v0.5.6

--no-self-update is necessary because the windows environment cannot
self-update rustup.exe.

.github/workflows/ci.yml

@@ -66,7 +66,8 @@ jobs:
     steps:
       - uses: actions/checkout@v2
       - name: Install Rust
-        run: rustup update stable && rustup default stable
+        # --no-self-update is necessary because the windows environment cannot self-update rustup.exe.
+        run: rustup update stable --no-self-update && rustup default stable
       - name: Test
         run: . ci/test-stable.sh test
 
@@ -120,7 +121,9 @@ jobs:
       - uses: actions/checkout@v2
       - name: Install Rust
         run: rustup update nightly && rustup default nightly
-      - name: TSAN / MSAN
+      - name: Install rust-src
+        run: rustup component add rust-src
+      - name: ASAN / TSAN
         run: . ci/tsan.sh
 
   # Loom

CHANGELOG.md

@@ -1,3 +1,10 @@
+# 0.5.6 (July 13, 2020)
+
+- Improve `BytesMut` to reuse buffer when fully `advance`d.
+- Mark `BytesMut::{as_mut, set_len}` with `#[inline]`.
+- Relax synchronization when cloning in shared vtable of `Bytes`.
+- Move `loom` to `dev-dependencies`.
+
 # 0.5.5 (June 18, 2020)
 
 ### Added

Cargo.toml

@@ -6,7 +6,7 @@ name = "bytes"
 # - Update CHANGELOG.md.
 # - Update doc URL.
 # - Create "v0.5.x" git tag.
-version = "0.5.5"
+version = "0.5.6"
 license = "MIT"
 authors = [
     "Carl Lerche <[email protected]>",
@@ -30,5 +30,5 @@ serde = { version = "1.0.60", optional = true, default-features = false, feature
 [dev-dependencies]
 serde_test = "1.0"
 
-[target.'cfg(loom)'.dependencies]
+[target.'cfg(loom)'.dev-dependencies]
 loom = "0.3"

benches/buf.rs

@@ -1,5 +1,5 @@
 #![feature(test)]
-#![deny(warnings, rust_2018_idioms)]
+#![warn(rust_2018_idioms)]
 
 extern crate test;
 

benches/bytes.rs

@@ -1,5 +1,5 @@
 #![feature(test)]
-#![deny(warnings, rust_2018_idioms)]
+#![warn(rust_2018_idioms)]
 
 extern crate test;
 

benches/bytes_mut.rs

@@ -1,5 +1,5 @@
 #![feature(test)]
-#![deny(warnings, rust_2018_idioms)]
+#![warn(rust_2018_idioms)]
 
 extern crate test;
 

ci/tsan

@@ -1,24 +0,0 @@
-# TSAN suppressions file for `bytes`
-
-# TSAN does not understand fences and `Arc::drop` is implemented using a fence.
-# This causes many false positives.
-race:Arc*drop
-race:arc*Weak*drop
-
-# `std` mpsc is not used in any Bytes code base. This race is triggered by some
-# rust runtime logic.
-race:std*mpsc_queue
-
-# Some test runtime races. Allocation should be race free
-race:alloc::alloc
-
-# Not sure why this is warning, but it is in the test harness and not the library.
-race:TestEvent*clone
-race:test::run_tests_console::*closure
-
-# Probably more fences in std.
-race:__call_tls_dtors
-
-# This ignores a false positive caused by `thread::park()`/`thread::unpark()`.
-# See: https://github.com/rust-lang/rust/pull/54806#issuecomment-436193353
-race:pthread_cond_destroy

ci/tsan.sh

@@ -2,9 +2,7 @@
 
 set -ex
 
-export RUST_TEST_THREADS=1
 export ASAN_OPTIONS="detect_odr_violation=0 detect_leaks=0"
-export TSAN_OPTIONS="suppressions=$(pwd)/ci/tsan"
 
 # Run address sanitizer
 RUSTFLAGS="-Z sanitizer=address" \
@@ -12,4 +10,4 @@ cargo test --target x86_64-unknown-linux-gnu --test test_bytes --test test_buf -
 
 # Run thread sanitizer
 RUSTFLAGS="-Z sanitizer=thread" \
-cargo test --target x86_64-unknown-linux-gnu --test test_bytes --test test_buf --test test_buf_mut
+cargo -Zbuild-std test --target x86_64-unknown-linux-gnu --test test_bytes --test test_buf --test test_buf_mut

src/bytes.rs

@@ -928,7 +928,7 @@ const KIND_VEC: usize = 0b1;
 const KIND_MASK: usize = 0b1;
 
 unsafe fn shared_clone(data: &AtomicPtr<()>, ptr: *const u8, len: usize) -> Bytes {
-    let shared = data.load(Ordering::Acquire);
+    let shared = data.load(Ordering::Relaxed);
     shallow_clone_arc(shared as _, ptr, len)
 }
 

src/bytes_mut.rs

@@ -22,8 +22,12 @@ use crate::{Buf, BufMut, Bytes};
 ///
 /// `BytesMut` represents a unique view into a potentially shared memory region.
 /// Given the uniqueness guarantee, owners of `BytesMut` handles are able to
-/// mutate the memory. It is similar to a `Vec<u8>` but with less copies and
-/// allocations.
+/// mutate the memory.
+///
+/// `BytesMut` can be thought of as containing a `buf: Arc<Vec<u8>>`, an offset
+/// into `buf`, a slice length, and a guarantee that no other `BytesMut` for the
+/// same `buf` overlaps with its slice. That guarantee means that a write lock
+/// is not required.
 ///
 /// # Growth
 ///
@@ -475,6 +479,7 @@ impl BytesMut {
     ///
     /// assert_eq!(&b[..], b"hello world");
     /// ```
+    #[inline]
     pub unsafe fn set_len(&mut self, len: usize) {
         debug_assert!(len <= self.cap, "set_len out of bounds");
         self.len = len;
@@ -558,9 +563,8 @@ impl BytesMut {
             unsafe {
                 let (off, prev) = self.get_vec_pos();
 
-                // Only reuse space if we stand to gain at least capacity/2
-                // bytes of space back
-                if off >= additional && off >= (self.cap / 2) {
+                // Only reuse space if we can satisfy the requested additional space.
+                if self.capacity() - self.len() + off >= additional {
                     // There's space - reuse it
                     //
                     // Just move the pointer back to the start after copying
@@ -1025,6 +1029,7 @@ impl Deref for BytesMut {
 }
 
 impl AsMut<[u8]> for BytesMut {
+    #[inline]
     fn as_mut(&mut self) -> &mut [u8] {
         self.as_slice_mut()
     }
@@ -1495,7 +1500,7 @@ static SHARED_VTABLE: Vtable = Vtable {
 };
 
 unsafe fn shared_v_clone(data: &AtomicPtr<()>, ptr: *const u8, len: usize) -> Bytes {
-    let shared = data.load(Ordering::Acquire) as *mut Shared;
+    let shared = data.load(Ordering::Relaxed) as *mut Shared;
     increment_shared(shared);
 
     let data = AtomicPtr::new(shared as _);

src/lib.rs

@@ -1,14 +1,9 @@
-#![deny(
-    warnings,
-    missing_docs,
-    missing_debug_implementations,
-    rust_2018_idioms
-)]
+#![warn(missing_docs, missing_debug_implementations, rust_2018_idioms)]
 #![doc(test(
     no_crate_inject,
     attr(deny(warnings, rust_2018_idioms), allow(dead_code, unused_variables))
 ))]
-#![doc(html_root_url = "https://docs.rs/bytes/0.5.5")]
+#![doc(html_root_url = "https://docs.rs/bytes/0.5.6")]
 #![no_std]
 
 //! Provides abstractions for working with bytes.

tests/test_buf.rs

@@ -1,4 +1,4 @@
-#![deny(warnings, rust_2018_idioms)]
+#![warn(rust_2018_idioms)]
 
 use bytes::Buf;
 #[cfg(feature = "std")]

tests/test_buf_mut.rs

@@ -1,4 +1,4 @@
-#![deny(warnings, rust_2018_idioms)]
+#![warn(rust_2018_idioms)]
 
 #[cfg(feature = "std")]
 use bytes::buf::IoSliceMut;

tests/test_bytes.rs

@@ -1,4 +1,4 @@
-#![deny(warnings, rust_2018_idioms)]
+#![warn(rust_2018_idioms)]
 
 use bytes::{Buf, BufMut, Bytes, BytesMut};
 
@@ -929,6 +929,22 @@ fn bytes_buf_mut_advance() {
     }
 }
 
+#[test]
+fn bytes_buf_mut_reuse_when_fully_consumed() {
+    use bytes::{Buf, BytesMut};
+    let mut buf = BytesMut::new();
+    buf.reserve(8192);
+    buf.extend_from_slice(&[0u8; 100][..]);
+
+    let p = &buf[0] as *const u8;
+    buf.advance(100);
+
+    buf.reserve(8192);
+    buf.extend_from_slice(b" ");
+
+    assert_eq!(&buf[0] as *const u8, p);
+}
+
 #[test]
 #[should_panic]
 fn bytes_reserve_overflow() {

tests/test_chain.rs

@@ -1,4 +1,4 @@
-#![deny(warnings, rust_2018_idioms)]
+#![warn(rust_2018_idioms)]
 
 use bytes::buf::{BufExt, BufMutExt};
 use bytes::{Buf, BufMut, Bytes};

tests/test_debug.rs

@@ -1,4 +1,4 @@
-#![deny(warnings, rust_2018_idioms)]
+#![warn(rust_2018_idioms)]
 
 use bytes::Bytes;
 

tests/test_iter.rs

@@ -1,4 +1,4 @@
-#![deny(warnings, rust_2018_idioms)]
+#![warn(rust_2018_idioms)]
 
 use bytes::Bytes;
 

tests/test_reader.rs

@@ -1,4 +1,4 @@
-#![deny(warnings, rust_2018_idioms)]
+#![warn(rust_2018_idioms)]
 #![cfg(feature = "std")]
 
 use std::io::{BufRead, Read};

tests/test_serde.rs

@@ -1,5 +1,5 @@
 #![cfg(feature = "serde")]
-#![deny(warnings, rust_2018_idioms)]
+#![warn(rust_2018_idioms)]
 
 use serde_test::{assert_tokens, Token};
 

tests/test_take.rs

@@ -1,4 +1,4 @@
-#![deny(warnings, rust_2018_idioms)]
+#![warn(rust_2018_idioms)]
 
 use bytes::buf::{Buf, BufExt};