[−][src]Struct wasmer::Memory
A WebAssembly memory
instance.
A memory instance is the runtime representation of a linear memory. It consists of a vector of bytes and an optional maximum size.
The length of the vector always is a multiple of the WebAssembly page size, which is defined to be the constant 65536 – abbreviated 64Ki. Like in a memory type, the maximum size in a memory instance is given in units of this page size.
A memory created by the host or in WebAssembly code will be accessible and mutable from both host and WebAssembly.
Spec: https://webassembly.github.io/spec/core/exec/runtime.html#memory-instances
Implementations
impl Memory
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pub fn new(store: &Store, ty: MemoryType) -> Result<Self, MemoryError>
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Creates a new host Memory
from the provided MemoryType
.
This function will construct the Memory
using the store
BaseTunables
.
Example
let m = Memory::new(&store, MemoryType::new(1, None, false)).unwrap();
pub fn ty(&self) -> &MemoryType
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Returns the MemoryType
of the Memory
.
Example
let mt = MemoryType::new(1, None, false); let m = Memory::new(&store, mt).unwrap(); assert_eq!(m.ty(), &mt);
pub fn store(&self) -> &Store
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Returns the Store
where the Memory
belongs.
Example
let m = Memory::new(&store, MemoryType::new(1, None, false)).unwrap(); assert_eq!(m.store(), &store);
pub unsafe fn data_unchecked(&self) -> &[u8]ⓘ
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Retrieve a slice of the memory contents.
Safety
Until the returned slice is dropped, it is undefined behaviour to modify the memory contents in any way including by calling a wasm function that writes to the memory or by resizing the memory.
pub unsafe fn data_unchecked_mut(&self) -> &mut [u8]ⓘ
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Retrieve a mutable slice of the memory contents.
Safety
This method provides interior mutability without an UnsafeCell. Until the returned value is dropped, it is undefined behaviour to read or write to the pointed-to memory in any way except through this slice, including by calling a wasm function that reads the memory contents or by resizing this Memory.
pub fn data_ptr(&self) -> *mut u8
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Returns the pointer to the raw bytes of the Memory
.
pub fn data_size(&self) -> u64
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Returns the size (in bytes) of the Memory
.
pub fn size(&self) -> Pages
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Returns the size (in Pages
) of the Memory
.
Example
let m = Memory::new(&store, MemoryType::new(1, None, false)).unwrap(); assert_eq!(m.size(), Pages(1));
pub fn grow<IntoPages>(&self, delta: IntoPages) -> Result<Pages, MemoryError> where
IntoPages: Into<Pages>,
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IntoPages: Into<Pages>,
Grow memory by the specified amount of WebAssembly Pages
and return
the previous memory size.
Example
let m = Memory::new(&store, MemoryType::new(1, Some(3), false)).unwrap(); let p = m.grow(2).unwrap(); assert_eq!(p, Pages(1)); assert_eq!(m.size(), Pages(3));
Errors
Returns an error if memory can't be grown by the specified amount of pages.
let m = Memory::new(&store, MemoryType::new(1, Some(1), false)).unwrap(); // This results in an error: `MemoryError::CouldNotGrow`. let s = m.grow(1).unwrap();
pub fn view<T: ValueType>(&self) -> MemoryView<'_, T>
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Return a "view" of the currently accessible memory. By
default, the view is unsynchronized, using regular memory
accesses. You can force a memory view to use atomic accesses
by calling the MemoryView::atomically
method.
Notes:
This method is safe (as in, it won't cause the host to crash or have UB), but it doesn't obey rust's rules involving data races, especially concurrent ones. Therefore, if this memory is shared between multiple threads, a single memory location can be mutated concurrently without synchronization.
Usage:
// Without synchronization. let view: MemoryView<u8> = memory.view(); for byte in view[0x1000 .. 0x1010].iter().map(Cell::get) { println!("byte: {}", byte); } // With synchronization. let atomic_view = view.atomically(); for byte in atomic_view[0x1000 .. 0x1010].iter().map(|atom| atom.load(Ordering::SeqCst)) { println!("byte: {}", byte); }
pub fn same(&self, other: &Self) -> bool
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Returns whether or not these two memories refer to the same data.
Example
let m = Memory::new(&store, MemoryType::new(1, None, false)).unwrap(); assert!(m.same(&m));
Trait Implementations
impl Clone for Memory
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impl Debug for Memory
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impl<'a> Exportable<'a> for Memory
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pub fn to_export(&self) -> Export
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pub fn get_self_from_extern(
_extern: &'a Extern
) -> Result<&'a Self, ExportError>
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_extern: &'a Extern
) -> Result<&'a Self, ExportError>
impl From<Memory> for Extern
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Auto Trait Implementations
impl !RefUnwindSafe for Memory
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impl Send for Memory
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impl Sync for Memory
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impl Unpin for Memory
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impl !UnwindSafe for Memory
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Blanket Implementations
impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,
impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
pub fn borrow_mut(&mut self) -> &mut T
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impl<T> From<T> for T
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impl<T> Instrument for T
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pub fn instrument(self, span: Span) -> Instrumented<Self>
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pub fn in_current_span(self) -> Instrumented<Self>
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impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<T> Pointable for T
pub const ALIGN: usize
type Init = T
The type for initializers.
pub unsafe fn init(init: <T as Pointable>::Init) -> usize
pub unsafe fn deref<'a>(ptr: usize) -> &'a T
pub unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut T
pub unsafe fn drop(ptr: usize)
impl<T> ToOwned for T where
T: Clone,
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T: Clone,
type Owned = T
The resulting type after obtaining ownership.
pub fn to_owned(&self) -> T
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pub fn clone_into(&self, target: &mut T)
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impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
pub fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,
type Error = <U as TryFrom<T>>::Error
The type returned in the event of a conversion error.
pub fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>
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impl<V, T> VZip<V> for T where
V: MultiLane<T>,
V: MultiLane<T>,