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<!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/git/checkouts/tokio-377c595163f99a10/dfe252d/tokio/src/runtime/scheduler/current_thread.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>current_thread.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="../../../../tokio/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="../../../../tokio/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 </span><span class="kw">crate</span>::future::poll_fn;
<span class="kw">use </span><span class="kw">crate</span>::loom::sync::atomic::AtomicBool;
<span class="kw">use </span><span class="kw">crate</span>::loom::sync::{Arc, Mutex};
<span class="kw">use </span><span class="kw">crate</span>::runtime::driver::{<span class="self">self</span>, Driver};
<span class="kw">use </span><span class="kw">crate</span>::runtime::task::{<span class="self">self</span>, JoinHandle, OwnedTasks, Schedule, Task};
<span class="kw">use </span><span class="kw">crate</span>::runtime::{blocking, context, scheduler, Config};
<span class="kw">use </span><span class="kw">crate</span>::runtime::{MetricsBatch, SchedulerMetrics, WorkerMetrics};
<span class="kw">use </span><span class="kw">crate</span>::sync::notify::Notify;
<span class="kw">use </span><span class="kw">crate</span>::util::atomic_cell::AtomicCell;
<span class="kw">use </span><span class="kw">crate</span>::util::{waker_ref, RngSeedGenerator, Wake, WakerRef};
<span class="kw">use </span>std::cell::RefCell;
<span class="kw">use </span>std::collections::VecDeque;
<span class="kw">use </span>std::fmt;
<span class="kw">use </span>std::future::Future;
<span class="kw">use </span>std::sync::atomic::Ordering::{AcqRel, Release};
<span class="kw">use </span>std::task::Poll::{Pending, Ready};
<span class="kw">use </span>std::time::Duration;
<span class="doccomment">/// Executes tasks on the current thread
</span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">struct </span>CurrentThread {
<span class="doccomment">/// Core scheduler data is acquired by a thread entering `block_on`.
</span>core: AtomicCell&lt;Core&gt;,
<span class="doccomment">/// Notifier for waking up other threads to steal the
/// driver.
</span>notify: Notify,
}
<span class="doccomment">/// Handle to the current thread scheduler
</span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">struct </span>Handle {
<span class="doccomment">/// Scheduler state shared across threads
</span>shared: Shared,
<span class="doccomment">/// Resource driver handles
</span><span class="kw">pub</span>(<span class="kw">crate</span>) driver: driver::Handle,
<span class="doccomment">/// Blocking pool spawner
</span><span class="kw">pub</span>(<span class="kw">crate</span>) blocking_spawner: blocking::Spawner,
<span class="doccomment">/// Current random number generator seed
</span><span class="kw">pub</span>(<span class="kw">crate</span>) seed_generator: RngSeedGenerator,
}
<span class="doccomment">/// Data required for executing the scheduler. The struct is passed around to
/// a function that will perform the scheduling work and acts as a capability token.
</span><span class="kw">struct </span>Core {
<span class="doccomment">/// Scheduler run queue
</span>tasks: VecDeque&lt;task::Notified&lt;Arc&lt;Handle&gt;&gt;&gt;,
<span class="doccomment">/// Current tick
</span>tick: u32,
<span class="doccomment">/// Runtime driver
///
/// The driver is removed before starting to park the thread
</span>driver: <span class="prelude-ty">Option</span>&lt;Driver&gt;,
<span class="doccomment">/// Metrics batch
</span>metrics: MetricsBatch,
<span class="doccomment">/// True if a task panicked without being handled and the runtime is
/// configured to shutdown on unhandled panic.
</span>unhandled_panic: bool,
}
<span class="doccomment">/// Scheduler state shared between threads.
</span><span class="kw">struct </span>Shared {
<span class="doccomment">/// Remote run queue. None if the `Runtime` has been dropped.
</span>queue: Mutex&lt;<span class="prelude-ty">Option</span>&lt;VecDeque&lt;task::Notified&lt;Arc&lt;Handle&gt;&gt;&gt;&gt;&gt;,
<span class="doccomment">/// Collection of all active tasks spawned onto this executor.
</span>owned: OwnedTasks&lt;Arc&lt;Handle&gt;&gt;,
<span class="doccomment">/// Indicates whether the blocked on thread was woken.
</span>woken: AtomicBool,
<span class="doccomment">/// Scheduler configuration options
</span>config: Config,
<span class="doccomment">/// Keeps track of various runtime metrics.
</span>scheduler_metrics: SchedulerMetrics,
<span class="doccomment">/// This scheduler only has one worker.
</span>worker_metrics: WorkerMetrics,
}
<span class="doccomment">/// Thread-local context.
</span><span class="kw">struct </span>Context {
<span class="doccomment">/// Scheduler handle
</span>handle: Arc&lt;Handle&gt;,
<span class="doccomment">/// Scheduler core, enabling the holder of `Context` to execute the
/// scheduler.
</span>core: RefCell&lt;<span class="prelude-ty">Option</span>&lt;Box&lt;Core&gt;&gt;&gt;,
}
<span class="doccomment">/// Initial queue capacity.
</span><span class="kw">const </span>INITIAL_CAPACITY: usize = <span class="number">64</span>;
<span class="comment">// Tracks the current CurrentThread.
</span><span class="macro">scoped_thread_local!</span>(<span class="kw">static </span>CURRENT: Context);
<span class="kw">impl </span>CurrentThread {
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>new(
driver: Driver,
driver_handle: driver::Handle,
blocking_spawner: blocking::Spawner,
seed_generator: RngSeedGenerator,
config: Config,
) -&gt; (CurrentThread, Arc&lt;Handle&gt;) {
<span class="kw">let </span>handle = Arc::new(Handle {
shared: Shared {
queue: Mutex::new(<span class="prelude-val">Some</span>(VecDeque::with_capacity(INITIAL_CAPACITY))),
owned: OwnedTasks::new(),
woken: AtomicBool::new(<span class="bool-val">false</span>),
config,
scheduler_metrics: SchedulerMetrics::new(),
worker_metrics: WorkerMetrics::new(),
},
driver: driver_handle,
blocking_spawner,
seed_generator,
});
<span class="kw">let </span>core = AtomicCell::new(<span class="prelude-val">Some</span>(Box::new(Core {
tasks: VecDeque::with_capacity(INITIAL_CAPACITY),
tick: <span class="number">0</span>,
driver: <span class="prelude-val">Some</span>(driver),
metrics: MetricsBatch::new(),
unhandled_panic: <span class="bool-val">false</span>,
})));
<span class="kw">let </span>scheduler = CurrentThread {
core,
notify: Notify::new(),
};
(scheduler, handle)
}
<span class="attribute">#[track_caller]
</span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>block_on&lt;F: Future&gt;(<span class="kw-2">&amp;</span><span class="self">self</span>, handle: <span class="kw-2">&amp;</span>scheduler::Handle, future: F) -&gt; F::Output {
<span class="macro">pin!</span>(future);
<span class="kw">let </span><span class="kw-2">mut </span>enter = <span class="kw">crate</span>::runtime::context::enter_runtime(handle, <span class="bool-val">false</span>);
<span class="kw">let </span>handle = handle.as_current_thread();
<span class="comment">// Attempt to steal the scheduler core and block_on the future if we can
// there, otherwise, lets select on a notification that the core is
// available or the future is complete.
</span><span class="kw">loop </span>{
<span class="kw">if let </span><span class="prelude-val">Some</span>(core) = <span class="self">self</span>.take_core(handle) {
<span class="kw">return </span>core.block_on(future);
} <span class="kw">else </span>{
<span class="kw">let </span>notified = <span class="self">self</span>.notify.notified();
<span class="macro">pin!</span>(notified);
<span class="kw">if let </span><span class="prelude-val">Some</span>(out) = enter
.blocking
.block_on(poll_fn(|cx| {
<span class="kw">if </span>notified.as_mut().poll(cx).is_ready() {
<span class="kw">return </span>Ready(<span class="prelude-val">None</span>);
}
<span class="kw">if let </span>Ready(out) = future.as_mut().poll(cx) {
<span class="kw">return </span>Ready(<span class="prelude-val">Some</span>(out));
}
Pending
}))
.expect(<span class="string">&quot;Failed to `Enter::block_on`&quot;</span>)
{
<span class="kw">return </span>out;
}
}
}
}
<span class="kw">fn </span>take_core(<span class="kw-2">&amp;</span><span class="self">self</span>, handle: <span class="kw-2">&amp;</span>Arc&lt;Handle&gt;) -&gt; <span class="prelude-ty">Option</span>&lt;CoreGuard&lt;<span class="lifetime">&#39;_</span>&gt;&gt; {
<span class="kw">let </span>core = <span class="self">self</span>.core.take()<span class="question-mark">?</span>;
<span class="prelude-val">Some</span>(CoreGuard {
context: Context {
handle: handle.clone(),
core: RefCell::new(<span class="prelude-val">Some</span>(core)),
},
scheduler: <span class="self">self</span>,
})
}
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>shutdown(<span class="kw-2">&amp;mut </span><span class="self">self</span>, handle: <span class="kw-2">&amp;</span>scheduler::Handle) {
<span class="kw">let </span>handle = handle.as_current_thread();
<span class="comment">// Avoid a double panic if we are currently panicking and
// the lock may be poisoned.
</span><span class="kw">let </span>core = <span class="kw">match </span><span class="self">self</span>.take_core(handle) {
<span class="prelude-val">Some</span>(core) =&gt; core,
<span class="prelude-val">None </span><span class="kw">if </span>std::thread::panicking() =&gt; <span class="kw">return</span>,
<span class="prelude-val">None </span>=&gt; <span class="macro">panic!</span>(<span class="string">&quot;Oh no! We never placed the Core back, this is a bug!&quot;</span>),
};
core.enter(|<span class="kw-2">mut </span>core, _context| {
<span class="comment">// Drain the OwnedTasks collection. This call also closes the
// collection, ensuring that no tasks are ever pushed after this
// call returns.
</span>handle.shared.owned.close_and_shutdown_all();
<span class="comment">// Drain local queue
// We already shut down every task, so we just need to drop the task.
</span><span class="kw">while let </span><span class="prelude-val">Some</span>(task) = core.pop_task(handle) {
drop(task);
}
<span class="comment">// Drain remote queue and set it to None
</span><span class="kw">let </span>remote_queue = handle.shared.queue.lock().take();
<span class="comment">// Using `Option::take` to replace the shared queue with `None`.
// We already shut down every task, so we just need to drop the task.
</span><span class="kw">if let </span><span class="prelude-val">Some</span>(remote_queue) = remote_queue {
<span class="kw">for </span>task <span class="kw">in </span>remote_queue {
drop(task);
}
}
<span class="macro">assert!</span>(handle.shared.owned.is_empty());
<span class="comment">// Submit metrics
</span>core.metrics.submit(<span class="kw-2">&amp;</span>handle.shared.worker_metrics);
<span class="comment">// Shutdown the resource drivers
</span><span class="kw">if let </span><span class="prelude-val">Some</span>(driver) = core.driver.as_mut() {
driver.shutdown(<span class="kw-2">&amp;</span>handle.driver);
}
(core, ())
});
}
}
<span class="kw">impl </span>fmt::Debug <span class="kw">for </span>CurrentThread {
<span class="kw">fn </span>fmt(<span class="kw-2">&amp;</span><span class="self">self</span>, fmt: <span class="kw-2">&amp;mut </span>fmt::Formatter&lt;<span class="lifetime">&#39;_</span>&gt;) -&gt; fmt::Result {
fmt.debug_struct(<span class="string">&quot;CurrentThread&quot;</span>).finish()
}
}
<span class="comment">// ===== impl Core =====
</span><span class="kw">impl </span>Core {
<span class="kw">fn </span>pop_task(<span class="kw-2">&amp;mut </span><span class="self">self</span>, handle: <span class="kw-2">&amp;</span>Handle) -&gt; <span class="prelude-ty">Option</span>&lt;task::Notified&lt;Arc&lt;Handle&gt;&gt;&gt; {
<span class="kw">let </span>ret = <span class="self">self</span>.tasks.pop_front();
handle
.shared
.worker_metrics
.set_queue_depth(<span class="self">self</span>.tasks.len());
ret
}
<span class="kw">fn </span>push_task(<span class="kw-2">&amp;mut </span><span class="self">self</span>, handle: <span class="kw-2">&amp;</span>Handle, task: task::Notified&lt;Arc&lt;Handle&gt;&gt;) {
<span class="self">self</span>.tasks.push_back(task);
<span class="self">self</span>.metrics.inc_local_schedule_count();
handle
.shared
.worker_metrics
.set_queue_depth(<span class="self">self</span>.tasks.len());
}
}
<span class="kw">fn </span>did_defer_tasks() -&gt; bool {
context::with_defer(|deferred| !deferred.is_empty()).unwrap()
}
<span class="kw">fn </span>wake_deferred_tasks() {
context::with_defer(|deferred| deferred.wake());
}
<span class="comment">// ===== impl Context =====
</span><span class="kw">impl </span>Context {
<span class="doccomment">/// Execute the closure with the given scheduler core stored in the
/// thread-local context.
</span><span class="kw">fn </span>run_task&lt;R&gt;(<span class="kw-2">&amp;</span><span class="self">self</span>, <span class="kw-2">mut </span>core: Box&lt;Core&gt;, f: <span class="kw">impl </span>FnOnce() -&gt; R) -&gt; (Box&lt;Core&gt;, R) {
core.metrics.incr_poll_count();
<span class="self">self</span>.enter(core, || <span class="kw">crate</span>::runtime::coop::budget(f))
}
<span class="doccomment">/// Blocks the current thread until an event is received by the driver,
/// including I/O events, timer events, ...
</span><span class="kw">fn </span>park(<span class="kw-2">&amp;</span><span class="self">self</span>, <span class="kw-2">mut </span>core: Box&lt;Core&gt;, handle: <span class="kw-2">&amp;</span>Handle) -&gt; Box&lt;Core&gt; {
<span class="kw">let </span><span class="kw-2">mut </span>driver = core.driver.take().expect(<span class="string">&quot;driver missing&quot;</span>);
<span class="kw">if let </span><span class="prelude-val">Some</span>(f) = <span class="kw-2">&amp;</span>handle.shared.config.before_park {
<span class="comment">// Incorrect lint, the closures are actually different types so `f`
// cannot be passed as an argument to `enter`.
</span><span class="attribute">#[allow(clippy::redundant_closure)]
</span><span class="kw">let </span>(c, <span class="kw">_</span>) = <span class="self">self</span>.enter(core, || f());
core = c;
}
<span class="comment">// This check will fail if `before_park` spawns a task for us to run
// instead of parking the thread
</span><span class="kw">if </span>core.tasks.is_empty() {
<span class="comment">// Park until the thread is signaled
</span>core.metrics.about_to_park();
core.metrics.submit(<span class="kw-2">&amp;</span>handle.shared.worker_metrics);
<span class="kw">let </span>(c, <span class="kw">_</span>) = <span class="self">self</span>.enter(core, || {
driver.park(<span class="kw-2">&amp;</span>handle.driver);
wake_deferred_tasks();
});
core = c;
core.metrics.returned_from_park();
}
<span class="kw">if let </span><span class="prelude-val">Some</span>(f) = <span class="kw-2">&amp;</span>handle.shared.config.after_unpark {
<span class="comment">// Incorrect lint, the closures are actually different types so `f`
// cannot be passed as an argument to `enter`.
</span><span class="attribute">#[allow(clippy::redundant_closure)]
</span><span class="kw">let </span>(c, <span class="kw">_</span>) = <span class="self">self</span>.enter(core, || f());
core = c;
}
core.driver = <span class="prelude-val">Some</span>(driver);
core
}
<span class="doccomment">/// Checks the driver for new events without blocking the thread.
</span><span class="kw">fn </span>park_yield(<span class="kw-2">&amp;</span><span class="self">self</span>, <span class="kw-2">mut </span>core: Box&lt;Core&gt;, handle: <span class="kw-2">&amp;</span>Handle) -&gt; Box&lt;Core&gt; {
<span class="kw">let </span><span class="kw-2">mut </span>driver = core.driver.take().expect(<span class="string">&quot;driver missing&quot;</span>);
core.metrics.submit(<span class="kw-2">&amp;</span>handle.shared.worker_metrics);
<span class="kw">let </span>(<span class="kw-2">mut </span>core, <span class="kw">_</span>) = <span class="self">self</span>.enter(core, || {
driver.park_timeout(<span class="kw-2">&amp;</span>handle.driver, Duration::from_millis(<span class="number">0</span>));
wake_deferred_tasks();
});
core.driver = <span class="prelude-val">Some</span>(driver);
core
}
<span class="kw">fn </span>enter&lt;R&gt;(<span class="kw-2">&amp;</span><span class="self">self</span>, core: Box&lt;Core&gt;, f: <span class="kw">impl </span>FnOnce() -&gt; R) -&gt; (Box&lt;Core&gt;, R) {
<span class="comment">// Store the scheduler core in the thread-local context
//
// A drop-guard is employed at a higher level.
</span><span class="kw-2">*</span><span class="self">self</span>.core.borrow_mut() = <span class="prelude-val">Some</span>(core);
<span class="comment">// Execute the closure while tracking the execution budget
</span><span class="kw">let </span>ret = f();
<span class="comment">// Take the scheduler core back
</span><span class="kw">let </span>core = <span class="self">self</span>.core.borrow_mut().take().expect(<span class="string">&quot;core missing&quot;</span>);
(core, ret)
}
}
<span class="comment">// ===== impl Handle =====
</span><span class="kw">impl </span>Handle {
<span class="doccomment">/// Spawns a future onto the `CurrentThread` scheduler
</span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>spawn&lt;F&gt;(
me: <span class="kw-2">&amp;</span>Arc&lt;<span class="self">Self</span>&gt;,
future: F,
id: <span class="kw">crate</span>::runtime::task::Id,
) -&gt; JoinHandle&lt;F::Output&gt;
<span class="kw">where
</span>F: <span class="kw">crate</span>::future::Future + Send + <span class="lifetime">&#39;static</span>,
F::Output: Send + <span class="lifetime">&#39;static</span>,
{
<span class="kw">let </span>(handle, notified) = me.shared.owned.bind(future, me.clone(), id);
<span class="kw">if let </span><span class="prelude-val">Some</span>(notified) = notified {
me.schedule(notified);
}
handle
}
<span class="kw">fn </span>pop(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; <span class="prelude-ty">Option</span>&lt;task::Notified&lt;Arc&lt;Handle&gt;&gt;&gt; {
<span class="kw">match </span><span class="self">self</span>.shared.queue.lock().as_mut() {
<span class="prelude-val">Some</span>(queue) =&gt; queue.pop_front(),
<span class="prelude-val">None </span>=&gt; <span class="prelude-val">None</span>,
}
}
<span class="kw">fn </span>waker_ref(me: <span class="kw-2">&amp;</span>Arc&lt;<span class="self">Self</span>&gt;) -&gt; WakerRef&lt;<span class="lifetime">&#39;_</span>&gt; {
<span class="comment">// Set woken to true when enter block_on, ensure outer future
// be polled for the first time when enter loop
</span>me.shared.woken.store(<span class="bool-val">true</span>, Release);
waker_ref(me)
}
<span class="comment">// reset woken to false and return original value
</span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>reset_woken(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; bool {
<span class="self">self</span>.shared.woken.swap(<span class="bool-val">false</span>, AcqRel)
}
}
<span class="macro">cfg_metrics! </span>{
<span class="kw">impl </span>Handle {
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>scheduler_metrics(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; <span class="kw-2">&amp;</span>SchedulerMetrics {
<span class="kw-2">&amp;</span><span class="self">self</span>.shared.scheduler_metrics
}
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>injection_queue_depth(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; usize {
<span class="comment">// TODO: avoid having to lock. The multi-threaded injection queue
// could probably be used here.
</span><span class="self">self</span>.shared
.queue
.lock()
.as_ref()
.map(|queue| queue.len())
.unwrap_or(<span class="number">0</span>)
}
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>worker_metrics(<span class="kw-2">&amp;</span><span class="self">self</span>, worker: usize) -&gt; <span class="kw-2">&amp;</span>WorkerMetrics {
<span class="macro">assert_eq!</span>(<span class="number">0</span>, worker);
<span class="kw-2">&amp;</span><span class="self">self</span>.shared.worker_metrics
}
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>num_blocking_threads(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; usize {
<span class="self">self</span>.blocking_spawner.num_threads()
}
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>num_idle_blocking_threads(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; usize {
<span class="self">self</span>.blocking_spawner.num_idle_threads()
}
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>blocking_queue_depth(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; usize {
<span class="self">self</span>.blocking_spawner.queue_depth()
}
}
}
<span class="kw">impl </span>fmt::Debug <span class="kw">for </span>Handle {
<span class="kw">fn </span>fmt(<span class="kw-2">&amp;</span><span class="self">self</span>, fmt: <span class="kw-2">&amp;mut </span>fmt::Formatter&lt;<span class="lifetime">&#39;_</span>&gt;) -&gt; fmt::Result {
fmt.debug_struct(<span class="string">&quot;current_thread::Handle { ... }&quot;</span>).finish()
}
}
<span class="comment">// ===== impl Shared =====
</span><span class="kw">impl </span>Schedule <span class="kw">for </span>Arc&lt;Handle&gt; {
<span class="kw">fn </span>release(<span class="kw-2">&amp;</span><span class="self">self</span>, task: <span class="kw-2">&amp;</span>Task&lt;<span class="self">Self</span>&gt;) -&gt; <span class="prelude-ty">Option</span>&lt;Task&lt;<span class="self">Self</span>&gt;&gt; {
<span class="self">self</span>.shared.owned.remove(task)
}
<span class="kw">fn </span>schedule(<span class="kw-2">&amp;</span><span class="self">self</span>, task: task::Notified&lt;<span class="self">Self</span>&gt;) {
CURRENT.with(|maybe_cx| <span class="kw">match </span>maybe_cx {
<span class="prelude-val">Some</span>(cx) <span class="kw">if </span>Arc::ptr_eq(<span class="self">self</span>, <span class="kw-2">&amp;</span>cx.handle) =&gt; {
<span class="kw">let </span><span class="kw-2">mut </span>core = cx.core.borrow_mut();
<span class="comment">// If `None`, the runtime is shutting down, so there is no need
// to schedule the task.
</span><span class="kw">if let </span><span class="prelude-val">Some</span>(core) = core.as_mut() {
core.push_task(<span class="self">self</span>, task);
}
}
<span class="kw">_ </span>=&gt; {
<span class="comment">// Track that a task was scheduled from **outside** of the runtime.
</span><span class="self">self</span>.shared.scheduler_metrics.inc_remote_schedule_count();
<span class="comment">// If the queue is None, then the runtime has shut down. We
// don&#39;t need to do anything with the notification in that case.
</span><span class="kw">let </span><span class="kw-2">mut </span>guard = <span class="self">self</span>.shared.queue.lock();
<span class="kw">if let </span><span class="prelude-val">Some</span>(queue) = guard.as_mut() {
queue.push_back(task);
drop(guard);
<span class="self">self</span>.driver.unpark();
}
}
});
}
<span class="macro">cfg_unstable! </span>{
<span class="kw">fn </span>unhandled_panic(<span class="kw-2">&amp;</span><span class="self">self</span>) {
<span class="kw">use </span><span class="kw">crate</span>::runtime::UnhandledPanic;
<span class="kw">match </span><span class="self">self</span>.shared.config.unhandled_panic {
UnhandledPanic::Ignore =&gt; {
<span class="comment">// Do nothing
</span>}
UnhandledPanic::ShutdownRuntime =&gt; {
<span class="comment">// This hook is only called from within the runtime, so
// `CURRENT` should match with `&amp;self`, i.e. there is no
// opportunity for a nested scheduler to be called.
</span>CURRENT.with(|maybe_cx| <span class="kw">match </span>maybe_cx {
<span class="prelude-val">Some</span>(cx) <span class="kw">if </span>Arc::ptr_eq(<span class="self">self</span>, <span class="kw-2">&amp;</span>cx.handle) =&gt; {
<span class="kw">let </span><span class="kw-2">mut </span>core = cx.core.borrow_mut();
<span class="comment">// If `None`, the runtime is shutting down, so there is no need to signal shutdown
</span><span class="kw">if let </span><span class="prelude-val">Some</span>(core) = core.as_mut() {
core.unhandled_panic = <span class="bool-val">true</span>;
<span class="self">self</span>.shared.owned.close_and_shutdown_all();
}
}
<span class="kw">_ </span>=&gt; <span class="macro">unreachable!</span>(<span class="string">&quot;runtime core not set in CURRENT thread-local&quot;</span>),
})
}
}
}
}
}
<span class="kw">impl </span>Wake <span class="kw">for </span>Handle {
<span class="kw">fn </span>wake(arc_self: Arc&lt;<span class="self">Self</span>&gt;) {
Wake::wake_by_ref(<span class="kw-2">&amp;</span>arc_self)
}
<span class="doccomment">/// Wake by reference
</span><span class="kw">fn </span>wake_by_ref(arc_self: <span class="kw-2">&amp;</span>Arc&lt;<span class="self">Self</span>&gt;) {
arc_self.shared.woken.store(<span class="bool-val">true</span>, Release);
arc_self.driver.unpark();
}
}
<span class="comment">// ===== CoreGuard =====
</span><span class="doccomment">/// Used to ensure we always place the `Core` value back into its slot in
/// `CurrentThread`, even if the future panics.
</span><span class="kw">struct </span>CoreGuard&lt;<span class="lifetime">&#39;a</span>&gt; {
context: Context,
scheduler: <span class="kw-2">&amp;</span><span class="lifetime">&#39;a </span>CurrentThread,
}
<span class="kw">impl </span>CoreGuard&lt;<span class="lifetime">&#39;_</span>&gt; {
<span class="attribute">#[track_caller]
</span><span class="kw">fn </span>block_on&lt;F: Future&gt;(<span class="self">self</span>, future: F) -&gt; F::Output {
<span class="kw">let </span>ret = <span class="self">self</span>.enter(|<span class="kw-2">mut </span>core, context| {
<span class="kw">let </span>waker = Handle::waker_ref(<span class="kw-2">&amp;</span>context.handle);
<span class="kw">let </span><span class="kw-2">mut </span>cx = std::task::Context::from_waker(<span class="kw-2">&amp;</span>waker);
<span class="macro">pin!</span>(future);
<span class="lifetime">&#39;outer</span>: <span class="kw">loop </span>{
<span class="kw">let </span>handle = <span class="kw-2">&amp;</span>context.handle;
<span class="kw">if </span>handle.reset_woken() {
<span class="kw">let </span>(c, res) = context.enter(core, || {
<span class="kw">crate</span>::runtime::coop::budget(|| future.as_mut().poll(<span class="kw-2">&amp;mut </span>cx))
});
core = c;
<span class="kw">if let </span>Ready(v) = res {
<span class="kw">return </span>(core, <span class="prelude-val">Some</span>(v));
}
}
<span class="kw">for _ in </span><span class="number">0</span>..handle.shared.config.event_interval {
<span class="comment">// Make sure we didn&#39;t hit an unhandled_panic
</span><span class="kw">if </span>core.unhandled_panic {
<span class="kw">return </span>(core, <span class="prelude-val">None</span>);
}
<span class="comment">// Get and increment the current tick
</span><span class="kw">let </span>tick = core.tick;
core.tick = core.tick.wrapping_add(<span class="number">1</span>);
<span class="kw">let </span>entry = <span class="kw">if </span>tick % handle.shared.config.global_queue_interval == <span class="number">0 </span>{
handle.pop().or_else(|| core.tasks.pop_front())
} <span class="kw">else </span>{
core.tasks.pop_front().or_else(|| handle.pop())
};
<span class="kw">let </span>task = <span class="kw">match </span>entry {
<span class="prelude-val">Some</span>(entry) =&gt; entry,
<span class="prelude-val">None </span>=&gt; {
core = <span class="kw">if </span>did_defer_tasks() {
context.park_yield(core, handle)
} <span class="kw">else </span>{
context.park(core, handle)
};
<span class="comment">// Try polling the `block_on` future next
</span><span class="kw">continue </span><span class="lifetime">&#39;outer</span>;
}
};
<span class="kw">let </span>task = context.handle.shared.owned.assert_owner(task);
<span class="kw">let </span>(c, <span class="kw">_</span>) = context.run_task(core, || {
task.run();
});
core = c;
}
<span class="comment">// Yield to the driver, this drives the timer and pulls any
// pending I/O events.
</span>core = context.park_yield(core, handle);
}
});
<span class="kw">match </span>ret {
<span class="prelude-val">Some</span>(ret) =&gt; ret,
<span class="prelude-val">None </span>=&gt; {
<span class="comment">// `block_on` panicked.
</span><span class="macro">panic!</span>(<span class="string">&quot;a spawned task panicked and the runtime is configured to shut down on unhandled panic&quot;</span>);
}
}
}
<span class="doccomment">/// Enters the scheduler context. This sets the queue and other necessary
/// scheduler state in the thread-local.
</span><span class="kw">fn </span>enter&lt;F, R&gt;(<span class="self">self</span>, f: F) -&gt; R
<span class="kw">where
</span>F: FnOnce(Box&lt;Core&gt;, <span class="kw-2">&amp;</span>Context) -&gt; (Box&lt;Core&gt;, R),
{
<span class="comment">// Remove `core` from `context` to pass into the closure.
</span><span class="kw">let </span>core = <span class="self">self</span>.context.core.borrow_mut().take().expect(<span class="string">&quot;core missing&quot;</span>);
<span class="comment">// Call the closure and place `core` back
</span><span class="kw">let </span>(core, ret) = CURRENT.set(<span class="kw-2">&amp;</span><span class="self">self</span>.context, || f(core, <span class="kw-2">&amp;</span><span class="self">self</span>.context));
<span class="kw-2">*</span><span class="self">self</span>.context.core.borrow_mut() = <span class="prelude-val">Some</span>(core);
ret
}
}
<span class="kw">impl </span>Drop <span class="kw">for </span>CoreGuard&lt;<span class="lifetime">&#39;_</span>&gt; {
<span class="kw">fn </span>drop(<span class="kw-2">&amp;mut </span><span class="self">self</span>) {
<span class="kw">if let </span><span class="prelude-val">Some</span>(core) = <span class="self">self</span>.context.core.borrow_mut().take() {
<span class="comment">// Replace old scheduler back into the state to allow
// other threads to pick it up and drive it.
</span><span class="self">self</span>.scheduler.core.set(core);
<span class="comment">// Wake up other possible threads that could steal the driver.
</span><span class="self">self</span>.scheduler.notify.notify_one()
}
}
}
</code></pre></div>
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