, RwLockWriteGuard, TryLockError};
 
-use crate::type_name::TypeName;
+use parking_lot::{
+    MappedRwLockReadGuard,
+    MappedRwLockWriteGuard,
+    RwLock,
+    RwLockReadGuard,
+    RwLockWriteGuard,
+};
 
-#[derive(Debug, Default)]
+#[derive(Debug)]
 pub struct Lock<Value>
-where
-    Value: TypeName,
 {
     inner: RwLock<Value>,
+    value_type_name: &'static str,
 }
 
 impl<Value> Lock<Value>
-where
-    Value: TypeName,
 {
-    pub fn new(value: Value) -> Self
+    pub fn new(value: Value, value_type_name: &'static str) -> Self
     {
-        Self { inner: RwLock::new(value) }
+        Self {
+            inner: RwLock::new(value),
+            value_type_name,
+        }
     }
 
     /// Tries to a acquire a handle to the resource with read access.
     ///
     /// # Errors
     /// Returns `Err` if unavailable (A mutable handle is hold).
-    pub fn read_nonblock(&self) -> Result<ReadGuard<Value>, Error>
+    pub fn read_nonblock(&self) -> Result<ReadGuard<'_, Value>, Error>
     {
-        let guard = self.inner.try_read().or_else(|err| match err {
-            TryLockError::WouldBlock => Err(Error::Unavailable),
-            TryLockError::Poisoned(poison_err) => Ok(poison_err.into_inner()),
-        })?;
+        let guard = self.inner.try_read().ok_or(Error::ReadUnavailable)?;
 
-        #[cfg(feature = "debug")]
-        tracing::trace!("Acquired lock to value of type {}", guard.type_name());
+        tracing::trace!("Acquired lock to value of type {}", self.value_type_name);
 
-        Ok(ReadGuard { inner: guard })
+        Ok(ReadGuard {
+            inner: guard,
+            value_type_name: self.value_type_name,
+        })
     }
 
     /// Tries to a acquire a handle to the resource with mutable access.
     ///
     /// # Errors
     /// Returns `Err` if unavailable (A mutable or immutable handle is hold).
-    pub fn write_nonblock(&self) -> Result<WriteGuard<Value>, Error>
+    pub fn write_nonblock(&self) -> Result<WriteGuard<'_, Value>, Error>
     {
-        let guard = self.inner.try_write().or_else(|err| match err {
-            TryLockError::WouldBlock => Err(Error::Unavailable),
-            TryLockError::Poisoned(poison_err) => Ok(poison_err.into_inner()),
-        })?;
+        let guard = self.inner.try_write().ok_or(Error::WriteUnavailable)?;
 
-        #[cfg(feature = "debug")]
         tracing::trace!(
             "Acquired mutable lock to value of type {}",
-            guard.type_name()
+            self.value_type_name
         );
 
-        Ok(WriteGuard { inner: guard })
+        Ok(WriteGuard {
+            inner: guard,
+            value_type_name: self.value_type_name,
+        })
     }
+}
 
-    pub fn into_inner(self) -> Value
+impl<Value: Default + 'static> Default for Lock<Value>
+{
+    fn default() -> Self
     {
-        self.inner
-            .into_inner()
-            .unwrap_or_else(PoisonError::into_inner)
+        Self::new(Value::default(), type_name::<Value>())
     }
 }
 
 #[derive(Debug, thiserror::Error)]
 pub enum Error
 {
-    #[error("Lock is unavailable")]
-    Unavailable,
+    #[error("Lock is unavailable for reading")]
+    ReadUnavailable,
+
+    #[error("Lock is unavailable for writing")]
+    WriteUnavailable,
 }
 
 #[derive(Debug)]
 pub struct ReadGuard<'guard, Value>
-where
-    Value: TypeName,
 {
     inner: RwLockReadGuard<'guard, Value>,
+    value_type_name: &'static str,
 }
 
 impl<'guard, Value> ReadGuard<'guard, Value>
-where
-    Value: TypeName,
 {
-    /// Converts the `ReadGuard` to a `ReadGuard` with a possibly longer lifetime.
-    ///
-    /// # Safety
-    /// The returned `ReadGuard` must **NOT** be used for longer than the original
-    /// lifetime.
-    #[must_use]
-    pub unsafe fn upgrade_lifetime<'new>(self) -> ReadGuard<'new, Value>
+    pub fn try_map<NewValue>(
+        this: Self,
+        func: impl FnOnce(&Value) -> Option<&NewValue>,
+    ) -> Result<MappedReadGuard<'guard, NewValue>, Self>
     {
-        unsafe { transmute(self) }
+        let value_type_name = this.value_type_name;
+
+        // The 'inner' field cannot be moved out of ReadGuard in a normal way since
+        // ReadGuard implements Drop
+        let inner = unsafe { std::ptr::read(&raw const this.inner) };
+        forget(this);
+
+        match RwLockReadGuard::try_map(inner, func) {
+            Ok(mapped_guard) => {
+                Ok(MappedReadGuard { inner: mapped_guard, value_type_name })
+            }
+            Err(unmapped_guard) => Err(Self {
+                inner: unmapped_guard,
+                value_type_name,
+            }),
+        }
     }
 }
 
-impl<'guard, Value> Deref for ReadGuard<'guard, Value>
-where
-    Value: TypeName,
+impl<Value> Deref for ReadGuard<'_, Value>
 {
     type Target = Value;
 
@@ -109,28 +124,112 @@ where
     }
 }
 
-impl<'guard, Value> Drop for ReadGuard<'guard, Value>
-where
-    Value: TypeName,
+impl<Value> Drop for ReadGuard<'_, Value>
 {
     fn drop(&mut self)
     {
-        #[cfg(feature = "debug")]
-        tracing::trace!("Dropped lock to value of type {}", self.type_name());
+        tracing::trace!("Dropped lock to value of type {}", self.value_type_name);
+    }
+}
+
+#[derive(Debug)]
+pub struct MappedReadGuard<'guard, Value>
+{
+    inner: MappedRwLockReadGuard<'guard, Value>,
+    value_type_name: &'static str,
+}
+
+impl<Value> Deref for MappedReadGuard<'_, Value>
+{
+    type Target = Value;
+
+    fn deref(&self) -> &Self::Target
+    {
+        &self.inner
+    }
+}
+
+impl<Value> Drop for MappedReadGuard<'_, Value>
+{
+    fn drop(&mut self)
+    {
+        tracing::trace!(
+            "Dropped mapped lock to value of type {}",
+            self.value_type_name
+        );
     }
 }
 
 #[derive(Debug)]
 pub struct WriteGuard<'guard, Value>
-where
-    Value: TypeName,
 {
     inner: RwLockWriteGuard<'guard, Value>,
+    value_type_name: &'static str,
 }
 
-impl<'guard, Value> Deref for WriteGuard<'guard, Value>
-where
-    Value: TypeName,
+impl<'guard, Value> WriteGuard<'guard, Value>
+{
+    pub fn try_map<NewValue>(
+        this: Self,
+        func: impl FnOnce(&mut Value) -> Option<&mut NewValue>,
+    ) -> Result<MappedWriteGuard<'guard, NewValue>, Self>
+    {
+        let value_type_name = this.value_type_name;
+
+        // The 'inner' field cannot be moved out of ReadGuard in a normal way since
+        // ReadGuard implements Drop
+        let inner = unsafe { std::ptr::read(&raw const this.inner) };
+        forget(this);
+
+        match RwLockWriteGuard::try_map(inner, func) {
+            Ok(mapped_guard) => {
+                Ok(MappedWriteGuard { inner: mapped_guard, value_type_name })
+            }
+            Err(unmapped_guard) => Err(Self {
+                inner: unmapped_guard,
+                value_type_name,
+            }),
+        }
+    }
+}
+
+impl<Value> Deref for WriteGuard<'_, Value>
+{
+    type Target = Value;
+
+    fn deref(&self) -> &Self::Target
+    {
+        &self.inner
+    }
+}
+
+impl<Value> DerefMut for WriteGuard<'_, Value>
+{
+    fn deref_mut(&mut self) -> &mut Self::Target
+    {
+        &mut self.inner
+    }
+}
+
+impl<Value> Drop for WriteGuard<'_, Value>
+{
+    fn drop(&mut self)
+    {
+        tracing::trace!(
+            "Dropped mutable lock to value of type {}",
+            self.value_type_name
+        );
+    }
+}
+
+#[derive(Debug)]
+pub struct MappedWriteGuard<'guard, Value>
+{
+    inner: MappedRwLockWriteGuard<'guard, Value>,
+    value_type_name: &'static str,
+}
+
+impl<Value> Deref for MappedWriteGuard<'_, Value>
 {
     type Target = Value;
 
@@ -140,9 +239,7 @@ where
     }
 }
 
-impl<'guard, Value> DerefMut for WriteGuard<'guard, Value>
-where
-    Value: TypeName,
+impl<Value> DerefMut for MappedWriteGuard<'_, Value>
 {
     fn deref_mut(&mut self) -> &mut Self::Target
     {
@@ -150,13 +247,13 @@ where
     }
 }
 
-impl<'guard, Value> Drop for WriteGuard<'guard, Value>
-where
-    Value: TypeName,
+impl<Value> Drop for MappedWriteGuard<'_, Value>
 {
     fn drop(&mut self)
     {
-        #[cfg(feature = "debug")]
-        tracing::trace!("Dropped mutable lock to value of type {}", self.type_name());
+        tracing::trace!(
+            "Dropped mapped mutable lock to value of type {}",
+            self.value_type_name
+        );
     }
 }