mentat/tokio_executor/park/index.html

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<title>tokio_executor::park - Rust</title>
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<p class='location'>Module park</p><div class="sidebar-elems"><div class="block items"><ul><li><a href="#structs">Structs</a></li><li><a href="#traits">Traits</a></li></ul></div><p class='location'><a href='../index.html'>tokio_executor</a></p><script>window.sidebarCurrent = {name: 'park', ty: 'mod', relpath: '../'};</script><script defer src="../sidebar-items.js"></script></div>
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<h1 class='fqn'><span class='in-band'>Module <a href='../index.html'>tokio_executor</a>::<wbr><a class="mod" href=''>park</a></span><span class='out-of-band'><span id='render-detail'>
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[<span class='inner'>&#x2212;</span>]
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</span><a class='srclink' href='../../src/tokio_executor/park.rs.html#1-302' title='goto source code'>[src]</a></span></h1>
<div class='docblock'><p>Abstraction over blocking and unblocking the current thread.</p>
<p>Provides an abstraction over blocking the current thread. This is similar to
the park / unpark constructs provided by <a href="https://doc.rust-lang.org/std/thread/fn.park.html"><code>std</code></a> but made generic. This
allows embedding custom functionality to perform when the thread is blocked.</p>
<p>A blocked <a href="trait.Park.html"><code>Park</code></a> instance is unblocked by calling <a href="trait.Unpark.html#tymethod.unpark"><code>unpark</code></a> on its
<a href="trait.Unpark.html"><code>Unpark</code></a> handle.</p>
<p>The <a href="struct.ParkThread.html"><code>ParkThread</code></a> struct implements <a href="trait.Park.html"><code>Park</code></a> using
<a href="https://doc.rust-lang.org/std/thread/fn.park.html"><code>thread::park</code></a> to put the thread to sleep. The Tokio reactor also
implements park, but uses <a href="https://docs.rs/mio/0.6/mio/struct.Poll.html"><code>mio::Poll</code></a> to block the thread instead.</p>
<p>The <a href="trait.Park.html"><code>Park</code></a> trait is composable. A timer implementation might decorate a
<a href="trait.Park.html"><code>Park</code></a> implementation by checking if any timeouts have elapsed after
the inner <a href="trait.Park.html"><code>Park</code></a> implementation unblocks.</p>
<h1 id="model" class="section-header"><a href="#model">Model</a></h1>
<p>Conceptually, each <a href="trait.Park.html"><code>Park</code></a> instance has an associated token, which is
initially not present:</p>
<ul>
<li>The <a href="trait.Park.html#tymethod.park"><code>park</code></a> method blocks the current thread unless or until the token
is available, at which point it atomically consumes the token.</li>
<li>The <a href="trait.Unpark.html#tymethod.unpark"><code>unpark</code></a> method atomically makes the token available if it wasn't
already.</li>
</ul>
<p>Some things to note:</p>
<ul>
<li>If <a href="trait.Unpark.html#tymethod.unpark"><code>unpark</code></a> is called before <a href="trait.Park.html#tymethod.park"><code>park</code></a>, the next call to <a href="trait.Park.html#tymethod.park"><code>park</code></a> will
<strong>not</strong> block the thread.</li>
<li><strong>Spurious</strong> wakeups are permitted, i.e., the <a href="trait.Park.html#tymethod.park"><code>park</code></a> method may unblock
even if <a href="trait.Unpark.html#tymethod.unpark"><code>unpark</code></a> was not called.</li>
<li><a href="trait.Park.html#tymethod.park_timeout"><code>park_timeout</code></a> does the same as <a href="trait.Park.html#tymethod.park"><code>park</code></a> but allows specifying a maximum
time to block the thread for.</li>
</ul>
</div><h2 id='structs' class='section-header'><a href="#structs">Structs</a></h2>
<table>
<tr class=' module-item'>
<td><a class="struct" href="struct.ParkError.html"
title='struct tokio_executor::park::ParkError'>ParkError</a></td>
<td class='docblock-short'>
<p>Error returned by <a href="struct.ParkThread.html"><code>ParkThread</code></a></p>
</td>
</tr>
<tr class=' module-item'>
<td><a class="struct" href="struct.ParkThread.html"
title='struct tokio_executor::park::ParkThread'>ParkThread</a></td>
<td class='docblock-short'>
<p>Blocks the current thread using a condition variable.</p>
</td>
</tr>
<tr class=' module-item'>
<td><a class="struct" href="struct.UnparkThread.html"
title='struct tokio_executor::park::UnparkThread'>UnparkThread</a></td>
<td class='docblock-short'>
<p>Unblocks a thread that was blocked by <code>ParkThread</code>.</p>
</td>
</tr></table><h2 id='traits' class='section-header'><a href="#traits">Traits</a></h2>
<table>
<tr class=' module-item'>
<td><a class="trait" href="trait.Park.html"
title='trait tokio_executor::park::Park'>Park</a></td>
<td class='docblock-short'>
<p>Block the current thread.</p>
</td>
</tr>
<tr class=' module-item'>
<td><a class="trait" href="trait.Unpark.html"
title='trait tokio_executor::park::Unpark'>Unpark</a></td>
<td class='docblock-short'>
<p>Unblock a thread blocked by the associated <a href="trait.Park.html"><code>Park</code></a> instance.</p>
</td>
</tr></table></section>
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