Struct mz_repr::SharedRow

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pub struct SharedRow(Rc<RefCell<Row>>);
Expand description

A thread-local row, which can be borrowed and returned.

§Example

Use this type instead of creating a new row:

use mz_repr::SharedRow;

let binding = SharedRow::get();
let mut row_builder = binding.borrow_mut();

This allows us to reuse an existing row allocation instead of creating a new one or retaining an allocation locally. Additionally, we can observe the size of the local row in a central place and potentially reallocate to reduce memory needs.

§Panic

SharedRow::get panics when trying to obtain multiple references to the shared row.

Tuple Fields§

§0: Rc<RefCell<Row>>

Implementations§

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impl SharedRow

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const SHARED_ROW: LocalKey<Rc<RefCell<Row>>> = _

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pub fn get() -> Self

Get the shared row.

The row’s contents are cleared before returning it.

§Panic

Panics when the row is already borrowed elsewhere.

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pub fn pack<'a, I, D>(iter: I) -> Row
where I: IntoIterator<Item = D>, D: Borrow<Datum<'a>>,

Gets the shared row and uses it to pack iter.

Methods from Deref<Target = RefCell<Row>>§

1.24.0 · source

pub fn replace(&self, t: T) -> T

Replaces the wrapped value with a new one, returning the old value, without deinitializing either one.

This function corresponds to std::mem::replace.

§Panics

Panics if the value is currently borrowed.

§Examples
use std::cell::RefCell;
let cell = RefCell::new(5);
let old_value = cell.replace(6);
assert_eq!(old_value, 5);
assert_eq!(cell, RefCell::new(6));
1.35.0 · source

pub fn replace_with<F>(&self, f: F) -> T
where F: FnOnce(&mut T) -> T,

Replaces the wrapped value with a new one computed from f, returning the old value, without deinitializing either one.

§Panics

Panics if the value is currently borrowed.

§Examples
use std::cell::RefCell;
let cell = RefCell::new(5);
let old_value = cell.replace_with(|&mut old| old + 1);
assert_eq!(old_value, 5);
assert_eq!(cell, RefCell::new(6));
1.24.0 · source

pub fn swap(&self, other: &RefCell<T>)

Swaps the wrapped value of self with the wrapped value of other, without deinitializing either one.

This function corresponds to std::mem::swap.

§Panics

Panics if the value in either RefCell is currently borrowed, or if self and other point to the same RefCell.

§Examples
use std::cell::RefCell;
let c = RefCell::new(5);
let d = RefCell::new(6);
c.swap(&d);
assert_eq!(c, RefCell::new(6));
assert_eq!(d, RefCell::new(5));
1.0.0 · source

pub fn borrow(&self) -> Ref<'_, T>

Immutably borrows the wrapped value.

The borrow lasts until the returned Ref exits scope. Multiple immutable borrows can be taken out at the same time.

§Panics

Panics if the value is currently mutably borrowed. For a non-panicking variant, use try_borrow.

§Examples
use std::cell::RefCell;

let c = RefCell::new(5);

let borrowed_five = c.borrow();
let borrowed_five2 = c.borrow();

An example of panic:

use std::cell::RefCell;

let c = RefCell::new(5);

let m = c.borrow_mut();
let b = c.borrow(); // this causes a panic
1.13.0 · source

pub fn try_borrow(&self) -> Result<Ref<'_, T>, BorrowError>

Immutably borrows the wrapped value, returning an error if the value is currently mutably borrowed.

The borrow lasts until the returned Ref exits scope. Multiple immutable borrows can be taken out at the same time.

This is the non-panicking variant of borrow.

§Examples
use std::cell::RefCell;

let c = RefCell::new(5);

{
    let m = c.borrow_mut();
    assert!(c.try_borrow().is_err());
}

{
    let m = c.borrow();
    assert!(c.try_borrow().is_ok());
}
1.0.0 · source

pub fn borrow_mut(&self) -> RefMut<'_, T>

Mutably borrows the wrapped value.

The borrow lasts until the returned RefMut or all RefMuts derived from it exit scope. The value cannot be borrowed while this borrow is active.

§Panics

Panics if the value is currently borrowed. For a non-panicking variant, use try_borrow_mut.

§Examples
use std::cell::RefCell;

let c = RefCell::new("hello".to_owned());

*c.borrow_mut() = "bonjour".to_owned();

assert_eq!(&*c.borrow(), "bonjour");

An example of panic:

use std::cell::RefCell;

let c = RefCell::new(5);
let m = c.borrow();

let b = c.borrow_mut(); // this causes a panic
1.13.0 · source

pub fn try_borrow_mut(&self) -> Result<RefMut<'_, T>, BorrowMutError>

Mutably borrows the wrapped value, returning an error if the value is currently borrowed.

The borrow lasts until the returned RefMut or all RefMuts derived from it exit scope. The value cannot be borrowed while this borrow is active.

This is the non-panicking variant of borrow_mut.

§Examples
use std::cell::RefCell;

let c = RefCell::new(5);

{
    let m = c.borrow();
    assert!(c.try_borrow_mut().is_err());
}

assert!(c.try_borrow_mut().is_ok());
1.12.0 · source

pub fn as_ptr(&self) -> *mut T

Returns a raw pointer to the underlying data in this cell.

§Examples
use std::cell::RefCell;

let c = RefCell::new(5);

let ptr = c.as_ptr();
1.37.0 · source

pub unsafe fn try_borrow_unguarded(&self) -> Result<&T, BorrowError>

Immutably borrows the wrapped value, returning an error if the value is currently mutably borrowed.

§Safety

Unlike RefCell::borrow, this method is unsafe because it does not return a Ref, thus leaving the borrow flag untouched. Mutably borrowing the RefCell while the reference returned by this method is alive is undefined behaviour.

§Examples
use std::cell::RefCell;

let c = RefCell::new(5);

{
    let m = c.borrow_mut();
    assert!(unsafe { c.try_borrow_unguarded() }.is_err());
}

{
    let m = c.borrow();
    assert!(unsafe { c.try_borrow_unguarded() }.is_ok());
}
1.50.0 · source

pub fn take(&self) -> T

Takes the wrapped value, leaving Default::default() in its place.

§Panics

Panics if the value is currently borrowed.

§Examples
use std::cell::RefCell;

let c = RefCell::new(5);
let five = c.take();

assert_eq!(five, 5);
assert_eq!(c.into_inner(), 0);

Trait Implementations§

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impl Debug for SharedRow

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

Formats the value using the given formatter. Read more
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impl Deref for SharedRow

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type Target = RefCell<Row>

The resulting type after dereferencing.
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fn deref(&self) -> &Self::Target

Dereferences the value.

Auto Trait Implementations§

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T, U> CastInto<U> for T
where U: CastFrom<T>,

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fn cast_into(self) -> U

Performs the cast.
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T> FutureExt for T

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fn with_context(self, otel_cx: Context) -> WithContext<Self>

Attaches the provided Context to this type, returning a WithContext wrapper. Read more
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fn with_current_context(self) -> WithContext<Self>

Attaches the current Context to this type, returning a WithContext wrapper. Read more
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impl<T> Instrument for T

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fn instrument(self, span: Span) -> Instrumented<Self>

Instruments this type with the provided Span, returning an Instrumented wrapper. Read more
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fn in_current_span(self) -> Instrumented<Self>

Instruments this type with the current Span, returning an Instrumented wrapper. Read more
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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> IntoRequest<T> for T

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fn into_request(self) -> Request<T>

Wrap the input message T in a tonic::Request
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impl<T, U> OverrideFrom<Option<&T>> for U
where U: OverrideFrom<T>,

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fn override_from(self, layer: &Option<&T>) -> U

Override the configuration represented by Self with values from the given layer.
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impl<T> Pointable for T

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const ALIGN: usize = _

The alignment of pointer.
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type Init = T

The type for initializers.
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unsafe fn init(init: <T as Pointable>::Init) -> usize

Initializes a with the given initializer. Read more
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unsafe fn deref<'a>(ptr: usize) -> &'a T

Dereferences the given pointer. Read more
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unsafe fn deref_mut<'a>(ptr: usize) -> &'a mut T

Mutably dereferences the given pointer. Read more
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unsafe fn drop(ptr: usize)

Drops the object pointed to by the given pointer. Read more
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impl<P, R> ProtoType<R> for P
where R: RustType<P>,

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impl<T> Same for T

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type Output = T

Should always be Self
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impl<'a, S, T> Semigroup<&'a S> for T
where T: Semigroup<S>,

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fn plus_equals(&mut self, rhs: &&'a S)

The method of std::ops::AddAssign, for types that do not implement AddAssign.
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.
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impl<V, T> VZip<V> for T
where V: MultiLane<T>,

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fn vzip(self) -> V

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impl<T> WithSubscriber for T

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where S: Into<Dispatch>,

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Attaches the current default Subscriber to this type, returning a WithDispatch wrapper. Read more