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// Copyright 2018 Theodore Cipicchio // // 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. //! Stack-like memory allocator with double-ended allocation support. //! //! # Table of Contents //! //! - [Overview](#overview) //! - [Basic Walkthrough](#basic-walkthrough) //! - [Allocating Pool Storage](#allocating-pool-storage) //! - [Creating the Scratchpad Instance](#creating-the-scratchpad-instance) //! - [Creating Allocation Markers](#creating-allocation-markers) //! - [Allocating Data](#allocating-data) //! - [Freeing Memory](#freeing-memory) //! - [Additional Operations](#additional-operations) //! - [Optional Crate Features](#optional-crate-features) //! - [Implementation Notes](#implementation-notes) //! - [Memory Management](#memory-management) //! - [Buffer Types](#buffer-types) //! - [Macros and Functions for Handling Buffers](#macros-and-functions-for-handling-buffers) //! - [Data Alignment](#data-alignment) //! - [`Buffer` and `Tracking` Alignments](#buffer-and-tracking-alignments) //! - [Alignment of Allocated Arrays](#alignment-of-allocated-arrays) //! - [Cache Alignment](#cache-alignment) //! - [Memory Overhead](#memory-overhead) //! - [Limitations](#limitations) //! - [Mutability Notes](#mutability-notes) //! - [Example - Temporary Thread-local Allocations](#example---temporary-thread-local-allocations) //! //! # Overview //! //! [`Scratchpad`] provides a method for quick and safe dynamic allocations of //! arbitrary types without relying on the global heap (e.g. using [`Box`] or //! [`Vec`]). Allocations are made from a fixed-size region of memory in a //! stack-like fashion using two separate stacks (one for each end of the //! allocation buffer) to allow different types of allocations with //! independent lifecycles to be made from each end. //! //! Such allocators are commonly used in game development, but are also useful //! in general for short-lived allocations or groups of allocations that share //! a common lifetime. While not quite as flexible as heap allocations, //! allocations from a stack allocator are usually much faster and are //! isolated from the rest of the heap, reducing memory fragmentation. //! //! In addition to general allocation operations, this crate also allows for //! adding to existing allocations and concatenating adjacent allocations. //! //! # Basic Walkthrough //! //! The following is a step-by-step example of how to create a scratchpad and //! use it for basic allocation operations. //! //! ## Allocating Pool Storage //! //! A scratchpad instance relies on two buffers of memory: //! //! - The pool from which memory is allocated. //! - A separate buffer for tracking allocation "markers". A marker defines a //! context in which a group of allocations is made. Objects are allocated //! through markers, and memory is only ever truly "freed" back to the pool //! when the marker is dropped. //! //! To keep things flexible, the user is required to provide either a static //! array, boxed slice, or borrowed slice reference for each. Any basic //! integer type (`u8`, `i64`, etc.) can be used as the array or slice element //! type, as well as the [`CacheAligned`] type provided by this crate if //! cache-aligned memory is desired. //! //! A handful of [macros and //! functions](#macros-and-functions-for-handling-buffers) are provided to //! help with defining buffers with specific storage requirements. Macros and //! functions related specifically to allocation pool storage are suffixed //! with "`_for_bytes`", while macros and functions related specifically to //! marker tracking storage are suffixed with "`_for_markers`". Here, we use //! [`uninitialized_boxed_slice_for_bytes()`] and //! [`uninitialized_boxed_slice_for_markers()`] to create two boxed slices of //! cache-aligned memory for our allocation pool and tracking buffer. //! //! ``` //! use scratchpad::uninitialized_boxed_slice_for_bytes; //! use scratchpad::uninitialized_boxed_slice_for_markers; //! use scratchpad::CacheAligned; //! //! const POOL_SIZE: usize = 1usize * 1024 * 1024; // 1 MB //! const MARKERS_MAX: usize = 16; //! //! let pool = unsafe { //! uninitialized_boxed_slice_for_bytes::<CacheAligned>(POOL_SIZE) //! }; //! let tracking = unsafe { //! uninitialized_boxed_slice_for_markers::<CacheAligned>(MARKERS_MAX) //! }; //! ``` //! //! ## Creating the Scratchpad Instance //! //! Now that we've defined the storage that our scratchpad will use, we can //! create a [`Scratchpad`] instance using this storage. Simply call //! [`Scratchpad::new()`], passing the allocation pool and marker tracking //! buffer as arguments. //! //! ``` //! use scratchpad::Scratchpad; //! //! # let pool = [0usize; 1]; //! # let tracking = [0usize; 1]; //! let scratchpad = Scratchpad::new(pool, tracking); //! ``` //! //! If you decide to use static arrays for both allocation storage and marker //! tracking, [`Scratchpad::static_new()`] can be used to create the //! scratchpad without having to construct the arrays separately. Note that //! using large static array buffers can cause the program to run out of stack //! space during initialization, so you may need to stick to either boxed //! slices or slices of externally owned arrays. //! //! ## Creating Allocation Markers //! //! When we're ready to allocate from the scratchpad, we must first create a //! [`Marker`]. A marker defines a context in which allocations will be made. //! Multiple allocations can be made from a single marker, but the memory //! isn't freed back to the scratchpad until the marker is dropped, even if //! the individual allocations are dropped. This helps keep things fast, as //! the scratchpad only needs to perform a limited amount of tracking of //! allocated memory. //! //! Markers can be created from either the "front" or "back" of a scratchpad. //! Front markers, created using [`Scratchpad::mark_front()`], allocate memory //! from the start of the allocation pool upward, while back markers, created //! using [`Scratchpad::mark_back()`], allocate memory from the end of the //! allocation pool downward. The stacks of such allocations are handled //! separately, so front markers don't affect back markers and vice-versa //! (with the exception of how much space is still available in the //! scratchpad). //! //! Here, we create a front marker for subsequent allocations. //! //! ``` //! # use scratchpad::Scratchpad; //! # let scratchpad = Scratchpad::<[usize; 1], [usize; 1]>::static_new(); //! let marker = scratchpad.mark_front().unwrap(); //! ``` //! //! ## Allocating Data //! //! Each marker provides a variety of allocation functions, allowing //! allocations of single elements or dynamically sized arrays of any type. //! Allocation functions can be found in the [`Marker`] docs, and are prefixed //! with "`allocate_`" (most `Marker` trait functions are also wrapped by //! methods of the [`MarkerFront`] and [`MarkerBack`] types as well, so you //! don't need to import the `Marker` trait into scope to use them). //! //! Allocations are wrapped in an [`Allocation`] instance. `Allocation` //! implements [`Deref`] and [`DerefMut`], allowing access to the wrapped data //! either explicitly using the unary `*` operator (e.g. `*allocation`) or //! implicitly, such as when calling methods provided by the allocated data //! type (e.g. `allocation.len()` for retrieving the number of elements in an //! `Allocation<[i32]>`). //! //! ``` //! # use scratchpad::Scratchpad; //! # let scratchpad = Scratchpad::<[usize; 16], [usize; 1]>::static_new(); //! # let marker = scratchpad.mark_front().unwrap(); //! // Allocate a single `f32`. //! let f32_allocation = marker.allocate(3.14159f32).unwrap(); //! assert_eq!(*f32_allocation, 3.14159f32); //! //! // Allocate an array of `i32` values. //! let i32_array_allocation = marker //! .allocate_array_with(5, |index| index as i32 * 2) //! .unwrap(); //! assert_eq!(*i32_array_allocation, [0, 2, 4, 6, 8]); //! ``` //! //! One thing to note is that allocations can only be made from the most //! recently created marker belonging to a given stack ("front" or "back"). A //! marker can be used again for allocations once any more-recent markers from //! the same stack are dropped. Creating a new front marker doesn't prevent //! allocations from being made from any back markers, and vice-versa. //! //! ``` //! # use scratchpad::Scratchpad; //! # let scratchpad = Scratchpad::<[usize; 16], [usize; 2]>::static_new(); //! // Allocations can be made from a marker immediately after it's created... //! let first_marker = scratchpad.mark_front().unwrap(); //! let result = first_marker.allocate(3.14159f32); //! assert!(result.is_ok()); //! //! { //! // ...but creating a second marker will prevent any new allocations //! // from being made using the first marker... //! let second_marker = scratchpad.mark_front().unwrap(); //! let result = first_marker.allocate([1, 2, 3, 4, 5]); //! assert!(result.is_err()); //! //! } // ...until the second marker is dropped (such as when going out of //! // scope here). //! //! let result = first_marker.allocate([1, 2, 3, 4, 5]); //! assert!(result.is_ok()); //! //! // Creating a back marker does not prevent us from allocating from our //! // front marker though. //! let back_marker = scratchpad.mark_back().unwrap(); //! let result = first_marker.allocate([6, 7, 8, 9, 10]); //! assert!(result.is_ok()); //! ``` //! //! ## Freeing Memory //! //! Memory is freed *only* when the *most recently created* [`Marker`] from a //! given stack ("front" or "back") is dropped. Despite this, markers are //! still allowed to be dropped out-of-order; if a marker that is not the most //! recently created marker from its stack is dropped, its memory will simply //! be unusable until the more recently created markers are also freed. This //! can fragment the memory pool, so it is recommended to drop markers in the //! reverse order in which they are created when possible. //! //! Dropping an [`Allocation`] will not cause the scratchpad memory used to be //! freed, but it will immediately call any [`Drop`] implementation for the //! allocated type. Allocations can also be dropped in any order. //! //! Each [`Allocation`] is bound to the lifetime of the [`Marker`] from which //! it is created, and each [`Marker`] is bound to the lifetime of the //! [`Scratchpad`] from which it is created, ensuring allocations and markers //! cannot outlive their parent objects. //! //! # Additional Operations //! //! Aside from general allocation and use of data, this crate provides support //! for a handful of additional operations: //! //! - Allocations that are adjacent in memory in the same scratchpad can be //! combined using [`Allocation::concat()`] and its unsafe counterpart, //! [`Allocation::concat_unchecked()`]. //! - Data can be added to the most recent allocation from a given stack: //! - Data can be appended to the most recent allocation from a front marker //! using [`MarkerFront::append()`], [`MarkerFront::append_clone()`], and //! [`MarkerFront::append_copy()`]. //! - Data can be prepended to the most recent allocation from a back marker //! using [`MarkerBack::prepend()`], [`MarkerBack::prepend_clone()`], and //! [`MarkerBack::prepend_copy()`]. //! - The [`Marker`] trait provides generic [`extend()`], //! [`extend_clone()`], and [`extend_copy()`] methods that either append //! or prepend depending on whether the marker is a front or back marker. //! - Arbitrary numbers of slices can be concatenated into a single allocation //! at once using [`Marker::concat_slices()`], //! [`Marker::concat_slices_clone()`], and [`Marker::concat_slices_copy()`]. //! - Allocations can be converted into slices using //! [`Allocation::into_slice_like_allocation()`]. //! - The data in an allocation can be moved out of the allocation using //! [`Allocation::unwrap()`]. //! //! # Optional Crate Features //! //! The following optional features can be set when building this crate: //! //! - **`std`**: Implements various traits for [`Box`] and [`Vec`] types, //! allowing boxed slices to be used as storage for allocations and marker //! tracking as well as both boxes and vectors to be used as slice sources //! for [`Marker`] methods that take slices as parameters. Enabled by //! default; can be disabled to build the crate with `#![no_std]`. //! - **`unstable`**: Enables unstable toolchain features (requires a nightly //! compiler). Disabled by default. Enabling this feature includes: //! - Support for [`Box`] and [`Vec`] types as mentioned with the `std` //! feature, regardless of whether the `std` feature is enabled (if `std` //! is disabled, this will use the `alloc` library directly). //! - Declaration of the function [`Scratchpad::new()`] as `const`. //! - [`ByteData`] trait implementations for `u128`/`i128` for Rust versions //! prior to 1.26 (`u128`/`i128` support is enabled by default with both //! stable and unstable toolchains if the detected Rust version is 1.26 or //! greater). //! //! # Implementation Notes //! //! ## Memory Management //! //! Scratchpad memory usage is explicitly controlled by the user. While this //! adds a bit to the complexity of setting up a scratchpad for use, it allows //! for scratchpads to be used under a variety of constraints, such as within //! low-memory embedded environments. //! //! ### Buffer Types //! //! The backing data structures used for allocation storage and marker //! tracking are specified by the generic parameters of the [`Scratchpad`] //! type. //! //! The allocation storage type is provided by the `BufferT` generic //! parameter, which is constrained by the [`Buffer`] trait. Allocation //! storage must be a contiguous region of memory, such as a static array, //! boxed slice, or mutable slice reference. Array element types are //! constrained to types that implement the [`ByteData`] trait; by default, //! this only includes basic integer types and the [`CacheAligned`] struct //! provided by this crate. //! //! The marker tracking buffer type is provided by the `TrackingT` generic //! parameter, which is constrained by the [`Tracking`] trait. This type must //! allow storage and retrieval of a fixed number of `usize` values. Unlike //! [`Buffer`], there is no restriction on how the values are stored so long //! as they can be set and subsequently retrieved by index. Any type //! implementing [`Buffer`] also implements [`Tracking`] by default. //! //! ### Macros and Functions for Handling Buffers //! //! Writing out the math needed to determine the number of elements needed for //! an array or boxed slice of a specific byte or marker capacity can be //! tedious and error-prone. This crate provides some macros and functions to //! help reduce the amount of work needed for declaring buffers based on their //! byte capacity or marker capacity: //! //! - [`array_type_for_bytes!()`] and [`array_type_for_markers!()`] can be //! used to declare static array types based on their capacity. //! - [`cache_aligned_zeroed_for_bytes!()`] and //! [`cache_aligned_zeroed_for_markers!()`] provide shorthand for creating //! static arrays of [`CacheAligned`] elements with their contents zeroed //! out. //! - [`uninitialized_boxed_slice_for_bytes()`] and //! [`uninitialized_boxed_slice_for_markers()`] can be used to allocate //! memory for a boxed slice of a given capacity without initializing its //! contents. //! //! Some lower level macros and functions are also available if needed: //! //! - [`array_len_for_bytes!()`] and [`array_len_for_markers!()`] return the //! number of elements needed for a static array with a given capacity. //! - [`cache_aligned_zeroed!()`] provides shorthand for creating a single //! [`CacheAligned`] value with its contents zeroed out. //! - [`uninitialized_boxed_slice()`] allocates a boxed slice of a given //! number of elements without initializing its contents. //! //! Additionally, all of the macros listed above evaluate to constant //! expressions when given constant expressions for input values. //! //! ## Data Alignment //! //! The alignment requirements of allocated objects are handled by padding the //! offset of the allocation within the allocation buffer. This can result in //! some amount of wasted space if mixing allocations of types that have //! different alignment requirements. This waste can be minimized if necessary //! by grouping allocations based on their alignment requirements or by using //! separate scratchpads for different alignments. //! //! ### `Buffer` and `Tracking` Alignments //! //! The alignment of the allocation buffer and marker tracking themselves are //! determined by the element type of the corresponding slice or array used, //! as specified by the generic parameters of the [`Scratchpad`] type and the //! parameters of [`Scratchpad::new()`]. If the alignment of the buffer itself //! doesn't match the alignment needed for the first allocation made, the //! allocation will be offset from the start of the buffer as needed, //! resulting in wasted space. //! //! To avoid this, use an element type for the buffer's slice or array that //! provides at least the same alignment as that which will be needed for //! allocations. For most types, a slice or array of `u64` elements should //! provide sufficient alignment to avoid any initial wasted space. //! //! Allocations that require non-standard alignments may require defining a //! custom [`ByteData`] type with an appropriate `#[repr(align)]` attribute to //! avoid any wasted space at the start of the allocation buffer. For example, //! a [`Scratchpad`] guaranteeing a minimum initial alignment of 16 bytes for //! SIMD allocations can be created as follows: //! //! ``` //! use std::mem::uninitialized; //! use scratchpad::{ByteData, Scratchpad}; //! //! #[repr(align(16))] //! struct Aligned16([u32; 4]); //! //! unsafe impl ByteData for Aligned16 {} //! //! let scratchpad = Scratchpad::<[Aligned16; 1024], [usize; 4]>::new( //! unsafe { uninitialized() }, //! unsafe { uninitialized() }, //! ); //! ``` //! //! ### Alignment of Allocated Arrays //! //! When allocating a dynamically sized array from a [`Marker`][`Marker`] //! (i.e. using one of the `allocate_array*()` or `allocate_slice*()` //! methods), the array is *only* guaranteed to be aligned based on the //! requirements of the element type. This means that, for example, it is //! unsafe to use an array of `u8` values as a buffer in which `f32` values //! will be written to or read from directly. It is strongly recommended that //! you only use arrays allocated from a marker as the element type specified, //! or that the array is allocated using an element type whose alignment is at //! least as large as the data it will contain. //! //! ### Cache Alignment //! //! Applications may prefer to keep data aligned to cache lines to avoid //! performance issues (e.g. multiple cache line loads for data crossing cache //! line boundaries, false sharing). The crate provides a custom data type, //! [`CacheAligned`], that can be used as the backing type for both allocation //! buffers and marker tracking. Simply providing an array or slice of //! [`CacheAligned`] objects instead of a built-in integer type will help //! ensure cache alignment of the buffer. //! //! This crate uses 64 bytes as the assumed cache line alignment, regardless //! of the build target. While the actual cache line alignment can vary //! between processors, 64 bytes is generally assumed to be a "safe" target. //! This value is exported in the [`CACHE_ALIGNMENT`] constant for //! applications that wish to reference it. //! //! The size of a single [`CacheAligned`] element will always be the same as //! the cache alignment, so buffers based on [`CacheAligned`] will always be //! a multiple of [`CACHE_ALIGNMENT`] in size. //! //! ## Memory Overhead //! //! Creating a marker requires a single `usize` value (4 bytes on platforms //! using 32-bit pointers, 8 bytes if using 64-bit pointers) within the //! scratchpad's tracking buffer. When using a slice or array for marker //! tracking, this memory is allocated up-front, so the footprint of the //! [`Scratchpad`] does not change after the scratchpad is created. //! //! Each [`Marker`] instance itself contains a reference back to its //! [`Scratchpad`] and its index within the scratchpad. This comes out to 8 //! bytes on platforms with 32-bit pointers and 16 bytes on platforms with //! 64-bit pointers. //! //! Individual allocations have effectively no overhead. Each [`Allocation`] //! instance itself only contains a pointer to its data, whose size can vary //! depending on whether a fat pointer is necessary (such as for dynamically //! sized arrays allocated using one of the `allocate_array*()` or //! `allocate_slice*()` marker methods). //! //! ## Limitations //! //! - Due to a lack of support in Rust for generically implementing traits for //! any size of a static array of a given type, traits that are implemented //! for static array types such as [`Buffer`] and [`SliceSource`] are only //! implemented for a limited number of array sizes. Mutable slice //! references and boxed slices do not have this restriction, so they can be //! used for unsupported array sizes if necessary. //! - [`SliceSourceCollection`] and [`SliceMoveSourceCollection`] (used by the //! slice concatenation methods of [`Marker`]) only support tuples with up //! to 12 items (most `std` library traits implemented for tuples are also //! limited to 12 items as well). //! - Using large static arrays as buffers can cause the program stack to //! overflow during scratchpad creation, particularly in debug builds. Using //! [`Scratchpad::static_new()`] instead of [`Scratchpad::new()`] can help //! avoid such issues, but it is not guaranteed to always work. Using either //! boxed slices or slice references of externally owned arrays for storage //! can help avoid such issues entirely. //! //! ## Mutability Notes //! //! [`Scratchpad`] uses internal mutability when allocating and freeing //! memory, with allocation methods operating on immutable [`Scratchpad`] and //! [`Marker`] references. This is necessary to cleanly allow for multiple //! concurrent allocations, as Rust's mutable borrowing restrictions would //! otherwise prevent such behavior. Allocation and free operations do not //! have any side effect on other existing allocations, so there are no //! special considerations necessary by the user. //! //! # Example - Temporary Thread-local Allocations //! //! Applications can create per-thread scratchpads for temporary allocations //! using thread-local variables, reducing fragmentation of the global memory //! heap and improving performance. The following example shows how one might //! use temporary storage to interface with a third-party library within some //! abstraction layer: //! //! ``` //! #[macro_use] //! extern crate scratchpad; //! //! use scratchpad::{CacheAligned, Scratchpad}; //! use scratchpad::uninitialized_boxed_slice_for_bytes; //! use std::mem::{size_of, uninitialized}; //! use std::os::raw::c_void; //! //! /// Thread-local scratchpad size, in bytes (1 MB). //! const THREAD_LOCAL_SCRATCHPAD_SIZE: usize = 1024 * 1024; //! /// Maximum thread-local scratchpad allocation marker count. //! const THREAD_LOCAL_SCRATCHPAD_MAX_MARKERS: usize = 8; //! //! /// Buffer type for thread-local scratchpad allocations. By using //! /// `CacheAligned`, we avoid false sharing of cache lines between threads. //! type ThreadLocalScratchBuffer = Box<[CacheAligned]>; //! //! /// Buffer type for tracking of thread-local scratchpad markers (each //! /// marker requires a `usize` value). //! type ThreadLocalScratchTracking = array_type_for_markers!( //! CacheAligned, //! THREAD_LOCAL_SCRATCHPAD_MAX_MARKERS, //! ); //! //! thread_local! { //! /// Thread-local scratchpad. The initial contents of the allocation //! /// buffer and marker tracking buffer are ignored, so we can create //! /// them as uninitialized. //! pub static THREAD_LOCAL_SCRATCHPAD: Scratchpad< //! ThreadLocalScratchBuffer, //! ThreadLocalScratchTracking, //! > = unsafe { Scratchpad::new( //! uninitialized_boxed_slice_for_bytes(THREAD_LOCAL_SCRATCHPAD_SIZE), //! uninitialized(), //! ) }; //! } //! //! /// Rust bindings for part of some fictional third-party API written in //! /// C/C++. //! pub mod libfoo { //! use std::os::raw::c_void; //! //! #[repr(C)] //! pub enum SequenceType { //! Integer, //! Float, //! Double, //! } //! //! #[derive(Debug, PartialEq)] //! #[repr(C)] //! pub enum SequenceResult { //! Red, //! Green, //! Blue, //! } //! //! #[repr(C)] //! pub struct SequenceParameters { //! pub data_type: SequenceType, //! pub data_count: usize, //! pub data: *const c_void, //! } //! //! pub unsafe extern "C" fn process_sequences( //! sequence_count: usize, //! sequences: *const SequenceParameters, //! ) -> SequenceResult { //! // ... //! # SequenceResult::Red //! } //! } //! //! /// Our abstraction of `libfoo::process_sequences()`, in which we only //! /// ever work with `f32` data. //! pub fn process_float_sequences<I, E, S>( //! sequences: I, //! ) -> Result<libfoo::SequenceResult, scratchpad::Error<()>> //! where //! I: IntoIterator<Item = S, IntoIter = E>, //! E: ExactSizeIterator<Item = S>, //! S: AsRef<[f32]>, //! { //! THREAD_LOCAL_SCRATCHPAD.with(|scratchpad| { //! // We need an array of `libfoo::SequenceParameters` structs for //! // the call to `libfoo::process_sequences()`. //! let mut sequences = sequences.into_iter(); //! let sequences_len = sequences.len(); //! //! let marker = scratchpad.mark_front()?; //! let foo_sequences = marker.allocate_array_with( //! sequences_len, //! |index| { //! let data = sequences.next().unwrap(); //! let data_ref = data.as_ref(); //! libfoo::SequenceParameters { //! data_type: libfoo::SequenceType::Float, //! data_count: data_ref.len(), //! data: data_ref.as_ptr() as *const c_void, //! } //! } //! )?; //! //! Ok(unsafe { libfoo::process_sequences( //! sequences_len, //! foo_sequences.as_ptr(), //! ) }) //! //! // The marker is dropped as it goes out of scope, freeing the //! // allocated memory. //! }) //! } //! //! fn main() { //! let sequence_a = [2.22f32, 9.99f32, -1234.56f32]; //! let sequence_b = [-1.0f32, 8.8f32, 27.0f32, 0.03f32]; //! let sequence_c = [88.0f32]; //! let sequences = [&sequence_a[..], &sequence_b[..], &sequence_c[..]]; //! assert_eq!( //! process_float_sequences(&sequences).unwrap(), //! libfoo::SequenceResult::Red, //! ); //! } //! ``` //! //! [`Allocation`]: struct.Allocation.html //! [`Allocation::concat()`]: struct.Allocation.html#method.concat //! [`Allocation::concat_unchecked()`]: struct.Allocation.html#method.concat_unchecked //! [`Allocation::into_slice_like_allocation()`]: struct.Allocation.html#method.into_slice_like_allocation //! [`Allocation::unwrap()`]: struct.Allocation.html#method.unwrap //! [`array_len_for_bytes!()`]: macro.array_len_for_bytes.html //! [`array_len_for_markers!()`]: macro.array_len_for_markers.html //! [`array_type_for_bytes!()`]: macro.array_type_for_bytes.html //! [`array_type_for_markers!()`]: macro.array_type_for_markers.html //! [`Box`]: https://doc.rust-lang.org/alloc/boxed/index.html //! [`Buffer`]: trait.Buffer.html //! [`ByteData`]: trait.ByteData.html //! [`cache_aligned_zeroed!()`]: macro.cache_aligned_zeroed.html //! [`cache_aligned_zeroed_for_bytes!()`]: macro.cache_aligned_zeroed_for_bytes.html //! [`cache_aligned_zeroed_for_markers!()`]: macro.cache_aligned_zeroed_for_markers.html //! [`CACHE_ALIGNMENT`]: constant.CACHE_ALIGNMENT.html //! [`CacheAligned`]: struct.CacheAligned.html //! [`Deref`]: https://doc.rust-lang.org/std/ops/trait.Deref.html //! [`DerefMut`]: https://doc.rust-lang.org/std/ops/trait.DerefMut.html //! [`Drop`]: https://doc.rust-lang.org/std/ops/trait.Drop.html //! [`extend()`]: trait.Marker.html#method.extend //! [`extend_clone()`]: trait.Marker.html#method.extend_clone //! [`extend_copy()`]: trait.Marker.html#method.extend_copy //! [`Marker`]: trait.Marker.html //! [`Marker::concat_slices()`]: trait.Marker.html#method.concat_slices //! [`Marker::concat_slices_clone()`]: trait.Marker.html#method.concat_slices_clone //! [`Marker::concat_slices_copy()`]: trait.Marker.html#method.concat_slices_copy //! [`MarkerBack`]: struct.MarkerBack.html //! [`MarkerBack::prepend()`]: struct.MarkerBack.html#method.prepend //! [`MarkerBack::prepend_clone()`]: struct.MarkerBack.html#method.prepend_clone //! [`MarkerBack::prepend_copy()`]: struct.MarkerBack.html#method.prepend_copy //! [`MarkerFront`]: struct.MarkerFront.html //! [`MarkerFront::append()`]: struct.MarkerFront.html#method.append //! [`MarkerFront::append_clone()`]: struct.MarkerFront.html#method.append_clone //! [`MarkerFront::append_copy()`]: struct.MarkerFront.html#method.append_copy //! [`Scratchpad`]: struct.Scratchpad.html //! [`Scratchpad::mark_back()`]: struct.Scratchpad.html#method.mark_back //! [`Scratchpad::mark_front()`]: struct.Scratchpad.html#method.mark_front //! [`Scratchpad::new()`]: struct.Scratchpad.html#method.new //! [`Scratchpad::static_new()`]: struct.Scratchpad.html#method.static_new //! [`SliceSource`]: trait.SliceSource.html //! [`SliceSourceCollection`]: trait.SliceSourceCollection.html //! [`SliceMoveSourceCollection`]: trait.SliceMoveSourceCollection.html //! [`Tracking`]: trait.Tracking.html //! [`uninitialized_boxed_slice()`]: fn.uninitialized_boxed_slice.html //! [`uninitialized_boxed_slice_for_bytes()`]: fn.uninitialized_boxed_slice_for_bytes.html //! [`uninitialized_boxed_slice_for_markers()`]: fn.uninitialized_boxed_slice_for_markers.html //! [`Vec`]: https://doc.rust-lang.org/alloc/vec/index.html #![cfg_attr(not(feature = "std"), no_std)] #![cfg_attr(all(feature = "unstable", not(feature = "std")), feature(alloc))] #![cfg_attr(feature = "unstable", feature(const_fn))] #[cfg(all(feature = "unstable", not(feature = "std")))] extern crate alloc; #[cfg(feature = "std")] extern crate core; #[cfg(test)] extern crate arrayvec; #[cfg(feature = "std")] use std::boxed::Box; #[cfg(feature = "std")] use std::vec::Vec; #[cfg(all(feature = "unstable", not(feature = "std")))] use alloc::boxed::Box; #[cfg(all(feature = "unstable", not(feature = "std")))] use alloc::vec::Vec; // Re-export `size_of()` for easier use with our exported macros. pub use core::mem::size_of; mod allocation; mod error; mod marker; mod scratchpad; mod traits; #[macro_use] mod utility; pub use allocation::*; pub use error::*; pub use marker::*; pub use scratchpad::*; pub use traits::*; pub use utility::*; #[cfg(test)] mod tests;