Struct ErrSpawnGroup 

pub struct ErrSpawnGroup<ValueType, ErrorType> {
    pub is_cancelled: bool,
    /* private fields */
}

Err Spawn Group

A kind of a spawn group that spawns asynchronous child tasks that returns a value of Result<ValueType, ErrorType>, that implicitly wait for the spawned tasks to return before being dropped unless by explicitly calling dont_wait_at_drop()

Child tasks are spawned by calling either spawn_task() or spawn_task_unless_cancelled() methods.

Running child tasks can be cancelled by calling cancel_all() method.

Child tasks spawned to a spawn group execute concurrently, and may be scheduled in any order.

It dereferences into a futures crate Stream type where the results of each finished child task is stored and it pops out the result in First-In First-Out FIFO order whenever it is being used

Fields

is_cancelled: bool

A field that indicates if the spawn group had been cancelled

Implementations

impl<ValueType, ErrorType> ErrSpawnGroup<ValueType, ErrorType>

pub fn new(num_of_threads: usize) -> Self

Instantiates ErrSpawnGroup with a specific number of threads to use in the underlying threadpool when polling futures

Parameters

• num_of_threads: number of threads to use

impl<ValueType, ErrorType> ErrSpawnGroup<ValueType, ErrorType>

pub fn dont_wait_at_drop(&mut self)

Don’t implicity wait for spawned child tasks to finish before being dropped

impl<ValueType, ErrorType> ErrSpawnGroup<ValueType, ErrorType>

pub fn spawn_task<F>(&mut self, priority: Priority, closure: F)

where F: Future<Output = Result<ValueType, ErrorType>> + Send + 'static,

Spawns a new task into the spawn group

Parameters

• priority: priority to use
• closure: an async closure that return a value of type Result<ValueType, ErrorType>

pub fn cancel_all(&mut self)

Cancels all running task in the spawn group

pub fn spawn_task_unlessed_cancelled<F>( &mut self, priority: Priority, closure: F, )

where F: Future<Output = Result<ValueType, ErrorType>> + Send + 'static,

Spawn a new task only if the group is not cancelled yet, otherwise does nothing

Parameters

• priority: priority to use
• closure: an async closure that return a value of type Result<ValueType, ErrorType>

impl<ValueType, ErrorType> ErrSpawnGroup<ValueType, ErrorType>

pub async fn first(&self) -> Option<Result<ValueType, ErrorType>>

Returns the first element of the stream, or None if it is empty.

impl<ValueType, ErrorType> ErrSpawnGroup<ValueType, ErrorType>

pub fn stream(&self) -> impl Stream<Item = Result<ValueType, ErrorType>>

Returns an instance of the Stream trait.

impl<ValueType, ErrorType> ErrSpawnGroup<ValueType, ErrorType>

pub async fn wait_for_all(&mut self)

Waits for all remaining child tasks for finish.

pub fn wait_non_async(&mut self)

Waits for all remaining child tasks for finish in non async context.

impl<ValueType, ErrorType> ErrSpawnGroup<ValueType, ErrorType>

pub fn is_empty(&self) -> bool

A Boolean value that indicates whether the group has any remaining tasks.

At the start of the body of a with_err_spawn_group function call, or before calling spawn_task or spawn_task_unless_cancelled methods the spawn group is always empty.

Returns

• true: if there’s no child task still running
• false: if any child task is still running

impl<ValueType, ErrorType> ErrSpawnGroup<ValueType, ErrorType>

pub async fn get_chunks( &self, of_count: usize, ) -> Vec<Result<ValueType, ErrorType>>

👎Deprecated since 2.0.0: Buggy

Waits for a specific number of spawned child tasks to finish and returns their respectively result as a vector

Panics

If the of_count parameter is larger than the number of already spawned child tasks, this method panics

Remember whenever you call either wait_for_all or cancel_all methods, the child tasks’ count reverts back to zero

Parameter

• of_count: The number of running child tasks to wait for their results to return

Returns

Returns a vector of length of_count elements from the spawn group instance

Trait Implementations

impl<ValueType, ErrorType> Default for ErrSpawnGroup<ValueType, ErrorType>

fn default() -> Self

Instantiates ErrSpawnGroup with the number of threads as the number of cores as the system to use in the underlying threadpool when polling futures

impl<ValueType, ErrorType> Drop for ErrSpawnGroup<ValueType, ErrorType>

fn drop(&mut self)

Executes the destructor for this type.

impl<ValueType, ErrorType> Stream for ErrSpawnGroup<ValueType, ErrorType>

type Item = Result<ValueType, ErrorType>

Values yielded by the stream.

fn poll_next( self: Pin<&mut Self>, cx: &mut Context<'_>, ) -> Poll<Option<Self::Item>>

Attempt to pull out the next value of this stream, registering the current task for wakeup if the value is not yet available, and returning None if the stream is exhausted.

fn size_hint(&self) -> (usize, Option<usize>)

Returns the bounds on the remaining length of the stream.