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</pre><div class="example-wrap"><pre class="rust ">
<span class="doccomment">//! Selection over an array of receivers</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! This module contains the implementation machinery necessary for selecting</span>
<span class="doccomment">//! over a number of receivers. One large goal of this module is to provide an</span>
<span class="doccomment">//! efficient interface to selecting over any receiver of any type.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! This is achieved through an architecture of a "receiver set" in which</span>
<span class="doccomment">//! receivers are added to a set and then the entire set is waited on at once.</span>
<span class="doccomment">//! The set can be waited on multiple times to prevent re-adding each receiver</span>
<span class="doccomment">//! to the set.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! Usage of this module is currently encouraged to go through the use of the</span>
<span class="doccomment">//! `select!` macro. This macro allows naturally binding of variables to the</span>
<span class="doccomment">//! received values of receivers in a much more natural syntax then usage of the</span>
<span class="doccomment">//! `Select` structure directly.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! # Examples</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! ```rust</span>
<span class="doccomment">//! #![feature(mpsc_select)]</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! use std::sync::mpsc::channel;</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! let (tx1, rx1) = channel();</span>
<span class="doccomment">//! let (tx2, rx2) = channel();</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! tx1.send(1).unwrap();</span>
<span class="doccomment">//! tx2.send(2).unwrap();</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! select! {</span>
<span class="doccomment">//! val = rx1.recv() => {</span>
<span class="doccomment">//! assert_eq!(val.unwrap(), 1);</span>
<span class="doccomment">//! },</span>
<span class="doccomment">//! val = rx2.recv() => {</span>
<span class="doccomment">//! assert_eq!(val.unwrap(), 2);</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//! }</span>
<span class="doccomment">//! ```</span>
<span class="attribute">#![<span class="ident">allow</span>(<span class="ident">dead_code</span>)]</span>
<span class="attribute">#![<span class="ident">unstable</span>(<span class="ident">feature</span> <span class="op">=</span> <span class="string">"mpsc_select"</span>,
<span class="ident">reason</span> <span class="op">=</span> <span class="string">"This implementation, while likely sufficient, is unsafe and \
likely to be error prone. At some point in the future this \
module will be removed."</span>,
<span class="ident">issue</span> <span class="op">=</span> <span class="string">"27800"</span>)]</span>
<span class="attribute">#![<span class="ident">rustc_deprecated</span>(<span class="ident">since</span> <span class="op">=</span> <span class="string">"1.32.0"</span>,
<span class="ident">reason</span> <span class="op">=</span> <span class="string">"channel selection will be removed in a future release"</span>)]</span>
<span class="kw">use</span> <span class="ident">core</span>::<span class="ident">cell</span>::{<span class="ident">Cell</span>, <span class="ident">UnsafeCell</span>};
<span class="kw">use</span> <span class="ident">core</span>::<span class="ident">marker</span>;
<span class="kw">use</span> <span class="ident">core</span>::<span class="ident">ptr</span>;
<span class="kw">use</span> <span class="ident">core</span>::<span class="ident">usize</span>;
<span class="kw">use</span> <span class="kw">crate</span>::<span class="ident">fmt</span>;
<span class="kw">use</span> <span class="kw">crate</span>::<span class="ident">sync</span>::<span class="ident">mpsc</span>::{<span class="ident">Receiver</span>, <span class="ident">RecvError</span>};
<span class="kw">use</span> <span class="kw">crate</span>::<span class="ident">sync</span>::<span class="ident">mpsc</span>::<span class="ident">blocking</span>::{<span class="self">self</span>, <span class="ident">SignalToken</span>};
<span class="doccomment">/// The "receiver set" of the select interface. This structure is used to manage</span>
<span class="doccomment">/// a set of receivers which are being selected over.</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Select</span> {
<span class="ident">inner</span>: <span class="ident">UnsafeCell</span><span class="op"><</span><span class="ident">SelectInner</span><span class="op">></span>,
<span class="ident">next_id</span>: <span class="ident">Cell</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>,
}
<span class="kw">struct</span> <span class="ident">SelectInner</span> {
<span class="ident">head</span>: <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">Handle</span><span class="op"><</span><span class="lifetime">'static</span>, ()<span class="op">></span>,
<span class="ident">tail</span>: <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">Handle</span><span class="op"><</span><span class="lifetime">'static</span>, ()<span class="op">></span>,
}
<span class="kw">impl</span> <span class="op">!</span><span class="ident">marker</span>::<span class="ident">Send</span> <span class="kw">for</span> <span class="ident">Select</span> {}
<span class="doccomment">/// A handle to a receiver which is currently a member of a `Select` set of</span>
<span class="doccomment">/// receivers. This handle is used to keep the receiver in the set as well as</span>
<span class="doccomment">/// interact with the underlying receiver.</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Handle</span><span class="op"><</span><span class="lifetime">'rx</span>, <span class="ident">T</span>:<span class="ident">Send</span><span class="op">+</span><span class="lifetime">'rx</span><span class="op">></span> {
<span class="doccomment">/// The ID of this handle, used to compare against the return value of</span>
<span class="doccomment">/// `Select::wait()`.</span>
<span class="ident">id</span>: <span class="ident">usize</span>,
<span class="ident">selector</span>: <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">SelectInner</span>,
<span class="ident">next</span>: <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">Handle</span><span class="op"><</span><span class="lifetime">'static</span>, ()<span class="op">></span>,
<span class="ident">prev</span>: <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">Handle</span><span class="op"><</span><span class="lifetime">'static</span>, ()<span class="op">></span>,
<span class="ident">added</span>: <span class="ident">bool</span>,
<span class="ident">packet</span>: <span class="kw-2">&</span><span class="lifetime">'rx</span> (<span class="kw">dyn</span> <span class="ident">Packet</span><span class="op">+</span><span class="lifetime">'rx</span>),
<span class="comment">// due to our fun transmutes, we be sure to place this at the end. (nothing</span>
<span class="comment">// previous relies on T)</span>
<span class="ident">rx</span>: <span class="kw-2">&</span><span class="lifetime">'rx</span> <span class="ident">Receiver</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>,
}
<span class="kw">struct</span> <span class="ident">Packets</span> { <span class="ident">cur</span>: <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">Handle</span><span class="op"><</span><span class="lifetime">'static</span>, ()<span class="op">></span> }
<span class="attribute">#[<span class="ident">doc</span>(<span class="ident">hidden</span>)]</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">PartialEq</span>, <span class="ident">Eq</span>)]</span>
<span class="kw">pub</span> <span class="kw">enum</span> <span class="ident">StartResult</span> {
<span class="ident">Installed</span>,
<span class="ident">Abort</span>,
}
<span class="attribute">#[<span class="ident">doc</span>(<span class="ident">hidden</span>)]</span>
<span class="kw">pub</span> <span class="kw">trait</span> <span class="ident">Packet</span> {
<span class="kw">fn</span> <span class="ident">can_recv</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">bool</span>;
<span class="kw">fn</span> <span class="ident">start_selection</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">token</span>: <span class="ident">SignalToken</span>) <span class="op">-></span> <span class="ident">StartResult</span>;
<span class="kw">fn</span> <span class="ident">abort_selection</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">bool</span>;
}
<span class="kw">impl</span> <span class="ident">Select</span> {
<span class="doccomment">/// Creates a new selection structure. This set is initially empty.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Usage of this struct directly can sometimes be burdensome, and usage is much easier through</span>
<span class="doccomment">/// the `select!` macro.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// #![feature(mpsc_select)]</span>
<span class="doccomment">///</span>
<span class="doccomment">/// use std::sync::mpsc::Select;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let select = Select::new();</span>
<span class="doccomment">/// ```</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">new</span>() <span class="op">-></span> <span class="ident">Select</span> {
<span class="ident">Select</span> {
<span class="ident">inner</span>: <span class="ident">UnsafeCell</span>::<span class="ident">new</span>(<span class="ident">SelectInner</span> {
<span class="ident">head</span>: <span class="ident">ptr</span>::<span class="ident">null_mut</span>(),
<span class="ident">tail</span>: <span class="ident">ptr</span>::<span class="ident">null_mut</span>(),
}),
<span class="ident">next_id</span>: <span class="ident">Cell</span>::<span class="ident">new</span>(<span class="number">1</span>),
}
}
<span class="doccomment">/// Creates a new handle into this receiver set for a new receiver. Note</span>
<span class="doccomment">/// that this does *not* add the receiver to the receiver set, for that you</span>
<span class="doccomment">/// must call the `add` method on the handle itself.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">handle</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">T</span>: <span class="ident">Send</span><span class="op">></span>(<span class="kw-2">&</span><span class="lifetime">'a</span> <span class="self">self</span>, <span class="ident">rx</span>: <span class="kw-2">&</span><span class="lifetime">'a</span> <span class="ident">Receiver</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>) <span class="op">-></span> <span class="ident">Handle</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">T</span><span class="op">></span> {
<span class="kw">let</span> <span class="ident">id</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">next_id</span>.<span class="ident">get</span>();
<span class="self">self</span>.<span class="ident">next_id</span>.<span class="ident">set</span>(<span class="ident">id</span> <span class="op">+</span> <span class="number">1</span>);
<span class="ident">Handle</span> {
<span class="ident">id</span>,
<span class="ident">selector</span>: <span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">get</span>(),
<span class="ident">next</span>: <span class="ident">ptr</span>::<span class="ident">null_mut</span>(),
<span class="ident">prev</span>: <span class="ident">ptr</span>::<span class="ident">null_mut</span>(),
<span class="ident">added</span>: <span class="bool-val">false</span>,
<span class="ident">rx</span>,
<span class="ident">packet</span>: <span class="ident">rx</span>,
}
}
<span class="doccomment">/// Waits for an event on this receiver set. The returned value is *not* an</span>
<span class="doccomment">/// index, but rather an ID. This ID can be queried against any active</span>
<span class="doccomment">/// `Handle` structures (each one has an `id` method). The handle with</span>
<span class="doccomment">/// the matching `id` will have some sort of event available on it. The</span>
<span class="doccomment">/// event could either be that data is available or the corresponding</span>
<span class="doccomment">/// channel has been closed.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">wait</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">usize</span> {
<span class="self">self</span>.<span class="ident">wait2</span>(<span class="bool-val">true</span>)
}
<span class="doccomment">/// Helper method for skipping the preflight checks during testing</span>
<span class="kw">pub</span>(<span class="kw">super</span>) <span class="kw">fn</span> <span class="ident">wait2</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">do_preflight_checks</span>: <span class="ident">bool</span>) <span class="op">-></span> <span class="ident">usize</span> {
<span class="comment">// Note that this is currently an inefficient implementation. We in</span>
<span class="comment">// theory have knowledge about all receivers in the set ahead of time,</span>
<span class="comment">// so this method shouldn't really have to iterate over all of them yet</span>
<span class="comment">// again. The idea with this "receiver set" interface is to get the</span>
<span class="comment">// interface right this time around, and later this implementation can</span>
<span class="comment">// be optimized.</span>
<span class="comment">//</span>
<span class="comment">// This implementation can be summarized by:</span>
<span class="comment">//</span>
<span class="comment">// fn select(receivers) {</span>
<span class="comment">// if any receiver ready { return ready index }</span>
<span class="comment">// deschedule {</span>
<span class="comment">// block on all receivers</span>
<span class="comment">// }</span>
<span class="comment">// unblock on all receivers</span>
<span class="comment">// return ready index</span>
<span class="comment">// }</span>
<span class="comment">//</span>
<span class="comment">// Most notably, the iterations over all of the receivers shouldn't be</span>
<span class="comment">// necessary.</span>
<span class="kw">unsafe</span> {
<span class="comment">// Stage 1: preflight checks. Look for any packets ready to receive</span>
<span class="kw">if</span> <span class="ident">do_preflight_checks</span> {
<span class="kw">for</span> <span class="ident">handle</span> <span class="kw">in</span> <span class="self">self</span>.<span class="ident">iter</span>() {
<span class="kw">if</span> (<span class="kw-2">*</span><span class="ident">handle</span>).<span class="ident">packet</span>.<span class="ident">can_recv</span>() {
<span class="kw">return</span> (<span class="kw-2">*</span><span class="ident">handle</span>).<span class="ident">id</span>();
}
}
}
<span class="comment">// Stage 2: begin the blocking process</span>
<span class="comment">//</span>
<span class="comment">// Create a number of signal tokens, and install each one</span>
<span class="comment">// sequentially until one fails. If one fails, then abort the</span>
<span class="comment">// selection on the already-installed tokens.</span>
<span class="kw">let</span> (<span class="ident">wait_token</span>, <span class="ident">signal_token</span>) <span class="op">=</span> <span class="ident">blocking</span>::<span class="ident">tokens</span>();
<span class="kw">for</span> (<span class="ident">i</span>, <span class="ident">handle</span>) <span class="kw">in</span> <span class="self">self</span>.<span class="ident">iter</span>().<span class="ident">enumerate</span>() {
<span class="kw">match</span> (<span class="kw-2">*</span><span class="ident">handle</span>).<span class="ident">packet</span>.<span class="ident">start_selection</span>(<span class="ident">signal_token</span>.<span class="ident">clone</span>()) {
<span class="ident">StartResult</span>::<span class="ident">Installed</span> <span class="op">=></span> {}
<span class="ident">StartResult</span>::<span class="ident">Abort</span> <span class="op">=></span> {
<span class="comment">// Go back and abort the already-begun selections</span>
<span class="kw">for</span> <span class="ident">handle</span> <span class="kw">in</span> <span class="self">self</span>.<span class="ident">iter</span>().<span class="ident">take</span>(<span class="ident">i</span>) {
(<span class="kw-2">*</span><span class="ident">handle</span>).<span class="ident">packet</span>.<span class="ident">abort_selection</span>();
}
<span class="kw">return</span> (<span class="kw-2">*</span><span class="ident">handle</span>).<span class="ident">id</span>;
}
}
}
<span class="comment">// Stage 3: no messages available, actually block</span>
<span class="ident">wait_token</span>.<span class="ident">wait</span>();
<span class="comment">// Stage 4: there *must* be message available; find it.</span>
<span class="comment">//</span>
<span class="comment">// Abort the selection process on each receiver. If the abort</span>
<span class="comment">// process returns `true`, then that means that the receiver is</span>
<span class="comment">// ready to receive some data. Note that this also means that the</span>
<span class="comment">// receiver may have yet to have fully read the `to_wake` field and</span>
<span class="comment">// woken us up (although the wakeup is guaranteed to fail).</span>
<span class="comment">//</span>
<span class="comment">// This situation happens in the window of where a sender invokes</span>
<span class="comment">// increment(), sees -1, and then decides to wake up the thread. After</span>
<span class="comment">// all this is done, the sending thread will set `selecting` to</span>
<span class="comment">// `false`. Until this is done, we cannot return. If we were to</span>
<span class="comment">// return, then a sender could wake up a receiver which has gone</span>
<span class="comment">// back to sleep after this call to `select`.</span>
<span class="comment">//</span>
<span class="comment">// Note that it is a "fairly small window" in which an increment()</span>
<span class="comment">// views that it should wake a thread up until the `selecting` bit</span>
<span class="comment">// is set to false. For now, the implementation currently just spins</span>
<span class="comment">// in a yield loop. This is very distasteful, but this</span>
<span class="comment">// implementation is already nowhere near what it should ideally be.</span>
<span class="comment">// A rewrite should focus on avoiding a yield loop, and for now this</span>
<span class="comment">// implementation is tying us over to a more efficient "don't</span>
<span class="comment">// iterate over everything every time" implementation.</span>
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">ready_id</span> <span class="op">=</span> <span class="ident">usize</span>::<span class="ident">MAX</span>;
<span class="kw">for</span> <span class="ident">handle</span> <span class="kw">in</span> <span class="self">self</span>.<span class="ident">iter</span>() {
<span class="kw">if</span> (<span class="kw-2">*</span><span class="ident">handle</span>).<span class="ident">packet</span>.<span class="ident">abort_selection</span>() {
<span class="ident">ready_id</span> <span class="op">=</span> (<span class="kw-2">*</span><span class="ident">handle</span>).<span class="ident">id</span>;
}
}
<span class="comment">// We must have found a ready receiver</span>
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">ready_id</span> <span class="op">!=</span> <span class="ident">usize</span>::<span class="ident">MAX</span>);
<span class="kw">return</span> <span class="ident">ready_id</span>;
}
}
<span class="kw">fn</span> <span class="ident">iter</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">Packets</span> { <span class="ident">Packets</span> { <span class="ident">cur</span>: <span class="kw">unsafe</span> { <span class="kw-2">&</span><span class="kw-2">*</span><span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">get</span>() }.<span class="ident">head</span> } }
}
<span class="kw">impl</span><span class="op"><</span><span class="lifetime">'rx</span>, <span class="ident">T</span>: <span class="ident">Send</span><span class="op">></span> <span class="ident">Handle</span><span class="op"><</span><span class="lifetime">'rx</span>, <span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Retrieves the ID of this handle.</span>
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">id</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="ident">usize</span> { <span class="self">self</span>.<span class="ident">id</span> }
<span class="doccomment">/// Blocks to receive a value on the underlying receiver, returning `Some` on</span>
<span class="doccomment">/// success or `None` if the channel disconnects. This function has the same</span>
<span class="doccomment">/// semantics as `Receiver.recv`</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">recv</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">T</span>, <span class="ident">RecvError</span><span class="op">></span> { <span class="self">self</span>.<span class="ident">rx</span>.<span class="ident">recv</span>() }
<span class="doccomment">/// Adds this handle to the receiver set that the handle was created from. This</span>
<span class="doccomment">/// method can be called multiple times, but it has no effect if `add` was</span>
<span class="doccomment">/// called previously.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This method is unsafe because it requires that the `Handle` is not moved</span>
<span class="doccomment">/// while it is added to the `Select` set.</span>
<span class="kw">pub</span> <span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">add</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">added</span> { <span class="kw">return</span> }
<span class="kw">let</span> <span class="ident">selector</span> <span class="op">=</span> <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="kw-2">*</span><span class="self">self</span>.<span class="ident">selector</span>;
<span class="kw">let</span> <span class="ident">me</span> <span class="op">=</span> <span class="self">self</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">Handle</span><span class="op"><</span><span class="lifetime">'rx</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">Handle</span><span class="op"><</span><span class="lifetime">'static</span>, ()<span class="op">></span>;
<span class="kw">if</span> <span class="ident">selector</span>.<span class="ident">head</span>.<span class="ident">is_null</span>() {
<span class="ident">selector</span>.<span class="ident">head</span> <span class="op">=</span> <span class="ident">me</span>;
<span class="ident">selector</span>.<span class="ident">tail</span> <span class="op">=</span> <span class="ident">me</span>;
} <span class="kw">else</span> {
(<span class="kw-2">*</span><span class="ident">me</span>).<span class="ident">prev</span> <span class="op">=</span> <span class="ident">selector</span>.<span class="ident">tail</span>;
<span class="macro">assert</span><span class="macro">!</span>((<span class="kw-2">*</span><span class="ident">me</span>).<span class="ident">next</span>.<span class="ident">is_null</span>());
(<span class="kw-2">*</span><span class="ident">selector</span>.<span class="ident">tail</span>).<span class="ident">next</span> <span class="op">=</span> <span class="ident">me</span>;
<span class="ident">selector</span>.<span class="ident">tail</span> <span class="op">=</span> <span class="ident">me</span>;
}
<span class="self">self</span>.<span class="ident">added</span> <span class="op">=</span> <span class="bool-val">true</span>;
}
<span class="doccomment">/// Removes this handle from the `Select` set. This method is unsafe because</span>
<span class="doccomment">/// it has no guarantee that the `Handle` was not moved since `add` was</span>
<span class="doccomment">/// called.</span>
<span class="kw">pub</span> <span class="kw">unsafe</span> <span class="kw">fn</span> <span class="ident">remove</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) {
<span class="kw">if</span> <span class="op">!</span><span class="self">self</span>.<span class="ident">added</span> { <span class="kw">return</span> }
<span class="kw">let</span> <span class="ident">selector</span> <span class="op">=</span> <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="kw-2">*</span><span class="self">self</span>.<span class="ident">selector</span>;
<span class="kw">let</span> <span class="ident">me</span> <span class="op">=</span> <span class="self">self</span> <span class="kw">as</span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">Handle</span><span class="op"><</span><span class="lifetime">'rx</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">Handle</span><span class="op"><</span><span class="lifetime">'static</span>, ()<span class="op">></span>;
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">prev</span>.<span class="ident">is_null</span>() {
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">selector</span>.<span class="ident">head</span>, <span class="ident">me</span>);
<span class="ident">selector</span>.<span class="ident">head</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">next</span>;
} <span class="kw">else</span> {
(<span class="kw-2">*</span><span class="self">self</span>.<span class="ident">prev</span>).<span class="ident">next</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">next</span>;
}
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">next</span>.<span class="ident">is_null</span>() {
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">selector</span>.<span class="ident">tail</span>, <span class="ident">me</span>);
<span class="ident">selector</span>.<span class="ident">tail</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">prev</span>;
} <span class="kw">else</span> {
(<span class="kw-2">*</span><span class="self">self</span>.<span class="ident">next</span>).<span class="ident">prev</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">prev</span>;
}
<span class="self">self</span>.<span class="ident">next</span> <span class="op">=</span> <span class="ident">ptr</span>::<span class="ident">null_mut</span>();
<span class="self">self</span>.<span class="ident">prev</span> <span class="op">=</span> <span class="ident">ptr</span>::<span class="ident">null_mut</span>();
<span class="self">self</span>.<span class="ident">added</span> <span class="op">=</span> <span class="bool-val">false</span>;
}
}
<span class="kw">impl</span> <span class="ident">Drop</span> <span class="kw">for</span> <span class="ident">Select</span> {
<span class="kw">fn</span> <span class="ident">drop</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) {
<span class="kw">unsafe</span> {
<span class="macro">assert</span><span class="macro">!</span>((<span class="kw-2">&</span><span class="kw-2">*</span><span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">get</span>()).<span class="ident">head</span>.<span class="ident">is_null</span>());
<span class="macro">assert</span><span class="macro">!</span>((<span class="kw-2">&</span><span class="kw-2">*</span><span class="self">self</span>.<span class="ident">inner</span>.<span class="ident">get</span>()).<span class="ident">tail</span>.<span class="ident">is_null</span>());
}
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="ident">Send</span><span class="op">></span> <span class="ident">Drop</span> <span class="kw">for</span> <span class="ident">Handle</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">drop</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) {
<span class="kw">unsafe</span> { <span class="self">self</span>.<span class="ident">remove</span>() }
}
}
<span class="kw">impl</span> <span class="ident">Iterator</span> <span class="kw">for</span> <span class="ident">Packets</span> {
<span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> <span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">Handle</span><span class="op"><</span><span class="lifetime">'static</span>, ()<span class="op">></span>;
<span class="kw">fn</span> <span class="ident">next</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="kw-2">*</span><span class="kw-2">mut</span> <span class="ident">Handle</span><span class="op"><</span><span class="lifetime">'static</span>, ()<span class="op">>></span> {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">cur</span>.<span class="ident">is_null</span>() {
<span class="prelude-val">None</span>
} <span class="kw">else</span> {
<span class="kw">let</span> <span class="ident">ret</span> <span class="op">=</span> <span class="prelude-val">Some</span>(<span class="self">self</span>.<span class="ident">cur</span>);
<span class="kw">unsafe</span> { <span class="self">self</span>.<span class="ident">cur</span> <span class="op">=</span> (<span class="kw-2">*</span><span class="self">self</span>.<span class="ident">cur</span>).<span class="ident">next</span>; }
<span class="ident">ret</span>
}
}
}
<span class="kw">impl</span> <span class="ident">fmt</span>::<span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">Select</span> {
<span class="kw">fn</span> <span class="ident">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span><span class="op"><</span><span class="lifetime">'_</span><span class="op">></span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="ident">f</span>.<span class="ident">debug_struct</span>(<span class="string">"Select"</span>).<span class="ident">finish</span>()
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="ident">Send</span><span class="op">></span> <span class="ident">fmt</span>::<span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">Handle</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">fmt</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">f</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">fmt</span>::<span class="ident">Formatter</span><span class="op"><</span><span class="lifetime">'_</span><span class="op">></span>) <span class="op">-></span> <span class="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="ident">f</span>.<span class="ident">debug_struct</span>(<span class="string">"Handle"</span>).<span class="ident">finish</span>()
}
}
</pre></div>
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distrib
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Mageia
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armv7hl
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0c2243f8a1696816431e7210e991fa52
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