Struct crndm::ptr::LogNonNull

pub struct LogNonNull<T: PSafe + ?Sized, A: MemPool> { /* fields omitted */ }

An unsafe pointer with dereferencing and logging capability

This type is !PSafe and its constructor functions are unsafe. This is because of LogNonNull treating like a raw pointer. LogNonNull objects are useful for obtaining performance. LogRefCell::as_non_null_mut() is an alternative to LogRefCell::borrow_mut() which provides unsafe mutable access to the underlying data.

PNonNullMut is an alias name in the pool module for LogNonNullMut.

Safety

• As in raw pointers, LogNonNull is Copy and is not bounded to a specific lifetime.
• It does not follow the borrow mechanism and thus multiple mutable access is possible.

Examples

use crndm::default::*;
use crndm::ptr::LogNonNull;
 
type P = BuddyAlloc;
 
fn multiply(mut obj: LogNonNull<i32,P>, m: i32) {
    // Takes a log if required and then provides mut ref to the object
    *obj *= m;
}
 
let root = P::open::<PRefCell<i32>>("foo.pool", O_CF).unwrap();
 
P::transaction(|j| {
    let mut borrow = root.borrow_mut(j);
    *borrow = 5;
 
    multiply( unsafe { root.as_non_null_mut(j) }, 10 );
}).unwrap();
 
assert_eq!(*root.borrow(), 50);

Implementations

impl<T: PSafe, A: MemPool> LogNonNull<T, A>

pub const unsafe fn new_unchecked(
    ptr: *mut T,
    logged: *mut u8,
    j: &Journal<A>
) -> Self

Creates a new LogNonNull.

Safety

ptr and logged must be non-null.

pub unsafe fn new(ptr: *mut T, logged: *mut u8, j: &Journal<A>) -> Option<Self>

Creates a Some(LogNonNull) if ptr is not null; otherwise None.

Trait Implementations

impl<T: PSafe + ?Sized, A: MemPool> Clone for LogNonNull<T, A>

pub fn clone(&self) -> Self

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<T: PSafe + ?Sized, A: MemPool> Copy for LogNonNull<T, A>

impl<T: Debug + PSafe + ?Sized, A: MemPool> Debug for LogNonNull<T, A>

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

Formats the value using the given formatter.

impl<T: PSafe + ?Sized, A: MemPool> Deref for LogNonNull<T, A>

type Target = T

The resulting type after dereferencing.

pub fn deref(&self) -> &T

Dereferences the value.

impl<T: PSafe + ?Sized, A: MemPool> DerefMut for LogNonNull<T, A>

pub fn deref_mut(&mut self) -> &mut T

Mutably dereferences the value.

impl<T: Display + PSafe + ?Sized, A: MemPool> Display for LogNonNull<T, A>

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

Formats the value using the given formatter.

impl<T: ?Sized, A: MemPool> !Send for LogNonNull<T, A>

impl<T: ?Sized, A: MemPool> !Sync for LogNonNull<T, A>

impl<T: ?Sized, A: MemPool> !TxOutSafe for LogNonNull<T, A>