Struct glommio::io::ReadManyResult

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pub struct ReadManyResult<V: IoVec + Unpin, S: Stream<Item = (ScheduledSource, ReadManyArgs<V>)> + Unpin> { /* private fields */ }
Expand description

A stream of ReadResult produced asynchronously.

See DmaFile::read_many for more information

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impl<V: IoVec + Unpin, S: Stream<Item = (ScheduledSource, ReadManyArgs<V>)> + Unpin> ReadManyResult<V, S>

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pub fn with_concurrency(self, concurrency: usize) -> Self

Set the amount of IO concurrency of this stream, i.e., the number of IO requests this stream will submit at any one time

Higher concurrency levels may improve performance and will extend the lifetime of IO requests, meaning they have a greater chance of being reused via IO request deduplication. However, higher values will increase memory usage and possibly starve by-standing IO-emitting tasks.

This function should be called before the stream is first polled and will panic otherwise.

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pub fn with_memory_limit(self, limit: Option<usize>) -> Self

Set a limit to the number of concurrent IO requests based on memory usage.

This is a useful knob in conjunction with IO requests coalescing because it makes sense to keep a high number of concurrent small IO requests but less so if they are extremely large. i.e., if all the IO requests are 4MiB large, it doesn’t make much sense to schedule more than a few at a time. Scheduling too many at once could starve other concurrent IO tasks for no throughput benefit. Conversely, It makes sense to schedule 4KiB requests with a higher concurrency level.

Note that this is a soft limit. No matter how small this limit is set to, a single IO request will always be allowed to run. This can happen if you configure the IO merging logic very aggressively.

Defaults to no limit.

Trait Implementations§

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impl<V: Debug + IoVec + Unpin, S: Debug + Stream<Item = (ScheduledSource, ReadManyArgs<V>)> + Unpin> Debug for ReadManyResult<V, S>

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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<V: IoVec + Unpin, S: Stream<Item = (ScheduledSource, ReadManyArgs<V>)> + Unpin> Stream for ReadManyResult<V, S>

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type Item = Result<(V, ReadResult), GlommioError<()>>

Values yielded by the stream.
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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. Read more
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fn size_hint(&self) -> (usize, Option<usize>)

Returns the bounds on the remaining length of the stream. Read more

Auto Trait Implementations§

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impl<V, S> Freeze for ReadManyResult<V, S>
where S: Freeze,

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impl<V, S> !RefUnwindSafe for ReadManyResult<V, S>

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impl<V, S> !Send for ReadManyResult<V, S>

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impl<V, S> !Sync for ReadManyResult<V, S>

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impl<V, S> Unpin for ReadManyResult<V, S>

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impl<V, S> !UnwindSafe for ReadManyResult<V, S>

Blanket 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> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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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> 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<S> StreamExt for S
where S: Stream + ?Sized,

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

A convenience for calling Stream::poll_next() on !Unpin types.
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fn next(&mut self) -> NextFuture<'_, Self>
where Self: Unpin,

Retrieves the next item in the stream. Read more
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fn try_next<T, E>(&mut self) -> TryNextFuture<'_, Self>
where Self: Stream<Item = Result<T, E>> + Unpin,

Retrieves the next item in the stream. Read more
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fn count(self) -> CountFuture<Self>
where Self: Sized,

Counts the number of items in the stream. Read more
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fn map<T, F>(self, f: F) -> Map<Self, F>
where Self: Sized, F: FnMut(Self::Item) -> T,

Maps items of the stream to new values using a closure. Read more
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fn flat_map<U, F>(self, f: F) -> FlatMap<Self, U, F>
where Self: Sized, U: Stream, F: FnMut(Self::Item) -> U,

Maps items to streams and then concatenates them. Read more
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fn flatten(self) -> Flatten<Self>
where Self: Sized, Self::Item: Stream,

Concatenates inner streams. Read more
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fn then<F, Fut>(self, f: F) -> Then<Self, F, Fut>
where Self: Sized, F: FnMut(Self::Item) -> Fut, Fut: Future,

Maps items of the stream to new values using an async closure. Read more
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fn filter<P>(self, predicate: P) -> Filter<Self, P>
where Self: Sized, P: FnMut(&Self::Item) -> bool,

Keeps items of the stream for which predicate returns true. Read more
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fn filter_map<T, F>(self, f: F) -> FilterMap<Self, F>
where Self: Sized, F: FnMut(Self::Item) -> Option<T>,

Filters and maps items of the stream using a closure. Read more
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fn take(self, n: usize) -> Take<Self>
where Self: Sized,

Takes only the first n items of the stream. Read more
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fn take_while<P>(self, predicate: P) -> TakeWhile<Self, P>
where Self: Sized, P: FnMut(&Self::Item) -> bool,

Takes items while predicate returns true. Read more
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fn skip(self, n: usize) -> Skip<Self>
where Self: Sized,

Skips the first n items of the stream. Read more
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fn skip_while<P>(self, predicate: P) -> SkipWhile<Self, P>
where Self: Sized, P: FnMut(&Self::Item) -> bool,

Skips items while predicate returns true. Read more
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fn step_by(self, step: usize) -> StepBy<Self>
where Self: Sized,

Yields every stepth item. Read more
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fn chain<U>(self, other: U) -> Chain<Self, U>
where Self: Sized, U: Stream<Item = Self::Item>,

Appends another stream to the end of this one. Read more
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fn cloned<'a, T>(self) -> Cloned<Self>
where Self: Stream<Item = &'a T> + Sized, T: Clone + 'a,

Clones all items. Read more
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fn copied<'a, T>(self) -> Copied<Self>
where Self: Stream<Item = &'a T> + Sized, T: Copy + 'a,

Copies all items. Read more
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fn collect<C>(self) -> CollectFuture<Self, C>
where Self: Sized, C: Default + Extend<Self::Item>,

Collects all items in the stream into a collection. Read more
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fn try_collect<T, E, C>(self) -> TryCollectFuture<Self, C>
where Self: Stream<Item = Result<T, E>> + Sized, C: Default + Extend<T>,

Collects all items in the fallible stream into a collection. Read more
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fn partition<B, P>(self, predicate: P) -> PartitionFuture<Self, P, B>
where Self: Sized, B: Default + Extend<Self::Item>, P: FnMut(&Self::Item) -> bool,

Partitions items into those for which predicate is true and those for which it is false, and then collects them into two collections. Read more
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fn fold<T, F>(self, init: T, f: F) -> FoldFuture<Self, F, T>
where Self: Sized, F: FnMut(T, Self::Item) -> T,

Accumulates a computation over the stream. Read more
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fn try_fold<T, E, F, B>( &mut self, init: B, f: F ) -> TryFoldFuture<'_, Self, F, B>
where Self: Stream<Item = Result<T, E>> + Unpin + Sized, F: FnMut(B, T) -> Result<B, E>,

Accumulates a fallible computation over the stream. Read more
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fn scan<St, B, F>(self, initial_state: St, f: F) -> Scan<Self, St, F>
where Self: Sized, F: FnMut(&mut St, Self::Item) -> Option<B>,

Maps items of the stream to new values using a state value and a closure. Read more
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fn fuse(self) -> Fuse<Self>
where Self: Sized,

Fuses the stream so that it stops yielding items after the first None. Read more
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fn cycle(self) -> Cycle<Self>
where Self: Clone + Sized,

Repeats the stream from beginning to end, forever. Read more
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fn enumerate(self) -> Enumerate<Self>
where Self: Sized,

Enumerates items, mapping them to (index, item). Read more
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fn inspect<F>(self, f: F) -> Inspect<Self, F>
where Self: Sized, F: FnMut(&Self::Item),

Calls a closure on each item and passes it on. Read more
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fn nth(&mut self, n: usize) -> NthFuture<'_, Self>
where Self: Unpin,

Gets the nth item of the stream. Read more
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fn last(self) -> LastFuture<Self>
where Self: Sized,

Returns the last item in the stream. Read more
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fn find<P>(&mut self, predicate: P) -> FindFuture<'_, Self, P>
where Self: Unpin, P: FnMut(&Self::Item) -> bool,

Finds the first item of the stream for which predicate returns true. Read more
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fn find_map<F, B>(&mut self, f: F) -> FindMapFuture<'_, Self, F>
where Self: Unpin, F: FnMut(Self::Item) -> Option<B>,

Applies a closure to items in the stream and returns the first Some result. Read more
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fn position<P>(&mut self, predicate: P) -> PositionFuture<'_, Self, P>
where Self: Unpin, P: FnMut(Self::Item) -> bool,

Finds the index of the first item of the stream for which predicate returns true. Read more
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fn all<P>(&mut self, predicate: P) -> AllFuture<'_, Self, P>
where Self: Unpin, P: FnMut(Self::Item) -> bool,

Tests if predicate returns true for all items in the stream. Read more
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fn any<P>(&mut self, predicate: P) -> AnyFuture<'_, Self, P>
where Self: Unpin, P: FnMut(Self::Item) -> bool,

Tests if predicate returns true for any item in the stream. Read more
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fn for_each<F>(self, f: F) -> ForEachFuture<Self, F>
where Self: Sized, F: FnMut(Self::Item),

Calls a closure on each item of the stream. Read more
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fn try_for_each<F, E>(&mut self, f: F) -> TryForEachFuture<'_, Self, F>
where Self: Unpin, F: FnMut(Self::Item) -> Result<(), E>,

Calls a fallible closure on each item of the stream, stopping on first error. Read more
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fn zip<U>(self, other: U) -> Zip<Self, U>
where Self: Sized, U: Stream,

Zips up two streams into a single stream of pairs. Read more
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fn unzip<A, B, FromA, FromB>(self) -> UnzipFuture<Self, FromA, FromB>
where FromA: Default + Extend<A>, FromB: Default + Extend<B>, Self: Stream<Item = (A, B)> + Sized,

Collects a stream of pairs into a pair of collections. Read more
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fn or<S>(self, other: S) -> Or<Self, S>
where Self: Sized, S: Stream<Item = Self::Item>,

Merges with other stream, preferring items from self whenever both streams are ready. Read more
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fn race<S>(self, other: S) -> Race<Self, S>
where Self: Sized, S: Stream<Item = Self::Item>,

Merges with other stream, with no preference for either stream when both are ready. Read more
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fn boxed<'a>(self) -> Pin<Box<dyn Stream<Item = Self::Item> + Send + 'a>>
where Self: Send + Sized + 'a,

Boxes the stream and changes its type to dyn Stream + Send + 'a. Read more
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fn boxed_local<'a>(self) -> Pin<Box<dyn Stream<Item = Self::Item> + 'a>>
where Self: Sized + 'a,

Boxes the stream and changes its type to dyn Stream + 'a. Read more
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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<S, T, E> TryStream for S
where S: Stream<Item = Result<T, E>> + ?Sized,

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type Ok = T

The type of successful values yielded by this future
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type Error = E

The type of failures yielded by this future
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fn try_poll_next( self: Pin<&mut S>, cx: &mut Context<'_> ) -> Poll<Option<Result<<S as TryStream>::Ok, <S as TryStream>::Error>>>

Poll this TryStream as if it were a Stream. Read more
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impl<T> WithSubscriber for T

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fn with_subscriber<S>(self, subscriber: S) -> WithDispatch<Self>
where S: Into<Dispatch>,

Attaches the provided Subscriber to this type, returning a WithDispatch wrapper. Read more
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fn with_current_subscriber(self) -> WithDispatch<Self>

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