Reorganize code for 1.64 Rust version

.github/workflows/ci.yml

@@ -11,6 +11,7 @@ on:
 env:
   RUSTFLAGS: -Dwarnings
   RUST_BACKTRACE: 1
+  RUST_VERSION: 1.64.0
 
 jobs:
   # Depends on all actions that are required for a "successful" CI run.
@@ -54,9 +55,14 @@ jobs:
   test:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - name: Checkout sources
+        uses: actions/checkout@v3
       - name: Install Rust
-        run: rustup update stable
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: ${{ env.RUST_VERSION }}
+          profile: minimal
+          override: true
       - run: cargo test
 
   test-docs:

Cargo.toml

@@ -3,6 +3,7 @@ name = "tokio-uring"
 version = "0.4.0"
 authors = ["Tokio Contributors <team@tokio.rs>"]
 edition = "2018"
+rust-version = "1.64"
 readme = "README.md"
 license = "MIT"
 documentation = "https://docs.rs/tokio-uring/0.4.0/tokio-uring"

README.md

@@ -10,7 +10,8 @@ provides new resource types that work with [`io-uring`].
 [`fs::File`]: https://docs.rs/tokio-uring/latest/tokio_uring/fs/struct.File.html
 
 [API Docs](https://docs.rs/tokio-uring/latest/tokio_uring) |
-[Chat](https://discord.gg/tokio)
+[Chat](https://discord.gg/tokio) |
+![rust 1.64.0 required](https://img.shields.io/badge/rust-1.64.0-blue.svg?label=MSRV)
 
 # Getting started
 

src/buf/fixed/plumbing/registry.rs

@@ -73,23 +73,23 @@ impl<T: IoBufMut> Registry<T> {
     // If the buffer is already checked out, returns None.
     pub(crate) fn check_out(&mut self, index: usize) -> Option<CheckedOutBuf> {
         let state = self.states.get_mut(index)?;
-        let BufState::Free { init_len } = *state else {
-            return None
-        };
-
-        *state = BufState::CheckedOut;
+        if let BufState::Free { init_len } = *state {
+            *state = BufState::CheckedOut;
 
-        // Safety: the allocated array under the pointer is valid
-        // for the lifetime of self, the index is inside the array
-        // as checked by Vec::get_mut above, called on the array of
-        // states that has the same length.
-        let iovec = unsafe { self.raw_bufs.as_ptr().add(index).read() };
-        debug_assert!(index <= u16::MAX as usize);
-        Some(CheckedOutBuf {
-            iovec,
-            init_len,
-            index: index as u16,
-        })
+            // Safety: the allocated array under the pointer is valid
+            // for the lifetime of self, the index is inside the array
+            // as checked by Vec::get_mut above, called on the array of
+            // states that has the same length.
+            let iovec = unsafe { self.raw_bufs.as_ptr().add(index).read() };
+            debug_assert!(index <= u16::MAX as usize);
+            Some(CheckedOutBuf {
+                iovec,
+                init_len,
+                index: index as u16,
+            })
+        } else {
+            None
+        }
     }
 
     fn check_in_internal(&mut self, index: u16, init_len: usize) {