WIP: Allocator- and fallibility-polymorphic collections

src/liballoc/abort_adapter.rs

@@ -0,0 +1,118 @@
+// Copyright 2015 The Rust Project Developers. See the COPYRIGHT
+// file at the top-level directory of this distribution and at
+// http://rust-lang.org/COPYRIGHT.
+//
+// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
+// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
+// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
+// option. This file may not be copied, modified, or distributed
+// except according to those terms.
+
+#![unstable(feature = "allocator_api",
+            reason = "the precise API and guarantees it provides may be tweaked \
+                      slightly, especially to possibly take into account the \
+                      types being stored to make room for a future \
+                      tracing garbage collector",
+            issue = "32838")]
+
+use core::usize;
+use core::ptr::NonNull;
+
+use crate::alloc::*;
+
+/// An allocator adapter that blows up by calling `Alloc::oom` on all errors.
+///
+/// On one hand, concrete allocator implementations should always be written
+/// without panicking on user error and OOM to give users maximum
+/// flexibility. On the other hand, code that depends on allocation succeeding
+/// should depend on `Alloc<Err=!>` to avoid repetitively handling errors from
+/// which it cannot recover.
+///
+/// This adapter bridges the gap, effectively allowing `Alloc<Err=!>` to be
+/// implemented by any allocator.
+#[derive(Copy, Clone, Debug, Default)]
+pub struct AbortAdapter<Alloc>(pub Alloc);
+
+impl<A: AllocHelper> AllocHelper for AbortAdapter<A> {
+    type Err = !;
+}
+
+unsafe impl<A: Alloc> Alloc for AbortAdapter<A> {
+    unsafe fn alloc(&mut self, layout: Layout) -> Result<NonNull<u8>, Self::Err> {
+        self.0.alloc(layout).or_else(|_| handle_alloc_error(layout))
+    }
+
+    unsafe fn dealloc(&mut self, ptr: NonNull<u8>, layout: Layout) {
+        self.0.dealloc(ptr, layout)
+    }
+
+    fn usable_size(&self, layout: &Layout) -> (usize, usize) {
+        self.0.usable_size(layout)
+    }
+
+    unsafe fn realloc(&mut self,
+                      ptr: NonNull<u8>,
+                      layout: Layout,
+                      new_size: usize) -> Result<NonNull<u8>, Self::Err> {
+        self.0.realloc(ptr, layout, new_size).or_else(|_| {
+            let layout = Layout::from_size_align_unchecked(new_size, layout.align());
+            handle_alloc_error(layout)
+        })
+    }
+
+    unsafe fn alloc_zeroed(&mut self, layout: Layout) -> Result<NonNull<u8>, Self::Err> {
+        self.0.alloc_zeroed(layout).or_else(|_| handle_alloc_error(layout))
+    }
+
+    unsafe fn alloc_excess(&mut self, layout: Layout) -> Result<Excess, Self::Err> {
+        self.0.alloc_excess(layout).or_else(|_| handle_alloc_error(layout))
+    }
+
+    unsafe fn grow_in_place(&mut self,
+                            ptr: NonNull<u8>,
+                            layout: Layout,
+                            new_size: usize) -> Result<(), CannotReallocInPlace> {
+        self.0.grow_in_place(ptr, layout, new_size)
+    }
+
+    unsafe fn shrink_in_place(&mut self,
+                              ptr: NonNull<u8>,
+                              layout: Layout,
+                              new_size: usize) -> Result<(), CannotReallocInPlace> {
+        self.0.shrink_in_place(ptr, layout, new_size)
+    }
+
+    fn alloc_one<T>(&mut self) -> Result<NonNull<T>, Self::Err>
+        where Self: Sized
+    {
+        self.0.alloc_one().or_else(|_| handle_alloc_error(Layout::new::<T>()))
+    }
+
+    unsafe fn dealloc_one<T>(&mut self, ptr: NonNull<T>)
+        where Self: Sized
+    {
+        self.0.dealloc_one(ptr)
+    }
+
+    fn alloc_array<T>(&mut self, n: usize) -> Result<NonNull<T>, Self::Err>
+        where Self: Sized
+    {
+        self.0.alloc_array(n).or_else(|_| handle_alloc_error(Layout::new::<T>()))
+    }
+
+    unsafe fn realloc_array<T>(&mut self,
+                               ptr: NonNull<T>,
+                               n_old: usize,
+                               n_new: usize) -> Result<NonNull<T>, Self::Err>
+        where Self: Sized
+    {
+        self.0.realloc_array(ptr, n_old, n_new)
+            .or_else(|_| handle_alloc_error(Layout::new::<T>()))
+    }
+
+    unsafe fn dealloc_array<T>(&mut self, ptr: NonNull<T>, n: usize) -> Result<(), Self::Err>
+        where Self: Sized
+    {
+        self.0.dealloc_array(ptr, n).or_else(|_| handle_alloc_error(Layout::new::<T>()))
+    }
+}

src/liballoc/alloc.rs

@@ -40,10 +40,14 @@ extern "Rust" {
 /// This type implements the [`Alloc`] trait by forwarding calls
 /// to the allocator registered with the `#[global_allocator]` attribute
 /// if there is one, or the `std` crate’s default.
+#[cfg(not(test))]
 #[unstable(feature = "allocator_api", issue = "32838")]
 #[derive(Copy, Clone, Default, Debug)]
 pub struct Global;
 
+#[cfg(test)]
+pub use std::alloc::Global;
+
 /// Allocate memory with the global allocator.
 ///
 /// This function forwards calls to the [`GlobalAlloc::alloc`] method
@@ -116,6 +120,13 @@ pub unsafe fn alloc_zeroed(layout: Layout) -> *mut u8 {
     __rust_alloc_zeroed(layout.size(), layout.align())
 }
 
+#[cfg(not(test))]
+#[unstable(feature = "allocator_api", issue = "32838")]
+impl AllocHelper for Global {
+    type Err = AllocErr;
+}
+
+#[cfg(not(test))]
 #[unstable(feature = "allocator_api", issue = "32838")]
 unsafe impl Alloc for Global {
     #[inline]
@@ -165,14 +176,19 @@ unsafe fn exchange_malloc(size: usize, align: usize) -> *mut u8 {
 
 #[cfg_attr(not(test), lang = "box_free")]
 #[inline]
-pub(crate) unsafe fn box_free<T: ?Sized>(ptr: Unique<T>) {
+pub(crate) unsafe fn box_free<T: ?Sized, A: Alloc>(ptr: Unique<T>, mut a: A) {
+    box_free_worker(ptr, &mut a)
+}
+
+#[inline]
+pub(crate) unsafe fn box_free_worker<T: ?Sized, A: Alloc>(ptr: Unique<T>, a: &mut A) {
     let ptr = ptr.as_ptr();
     let size = size_of_val(&*ptr);
     let align = min_align_of_val(&*ptr);
     // We do not allocate for Box<T> when T is ZST, so deallocation is also not necessary.
     if size != 0 {
         let layout = Layout::from_size_align_unchecked(size, align);
-        dealloc(ptr as *mut u8, layout);
+        a.dealloc(NonNull::new_unchecked(ptr).cast(), layout);
     }
 }