feat(io): buffer pool IO traits (#356)

* feat(io): buffer pool traits

* fix(io): name of Buffer

* feat(io): impl for Cursor

* feat(io): owned managed buffer

* feat(io): use IoBuf instead of Deref

Closes #365

compio-io/src/read/managed.rs

@@ -0,0 +1,67 @@
+use std::io::Cursor;
+
+use compio_buf::IoBuf;
+
+use crate::IoResult;
+
+/// # AsyncReadManaged
+///
+/// Async read with buffer pool
+pub trait AsyncReadManaged {
+    /// Buffer pool type
+    type BufferPool;
+    /// Filled buffer type
+    type Buffer: IoBuf;
+
+    /// Read some bytes from this source with [`BufferPool`] and return
+    /// a [`Buffer`].
+    ///
+    /// If `len` == 0, will use [`BufferPool`] inner buffer size as the max len,
+    /// if `len` > 0, `min(len, inner buffer size)` will be the read max len
+    async fn read_managed(
+        &mut self,
+        buffer_pool: &Self::BufferPool,
+        len: usize,
+    ) -> IoResult<Self::Buffer>;
+}
+
+/// # AsyncReadAtManaged
+///
+/// Async read with buffer pool and position
+pub trait AsyncReadManagedAt {
+    /// Buffer pool type
+    type BufferPool;
+    /// Filled buffer type
+    type Buffer: IoBuf;
+
+    /// Read some bytes from this source at position with [`BufferPool`] and
+    /// return a [`Buffer`].
+    ///
+    /// If `len` == 0, will use [`BufferPool`] inner buffer size as the max len,
+    /// if `len` > 0, `min(len, inner buffer size)` will be the read max len
+    async fn read_managed_at(
+        &self,
+        pos: u64,
+        buffer_pool: &Self::BufferPool,
+        len: usize,
+    ) -> IoResult<Self::Buffer>;
+}
+
+impl<A: AsyncReadManagedAt> AsyncReadManaged for Cursor<A> {
+    type Buffer = A::Buffer;
+    type BufferPool = A::BufferPool;
+
+    async fn read_managed(
+        &mut self,
+        buffer_pool: &Self::BufferPool,
+        len: usize,
+    ) -> IoResult<Self::Buffer> {
+        let pos = self.position();
+        let buf = self
+            .get_ref()
+            .read_managed_at(pos, buffer_pool, len)
+            .await?;
+        self.set_position(pos + buf.buf_len() as u64);
+        Ok(buf)
+    }
+}

compio-io/src/read/mod.rs

@@ -7,9 +7,11 @@ use compio_buf::{BufResult, IntoInner, IoBuf, IoBufMut, IoVectoredBufMut, buf_tr
 mod buf;
 #[macro_use]
 mod ext;
+mod managed;
 
 pub use buf::*;
 pub use ext::*;
+pub use managed::*;
 
 use crate::util::slice_to_buf;