Struct TVar

pub struct TVar<T> { /* private fields */ }

A variable that can be used in a STM-Block

Implementations

impl<T> TVar<T>

where T: Any + Sync + Send + Clone,

pub fn new(val: T) -> TVar<T>

Create a new TVar.

pub fn read_atomic(&self) -> T

read_atomic reads a value atomically, without starting a transaction.

It is semantically equivalent to

let var = TVar::new(0);
atomically(|trans| var.read(trans));

but more efficient.

read_atomic returns a clone of the value.

pub fn read_ref_atomic(&self) -> Arc<dyn Any + Send + Sync>

Read a value atomically but return a reference.

This is mostly used internally, but can be useful in some cases, because read_atomic clones the inner value, which may be expensive.

pub fn read(&self, transaction: &mut Transaction) -> StmResult<T>

The normal way to access a var.

It is equivalent to transaction.read(&var), but more convenient.

pub fn write(&self, transaction: &mut Transaction, value: T) -> StmResult<()>

The normal way to write a var.

It is equivalent to transaction.write(&var, value), but more convenient.

pub fn modify<F>(&self, transaction: &mut Transaction, f: F) -> StmResult<()>

where F: FnOnce(T) -> T,

Modify the content of a TVar with the function f.

let var = TVar::new(21);
atomically(|trans|
    var.modify(trans, |x| x*2)
);

assert_eq!(var.read_atomic(), 42);

pub fn replace(&self, transaction: &mut Transaction, value: T) -> StmResult<T>

Replaces the value of a TVar with a new one, returning the old one.

let var = TVar::new(0);
let x = atomically(|trans|
    var.replace(trans, 42)
);

assert_eq!(x, 0);
assert_eq!(var.read_atomic(), 42);

pub fn ref_eq(this: &TVar<T>, other: &TVar<T>) -> bool

Check if two TVars refer to the same position.

pub fn control_block(&self) -> &Arc<VarControlBlock>

Access the control block of the var.

Internal use only!

Trait Implementations

impl<T: Clone> Clone for TVar<T>

fn clone(&self) -> TVar<T>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<T> Debug for TVar<T>

where T: Any + Sync + Send + Clone + Debug,

Debug output a struct.

Note that this function does not print the state atomically. If another thread modifies the datastructure at the same time, it may print an inconsistent state. If you need an accurate view, that reflects current thread-local state, you can implement it easily yourself with atomically.

Running atomically inside a running transaction panics. Therefore fmt uses prints the state.

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

Formats the value using the given formatter.