| <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/tower-0.4.13/src/buffer/worker.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>worker.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../../normalize.css"><link rel="stylesheet" href="../../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../../ayu.css" disabled><link rel="stylesheet" href="../../../dark.css" disabled><link rel="stylesheet" href="../../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../../storage.js"></script><script defer src="../../../source-script.js"></script><script defer src="../../../source-files.js"></script><script defer src="../../../main.js"></script><noscript><link rel="stylesheet" href="../../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../../tower/index.html"><div class="logo-container"><img class="rust-logo" src="../../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../../tower/index.html"><img class="rust-logo" src="../../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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| </pre><pre class="rust"><code><span class="kw">use super</span>::{ |
| error::{Closed, ServiceError}, |
| message::Message, |
| }; |
| <span class="kw">use </span>futures_core::ready; |
| <span class="kw">use </span>std::sync::{Arc, Mutex, Weak}; |
| <span class="kw">use </span>std::{ |
| future::Future, |
| pin::Pin, |
| task::{Context, Poll}, |
| }; |
| <span class="kw">use </span>tokio::sync::{mpsc, Semaphore}; |
| <span class="kw">use </span>tower_service::Service; |
| |
| <span class="macro">pin_project_lite::pin_project! </span>{ |
| <span class="doccomment">/// Task that handles processing the buffer. This type should not be used |
| /// directly, instead `Buffer` requires an `Executor` that can accept this task. |
| /// |
| /// The struct is `pub` in the private module and the type is *not* re-exported |
| /// as part of the public API. This is the "sealed" pattern to include "private" |
| /// types in public traits that are not meant for consumers of the library to |
| /// implement (only call). |
| </span><span class="attribute">#[derive(Debug)] |
| </span><span class="kw">pub struct </span>Worker<T, Request> |
| <span class="kw">where |
| </span>T: Service<Request>, |
| { |
| current_message: <span class="prelude-ty">Option</span><Message<Request, T::Future>>, |
| rx: mpsc::UnboundedReceiver<Message<Request, T::Future>>, |
| service: T, |
| finish: bool, |
| failed: <span class="prelude-ty">Option</span><ServiceError>, |
| handle: Handle, |
| close: <span class="prelude-ty">Option</span><Weak<Semaphore>>, |
| } |
| |
| <span class="kw">impl</span><T: Service<Request>, Request> PinnedDrop <span class="kw">for </span>Worker<T, Request> |
| { |
| <span class="kw">fn </span>drop(<span class="kw-2">mut </span>this: Pin<<span class="kw-2">&mut </span><span class="self">Self</span>>) { |
| this.as_mut().close_semaphore(); |
| } |
| } |
| } |
| |
| <span class="doccomment">/// Get the error out |
| </span><span class="attribute">#[derive(Debug)] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">struct </span>Handle { |
| inner: Arc<Mutex<<span class="prelude-ty">Option</span><ServiceError>>>, |
| } |
| |
| <span class="kw">impl</span><T, Request> Worker<T, Request> |
| <span class="kw">where |
| </span>T: Service<Request>, |
| { |
| <span class="doccomment">/// Closes the buffer's semaphore if it is still open, waking any pending |
| /// tasks. |
| </span><span class="kw">fn </span>close_semaphore(<span class="kw-2">&mut </span><span class="self">self</span>) { |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(close) = <span class="self">self</span>.close.take().as_ref().and_then(Weak::upgrade) { |
| <span class="macro">tracing::debug!</span>(<span class="string">"buffer closing; waking pending tasks"</span>); |
| close.close(); |
| } <span class="kw">else </span>{ |
| <span class="macro">tracing::trace!</span>(<span class="string">"buffer already closed"</span>); |
| } |
| } |
| } |
| |
| <span class="kw">impl</span><T, Request> Worker<T, Request> |
| <span class="kw">where |
| </span>T: Service<Request>, |
| T::Error: Into<<span class="kw">crate</span>::BoxError>, |
| { |
| <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>new( |
| service: T, |
| rx: mpsc::UnboundedReceiver<Message<Request, T::Future>>, |
| semaphore: <span class="kw-2">&</span>Arc<Semaphore>, |
| ) -> (Handle, Worker<T, Request>) { |
| <span class="kw">let </span>handle = Handle { |
| inner: Arc::new(Mutex::new(<span class="prelude-val">None</span>)), |
| }; |
| |
| <span class="kw">let </span>semaphore = Arc::downgrade(semaphore); |
| <span class="kw">let </span>worker = Worker { |
| current_message: <span class="prelude-val">None</span>, |
| finish: <span class="bool-val">false</span>, |
| failed: <span class="prelude-val">None</span>, |
| rx, |
| service, |
| handle: handle.clone(), |
| close: <span class="prelude-val">Some</span>(semaphore), |
| }; |
| |
| (handle, worker) |
| } |
| |
| <span class="doccomment">/// Return the next queued Message that hasn't been canceled. |
| /// |
| /// If a `Message` is returned, the `bool` is true if this is the first time we received this |
| /// message, and false otherwise (i.e., we tried to forward it to the backing service before). |
| </span><span class="kw">fn </span>poll_next_msg( |
| <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="prelude-ty">Option</span><(Message<Request, T::Future>, bool)>> { |
| <span class="kw">if </span><span class="self">self</span>.finish { |
| <span class="comment">// We've already received None and are shutting down |
| </span><span class="kw">return </span>Poll::Ready(<span class="prelude-val">None</span>); |
| } |
| |
| <span class="macro">tracing::trace!</span>(<span class="string">"worker polling for next message"</span>); |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(msg) = <span class="self">self</span>.current_message.take() { |
| <span class="comment">// If the oneshot sender is closed, then the receiver is dropped, |
| // and nobody cares about the response. If this is the case, we |
| // should continue to the next request. |
| </span><span class="kw">if </span>!msg.tx.is_closed() { |
| <span class="macro">tracing::trace!</span>(<span class="string">"resuming buffered request"</span>); |
| <span class="kw">return </span>Poll::Ready(<span class="prelude-val">Some</span>((msg, <span class="bool-val">false</span>))); |
| } |
| |
| <span class="macro">tracing::trace!</span>(<span class="string">"dropping cancelled buffered request"</span>); |
| } |
| |
| <span class="comment">// Get the next request |
| </span><span class="kw">while let </span><span class="prelude-val">Some</span>(msg) = <span class="macro">ready!</span>(Pin::new(<span class="kw-2">&mut </span><span class="self">self</span>.rx).poll_recv(cx)) { |
| <span class="kw">if </span>!msg.tx.is_closed() { |
| <span class="macro">tracing::trace!</span>(<span class="string">"processing new request"</span>); |
| <span class="kw">return </span>Poll::Ready(<span class="prelude-val">Some</span>((msg, <span class="bool-val">true</span>))); |
| } |
| <span class="comment">// Otherwise, request is canceled, so pop the next one. |
| </span><span class="macro">tracing::trace!</span>(<span class="string">"dropping cancelled request"</span>); |
| } |
| |
| Poll::Ready(<span class="prelude-val">None</span>) |
| } |
| |
| <span class="kw">fn </span>failed(<span class="kw-2">&mut </span><span class="self">self</span>, error: <span class="kw">crate</span>::BoxError) { |
| <span class="comment">// The underlying service failed when we called `poll_ready` on it with the given `error`. We |
| // need to communicate this to all the `Buffer` handles. To do so, we wrap up the error in |
| // an `Arc`, send that `Arc<E>` to all pending requests, and store it so that subsequent |
| // requests will also fail with the same error. |
| |
| // Note that we need to handle the case where some handle is concurrently trying to send us |
| // a request. We need to make sure that *either* the send of the request fails *or* it |
| // receives an error on the `oneshot` it constructed. Specifically, we want to avoid the |
| // case where we send errors to all outstanding requests, and *then* the caller sends its |
| // request. We do this by *first* exposing the error, *then* closing the channel used to |
| // send more requests (so the client will see the error when the send fails), and *then* |
| // sending the error to all outstanding requests. |
| </span><span class="kw">let </span>error = ServiceError::new(error); |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>inner = <span class="self">self</span>.handle.inner.lock().unwrap(); |
| |
| <span class="kw">if </span>inner.is_some() { |
| <span class="comment">// Future::poll was called after we've already errored out! |
| </span><span class="kw">return</span>; |
| } |
| |
| <span class="kw-2">*</span>inner = <span class="prelude-val">Some</span>(error.clone()); |
| drop(inner); |
| |
| <span class="self">self</span>.rx.close(); |
| |
| <span class="comment">// By closing the mpsc::Receiver, we know that poll_next_msg will soon return Ready(None), |
| // which will trigger the `self.finish == true` phase. We just need to make sure that any |
| // requests that we receive before we've exhausted the receiver receive the error: |
| </span><span class="self">self</span>.failed = <span class="prelude-val">Some</span>(error); |
| } |
| } |
| |
| <span class="kw">impl</span><T, Request> Future <span class="kw">for </span>Worker<T, Request> |
| <span class="kw">where |
| </span>T: Service<Request>, |
| T::Error: Into<<span class="kw">crate</span>::BoxError>, |
| { |
| <span class="kw">type </span>Output = (); |
| |
| <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">if </span><span class="self">self</span>.finish { |
| <span class="kw">return </span>Poll::Ready(()); |
| } |
| |
| <span class="kw">loop </span>{ |
| <span class="kw">match </span><span class="macro">ready!</span>(<span class="self">self</span>.poll_next_msg(cx)) { |
| <span class="prelude-val">Some</span>((msg, first)) => { |
| <span class="kw">let </span>_guard = msg.span.enter(); |
| <span class="kw">if let </span><span class="prelude-val">Some</span>(<span class="kw-2">ref </span>failed) = <span class="self">self</span>.failed { |
| <span class="macro">tracing::trace!</span>(<span class="string">"notifying caller about worker failure"</span>); |
| <span class="kw">let _ </span>= msg.tx.send(<span class="prelude-val">Err</span>(failed.clone())); |
| <span class="kw">continue</span>; |
| } |
| |
| <span class="comment">// Wait for the service to be ready |
| </span><span class="macro">tracing::trace!</span>( |
| resumed = !first, |
| message = <span class="string">"worker received request; waiting for service readiness" |
| </span>); |
| <span class="kw">match </span><span class="self">self</span>.service.poll_ready(cx) { |
| Poll::Ready(<span class="prelude-val">Ok</span>(())) => { |
| <span class="macro">tracing::debug!</span>(service.ready = <span class="bool-val">true</span>, message = <span class="string">"processing request"</span>); |
| <span class="kw">let </span>response = <span class="self">self</span>.service.call(msg.request); |
| |
| <span class="comment">// Send the response future back to the sender. |
| // |
| // An error means the request had been canceled in-between |
| // our calls, the response future will just be dropped. |
| </span><span class="macro">tracing::trace!</span>(<span class="string">"returning response future"</span>); |
| <span class="kw">let _ </span>= msg.tx.send(<span class="prelude-val">Ok</span>(response)); |
| } |
| Poll::Pending => { |
| <span class="macro">tracing::trace!</span>(service.ready = <span class="bool-val">false</span>, message = <span class="string">"delay"</span>); |
| <span class="comment">// Put out current message back in its slot. |
| </span>drop(_guard); |
| <span class="self">self</span>.current_message = <span class="prelude-val">Some</span>(msg); |
| <span class="kw">return </span>Poll::Pending; |
| } |
| Poll::Ready(<span class="prelude-val">Err</span>(e)) => { |
| <span class="kw">let </span>error = e.into(); |
| <span class="macro">tracing::debug!</span>({ %error }, <span class="string">"service failed"</span>); |
| drop(_guard); |
| <span class="self">self</span>.failed(error); |
| <span class="kw">let _ </span>= msg.tx.send(<span class="prelude-val">Err</span>(<span class="self">self |
| </span>.failed |
| .as_ref() |
| .expect(<span class="string">"Worker::failed did not set self.failed?"</span>) |
| .clone())); |
| <span class="comment">// Wake any tasks waiting on channel capacity. |
| </span><span class="self">self</span>.close_semaphore(); |
| } |
| } |
| } |
| <span class="prelude-val">None </span>=> { |
| <span class="comment">// No more more requests _ever_. |
| </span><span class="self">self</span>.finish = <span class="bool-val">true</span>; |
| <span class="kw">return </span>Poll::Ready(()); |
| } |
| } |
| } |
| } |
| } |
| |
| <span class="kw">impl </span>Handle { |
| <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>get_error_on_closed(<span class="kw-2">&</span><span class="self">self</span>) -> <span class="kw">crate</span>::BoxError { |
| <span class="self">self</span>.inner |
| .lock() |
| .unwrap() |
| .as_ref() |
| .map(|svc_err| svc_err.clone().into()) |
| .unwrap_or_else(|| Closed::new().into()) |
| } |
| } |
| |
| <span class="kw">impl </span>Clone <span class="kw">for </span>Handle { |
| <span class="kw">fn </span>clone(<span class="kw-2">&</span><span class="self">self</span>) -> Handle { |
| Handle { |
| inner: <span class="self">self</span>.inner.clone(), |
| } |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../../" data-current-crate="tower" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
