Struct context_allocator::mmap::MemoryMapAllocator

pub struct MemoryMapAllocator { /* fields omitted */ }

This allocator allocates memory-mapped data, optionally using NUMA policy to allocate on a memory node closest to the current thread.

It is slow and uses system calls.

On non-Linux systems except for NetBSD, this allocator is extremely inefficient when reallocating.

On Android, DragonFlyBSD, FreeBSD, Linux and OpenBSD mappings are omitted from core dumps for data privacy.

When dropped, any memory allocated with this allocator is NOT freed.

However, it is appropriate as a 'backing store' for other allocators.

Methods

impl MemoryMapAllocator

pub fn new(
    lock: bool,
    prefault: bool,
    do_not_reserve_swap_space: bool,
    allocate_within_first_32Gb: bool,
    huge_page_size: HugePageSize,
    numa_settings: Option<NumaSettings>
) -> Self

Create a new instance.

• lock: Should allocated memory be locked (through a process equivalent to mlock()), thereby making out-of-memory fail fast. This setting will cause failures if rlimit() has not been increased.
• prefault: Should allocated memory be pre-faulted, ie all pages loaded and made resident in RAM when allocation occurs? This slows down allocation but make subsequent accesses faster. Only on Android, FreeBSD and Linux.
• do_not_reserve_swap_space: Do not reserve swap space for the mapping. Only on Android, Linux and NetBSD.
• allocate_within_first_32Gb: Useful for stacks and creating executable code. Only on Android, FreeBSD and Linux on 64-bit CPUs.
• huge_page_size: Huge page size to use with Transparent Huge Pages (THP). On operating systems other than Android and Linux, specifying a huge page size has no effect.
• numa_settings: NUMA policy settings for optimizing memory allocations to the nearest node. On operating systems other than Android and Linux, specifying a value has no effect.

Trait Implementations

impl Allocator for MemoryMapAllocator

fn allocate(
    &self,
    non_zero_size: NonZeroUsize,
    non_zero_power_of_two_alignment: NonZeroUsize
) -> Result<NonNull<u8>, AllocErr>

Allocate memory.

fn deallocate(
    &self,
    non_zero_size: NonZeroUsize,
    _non_zero_power_of_two_alignment: NonZeroUsize,
    current_memory: NonNull<u8>
)

Deallocate (free) memory.

fn growing_reallocate(
    &self,
    non_zero_new_size: NonZeroUsize,
    _non_zero_power_of_two_alignment: NonZeroUsize,
    non_zero_current_size: NonZeroUsize,
    current_memory: NonNull<u8>
) -> Result<NonNull<u8>, AllocErr>

Reallocate memory by growing it.

fn shrinking_reallocate(
    &self,
    non_zero_new_size: NonZeroUsize,
    _non_zero_power_of_two_alignment: NonZeroUsize,
    non_zero_current_size: NonZeroUsize,
    current_memory: NonNull<u8>
) -> Result<NonNull<u8>, AllocErr>

Reallocate memory by shrinking it.

const ZeroSizedAllocation: NonNull<u8>

The sentinel value used for a zero-sized allocation.

fn adapt<'a>(&'a self) -> AllocatorAdaptor<'a, Self>

Adapts to a GlobalAlloc and Alloc.

fn adapt_reference<'a>(&'a self) -> &'a AllocatorAdaptor<'a, Self>

Adapts a reference to a GlobalAlloc and Alloc reference.

impl MemorySource for MemoryMapAllocator

fn obtain(&self, non_zero_size: NonZeroUsize) -> Result<NonNull<u8>, AllocErr>

Obtain memory from the operating system, say.

fn release(&self, non_zero_size: NonZeroUsize, current_memory: NonNull<u8>)

Release memory to the operating system, say.

impl Eq for MemoryMapAllocator

impl PartialOrd<MemoryMapAllocator> for MemoryMapAllocator

fn partial_cmp(&self, other: &MemoryMapAllocator) -> Option<Ordering>

This method returns an ordering between self and other values if one exists.

fn lt(&self, other: &MemoryMapAllocator) -> bool

This method tests less than (for self and other) and is used by the < operator.

fn le(&self, other: &MemoryMapAllocator) -> bool

This method tests less than or equal to (for self and other) and is used by the <= operator.

fn gt(&self, other: &MemoryMapAllocator) -> bool

This method tests greater than (for self and other) and is used by the > operator.

fn ge(&self, other: &MemoryMapAllocator) -> bool

This method tests greater than or equal to (for self and other) and is used by the >= operator.

impl PartialEq<MemoryMapAllocator> for MemoryMapAllocator

fn eq(&self, other: &MemoryMapAllocator) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &MemoryMapAllocator) -> bool

This method tests for !=.

impl Clone for MemoryMapAllocator

fn clone(&self) -> MemoryMapAllocator

Returns a copy of the value.

default fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Default for MemoryMapAllocator

fn default() -> Self

Returns the "default value" for a type.

impl Ord for MemoryMapAllocator

fn cmp(&self, other: &MemoryMapAllocator) -> Ordering

This method returns an Ordering between self and other.

default fn max(self, other: Self) -> Self

Compares and returns the maximum of two values.

default fn min(self, other: Self) -> Self

Compares and returns the minimum of two values.

default fn clamp(self, min: Self, max: Self) -> Self

🔬 This is a nightly-only experimental API. (clamp)

Restrict a value to a certain interval.

impl Debug for MemoryMapAllocator

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

Formats the value using the given formatter.

impl Hash for MemoryMapAllocator

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given [Hasher].

default fn hash_slice<H>(data: &[Self], state: &mut H) where
    H: Hasher, 

Feeds a slice of this type into the given [Hasher].