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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/runtime.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>runtime.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>::runtime::blocking::BlockingPool;
<span class="kw">use </span><span class="kw">crate</span>::runtime::scheduler::CurrentThread;
<span class="kw">use </span><span class="kw">crate</span>::runtime::{context, EnterGuard, Handle};
<span class="kw">use </span><span class="kw">crate</span>::task::JoinHandle;
<span class="kw">use </span>std::future::Future;
<span class="kw">use </span>std::time::Duration;
<span class="macro">cfg_rt_multi_thread! </span>{
<span class="kw">use </span><span class="kw">crate</span>::runtime::Builder;
<span class="kw">use </span><span class="kw">crate</span>::runtime::scheduler::MultiThread;
}
<span class="doccomment">/// The Tokio runtime.
///
/// The runtime provides an I/O driver, task scheduler, [timer], and
/// blocking pool, necessary for running asynchronous tasks.
///
/// Instances of `Runtime` can be created using [`new`], or [`Builder`].
/// However, most users will use the `#[tokio::main]` annotation on their
/// entry point instead.
///
/// See [module level][mod] documentation for more details.
///
/// # Shutdown
///
/// Shutting down the runtime is done by dropping the value. The current
/// thread will block until the shut down operation has completed.
///
/// * Drain any scheduled work queues.
/// * Drop any futures that have not yet completed.
/// * Drop the reactor.
///
/// Once the reactor has dropped, any outstanding I/O resources bound to
/// that reactor will no longer function. Calling any method on them will
/// result in an error.
///
/// # Sharing
///
/// The Tokio runtime implements `Sync` and `Send` to allow you to wrap it
/// in a `Arc`. Most fn take `&amp;self` to allow you to call them concurrently
/// across multiple threads.
///
/// Calls to `shutdown` and `shutdown_timeout` require exclusive ownership of
/// the runtime type and this can be achieved via `Arc::try_unwrap` when only
/// one strong count reference is left over.
///
/// [timer]: crate::time
/// [mod]: index.html
/// [`new`]: method@Self::new
/// [`Builder`]: struct@Builder
</span><span class="attribute">#[derive(Debug)]
</span><span class="kw">pub struct </span>Runtime {
<span class="doccomment">/// Task scheduler
</span>scheduler: Scheduler,
<span class="doccomment">/// Handle to runtime, also contains driver handles
</span>handle: Handle,
<span class="doccomment">/// Blocking pool handle, used to signal shutdown
</span>blocking_pool: BlockingPool,
}
<span class="doccomment">/// The flavor of a `Runtime`.
///
/// This is the return type for [`Handle::runtime_flavor`](crate::runtime::Handle::runtime_flavor()).
</span><span class="attribute">#[derive(Debug, PartialEq, Eq)]
#[non_exhaustive]
</span><span class="kw">pub enum </span>RuntimeFlavor {
<span class="doccomment">/// The flavor that executes all tasks on the current thread.
</span>CurrentThread,
<span class="doccomment">/// The flavor that executes tasks across multiple threads.
</span>MultiThread,
}
<span class="doccomment">/// The runtime scheduler is either a multi-thread or a current-thread executor.
</span><span class="attribute">#[derive(Debug)]
</span><span class="kw">pub</span>(<span class="kw">super</span>) <span class="kw">enum </span>Scheduler {
<span class="doccomment">/// Execute all tasks on the current-thread.
</span>CurrentThread(CurrentThread),
<span class="doccomment">/// Execute tasks across multiple threads.
</span><span class="attribute">#[cfg(all(feature = <span class="string">&quot;rt-multi-thread&quot;</span>, not(tokio_wasi)))]
</span>MultiThread(MultiThread),
}
<span class="kw">impl </span>Runtime {
<span class="kw">pub</span>(<span class="kw">super</span>) <span class="kw">fn </span>from_parts(
scheduler: Scheduler,
handle: Handle,
blocking_pool: BlockingPool,
) -&gt; Runtime {
Runtime {
scheduler,
handle,
blocking_pool,
}
}
<span class="macro">cfg_not_wasi! </span>{
<span class="doccomment">/// Creates a new runtime instance with default configuration values.
///
/// This results in the multi threaded scheduler, I/O driver, and time driver being
/// initialized.
///
/// Most applications will not need to call this function directly. Instead,
/// they will use the [`#[tokio::main]` attribute][main]. When a more complex
/// configuration is necessary, the [runtime builder] may be used.
///
/// See [module level][mod] documentation for more details.
///
/// # Examples
///
/// Creating a new `Runtime` with default configuration values.
///
/// ```
/// use tokio::runtime::Runtime;
///
/// let rt = Runtime::new()
/// .unwrap();
///
/// // Use the runtime...
/// ```
///
/// [mod]: index.html
/// [main]: ../attr.main.html
/// [threaded scheduler]: index.html#threaded-scheduler
/// [runtime builder]: crate::runtime::Builder
</span><span class="attribute">#[cfg(feature = <span class="string">&quot;rt-multi-thread&quot;</span>)]
#[cfg_attr(docsrs, doc(cfg(feature = <span class="string">&quot;rt-multi-thread&quot;</span>)))]
</span><span class="kw">pub fn </span>new() -&gt; std::io::Result&lt;Runtime&gt; {
Builder::new_multi_thread().enable_all().build()
}
}
<span class="doccomment">/// Returns a handle to the runtime&#39;s spawner.
///
/// The returned handle can be used to spawn tasks that run on this runtime, and can
/// be cloned to allow moving the `Handle` to other threads.
///
/// Calling [`Handle::block_on`] on a handle to a `current_thread` runtime is error-prone.
/// Refer to the documentation of [`Handle::block_on`] for more.
///
/// # Examples
///
/// ```
/// use tokio::runtime::Runtime;
///
/// let rt = Runtime::new()
/// .unwrap();
///
/// let handle = rt.handle();
///
/// // Use the handle...
/// ```
</span><span class="kw">pub fn </span>handle(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; <span class="kw-2">&amp;</span>Handle {
<span class="kw-2">&amp;</span><span class="self">self</span>.handle
}
<span class="doccomment">/// Spawns a future onto the Tokio runtime.
///
/// This spawns the given future onto the runtime&#39;s executor, usually a
/// thread pool. The thread pool is then responsible for polling the future
/// until it completes.
///
/// You do not have to `.await` the returned `JoinHandle` to make the
/// provided future start execution. It will start running in the
/// background immediately when `spawn` is called.
///
/// See [module level][mod] documentation for more details.
///
/// [mod]: index.html
///
/// # Examples
///
/// ```
/// use tokio::runtime::Runtime;
///
/// # fn dox() {
/// // Create the runtime
/// let rt = Runtime::new().unwrap();
///
/// // Spawn a future onto the runtime
/// rt.spawn(async {
/// println!(&quot;now running on a worker thread&quot;);
/// });
/// # }
/// ```
</span><span class="attribute">#[track_caller]
</span><span class="kw">pub fn </span>spawn&lt;F&gt;(<span class="kw-2">&amp;</span><span class="self">self</span>, future: F) -&gt; JoinHandle&lt;F::Output&gt;
<span class="kw">where
</span>F: Future + Send + <span class="lifetime">&#39;static</span>,
F::Output: Send + <span class="lifetime">&#39;static</span>,
{
<span class="self">self</span>.handle.spawn(future)
}
<span class="doccomment">/// Runs the provided function on an executor dedicated to blocking operations.
///
/// # Examples
///
/// ```
/// use tokio::runtime::Runtime;
///
/// # fn dox() {
/// // Create the runtime
/// let rt = Runtime::new().unwrap();
///
/// // Spawn a blocking function onto the runtime
/// rt.spawn_blocking(|| {
/// println!(&quot;now running on a worker thread&quot;);
/// });
/// # }
</span><span class="attribute">#[track_caller]
</span><span class="kw">pub fn </span>spawn_blocking&lt;F, R&gt;(<span class="kw-2">&amp;</span><span class="self">self</span>, func: F) -&gt; JoinHandle&lt;R&gt;
<span class="kw">where
</span>F: FnOnce() -&gt; R + Send + <span class="lifetime">&#39;static</span>,
R: Send + <span class="lifetime">&#39;static</span>,
{
<span class="self">self</span>.handle.spawn_blocking(func)
}
<span class="doccomment">/// Runs a future to completion on the Tokio runtime. This is the
/// runtime&#39;s entry point.
///
/// This runs the given future on the current thread, blocking until it is
/// complete, and yielding its resolved result. Any tasks or timers
/// which the future spawns internally will be executed on the runtime.
///
/// # Multi thread scheduler
///
/// When the multi thread scheduler is used this will allow futures
/// to run within the io driver and timer context of the overall runtime.
///
/// Any spawned tasks will continue running after `block_on` returns.
///
/// # Current thread scheduler
///
/// When the current thread scheduler is enabled `block_on`
/// can be called concurrently from multiple threads. The first call
/// will take ownership of the io and timer drivers. This means
/// other threads which do not own the drivers will hook into that one.
/// When the first `block_on` completes, other threads will be able to
/// &quot;steal&quot; the driver to allow continued execution of their futures.
///
/// Any spawned tasks will be suspended after `block_on` returns. Calling
/// `block_on` again will resume previously spawned tasks.
///
/// # Panics
///
/// This function panics if the provided future panics, or if called within an
/// asynchronous execution context.
///
/// # Examples
///
/// ```no_run
/// use tokio::runtime::Runtime;
///
/// // Create the runtime
/// let rt = Runtime::new().unwrap();
///
/// // Execute the future, blocking the current thread until completion
/// rt.block_on(async {
/// println!(&quot;hello&quot;);
/// });
/// ```
///
/// [handle]: fn@Handle::block_on
</span><span class="attribute">#[track_caller]
</span><span class="kw">pub fn </span>block_on&lt;F: Future&gt;(<span class="kw-2">&amp;</span><span class="self">self</span>, future: F) -&gt; F::Output {
<span class="attribute">#[cfg(all(tokio_unstable, feature = <span class="string">&quot;tracing&quot;</span>))]
</span><span class="kw">let </span>future = <span class="kw">crate</span>::util::trace::task(
future,
<span class="string">&quot;block_on&quot;</span>,
<span class="prelude-val">None</span>,
<span class="kw">crate</span>::runtime::task::Id::next().as_u64(),
);
<span class="kw">let </span>_enter = <span class="self">self</span>.enter();
<span class="kw">match </span><span class="kw-2">&amp;</span><span class="self">self</span>.scheduler {
Scheduler::CurrentThread(exec) =&gt; exec.block_on(<span class="kw-2">&amp;</span><span class="self">self</span>.handle.inner, future),
<span class="attribute">#[cfg(all(feature = <span class="string">&quot;rt-multi-thread&quot;</span>, not(tokio_wasi)))]
</span>Scheduler::MultiThread(exec) =&gt; exec.block_on(<span class="kw-2">&amp;</span><span class="self">self</span>.handle.inner, future),
}
}
<span class="doccomment">/// Enters the runtime context.
///
/// This allows you to construct types that must have an executor
/// available on creation such as [`Sleep`] or [`TcpStream`]. It will
/// also allow you to call methods such as [`tokio::spawn`].
///
/// [`Sleep`]: struct@crate::time::Sleep
/// [`TcpStream`]: struct@crate::net::TcpStream
/// [`tokio::spawn`]: fn@crate::spawn
///
/// # Example
///
/// ```
/// use tokio::runtime::Runtime;
///
/// fn function_that_spawns(msg: String) {
/// // Had we not used `rt.enter` below, this would panic.
/// tokio::spawn(async move {
/// println!(&quot;{}&quot;, msg);
/// });
/// }
///
/// fn main() {
/// let rt = Runtime::new().unwrap();
///
/// let s = &quot;Hello World!&quot;.to_string();
///
/// // By entering the context, we tie `tokio::spawn` to this executor.
/// let _guard = rt.enter();
/// function_that_spawns(s);
/// }
/// ```
</span><span class="kw">pub fn </span>enter(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; EnterGuard&lt;<span class="lifetime">&#39;_</span>&gt; {
<span class="self">self</span>.handle.enter()
}
<span class="doccomment">/// Shuts down the runtime, waiting for at most `duration` for all spawned
/// task to shutdown.
///
/// Usually, dropping a `Runtime` handle is sufficient as tasks are able to
/// shutdown in a timely fashion. However, dropping a `Runtime` will wait
/// indefinitely for all tasks to terminate, and there are cases where a long
/// blocking task has been spawned, which can block dropping `Runtime`.
///
/// In this case, calling `shutdown_timeout` with an explicit wait timeout
/// can work. The `shutdown_timeout` will signal all tasks to shutdown and
/// will wait for at most `duration` for all spawned tasks to terminate. If
/// `timeout` elapses before all tasks are dropped, the function returns and
/// outstanding tasks are potentially leaked.
///
/// # Examples
///
/// ```
/// use tokio::runtime::Runtime;
/// use tokio::task;
///
/// use std::thread;
/// use std::time::Duration;
///
/// fn main() {
/// let runtime = Runtime::new().unwrap();
///
/// runtime.block_on(async move {
/// task::spawn_blocking(move || {
/// thread::sleep(Duration::from_secs(10_000));
/// });
/// });
///
/// runtime.shutdown_timeout(Duration::from_millis(100));
/// }
/// ```
</span><span class="kw">pub fn </span>shutdown_timeout(<span class="kw-2">mut </span><span class="self">self</span>, duration: Duration) {
<span class="comment">// Wakeup and shutdown all the worker threads
</span><span class="self">self</span>.handle.inner.shutdown();
<span class="self">self</span>.blocking_pool.shutdown(<span class="prelude-val">Some</span>(duration));
}
<span class="doccomment">/// Shuts down the runtime, without waiting for any spawned tasks to shutdown.
///
/// This can be useful if you want to drop a runtime from within another runtime.
/// Normally, dropping a runtime will block indefinitely for spawned blocking tasks
/// to complete, which would normally not be permitted within an asynchronous context.
/// By calling `shutdown_background()`, you can drop the runtime from such a context.
///
/// Note however, that because we do not wait for any blocking tasks to complete, this
/// may result in a resource leak (in that any blocking tasks are still running until they
/// return.
///
/// This function is equivalent to calling `shutdown_timeout(Duration::from_nanos(0))`.
///
/// ```
/// use tokio::runtime::Runtime;
///
/// fn main() {
/// let runtime = Runtime::new().unwrap();
///
/// runtime.block_on(async move {
/// let inner_runtime = Runtime::new().unwrap();
/// // ...
/// inner_runtime.shutdown_background();
/// });
/// }
/// ```
</span><span class="kw">pub fn </span>shutdown_background(<span class="self">self</span>) {
<span class="self">self</span>.shutdown_timeout(Duration::from_nanos(<span class="number">0</span>))
}
}
<span class="attribute">#[allow(clippy::single_match)] </span><span class="comment">// there are comments in the error branch, so we don&#39;t want if-let
</span><span class="kw">impl </span>Drop <span class="kw">for </span>Runtime {
<span class="kw">fn </span>drop(<span class="kw-2">&amp;mut </span><span class="self">self</span>) {
<span class="kw">match </span><span class="kw-2">&amp;mut </span><span class="self">self</span>.scheduler {
Scheduler::CurrentThread(current_thread) =&gt; {
<span class="comment">// This ensures that tasks spawned on the current-thread
// runtime are dropped inside the runtime&#39;s context.
</span><span class="kw">let </span>_guard = context::try_set_current(<span class="kw-2">&amp;</span><span class="self">self</span>.handle.inner);
current_thread.shutdown(<span class="kw-2">&amp;</span><span class="self">self</span>.handle.inner);
}
<span class="attribute">#[cfg(all(feature = <span class="string">&quot;rt-multi-thread&quot;</span>, not(tokio_wasi)))]
</span>Scheduler::MultiThread(multi_thread) =&gt; {
<span class="comment">// The threaded scheduler drops its tasks on its worker threads, which is
// already in the runtime&#39;s context.
</span>multi_thread.shutdown(<span class="kw-2">&amp;</span><span class="self">self</span>.handle.inner);
}
}
}
}
<span class="macro">cfg_metrics! </span>{
<span class="kw">impl </span>Runtime {
<span class="doccomment">/// TODO
</span><span class="kw">pub fn </span>metrics(<span class="kw-2">&amp;</span><span class="self">self</span>) -&gt; <span class="kw">crate</span>::runtime::RuntimeMetrics {
<span class="self">self</span>.handle.metrics()
}
}
}
</code></pre></div>
</section></div></main><div id="rustdoc-vars" data-root-path="../../../" data-current-crate="tokio" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html>