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| </pre><pre class="rust"><code><span class="doccomment">//! Definition of the `TryJoinAll` combinator, waiting for all of a list of |
| //! futures to finish with either success or error. |
| |
| </span><span class="kw">use </span>alloc::boxed::Box; |
| <span class="kw">use </span>alloc::vec::Vec; |
| <span class="kw">use </span>core::fmt; |
| <span class="kw">use </span>core::future::Future; |
| <span class="kw">use </span>core::iter::FromIterator; |
| <span class="kw">use </span>core::mem; |
| <span class="kw">use </span>core::pin::Pin; |
| <span class="kw">use </span>core::task::{Context, Poll}; |
| |
| <span class="kw">use super</span>::{assert_future, join_all, IntoFuture, TryFuture, TryMaybeDone}; |
| |
| <span class="attribute">#[cfg(not(futures_no_atomic_cas))] |
| </span><span class="kw">use </span><span class="kw">crate</span>::stream::{FuturesOrdered, TryCollect, TryStreamExt}; |
| <span class="kw">use </span><span class="kw">crate</span>::TryFutureExt; |
| |
| <span class="kw">enum </span>FinalState<E = ()> { |
| Pending, |
| AllDone, |
| Error(E), |
| } |
| |
| <span class="doccomment">/// Future for the [`try_join_all`] function. |
| </span><span class="attribute">#[must_use = <span class="string">"futures do nothing unless you `.await` or poll them"</span>] |
| </span><span class="kw">pub struct </span>TryJoinAll<F> |
| <span class="kw">where |
| </span>F: TryFuture, |
| { |
| kind: TryJoinAllKind<F>, |
| } |
| |
| <span class="kw">enum </span>TryJoinAllKind<F> |
| <span class="kw">where |
| </span>F: TryFuture, |
| { |
| Small { |
| elems: Pin<Box<[TryMaybeDone<IntoFuture<F>>]>>, |
| }, |
| <span class="attribute">#[cfg(not(futures_no_atomic_cas))] |
| </span>Big { |
| fut: TryCollect<FuturesOrdered<IntoFuture<F>>, Vec<F::Ok>>, |
| }, |
| } |
| |
| <span class="kw">impl</span><F> fmt::Debug <span class="kw">for </span>TryJoinAll<F> |
| <span class="kw">where |
| </span>F: TryFuture + fmt::Debug, |
| F::Ok: fmt::Debug, |
| F::Error: fmt::Debug, |
| F::Output: fmt::Debug, |
| { |
| <span class="kw">fn </span>fmt(<span class="kw-2">&</span><span class="self">self</span>, f: <span class="kw-2">&mut </span>fmt::Formatter<<span class="lifetime">'_</span>>) -> fmt::Result { |
| <span class="kw">match </span><span class="self">self</span>.kind { |
| TryJoinAllKind::Small { <span class="kw-2">ref </span>elems } => { |
| f.debug_struct(<span class="string">"TryJoinAll"</span>).field(<span class="string">"elems"</span>, elems).finish() |
| } |
| <span class="attribute">#[cfg(not(futures_no_atomic_cas))] |
| </span>TryJoinAllKind::Big { <span class="kw-2">ref </span>fut, .. } => fmt::Debug::fmt(fut, f), |
| } |
| } |
| } |
| |
| <span class="doccomment">/// Creates a future which represents either a collection of the results of the |
| /// futures given or an error. |
| /// |
| /// The returned future will drive execution for all of its underlying futures, |
| /// collecting the results into a destination `Vec<T>` in the same order as they |
| /// were provided. |
| /// |
| /// If any future returns an error then all other futures will be canceled and |
| /// an error will be returned immediately. If all futures complete successfully, |
| /// however, then the returned future will succeed with a `Vec` of all the |
| /// successful results. |
| /// |
| /// This function is only available when the `std` or `alloc` feature of this |
| /// library is activated, and it is activated by default. |
| /// |
| /// # See Also |
| /// |
| /// `try_join_all` will switch to the more powerful [`FuturesOrdered`] for performance |
| /// reasons if the number of futures is large. You may want to look into using it or |
| /// it's counterpart [`FuturesUnordered`][crate::stream::FuturesUnordered] directly. |
| /// |
| /// Some examples for additional functionality provided by these are: |
| /// |
| /// * Adding new futures to the set even after it has been started. |
| /// |
| /// * Only polling the specific futures that have been woken. In cases where |
| /// you have a lot of futures this will result in much more efficient polling. |
| /// |
| /// |
| /// # Examples |
| /// |
| /// ``` |
| /// # futures::executor::block_on(async { |
| /// use futures::future::{self, try_join_all}; |
| /// |
| /// let futures = vec![ |
| /// future::ok::<u32, u32>(1), |
| /// future::ok::<u32, u32>(2), |
| /// future::ok::<u32, u32>(3), |
| /// ]; |
| /// |
| /// assert_eq!(try_join_all(futures).await, Ok(vec![1, 2, 3])); |
| /// |
| /// let futures = vec![ |
| /// future::ok::<u32, u32>(1), |
| /// future::err::<u32, u32>(2), |
| /// future::ok::<u32, u32>(3), |
| /// ]; |
| /// |
| /// assert_eq!(try_join_all(futures).await, Err(2)); |
| /// # }); |
| /// ``` |
| </span><span class="kw">pub fn </span>try_join_all<I>(iter: I) -> TryJoinAll<I::Item> |
| <span class="kw">where |
| </span>I: IntoIterator, |
| I::Item: TryFuture, |
| { |
| <span class="kw">let </span>iter = iter.into_iter().map(TryFutureExt::into_future); |
| |
| <span class="attribute">#[cfg(futures_no_atomic_cas)] |
| </span>{ |
| <span class="kw">let </span>kind = TryJoinAllKind::Small { |
| elems: iter.map(TryMaybeDone::Future).collect::<Box<[<span class="kw">_</span>]>>().into(), |
| }; |
| |
| assert_future::<<span class="prelude-ty">Result</span><Vec<<I::Item <span class="kw">as </span>TryFuture>::Ok>, <I::Item <span class="kw">as </span>TryFuture>::Error>, <span class="kw">_</span>>( |
| TryJoinAll { kind }, |
| ) |
| } |
| |
| <span class="attribute">#[cfg(not(futures_no_atomic_cas))] |
| </span>{ |
| <span class="kw">let </span>kind = <span class="kw">match </span>iter.size_hint().<span class="number">1 </span>{ |
| <span class="prelude-val">Some</span>(max) <span class="kw">if </span>max <= join_all::SMALL => TryJoinAllKind::Small { |
| elems: iter.map(TryMaybeDone::Future).collect::<Box<[<span class="kw">_</span>]>>().into(), |
| }, |
| <span class="kw">_ </span>=> TryJoinAllKind::Big { fut: iter.collect::<FuturesOrdered<<span class="kw">_</span>>>().try_collect() }, |
| }; |
| |
| assert_future::<<span class="prelude-ty">Result</span><Vec<<I::Item <span class="kw">as </span>TryFuture>::Ok>, <I::Item <span class="kw">as </span>TryFuture>::Error>, <span class="kw">_</span>>( |
| TryJoinAll { kind }, |
| ) |
| } |
| } |
| |
| <span class="kw">impl</span><F> Future <span class="kw">for </span>TryJoinAll<F> |
| <span class="kw">where |
| </span>F: TryFuture, |
| { |
| <span class="kw">type </span>Output = <span class="prelude-ty">Result</span><Vec<F::Ok>, F::Error>; |
| |
| <span class="kw">fn </span>poll(<span class="kw-2">mut </span><span class="self">self</span>: Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>, cx: <span class="kw-2">&mut </span>Context<<span class="lifetime">'_</span>>) -> Poll<<span class="self">Self</span>::Output> { |
| <span class="kw">match </span><span class="kw-2">&mut </span><span class="self">self</span>.kind { |
| TryJoinAllKind::Small { elems } => { |
| <span class="kw">let </span><span class="kw-2">mut </span>state = FinalState::AllDone; |
| |
| <span class="kw">for </span>elem <span class="kw">in </span>join_all::iter_pin_mut(elems.as_mut()) { |
| <span class="kw">match </span>elem.try_poll(cx) { |
| Poll::Pending => state = FinalState::Pending, |
| Poll::Ready(<span class="prelude-val">Ok</span>(())) => {} |
| Poll::Ready(<span class="prelude-val">Err</span>(e)) => { |
| state = FinalState::Error(e); |
| <span class="kw">break</span>; |
| } |
| } |
| } |
| |
| <span class="kw">match </span>state { |
| FinalState::Pending => Poll::Pending, |
| FinalState::AllDone => { |
| <span class="kw">let </span><span class="kw-2">mut </span>elems = mem::replace(elems, Box::pin([])); |
| <span class="kw">let </span>results = join_all::iter_pin_mut(elems.as_mut()) |
| .map(|e| e.take_output().unwrap()) |
| .collect(); |
| Poll::Ready(<span class="prelude-val">Ok</span>(results)) |
| } |
| FinalState::Error(e) => { |
| <span class="kw">let _ </span>= mem::replace(elems, Box::pin([])); |
| Poll::Ready(<span class="prelude-val">Err</span>(e)) |
| } |
| } |
| } |
| <span class="attribute">#[cfg(not(futures_no_atomic_cas))] |
| </span>TryJoinAllKind::Big { fut } => Pin::new(fut).poll(cx), |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><F> FromIterator<F> <span class="kw">for </span>TryJoinAll<F> |
| <span class="kw">where |
| </span>F: TryFuture, |
| { |
| <span class="kw">fn </span>from_iter<T: IntoIterator<Item = F>>(iter: T) -> <span class="self">Self </span>{ |
| try_join_all(iter) |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../../" data-current-crate="futures_util" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
