<!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 `/home/sangenya/.cargo/registry/src/github.com-1ecc6299db9ec823/crossbeam-channel-0.5.1/src/flavors/zero.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>zero.rs - source</title><link rel="stylesheet" type="text/css" href="../../../normalize.css"><link rel="stylesheet" type="text/css" href="../../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../../../light.css" id="themeStyle"><link rel="stylesheet" type="text/css" href="../../../dark.css" disabled ><link rel="stylesheet" type="text/css" href="../../../ayu.css" disabled ><script id="default-settings"></script><script src="../../../storage.js"></script><script src="../../../crates.js"></script><noscript><link rel="stylesheet" href="../../../noscript.css"></noscript><link rel="icon" type="image/svg+xml" href="../../../favicon.svg">
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</pre><pre class="rust">
<span class="doccomment">//! Zero-capacity channel.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! This kind of channel is also known as *rendezvous* channel.</span>
<span class="kw">use</span> <span class="ident">std::cell::UnsafeCell</span>;
<span class="kw">use</span> <span class="ident">std::marker::PhantomData</span>;
<span class="kw">use</span> <span class="ident">std::sync::atomic</span>::{<span class="ident">AtomicBool</span>, <span class="ident">Ordering</span>};
<span class="kw">use</span> <span class="ident">std::time::Instant</span>;
<span class="kw">use</span> <span class="ident">crossbeam_utils::Backoff</span>;
<span class="kw">use</span> <span class="kw">crate</span><span class="ident">::context::Context</span>;
<span class="kw">use</span> <span class="kw">crate</span><span class="ident">::err</span>::{<span class="ident">RecvTimeoutError</span>, <span class="ident">SendTimeoutError</span>, <span class="ident">TryRecvError</span>, <span class="ident">TrySendError</span>};
<span class="kw">use</span> <span class="kw">crate</span><span class="ident">::select</span>::{<span class="ident">Operation</span>, <span class="ident">SelectHandle</span>, <span class="ident">Selected</span>, <span class="ident">Token</span>};
<span class="kw">use</span> <span class="kw">crate</span><span class="ident">::utils::Spinlock</span>;
<span class="kw">use</span> <span class="kw">crate</span><span class="ident">::waker::Waker</span>;
<span class="doccomment">/// A pointer to a packet.</span>
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">type</span> <span class="ident">ZeroToken</span> <span class="op">=</span> <span class="ident">usize</span>;
<span class="doccomment">/// A slot for passing one message from a sender to a receiver.</span>
<span class="kw">struct</span> <span class="ident">Packet</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Equals `true` if the packet is allocated on the stack.</span>
<span class="ident">on_stack</span>: <span class="ident">bool</span>,
<span class="doccomment">/// Equals `true` once the packet is ready for reading or writing.</span>
<span class="ident">ready</span>: <span class="ident">AtomicBool</span>,
<span class="doccomment">/// The message.</span>
<span class="ident">msg</span>: <span class="ident">UnsafeCell</span><span class="op"><</span><span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">T</span><span class="op">></span><span class="op">></span>,
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">Packet</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Creates an empty packet on the stack.</span>
<span class="kw">fn</span> <span class="ident">empty_on_stack</span>() <span class="op">-</span><span class="op">></span> <span class="ident">Packet</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="ident">Packet</span> {
<span class="ident">on_stack</span>: <span class="bool-val">true</span>,
<span class="ident">ready</span>: <span class="ident">AtomicBool::new</span>(<span class="bool-val">false</span>),
<span class="ident">msg</span>: <span class="ident">UnsafeCell::new</span>(<span class="prelude-val">None</span>),
}
}
<span class="doccomment">/// Creates an empty packet on the heap.</span>
<span class="kw">fn</span> <span class="ident">empty_on_heap</span>() <span class="op">-</span><span class="op">></span> <span class="ident">Box</span><span class="op"><</span><span class="ident">Packet</span><span class="op"><</span><span class="ident">T</span><span class="op">></span><span class="op">></span> {
<span class="ident">Box::new</span>(<span class="ident">Packet</span> {
<span class="ident">on_stack</span>: <span class="bool-val">false</span>,
<span class="ident">ready</span>: <span class="ident">AtomicBool::new</span>(<span class="bool-val">false</span>),
<span class="ident">msg</span>: <span class="ident">UnsafeCell::new</span>(<span class="prelude-val">None</span>),
})
}
<span class="doccomment">/// Creates a packet on the stack, containing a message.</span>
<span class="kw">fn</span> <span class="ident">message_on_stack</span>(<span class="ident">msg</span>: <span class="ident">T</span>) <span class="op">-</span><span class="op">></span> <span class="ident">Packet</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="ident">Packet</span> {
<span class="ident">on_stack</span>: <span class="bool-val">true</span>,
<span class="ident">ready</span>: <span class="ident">AtomicBool::new</span>(<span class="bool-val">false</span>),
<span class="ident">msg</span>: <span class="ident">UnsafeCell::new</span>(<span class="prelude-val">Some</span>(<span class="ident">msg</span>)),
}
}
<span class="doccomment">/// Waits until the packet becomes ready for reading or writing.</span>
<span class="kw">fn</span> <span class="ident">wait_ready</span>(<span class="kw-2">&</span><span class="self">self</span>) {
<span class="kw">let</span> <span class="ident">backoff</span> <span class="op">=</span> <span class="ident">Backoff::new</span>();
<span class="kw">while</span> <span class="op">!</span><span class="self">self</span>.<span class="ident">ready</span>.<span class="ident">load</span>(<span class="ident">Ordering::Acquire</span>) {
<span class="ident">backoff</span>.<span class="ident">snooze</span>();
}
}
}
<span class="doccomment">/// Inner representation of a zero-capacity channel.</span>
<span class="kw">struct</span> <span class="ident">Inner</span> {
<span class="doccomment">/// Senders waiting to pair up with a receive operation.</span>
<span class="ident">senders</span>: <span class="ident">Waker</span>,
<span class="doccomment">/// Receivers waiting to pair up with a send operation.</span>
<span class="ident">receivers</span>: <span class="ident">Waker</span>,
<span class="doccomment">/// Equals `true` when the channel is disconnected.</span>
<span class="ident">is_disconnected</span>: <span class="ident">bool</span>,
}
<span class="doccomment">/// Zero-capacity channel.</span>
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">struct</span> <span class="ident">Channel</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Inner representation of the channel.</span>
<span class="ident">inner</span>: <span class="ident">Spinlock</span><span class="op"><</span><span class="ident">Inner</span><span class="op">></span>,
<span class="doccomment">/// Indicates that dropping a `Channel<T>` may drop values of type `T`.</span>
<span class="ident">_marker</span>: <span class="ident">PhantomData</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>,
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">Channel</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Constructs a new zero-capacity channel.</span>
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn</span> <span class="ident">new</span>() <span class="op">-</span><span class="op">></span> <span class="self">Self</span> {
<span class="ident">Channel</span> {
<span class="ident">inner</span>: <span class="ident">Spinlock::new</span>(<span class="ident">Inner</span> {
<span class="ident">senders</span>: <span class="ident">Waker::new</span>(),
<span class="ident">receivers</span>: <span class="ident">Waker::new</span>(),
<span class="ident">is_disconnected</span>: <span class="bool-val">false</span>,
}),
<span class="ident">_marker</span>: <span class="ident">PhantomData</span>,
}
}
<span class="doccomment">/// Returns a receiver handle to the channel.</span>
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn</span> <span class="ident">receiver</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">Receiver</span><span class="op"><</span><span class="lifetime">'_</span>, <span class="ident">T</span><span class="op">></span> {
<span class="ident">Receiver</span>(<span class="self">self</span>)
}
<span class="doccomment">/// Returns a sender handle to the channel.</span>
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn</span> <span class="ident">sender</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">Sender</span><span class="op"><</span><span class="lifetime">'_</span>, <span class="ident">T</span><span class="op">></span> {
<span class="ident">Sender</span>(<span class="self">self</span>)
}
<span class="doccomment">/// Attempts to reserve a slot for sending a message.</span>
<span class="kw">fn</span> <span class="ident">start_send</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">token</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">Token</span>) <span class="op">-</span><span class="op">></span> <span class="ident">bool</span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">inner</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">lock</span>();
<span class="comment">// If there's a waiting receiver, pair up with it.</span>
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">operation</span>) <span class="op">=</span> <span class="ident">inner</span>.<span class="ident">receivers</span>.<span class="ident">try_select</span>() {
<span class="ident">token</span>.<span class="ident">zero</span> <span class="op">=</span> <span class="ident">operation</span>.<span class="ident">packet</span>;
<span class="bool-val">true</span>
} <span class="kw">else</span> <span class="kw">if</span> <span class="ident">inner</span>.<span class="ident">is_disconnected</span> {
<span class="ident">token</span>.<span class="ident">zero</span> <span class="op">=</span> <span class="number">0</span>;
<span class="bool-val">true</span>
} <span class="kw">else</span> {
<span class="bool-val">false</span>
}
}
<span class="doccomment">/// Writes a message into the packet.</span>
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">write</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">token</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">Token</span>, <span class="ident">msg</span>: <span class="ident">T</span>) <span class="op">-</span><span class="op">></span> <span class="prelude-ty">Result</span><span class="op"><</span>(), <span class="ident">T</span><span class="op">></span> {
<span class="comment">// If there is no packet, the channel is disconnected.</span>
<span class="kw">if</span> <span class="ident">token</span>.<span class="ident">zero</span> <span class="op">=</span><span class="op">=</span> <span class="number">0</span> {
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">msg</span>);
}
<span class="kw">let</span> <span class="ident">packet</span> <span class="op">=</span> <span class="kw-2">&</span><span class="kw-2">*</span>(<span class="ident">token</span>.<span class="ident">zero</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw">const</span> <span class="ident">Packet</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>);
<span class="ident">packet</span>.<span class="ident">msg</span>.<span class="ident">get</span>().<span class="ident">write</span>(<span class="prelude-val">Some</span>(<span class="ident">msg</span>));
<span class="ident">packet</span>.<span class="ident">ready</span>.<span class="ident">store</span>(<span class="bool-val">true</span>, <span class="ident">Ordering::Release</span>);
<span class="prelude-val">Ok</span>(())
}
<span class="doccomment">/// Attempts to pair up with a sender.</span>
<span class="kw">fn</span> <span class="ident">start_recv</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">token</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">Token</span>) <span class="op">-</span><span class="op">></span> <span class="ident">bool</span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">inner</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">lock</span>();
<span class="comment">// If there's a waiting sender, pair up with it.</span>
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">operation</span>) <span class="op">=</span> <span class="ident">inner</span>.<span class="ident">senders</span>.<span class="ident">try_select</span>() {
<span class="ident">token</span>.<span class="ident">zero</span> <span class="op">=</span> <span class="ident">operation</span>.<span class="ident">packet</span>;
<span class="bool-val">true</span>
} <span class="kw">else</span> <span class="kw">if</span> <span class="ident">inner</span>.<span class="ident">is_disconnected</span> {
<span class="ident">token</span>.<span class="ident">zero</span> <span class="op">=</span> <span class="number">0</span>;
<span class="bool-val">true</span>
} <span class="kw">else</span> {
<span class="bool-val">false</span>
}
}
<span class="doccomment">/// Reads a message from the packet.</span>
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">read</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">token</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">Token</span>) <span class="op">-</span><span class="op">></span> <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">T</span>, ()<span class="op">></span> {
<span class="comment">// If there is no packet, the channel is disconnected.</span>
<span class="kw">if</span> <span class="ident">token</span>.<span class="ident">zero</span> <span class="op">=</span><span class="op">=</span> <span class="number">0</span> {
<span class="kw">return</span> <span class="prelude-val">Err</span>(());
}
<span class="kw">let</span> <span class="ident">packet</span> <span class="op">=</span> <span class="kw-2">&</span><span class="kw-2">*</span>(<span class="ident">token</span>.<span class="ident">zero</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw">const</span> <span class="ident">Packet</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>);
<span class="kw">if</span> <span class="ident">packet</span>.<span class="ident">on_stack</span> {
<span class="comment">// The message has been in the packet from the beginning, so there is no need to wait</span>
<span class="comment">// for it. However, after reading the message, we need to set `ready` to `true` in</span>
<span class="comment">// order to signal that the packet can be destroyed.</span>
<span class="kw">let</span> <span class="ident">msg</span> <span class="op">=</span> <span class="ident">packet</span>.<span class="ident">msg</span>.<span class="ident">get</span>().<span class="ident">replace</span>(<span class="prelude-val">None</span>).<span class="ident">unwrap</span>();
<span class="ident">packet</span>.<span class="ident">ready</span>.<span class="ident">store</span>(<span class="bool-val">true</span>, <span class="ident">Ordering::Release</span>);
<span class="prelude-val">Ok</span>(<span class="ident">msg</span>)
} <span class="kw">else</span> {
<span class="comment">// Wait until the message becomes available, then read it and destroy the</span>
<span class="comment">// heap-allocated packet.</span>
<span class="ident">packet</span>.<span class="ident">wait_ready</span>();
<span class="kw">let</span> <span class="ident">msg</span> <span class="op">=</span> <span class="ident">packet</span>.<span class="ident">msg</span>.<span class="ident">get</span>().<span class="ident">replace</span>(<span class="prelude-val">None</span>).<span class="ident">unwrap</span>();
<span class="ident">drop</span>(<span class="ident">Box::from_raw</span>(<span class="ident">packet</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw">const</span> <span class="ident">Packet</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">Packet</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>));
<span class="prelude-val">Ok</span>(<span class="ident">msg</span>)
}
}
<span class="doccomment">/// Attempts to send a message into the channel.</span>
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn</span> <span class="ident">try_send</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">msg</span>: <span class="ident">T</span>) <span class="op">-</span><span class="op">></span> <span class="prelude-ty">Result</span><span class="op"><</span>(), <span class="ident">TrySendError</span><span class="op"><</span><span class="ident">T</span><span class="op">></span><span class="op">></span> {
<span class="kw">let</span> <span class="ident">token</span> <span class="op">=</span> <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">Token::default</span>();
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">inner</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">lock</span>();
<span class="comment">// If there's a waiting receiver, pair up with it.</span>
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">operation</span>) <span class="op">=</span> <span class="ident">inner</span>.<span class="ident">receivers</span>.<span class="ident">try_select</span>() {
<span class="ident">token</span>.<span class="ident">zero</span> <span class="op">=</span> <span class="ident">operation</span>.<span class="ident">packet</span>;
<span class="ident">drop</span>(<span class="ident">inner</span>);
<span class="kw">unsafe</span> {
<span class="self">self</span>.<span class="ident">write</span>(<span class="ident">token</span>, <span class="ident">msg</span>).<span class="ident">ok</span>().<span class="ident">unwrap</span>();
}
<span class="prelude-val">Ok</span>(())
} <span class="kw">else</span> <span class="kw">if</span> <span class="ident">inner</span>.<span class="ident">is_disconnected</span> {
<span class="prelude-val">Err</span>(<span class="ident">TrySendError::Disconnected</span>(<span class="ident">msg</span>))
} <span class="kw">else</span> {
<span class="prelude-val">Err</span>(<span class="ident">TrySendError::Full</span>(<span class="ident">msg</span>))
}
}
<span class="doccomment">/// Sends a message into the channel.</span>
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn</span> <span class="ident">send</span>(
<span class="kw-2">&</span><span class="self">self</span>,
<span class="ident">msg</span>: <span class="ident">T</span>,
<span class="ident">deadline</span>: <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">Instant</span><span class="op">></span>,
) <span class="op">-</span><span class="op">></span> <span class="prelude-ty">Result</span><span class="op"><</span>(), <span class="ident">SendTimeoutError</span><span class="op"><</span><span class="ident">T</span><span class="op">></span><span class="op">></span> {
<span class="kw">let</span> <span class="ident">token</span> <span class="op">=</span> <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">Token::default</span>();
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">inner</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">lock</span>();
<span class="comment">// If there's a waiting receiver, pair up with it.</span>
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">operation</span>) <span class="op">=</span> <span class="ident">inner</span>.<span class="ident">receivers</span>.<span class="ident">try_select</span>() {
<span class="ident">token</span>.<span class="ident">zero</span> <span class="op">=</span> <span class="ident">operation</span>.<span class="ident">packet</span>;
<span class="ident">drop</span>(<span class="ident">inner</span>);
<span class="kw">unsafe</span> {
<span class="self">self</span>.<span class="ident">write</span>(<span class="ident">token</span>, <span class="ident">msg</span>).<span class="ident">ok</span>().<span class="ident">unwrap</span>();
}
<span class="kw">return</span> <span class="prelude-val">Ok</span>(());
}
<span class="kw">if</span> <span class="ident">inner</span>.<span class="ident">is_disconnected</span> {
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">SendTimeoutError::Disconnected</span>(<span class="ident">msg</span>));
}
<span class="ident">Context::with</span>(<span class="op">|</span><span class="ident">cx</span><span class="op">|</span> {
<span class="comment">// Prepare for blocking until a receiver wakes us up.</span>
<span class="kw">let</span> <span class="ident">oper</span> <span class="op">=</span> <span class="ident">Operation::hook</span>(<span class="ident">token</span>);
<span class="kw">let</span> <span class="ident">packet</span> <span class="op">=</span> <span class="ident">Packet</span>::<span class="op"><</span><span class="ident">T</span><span class="op">></span><span class="ident">::message_on_stack</span>(<span class="ident">msg</span>);
<span class="ident">inner</span>
.<span class="ident">senders</span>
.<span class="ident">register_with_packet</span>(<span class="ident">oper</span>, <span class="kw-2">&</span><span class="ident">packet</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw">const</span> <span class="ident">Packet</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="kw">as</span> <span class="ident">usize</span>, <span class="ident">cx</span>);
<span class="ident">inner</span>.<span class="ident">receivers</span>.<span class="ident">notify</span>();
<span class="ident">drop</span>(<span class="ident">inner</span>);
<span class="comment">// Block the current thread.</span>
<span class="kw">let</span> <span class="ident">sel</span> <span class="op">=</span> <span class="ident">cx</span>.<span class="ident">wait_until</span>(<span class="ident">deadline</span>);
<span class="kw">match</span> <span class="ident">sel</span> {
<span class="ident">Selected::Waiting</span> <span class="op">=</span><span class="op">></span> <span class="macro">unreachable!</span>(),
<span class="ident">Selected::Aborted</span> <span class="op">=</span><span class="op">></span> {
<span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">lock</span>().<span class="ident">senders</span>.<span class="ident">unregister</span>(<span class="ident">oper</span>).<span class="ident">unwrap</span>();
<span class="kw">let</span> <span class="ident">msg</span> <span class="op">=</span> <span class="kw">unsafe</span> { <span class="ident">packet</span>.<span class="ident">msg</span>.<span class="ident">get</span>().<span class="ident">replace</span>(<span class="prelude-val">None</span>).<span class="ident">unwrap</span>() };
<span class="prelude-val">Err</span>(<span class="ident">SendTimeoutError::Timeout</span>(<span class="ident">msg</span>))
}
<span class="ident">Selected::Disconnected</span> <span class="op">=</span><span class="op">></span> {
<span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">lock</span>().<span class="ident">senders</span>.<span class="ident">unregister</span>(<span class="ident">oper</span>).<span class="ident">unwrap</span>();
<span class="kw">let</span> <span class="ident">msg</span> <span class="op">=</span> <span class="kw">unsafe</span> { <span class="ident">packet</span>.<span class="ident">msg</span>.<span class="ident">get</span>().<span class="ident">replace</span>(<span class="prelude-val">None</span>).<span class="ident">unwrap</span>() };
<span class="prelude-val">Err</span>(<span class="ident">SendTimeoutError::Disconnected</span>(<span class="ident">msg</span>))
}
<span class="ident">Selected::Operation</span>(<span class="kw">_</span>) <span class="op">=</span><span class="op">></span> {
<span class="comment">// Wait until the message is read, then drop the packet.</span>
<span class="ident">packet</span>.<span class="ident">wait_ready</span>();
<span class="prelude-val">Ok</span>(())
}
}
})
}
<span class="doccomment">/// Attempts to receive a message without blocking.</span>
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn</span> <span class="ident">try_recv</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">T</span>, <span class="ident">TryRecvError</span><span class="op">></span> {
<span class="kw">let</span> <span class="ident">token</span> <span class="op">=</span> <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">Token::default</span>();
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">inner</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">lock</span>();
<span class="comment">// If there's a waiting sender, pair up with it.</span>
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">operation</span>) <span class="op">=</span> <span class="ident">inner</span>.<span class="ident">senders</span>.<span class="ident">try_select</span>() {
<span class="ident">token</span>.<span class="ident">zero</span> <span class="op">=</span> <span class="ident">operation</span>.<span class="ident">packet</span>;
<span class="ident">drop</span>(<span class="ident">inner</span>);
<span class="kw">unsafe</span> { <span class="self">self</span>.<span class="ident">read</span>(<span class="ident">token</span>).<span class="ident">map_err</span>(<span class="op">|</span><span class="kw">_</span><span class="op">|</span> <span class="ident">TryRecvError::Disconnected</span>) }
} <span class="kw">else</span> <span class="kw">if</span> <span class="ident">inner</span>.<span class="ident">is_disconnected</span> {
<span class="prelude-val">Err</span>(<span class="ident">TryRecvError::Disconnected</span>)
} <span class="kw">else</span> {
<span class="prelude-val">Err</span>(<span class="ident">TryRecvError::Empty</span>)
}
}
<span class="doccomment">/// Receives a message from the channel.</span>
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn</span> <span class="ident">recv</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">deadline</span>: <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">Instant</span><span class="op">></span>) <span class="op">-</span><span class="op">></span> <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">T</span>, <span class="ident">RecvTimeoutError</span><span class="op">></span> {
<span class="kw">let</span> <span class="ident">token</span> <span class="op">=</span> <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">Token::default</span>();
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">inner</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">lock</span>();
<span class="comment">// If there's a waiting sender, pair up with it.</span>
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">operation</span>) <span class="op">=</span> <span class="ident">inner</span>.<span class="ident">senders</span>.<span class="ident">try_select</span>() {
<span class="ident">token</span>.<span class="ident">zero</span> <span class="op">=</span> <span class="ident">operation</span>.<span class="ident">packet</span>;
<span class="ident">drop</span>(<span class="ident">inner</span>);
<span class="kw">unsafe</span> {
<span class="kw">return</span> <span class="self">self</span>.<span class="ident">read</span>(<span class="ident">token</span>).<span class="ident">map_err</span>(<span class="op">|</span><span class="kw">_</span><span class="op">|</span> <span class="ident">RecvTimeoutError::Disconnected</span>);
}
}
<span class="kw">if</span> <span class="ident">inner</span>.<span class="ident">is_disconnected</span> {
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">RecvTimeoutError::Disconnected</span>);
}
<span class="ident">Context::with</span>(<span class="op">|</span><span class="ident">cx</span><span class="op">|</span> {
<span class="comment">// Prepare for blocking until a sender wakes us up.</span>
<span class="kw">let</span> <span class="ident">oper</span> <span class="op">=</span> <span class="ident">Operation::hook</span>(<span class="ident">token</span>);
<span class="kw">let</span> <span class="ident">packet</span> <span class="op">=</span> <span class="ident">Packet</span>::<span class="op"><</span><span class="ident">T</span><span class="op">></span><span class="ident">::empty_on_stack</span>();
<span class="ident">inner</span>
.<span class="ident">receivers</span>
.<span class="ident">register_with_packet</span>(<span class="ident">oper</span>, <span class="kw-2">&</span><span class="ident">packet</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw">const</span> <span class="ident">Packet</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="kw">as</span> <span class="ident">usize</span>, <span class="ident">cx</span>);
<span class="ident">inner</span>.<span class="ident">senders</span>.<span class="ident">notify</span>();
<span class="ident">drop</span>(<span class="ident">inner</span>);
<span class="comment">// Block the current thread.</span>
<span class="kw">let</span> <span class="ident">sel</span> <span class="op">=</span> <span class="ident">cx</span>.<span class="ident">wait_until</span>(<span class="ident">deadline</span>);
<span class="kw">match</span> <span class="ident">sel</span> {
<span class="ident">Selected::Waiting</span> <span class="op">=</span><span class="op">></span> <span class="macro">unreachable!</span>(),
<span class="ident">Selected::Aborted</span> <span class="op">=</span><span class="op">></span> {
<span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">lock</span>().<span class="ident">receivers</span>.<span class="ident">unregister</span>(<span class="ident">oper</span>).<span class="ident">unwrap</span>();
<span class="prelude-val">Err</span>(<span class="ident">RecvTimeoutError::Timeout</span>)
}
<span class="ident">Selected::Disconnected</span> <span class="op">=</span><span class="op">></span> {
<span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">lock</span>().<span class="ident">receivers</span>.<span class="ident">unregister</span>(<span class="ident">oper</span>).<span class="ident">unwrap</span>();
<span class="prelude-val">Err</span>(<span class="ident">RecvTimeoutError::Disconnected</span>)
}
<span class="ident">Selected::Operation</span>(<span class="kw">_</span>) <span class="op">=</span><span class="op">></span> {
<span class="comment">// Wait until the message is provided, then read it.</span>
<span class="ident">packet</span>.<span class="ident">wait_ready</span>();
<span class="kw">unsafe</span> { <span class="prelude-val">Ok</span>(<span class="ident">packet</span>.<span class="ident">msg</span>.<span class="ident">get</span>().<span class="ident">replace</span>(<span class="prelude-val">None</span>).<span class="ident">unwrap</span>()) }
}
}
})
}
<span class="doccomment">/// Disconnects the channel and wakes up all blocked senders and receivers.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Returns `true` if this call disconnected the channel.</span>
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn</span> <span class="ident">disconnect</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">bool</span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">inner</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">lock</span>();
<span class="kw">if</span> <span class="op">!</span><span class="ident">inner</span>.<span class="ident">is_disconnected</span> {
<span class="ident">inner</span>.<span class="ident">is_disconnected</span> <span class="op">=</span> <span class="bool-val">true</span>;
<span class="ident">inner</span>.<span class="ident">senders</span>.<span class="ident">disconnect</span>();
<span class="ident">inner</span>.<span class="ident">receivers</span>.<span class="ident">disconnect</span>();
<span class="bool-val">true</span>
} <span class="kw">else</span> {
<span class="bool-val">false</span>
}
}
<span class="doccomment">/// Returns the current number of messages inside the channel.</span>
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn</span> <span class="ident">len</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">usize</span> {
<span class="number">0</span>
}
<span class="doccomment">/// Returns the capacity of the channel.</span>
<span class="attribute">#[<span class="ident">allow</span>(<span class="ident">clippy::unnecessary_wraps</span>)]</span> <span class="comment">// This is intentional.</span>
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn</span> <span class="ident">capacity</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span> {
<span class="prelude-val">Some</span>(<span class="number">0</span>)
}
<span class="doccomment">/// Returns `true` if the channel is empty.</span>
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn</span> <span class="ident">is_empty</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">bool</span> {
<span class="bool-val">true</span>
}
<span class="doccomment">/// Returns `true` if the channel is full.</span>
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn</span> <span class="ident">is_full</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">bool</span> {
<span class="bool-val">true</span>
}
}
<span class="doccomment">/// Receiver handle to a channel.</span>
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">struct</span> <span class="ident">Receiver</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">T</span><span class="op">></span>(<span class="kw-2">&</span><span class="lifetime">'a</span> <span class="ident">Channel</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>);
<span class="doccomment">/// Sender handle to a channel.</span>
<span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">struct</span> <span class="ident">Sender</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">T</span><span class="op">></span>(<span class="kw-2">&</span><span class="lifetime">'a</span> <span class="ident">Channel</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>);
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">SelectHandle</span> <span class="kw">for</span> <span class="ident">Receiver</span><span class="op"><</span><span class="lifetime">'_</span>, <span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">try_select</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">token</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">Token</span>) <span class="op">-</span><span class="op">></span> <span class="ident">bool</span> {
<span class="self">self</span>.<span class="number">0</span>.<span class="ident">start_recv</span>(<span class="ident">token</span>)
}
<span class="kw">fn</span> <span class="ident">deadline</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">Instant</span><span class="op">></span> {
<span class="prelude-val">None</span>
}
<span class="kw">fn</span> <span class="ident">register</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">oper</span>: <span class="ident">Operation</span>, <span class="ident">cx</span>: <span class="kw-2">&</span><span class="ident">Context</span>) <span class="op">-</span><span class="op">></span> <span class="ident">bool</span> {
<span class="kw">let</span> <span class="ident">packet</span> <span class="op">=</span> <span class="ident">Box::into_raw</span>(<span class="ident">Packet</span>::<span class="op"><</span><span class="ident">T</span><span class="op">></span><span class="ident">::empty_on_heap</span>());
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">inner</span> <span class="op">=</span> <span class="self">self</span>.<span class="number">0</span>.<span class="ident">inner</span>.<span class="ident">lock</span>();
<span class="ident">inner</span>
.<span class="ident">receivers</span>
.<span class="ident">register_with_packet</span>(<span class="ident">oper</span>, <span class="ident">packet</span> <span class="kw">as</span> <span class="ident">usize</span>, <span class="ident">cx</span>);
<span class="ident">inner</span>.<span class="ident">senders</span>.<span class="ident">notify</span>();
<span class="ident">inner</span>.<span class="ident">senders</span>.<span class="ident">can_select</span>() <span class="op">|</span><span class="op">|</span> <span class="ident">inner</span>.<span class="ident">is_disconnected</span>
}
<span class="kw">fn</span> <span class="ident">unregister</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">oper</span>: <span class="ident">Operation</span>) {
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">operation</span>) <span class="op">=</span> <span class="self">self</span>.<span class="number">0</span>.<span class="ident">inner</span>.<span class="ident">lock</span>().<span class="ident">receivers</span>.<span class="ident">unregister</span>(<span class="ident">oper</span>) {
<span class="kw">unsafe</span> {
<span class="ident">drop</span>(<span class="ident">Box::from_raw</span>(<span class="ident">operation</span>.<span class="ident">packet</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">Packet</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>));
}
}
}
<span class="kw">fn</span> <span class="ident">accept</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">token</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">Token</span>, <span class="ident">cx</span>: <span class="kw-2">&</span><span class="ident">Context</span>) <span class="op">-</span><span class="op">></span> <span class="ident">bool</span> {
<span class="ident">token</span>.<span class="ident">zero</span> <span class="op">=</span> <span class="ident">cx</span>.<span class="ident">wait_packet</span>();
<span class="bool-val">true</span>
}
<span class="kw">fn</span> <span class="ident">is_ready</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">bool</span> {
<span class="kw">let</span> <span class="ident">inner</span> <span class="op">=</span> <span class="self">self</span>.<span class="number">0</span>.<span class="ident">inner</span>.<span class="ident">lock</span>();
<span class="ident">inner</span>.<span class="ident">senders</span>.<span class="ident">can_select</span>() <span class="op">|</span><span class="op">|</span> <span class="ident">inner</span>.<span class="ident">is_disconnected</span>
}
<span class="kw">fn</span> <span class="ident">watch</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">oper</span>: <span class="ident">Operation</span>, <span class="ident">cx</span>: <span class="kw-2">&</span><span class="ident">Context</span>) <span class="op">-</span><span class="op">></span> <span class="ident">bool</span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">inner</span> <span class="op">=</span> <span class="self">self</span>.<span class="number">0</span>.<span class="ident">inner</span>.<span class="ident">lock</span>();
<span class="ident">inner</span>.<span class="ident">receivers</span>.<span class="ident">watch</span>(<span class="ident">oper</span>, <span class="ident">cx</span>);
<span class="ident">inner</span>.<span class="ident">senders</span>.<span class="ident">can_select</span>() <span class="op">|</span><span class="op">|</span> <span class="ident">inner</span>.<span class="ident">is_disconnected</span>
}
<span class="kw">fn</span> <span class="ident">unwatch</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">oper</span>: <span class="ident">Operation</span>) {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">inner</span> <span class="op">=</span> <span class="self">self</span>.<span class="number">0</span>.<span class="ident">inner</span>.<span class="ident">lock</span>();
<span class="ident">inner</span>.<span class="ident">receivers</span>.<span class="ident">unwatch</span>(<span class="ident">oper</span>);
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">SelectHandle</span> <span class="kw">for</span> <span class="ident">Sender</span><span class="op"><</span><span class="lifetime">'_</span>, <span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">try_select</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">token</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">Token</span>) <span class="op">-</span><span class="op">></span> <span class="ident">bool</span> {
<span class="self">self</span>.<span class="number">0</span>.<span class="ident">start_send</span>(<span class="ident">token</span>)
}
<span class="kw">fn</span> <span class="ident">deadline</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">Instant</span><span class="op">></span> {
<span class="prelude-val">None</span>
}
<span class="kw">fn</span> <span class="ident">register</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">oper</span>: <span class="ident">Operation</span>, <span class="ident">cx</span>: <span class="kw-2">&</span><span class="ident">Context</span>) <span class="op">-</span><span class="op">></span> <span class="ident">bool</span> {
<span class="kw">let</span> <span class="ident">packet</span> <span class="op">=</span> <span class="ident">Box::into_raw</span>(<span class="ident">Packet</span>::<span class="op"><</span><span class="ident">T</span><span class="op">></span><span class="ident">::empty_on_heap</span>());
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">inner</span> <span class="op">=</span> <span class="self">self</span>.<span class="number">0</span>.<span class="ident">inner</span>.<span class="ident">lock</span>();
<span class="ident">inner</span>
.<span class="ident">senders</span>
.<span class="ident">register_with_packet</span>(<span class="ident">oper</span>, <span class="ident">packet</span> <span class="kw">as</span> <span class="ident">usize</span>, <span class="ident">cx</span>);
<span class="ident">inner</span>.<span class="ident">receivers</span>.<span class="ident">notify</span>();
<span class="ident">inner</span>.<span class="ident">receivers</span>.<span class="ident">can_select</span>() <span class="op">|</span><span class="op">|</span> <span class="ident">inner</span>.<span class="ident">is_disconnected</span>
}
<span class="kw">fn</span> <span class="ident">unregister</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">oper</span>: <span class="ident">Operation</span>) {
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">operation</span>) <span class="op">=</span> <span class="self">self</span>.<span class="number">0</span>.<span class="ident">inner</span>.<span class="ident">lock</span>().<span class="ident">senders</span>.<span class="ident">unregister</span>(<span class="ident">oper</span>) {
<span class="kw">unsafe</span> {
<span class="ident">drop</span>(<span class="ident">Box::from_raw</span>(<span class="ident">operation</span>.<span class="ident">packet</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">Packet</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>));
}
}
}
<span class="kw">fn</span> <span class="ident">accept</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">token</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">Token</span>, <span class="ident">cx</span>: <span class="kw-2">&</span><span class="ident">Context</span>) <span class="op">-</span><span class="op">></span> <span class="ident">bool</span> {
<span class="ident">token</span>.<span class="ident">zero</span> <span class="op">=</span> <span class="ident">cx</span>.<span class="ident">wait_packet</span>();
<span class="bool-val">true</span>
}
<span class="kw">fn</span> <span class="ident">is_ready</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">bool</span> {
<span class="kw">let</span> <span class="ident">inner</span> <span class="op">=</span> <span class="self">self</span>.<span class="number">0</span>.<span class="ident">inner</span>.<span class="ident">lock</span>();
<span class="ident">inner</span>.<span class="ident">receivers</span>.<span class="ident">can_select</span>() <span class="op">|</span><span class="op">|</span> <span class="ident">inner</span>.<span class="ident">is_disconnected</span>
}
<span class="kw">fn</span> <span class="ident">watch</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">oper</span>: <span class="ident">Operation</span>, <span class="ident">cx</span>: <span class="kw-2">&</span><span class="ident">Context</span>) <span class="op">-</span><span class="op">></span> <span class="ident">bool</span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">inner</span> <span class="op">=</span> <span class="self">self</span>.<span class="number">0</span>.<span class="ident">inner</span>.<span class="ident">lock</span>();
<span class="ident">inner</span>.<span class="ident">senders</span>.<span class="ident">watch</span>(<span class="ident">oper</span>, <span class="ident">cx</span>);
<span class="ident">inner</span>.<span class="ident">receivers</span>.<span class="ident">can_select</span>() <span class="op">|</span><span class="op">|</span> <span class="ident">inner</span>.<span class="ident">is_disconnected</span>
}
<span class="kw">fn</span> <span class="ident">unwatch</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">oper</span>: <span class="ident">Operation</span>) {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">inner</span> <span class="op">=</span> <span class="self">self</span>.<span class="number">0</span>.<span class="ident">inner</span>.<span class="ident">lock</span>();
<span class="ident">inner</span>.<span class="ident">senders</span>.<span class="ident">unwatch</span>(<span class="ident">oper</span>);
}
}
</pre></div>
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