Merge pull request #44 from PolyMeilex/drop-generational-arena

Drop generational-arena dependency

oxisynth/Cargo.toml

@@ -24,7 +24,6 @@ log.workspace = true
 bitflags = "2.4"
 byte-slice-cast = "1.0.0"
 byteorder = "1.4.3"
-generational-arena = "0.2.8"
 
 # i16-out
 getrandom = { version = "0.2", features = ["js"], optional = true }

oxisynth/src/arena.rs

@@ -1,71 +1,204 @@
-use generational_arena::{Arena, Index};
+use std::marker::PhantomData;
 
-use std::{cmp::PartialEq, fmt, marker::PhantomData};
+enum Slot<T> {
+    Free,
+    Occupied { generation: usize, value: T },
+}
 
-pub struct TypedIndex<T>(Index, PhantomData<T>);
+impl<T> Slot<T> {
+    fn is_free(&self) -> bool {
+        matches!(self, Self::Free)
+    }
 
-impl<T> From<Index> for TypedIndex<T> {
-    fn from(id: Index) -> Self {
-        Self(id, PhantomData)
+    fn is_occupied(&self) -> bool {
+        !self.is_free()
     }
 }
 
-impl<T> fmt::Display for TypedIndex<T> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        write!(f, "{:?}", self.0)
+pub struct Index<T> {
+    id: usize,
+    generation: usize,
+    _ph: PhantomData<fn() -> T>,
+}
+
+impl<T> PartialEq for Index<T> {
+    fn eq(&self, other: &Self) -> bool {
+        self.id == other.id && self.generation == other.generation
     }
 }
 
-impl<T> fmt::Debug for TypedIndex<T> {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        self.0.fmt(f)
+impl<T> Eq for Index<T> {}
+
+impl<T> std::fmt::Debug for Index<T> {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("Index")
+            .field("id", &self.id)
+            .field("generation", &self.generation)
+            .finish()
     }
 }
 
-impl<T> Clone for TypedIndex<T> {
+impl<T> Copy for Index<T> {}
+impl<T> Clone for Index<T> {
     fn clone(&self) -> Self {
-        Self(self.0, PhantomData)
+        *self
     }
 }
 
-impl<T> Copy for TypedIndex<T> {}
+pub(crate) struct Arena<T> {
+    slots: Vec<Slot<T>>,
+    generation: usize,
+}
 
-impl<T> PartialEq for TypedIndex<T> {
-    fn eq(&self, other: &TypedIndex<T>) -> bool {
-        self.0 == other.0
+impl<T> Default for Arena<T> {
+    fn default() -> Self {
+        Self::new()
     }
 }
 
-pub(crate) struct TypedArena<T>(Arena<T>);
-
-impl<T> TypedArena<T> {
+impl<T> Arena<T> {
     pub fn new() -> Self {
-        Self(Arena::new())
+        Self {
+            slots: Vec::new(),
+            generation: 0,
+        }
     }
 
-    pub fn insert(&mut self, value: T) -> TypedIndex<T> {
-        self.0.insert(value).into()
+    pub fn insert(&mut self, value: T) -> Index<T> {
+        let entry = self.slots.iter_mut().enumerate().find(|(_, e)| e.is_free());
+
+        match entry {
+            Some((id, entry)) => {
+                *entry = Slot::Occupied {
+                    generation: self.generation,
+                    value,
+                };
+
+                Index {
+                    id,
+                    generation: self.generation,
+                    _ph: PhantomData,
+                }
+            }
+            None => {
+                // No free slots found, insert new one
+
+                let id = self.slots.len();
+
+                self.slots.push(Slot::Occupied {
+                    generation: self.generation,
+                    value,
+                });
+
+                Index {
+                    id,
+                    generation: self.generation,
+                    _ph: PhantomData,
+                }
+            }
+        }
     }
 
-    pub fn get(&self, index: TypedIndex<T>) -> Option<&T> {
-        self.0.get(index.0)
+    pub fn len(&self) -> usize {
+        self.slots.iter().filter(|v| v.is_occupied()).count()
     }
 
-    pub fn remove(&mut self, index: TypedIndex<T>) -> Option<T> {
-        self.0.remove(index.0)
+    pub fn get(&self, index: Index<T>) -> Option<&T> {
+        match self.slots.get(index.id)? {
+            Slot::Occupied { generation, value } if *generation == index.generation => Some(value),
+            _ => None,
+        }
+    }
+
+    pub fn remove(&mut self, index: Index<T>) -> Option<T> {
+        match self.slots.get_mut(index.id)? {
+            Slot::Occupied { generation, .. } if *generation == index.generation => {
+                let Slot::Occupied { value, .. } =
+                    std::mem::replace(&mut self.slots[index.id], Slot::Free)
+                else {
+                    unreachable!();
+                };
+
+                self.generation += 1;
+                Some(value)
+            }
+            _ => None,
+        }
     }
 }
 
-impl<T> std::ops::Deref for TypedArena<T> {
-    type Target = Arena<T>;
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn insert() {
+        let mut arena = Arena::new();
 
-    fn deref(&self) -> &Self::Target {
-        &self.0
+        let a = arena.insert(1);
+        let b = arena.insert(2);
+        let c = arena.insert(3);
+
+        assert_eq!((a.generation, a.id), (0, 0));
+        assert_eq!((b.generation, b.id), (0, 1));
+        assert_eq!((c.generation, c.id), (0, 2));
+
+        assert_eq!(arena.get(a), Some(&1));
+        assert_eq!(arena.get(b), Some(&2));
+        assert_eq!(arena.get(c), Some(&3));
     }
-}
 
-impl<T> std::ops::DerefMut for TypedArena<T> {
-    fn deref_mut(&mut self) -> &mut Self::Target {
-        &mut self.0
+    #[test]
+    fn remove() {
+        let mut arena = Arena::new();
+
+        let a = arena.insert(1);
+        let b = arena.insert(2);
+        let c = arena.insert(3);
+
+        assert_eq!((a.generation, a.id), (0, 0));
+        assert_eq!((b.generation, b.id), (0, 1));
+        assert_eq!((c.generation, c.id), (0, 2));
+
+        assert_eq!(arena.remove(a), Some(1));
+        assert_eq!(arena.remove(b), Some(2));
+        assert_eq!(arena.remove(c), Some(3));
+
+        assert_eq!(arena.get(a), None);
+        assert_eq!(arena.get(b), None);
+        assert_eq!(arena.get(c), None);
+    }
+
+    #[test]
+    fn remove_and_reinsert() {
+        let mut arena = Arena::new();
+
+        let a = arena.insert(1);
+        let b = arena.insert(2);
+        let c = arena.insert(3);
+
+        assert_eq!((a.generation, a.id), (0, 0));
+        assert_eq!((b.generation, b.id), (0, 1));
+        assert_eq!((c.generation, c.id), (0, 2));
+
+        assert_eq!(arena.remove(a), Some(1));
+        assert_eq!(arena.remove(b), Some(2));
+        assert_eq!(arena.remove(c), Some(3));
+
+        let aa = arena.insert(1);
+        let bb = arena.insert(2);
+        let cc = arena.insert(3);
+
+        assert_eq!((aa.generation, aa.id), (3, 0));
+        assert_eq!((bb.generation, bb.id), (3, 1));
+        assert_eq!((cc.generation, cc.id), (3, 2));
+
+        assert_eq!(arena.get(a), None);
+        assert_eq!(arena.get(b), None);
+        assert_eq!(arena.get(c), None);
+
+        assert_eq!(arena.get(aa), Some(&1));
+        assert_eq!(arena.get(bb), Some(&2));
+        assert_eq!(arena.get(cc), Some(&3));
     }
 }

oxisynth/src/core/channel_pool/channel.rs

@@ -2,7 +2,7 @@ use std::sync::Arc;
 
 use super::super::soundfont::{Preset, SoundFont};
 
-use crate::arena::TypedIndex;
+use crate::arena::Index;
 use crate::GeneratorType;
 use crate::Tuning;
 
@@ -48,7 +48,7 @@ impl Default for InterpolationMethod {
 pub struct Channel {
     id: usize,
 
-    sfontnum: Option<TypedIndex<SoundFont>>,
+    sfontnum: Option<Index<SoundFont>>,
 
     banknum: u32,
     prognum: u8,
@@ -171,11 +171,11 @@ impl Channel {
         self.id
     }
 
-    pub fn sfontnum(&self) -> Option<TypedIndex<SoundFont>> {
+    pub fn sfontnum(&self) -> Option<Index<SoundFont>> {
         self.sfontnum
     }
 
-    pub fn set_sfontnum(&mut self, sfontnum: Option<TypedIndex<SoundFont>>) {
+    pub fn set_sfontnum(&mut self, sfontnum: Option<Index<SoundFont>>) {
         self.sfontnum = sfontnum;
     }
 
@@ -283,7 +283,7 @@ impl Channel {
         self.nrpn_active = value;
     }
 
-    /// Retreive the value of a generator. This function returns the value
+    /// Retrieve the value of a generator. This function returns the value
     /// set by a previous call 'set_gen()' or by an NRPN message.
     ///
     /// Returns the value of the generator.