Merge #820

820: Change AioCb to primarily use Bytes instead of Rc<[u8]> r=asomers a=asomers

`Rc<[u8]>` isn't a very good buffer type to use for aio.  For one thing, it lacks interior mutability.  For another, a single `Rc<[u8]>` can't be carved up into smaller buffers of the same type.  `Bytes` and `BytesMut` fix both problems.  This PR removes the ability to construct an `AioCb` from `Rc<[u8]>` and adds the ability to construct one from `Bytes`, `BytesMut`, or raw pointers (for consumers who need even more flexibility).  At this stage, the PR has the following warts:

1. A hack is necessary to force small `Bytes` buffers to allocate on the heap.  I plan to fix this with an enhancement to the bytes crate.
2. The `AioCb::buffer` method is necessary due to a deficiency in the tokio-core crate.  Once I fix that, then only `AioCb::into_buffer`will need to be public.

CHANGELOG.md

@@ -6,6 +6,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 ## [Unreleased]
 
 ### Added
+- Added `AioCb::from_ptr` and `AioCb::from_mut_ptr`
+  ([#820](https://github.com/nix-rust/nix/pull/820))
 - Added specialized wrappers: `sys::ptrace::{traceme, syscall, cont, attach}`. Using the matching routines
   with `sys::ptrace::ptrace` is now deprecated.
 - Added `nix::poll` module for all platforms
@@ -108,6 +110,9 @@ This project adheres to [Semantic Versioning](http://semver.org/).
   ([#648](https://github.com/nix-rust/nix/pull/648))
 
 ### Removed
+- `AioCb::from_boxed_slice` has been removed.  It was never actually safe.  Use
+  `from_bytes` or `from_bytes_mut` instead.
+  ([#820](https://github.com/nix-rust/nix/pull/820))
 - The syscall module has been removed. This only exposed enough functionality for
   `memfd_create()` and `pivot_root()`, which are still exposed as separate functions.
   ([#747](https://github.com/nix-rust/nix/pull/747))

Cargo.toml

@@ -18,6 +18,11 @@ bitflags = "1.0"
 cfg-if = "0.1.0"
 void = "1.0.2"
 
+[dependencies.bytes]
+version = "0.4.5"
+# Don't include the optional serde feature
+default-features = false
+
 [target.'cfg(target_os = "dragonfly")'.build-dependencies]
 gcc = "0.3"
 

src/lib.rs

@@ -11,6 +11,7 @@
 #![cfg_attr(test, deny(warnings))]
 #![recursion_limit = "500"]
 
+extern crate bytes;
 #[macro_use]
 extern crate bitflags;