Struct WasmAlloc 

pub struct WasmAlloc;

Available on WebAssembly and crate feature alloc and crate feature unsafe_layout only.

⬡ 🧺 A WebAssembly global memory allocator that uses a bump allocation strategy.

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^{📍 sys/mem}

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This allocator manages memory starting from __heap_base (the WASM heap start) and grows memory as needed using memory.grow. It’s designed for single-threaded WASM environments where synchronization isn’t required.

Safety

• This allocator is not thread-safe. The unsafe Sync implementation is only valid in single-threaded WASM environments.

Examples

#[global_allocator]
static ALLOCATOR: WasmAlloc = WasmAlloc::INIT;

Vendored

This is adapted work from mini-alloc.

Implementations

impl WasmAlloc

pub const INIT: Self = WasmAlloc

Initial value for WasmAlloc.

Trait Implementations

impl Debug for WasmAlloc

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl GlobalAlloc for WasmAlloc

unsafe fn alloc(&self, l: MemLayout) -> *mut u8

Allocates memory with the given layout.

unsafe fn alloc_zeroed(&self, l: MemLayout) -> *mut u8

Allocates zeroed memory with the given layout. This is the same as alloc since WASM memory is always zero-initialized.

unsafe fn dealloc(&self, _ptr: *mut u8, _l: MemLayout)

No-op. Memory is only reclaimed when the entire WASM instance is dropped.

unsafe fn realloc( &self, ptr: *mut u8, layout: Layout, new_size: usize, ) -> *mut u8

Shrinks or grows a block of memory to the given new_size in bytes. The block is described by the given ptr pointer and layout.

impl Sync for WasmAlloc

This is safe in single-threaded WASM environments, but invalid in multi-threaded contexts.