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</pre><pre class="rust ">
<span class="doccomment">//! A multi-producer, single-consumer, futures-aware, FIFO queue with back</span>
<span class="doccomment">//! pressure, for use communicating between tasks on the same thread.</span>
<span class="doccomment">//!</span>
<span class="doccomment">//! These queues are the same as those in `futures::sync`, except they're not</span>
<span class="doccomment">//! intended to be sent across threads.</span>
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">any</span>::<span class="ident">Any</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">cell</span>::<span class="ident">RefCell</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">collections</span>::<span class="ident">VecDeque</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">error</span>::<span class="ident">Error</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">fmt</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">mem</span>;
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">rc</span>::{<span class="ident">Rc</span>, <span class="ident">Weak</span>};
<span class="kw">use</span> <span class="ident">task</span>::{<span class="self">self</span>, <span class="ident">Task</span>};
<span class="kw">use</span> {<span class="ident">Async</span>, <span class="ident">AsyncSink</span>, <span class="ident">Poll</span>, <span class="ident">StartSend</span>, <span class="ident">Sink</span>, <span class="ident">Stream</span>};
<span class="doccomment">/// Creates a bounded in-memory channel with buffered storage.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This method creates concrete implementations of the `Stream` and `Sink`</span>
<span class="doccomment">/// traits which can be used to communicate a stream of values between tasks</span>
<span class="doccomment">/// with backpressure. The channel capacity is exactly `buffer`. On average,</span>
<span class="doccomment">/// sending a message through this channel performs no dynamic allocation.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">channel</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>(<span class="ident">buffer</span>: <span class="ident">usize</span>) <span class="op">-></span> (<span class="ident">Sender</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>, <span class="ident">Receiver</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>) {
<span class="ident">channel_</span>(<span class="prelude-val">Some</span>(<span class="ident">buffer</span>))
}
<span class="kw">fn</span> <span class="ident">channel_</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>(<span class="ident">buffer</span>: <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>) <span class="op">-></span> (<span class="ident">Sender</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>, <span class="ident">Receiver</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>) {
<span class="kw">let</span> <span class="ident">shared</span> <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">new</span>(<span class="ident">RefCell</span>::<span class="ident">new</span>(<span class="ident">Shared</span> {
<span class="ident">buffer</span>: <span class="ident">VecDeque</span>::<span class="ident">new</span>(),
<span class="ident">capacity</span>: <span class="ident">buffer</span>,
<span class="ident">blocked_senders</span>: <span class="ident">VecDeque</span>::<span class="ident">new</span>(),
<span class="ident">blocked_recv</span>: <span class="prelude-val">None</span>,
<span class="ident">sender_count</span>: <span class="number">1</span>,
}));
<span class="kw">let</span> <span class="ident">sender</span> <span class="op">=</span> <span class="ident">Sender</span> { <span class="ident">shared</span>: <span class="ident">Rc</span>::<span class="ident">downgrade</span>(<span class="kw-2">&</span><span class="ident">shared</span>) };
<span class="kw">let</span> <span class="ident">receiver</span> <span class="op">=</span> <span class="ident">Receiver</span> { <span class="ident">state</span>: <span class="ident">State</span>::<span class="ident">Open</span>(<span class="ident">shared</span>) };
(<span class="ident">sender</span>, <span class="ident">receiver</span>)
}
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Debug</span>)]</span>
<span class="kw">struct</span> <span class="ident">Shared</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="ident">buffer</span>: <span class="ident">VecDeque</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>,
<span class="ident">capacity</span>: <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">usize</span><span class="op">></span>,
<span class="ident">blocked_senders</span>: <span class="ident">VecDeque</span><span class="op"><</span><span class="ident">Task</span><span class="op">></span>,
<span class="ident">blocked_recv</span>: <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">Task</span><span class="op">></span>,
<span class="comment">// TODO: Redundant to Rc::weak_count; use that if/when stabilized</span>
<span class="ident">sender_count</span>: <span class="ident">usize</span>,
}
<span class="doccomment">/// The transmission end of a channel.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This is created by the `channel` function.</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Debug</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Sender</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="ident">shared</span>: <span class="ident">Weak</span><span class="op"><</span><span class="ident">RefCell</span><span class="op"><</span><span class="ident">Shared</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">Sender</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">do_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="ident">StartSend</span><span class="op"><</span><span class="ident">T</span>, <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span> {
<span class="kw">let</span> <span class="ident">shared</span> <span class="op">=</span> <span class="kw">match</span> <span class="self">self</span>.<span class="ident">shared</span>.<span class="ident">upgrade</span>() {
<span class="prelude-val">Some</span>(<span class="ident">shared</span>) <span class="op">=></span> <span class="ident">shared</span>,
<span class="prelude-val">None</span> <span class="op">=></span> <span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">SendError</span>(<span class="ident">msg</span>)),
};
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">shared</span> <span class="op">=</span> <span class="ident">shared</span>.<span class="ident">borrow_mut</span>();
<span class="kw">match</span> <span class="ident">shared</span>.<span class="ident">capacity</span> {
<span class="prelude-val">Some</span>(<span class="ident">capacity</span>) <span class="kw">if</span> <span class="ident">shared</span>.<span class="ident">buffer</span>.<span class="ident">len</span>() <span class="op">==</span> <span class="ident">capacity</span> <span class="op">=></span> {
<span class="ident">shared</span>.<span class="ident">blocked_senders</span>.<span class="ident">push_back</span>(<span class="ident">task</span>::<span class="ident">current</span>());
<span class="prelude-val">Ok</span>(<span class="ident">AsyncSink</span>::<span class="ident">NotReady</span>(<span class="ident">msg</span>))
}
_ <span class="op">=></span> {
<span class="ident">shared</span>.<span class="ident">buffer</span>.<span class="ident">push_back</span>(<span class="ident">msg</span>);
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">task</span>) <span class="op">=</span> <span class="ident">shared</span>.<span class="ident">blocked_recv</span>.<span class="ident">take</span>() {
<span class="ident">drop</span>(<span class="ident">shared</span>);
<span class="ident">task</span>.<span class="ident">notify</span>();
}
<span class="prelude-val">Ok</span>(<span class="ident">AsyncSink</span>::<span class="ident">Ready</span>)
}
}
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">Clone</span> <span class="kw">for</span> <span class="ident">Sender</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">clone</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="self">Self</span> {
<span class="kw">let</span> <span class="ident">result</span> <span class="op">=</span> <span class="ident">Sender</span> { <span class="ident">shared</span>: <span class="self">self</span>.<span class="ident">shared</span>.<span class="ident">clone</span>() };
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">shared</span>) <span class="op">=</span> <span class="self">self</span>.<span class="ident">shared</span>.<span class="ident">upgrade</span>() {
<span class="ident">shared</span>.<span class="ident">borrow_mut</span>().<span class="ident">sender_count</span> <span class="op">+=</span> <span class="number">1</span>;
}
<span class="ident">result</span>
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">Sink</span> <span class="kw">for</span> <span class="ident">Sender</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">type</span> <span class="ident">SinkItem</span> <span class="op">=</span> <span class="ident">T</span>;
<span class="kw">type</span> <span class="ident">SinkError</span> <span class="op">=</span> <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>;
<span class="kw">fn</span> <span class="ident">start_send</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">msg</span>: <span class="ident">T</span>) <span class="op">-></span> <span class="ident">StartSend</span><span class="op"><</span><span class="ident">T</span>, <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span> {
<span class="self">self</span>.<span class="ident">do_send</span>(<span class="ident">msg</span>)
}
<span class="kw">fn</span> <span class="ident">poll_complete</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="ident">Poll</span><span class="op"><</span>(), <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span> {
<span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">Ready</span>(()))
}
<span class="kw">fn</span> <span class="ident">close</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="ident">Poll</span><span class="op"><</span>(), <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span> {
<span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">Ready</span>(()))
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">Drop</span> <span class="kw">for</span> <span class="ident">Sender</span><span class="op"><</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">let</span> <span class="ident">shared</span> <span class="op">=</span> <span class="kw">match</span> <span class="self">self</span>.<span class="ident">shared</span>.<span class="ident">upgrade</span>() {
<span class="prelude-val">Some</span>(<span class="ident">shared</span>) <span class="op">=></span> <span class="ident">shared</span>,
<span class="prelude-val">None</span> <span class="op">=></span> <span class="kw">return</span>,
};
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">shared</span> <span class="op">=</span> <span class="ident">shared</span>.<span class="ident">borrow_mut</span>();
<span class="ident">shared</span>.<span class="ident">sender_count</span> <span class="op">-=</span> <span class="number">1</span>;
<span class="kw">if</span> <span class="ident">shared</span>.<span class="ident">sender_count</span> <span class="op">==</span> <span class="number">0</span> {
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">task</span>) <span class="op">=</span> <span class="ident">shared</span>.<span class="ident">blocked_recv</span>.<span class="ident">take</span>() {
<span class="comment">// Wake up receiver as its stream has ended</span>
<span class="ident">drop</span>(<span class="ident">shared</span>);
<span class="ident">task</span>.<span class="ident">notify</span>();
}
}
}
}
<span class="doccomment">/// The receiving end of a channel which implements the `Stream` trait.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This is created by the `channel` function.</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Debug</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Receiver</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="ident">state</span>: <span class="ident">State</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>,
}
<span class="doccomment">/// Possible states of a receiver. We're either Open (can receive more messages)</span>
<span class="doccomment">/// or we're closed with a list of messages we have left to receive.</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Debug</span>)]</span>
<span class="kw">enum</span> <span class="ident">State</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="ident">Open</span>(<span class="ident">Rc</span><span class="op"><</span><span class="ident">RefCell</span><span class="op"><</span><span class="ident">Shared</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span><span class="op">></span>),
<span class="ident">Closed</span>(<span class="ident">VecDeque</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">Receiver</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Closes the receiving half</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This prevents any further messages from being sent on the channel while</span>
<span class="doccomment">/// still enabling the receiver to drain messages that are buffered.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">close</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) {
<span class="kw">let</span> (<span class="ident">blockers</span>, <span class="ident">items</span>) <span class="op">=</span> <span class="kw">match</span> <span class="self">self</span>.<span class="ident">state</span> {
<span class="ident">State</span>::<span class="ident">Open</span>(<span class="kw-2">ref</span> <span class="ident">state</span>) <span class="op">=></span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">state</span> <span class="op">=</span> <span class="ident">state</span>.<span class="ident">borrow_mut</span>();
<span class="kw">let</span> <span class="ident">items</span> <span class="op">=</span> <span class="ident">mem</span>::<span class="ident">replace</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">state</span>.<span class="ident">buffer</span>, <span class="ident">VecDeque</span>::<span class="ident">new</span>());
<span class="kw">let</span> <span class="ident">blockers</span> <span class="op">=</span> <span class="ident">mem</span>::<span class="ident">replace</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">state</span>.<span class="ident">blocked_senders</span>, <span class="ident">VecDeque</span>::<span class="ident">new</span>());
(<span class="ident">blockers</span>, <span class="ident">items</span>)
}
<span class="ident">State</span>::<span class="ident">Closed</span>(_) <span class="op">=></span> <span class="kw">return</span>,
};
<span class="self">self</span>.<span class="ident">state</span> <span class="op">=</span> <span class="ident">State</span>::<span class="ident">Closed</span>(<span class="ident">items</span>);
<span class="kw">for</span> <span class="ident">task</span> <span class="kw">in</span> <span class="ident">blockers</span> {
<span class="ident">task</span>.<span class="ident">notify</span>();
}
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">Stream</span> <span class="kw">for</span> <span class="ident">Receiver</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> <span class="ident">T</span>;
<span class="kw">type</span> <span class="ident">Error</span> <span class="op">=</span> ();
<span class="kw">fn</span> <span class="ident">poll</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="ident">Poll</span><span class="op"><</span><span class="prelude-ty">Option</span><span class="op"><</span><span class="self">Self</span>::<span class="ident">Item</span><span class="op">></span>, <span class="self">Self</span>::<span class="ident">Error</span><span class="op">></span> {
<span class="kw">let</span> <span class="ident">me</span> <span class="op">=</span> <span class="kw">match</span> <span class="self">self</span>.<span class="ident">state</span> {
<span class="ident">State</span>::<span class="ident">Open</span>(<span class="kw-2">ref</span> <span class="kw-2">mut</span> <span class="ident">me</span>) <span class="op">=></span> <span class="ident">me</span>,
<span class="ident">State</span>::<span class="ident">Closed</span>(<span class="kw-2">ref</span> <span class="kw-2">mut</span> <span class="ident">items</span>) <span class="op">=></span> {
<span class="kw">return</span> <span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">Ready</span>(<span class="ident">items</span>.<span class="ident">pop_front</span>()))
}
};
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">shared</span>) <span class="op">=</span> <span class="ident">Rc</span>::<span class="ident">get_mut</span>(<span class="ident">me</span>) {
<span class="comment">// All senders have been dropped, so drain the buffer and end the</span>
<span class="comment">// stream.</span>
<span class="kw">return</span> <span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">Ready</span>(<span class="ident">shared</span>.<span class="ident">borrow_mut</span>().<span class="ident">buffer</span>.<span class="ident">pop_front</span>()));
}
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">shared</span> <span class="op">=</span> <span class="ident">me</span>.<span class="ident">borrow_mut</span>();
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">msg</span>) <span class="op">=</span> <span class="ident">shared</span>.<span class="ident">buffer</span>.<span class="ident">pop_front</span>() {
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">task</span>) <span class="op">=</span> <span class="ident">shared</span>.<span class="ident">blocked_senders</span>.<span class="ident">pop_front</span>() {
<span class="ident">drop</span>(<span class="ident">shared</span>);
<span class="ident">task</span>.<span class="ident">notify</span>();
}
<span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">Ready</span>(<span class="prelude-val">Some</span>(<span class="ident">msg</span>)))
} <span class="kw">else</span> {
<span class="ident">shared</span>.<span class="ident">blocked_recv</span> <span class="op">=</span> <span class="prelude-val">Some</span>(<span class="ident">task</span>::<span class="ident">current</span>());
<span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">NotReady</span>)
}
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">Drop</span> <span class="kw">for</span> <span class="ident">Receiver</span><span class="op"><</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="self">self</span>.<span class="ident">close</span>();
}
}
<span class="doccomment">/// The transmission end of an unbounded channel.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This is created by the `unbounded` function.</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Debug</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">UnboundedSender</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>(<span class="ident">Sender</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">Clone</span> <span class="kw">for</span> <span class="ident">UnboundedSender</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">clone</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="self">Self</span> {
<span class="ident">UnboundedSender</span>(<span class="self">self</span>.<span class="number">0</span>.<span class="ident">clone</span>())
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">Sink</span> <span class="kw">for</span> <span class="ident">UnboundedSender</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">type</span> <span class="ident">SinkItem</span> <span class="op">=</span> <span class="ident">T</span>;
<span class="kw">type</span> <span class="ident">SinkError</span> <span class="op">=</span> <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>;
<span class="kw">fn</span> <span class="ident">start_send</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">msg</span>: <span class="ident">T</span>) <span class="op">-></span> <span class="ident">StartSend</span><span class="op"><</span><span class="ident">T</span>, <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span> {
<span class="self">self</span>.<span class="number">0</span>.<span class="ident">start_send</span>(<span class="ident">msg</span>)
}
<span class="kw">fn</span> <span class="ident">poll_complete</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="ident">Poll</span><span class="op"><</span>(), <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span> {
<span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">Ready</span>(()))
}
<span class="kw">fn</span> <span class="ident">close</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="ident">Poll</span><span class="op"><</span>(), <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span> {
<span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">Ready</span>(()))
}
}
<span class="kw">impl</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">T</span><span class="op">></span> <span class="ident">Sink</span> <span class="kw">for</span> <span class="kw-2">&</span><span class="lifetime">'a</span> <span class="ident">UnboundedSender</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">type</span> <span class="ident">SinkItem</span> <span class="op">=</span> <span class="ident">T</span>;
<span class="kw">type</span> <span class="ident">SinkError</span> <span class="op">=</span> <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>;
<span class="kw">fn</span> <span class="ident">start_send</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">msg</span>: <span class="ident">T</span>) <span class="op">-></span> <span class="ident">StartSend</span><span class="op"><</span><span class="ident">T</span>, <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span> {
<span class="self">self</span>.<span class="number">0</span>.<span class="ident">do_send</span>(<span class="ident">msg</span>)
}
<span class="kw">fn</span> <span class="ident">poll_complete</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="ident">Poll</span><span class="op"><</span>(), <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span> {
<span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">Ready</span>(()))
}
<span class="kw">fn</span> <span class="ident">close</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="ident">Poll</span><span class="op"><</span>(), <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span> {
<span class="prelude-val">Ok</span>(<span class="ident">Async</span>::<span class="ident">Ready</span>(()))
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">UnboundedSender</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Sends the provided message along this channel.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This is an unbounded sender, so this function differs from `Sink::send`</span>
<span class="doccomment">/// by ensuring the return type reflects that the channel is always ready to</span>
<span class="doccomment">/// receive messages.</span>
<span class="kw">pub</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="op">-></span> <span class="prelude-ty">Result</span><span class="op"><</span>(), <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">>></span> {
<span class="kw">let</span> <span class="ident">shared</span> <span class="op">=</span> <span class="kw">match</span> <span class="self">self</span>.<span class="number">0</span>.<span class="ident">shared</span>.<span class="ident">upgrade</span>() {
<span class="prelude-val">Some</span>(<span class="ident">shared</span>) <span class="op">=></span> <span class="ident">shared</span>,
<span class="prelude-val">None</span> <span class="op">=></span> <span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">SendError</span>(<span class="ident">msg</span>)),
};
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">shared</span> <span class="op">=</span> <span class="ident">shared</span>.<span class="ident">borrow_mut</span>();
<span class="ident">shared</span>.<span class="ident">buffer</span>.<span class="ident">push_back</span>(<span class="ident">msg</span>);
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">task</span>) <span class="op">=</span> <span class="ident">shared</span>.<span class="ident">blocked_recv</span>.<span class="ident">take</span>() {
<span class="ident">drop</span>(<span class="ident">shared</span>);
<span class="ident">task</span>.<span class="ident">notify</span>();
}
<span class="prelude-val">Ok</span>(())
}
}
<span class="doccomment">/// The receiving end of an unbounded channel.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This is created by the `unbounded` function.</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Debug</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">UnboundedReceiver</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>(<span class="ident">Receiver</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">UnboundedReceiver</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Closes the receiving half</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This prevents any further messages from being sent on the channel while</span>
<span class="doccomment">/// still enabling the receiver to drain messages that are buffered.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">close</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) {
<span class="self">self</span>.<span class="number">0</span>.<span class="ident">close</span>();
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">Stream</span> <span class="kw">for</span> <span class="ident">UnboundedReceiver</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">type</span> <span class="ident">Item</span> <span class="op">=</span> <span class="ident">T</span>;
<span class="kw">type</span> <span class="ident">Error</span> <span class="op">=</span> ();
<span class="kw">fn</span> <span class="ident">poll</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-></span> <span class="ident">Poll</span><span class="op"><</span><span class="prelude-ty">Option</span><span class="op"><</span><span class="self">Self</span>::<span class="ident">Item</span><span class="op">></span>, <span class="self">Self</span>::<span class="ident">Error</span><span class="op">></span> {
<span class="self">self</span>.<span class="number">0</span>.<span class="ident">poll</span>()
}
}
<span class="doccomment">/// Creates an unbounded in-memory channel with buffered storage.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Identical semantics to `channel`, except with no limit to buffer size.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">unbounded</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>() <span class="op">-></span> (<span class="ident">UnboundedSender</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>, <span class="ident">UnboundedReceiver</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>) {
<span class="kw">let</span> (<span class="ident">send</span>, <span class="ident">recv</span>) <span class="op">=</span> <span class="ident">channel_</span>(<span class="prelude-val">None</span>);
(<span class="ident">UnboundedSender</span>(<span class="ident">send</span>), <span class="ident">UnboundedReceiver</span>(<span class="ident">recv</span>))
}
<span class="doccomment">/// Error type for sending, used when the receiving end of a channel is</span>
<span class="doccomment">/// dropped</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">></span>(<span class="ident">T</span>);
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">fmt</span>::<span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">SendError</span><span class="op"><</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">fmt</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="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="ident">fmt</span>.<span class="ident">debug_tuple</span>(<span class="string">"SendError"</span>)
.<span class="ident">field</span>(<span class="kw-2">&</span><span class="string">"..."</span>)
.<span class="ident">finish</span>()
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">fmt</span>::<span class="ident">Display</span> <span class="kw">for</span> <span class="ident">SendError</span><span class="op"><</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">fmt</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="ident">fmt</span>::<span class="prelude-ty">Result</span> {
<span class="macro">write</span><span class="macro">!</span>(<span class="ident">fmt</span>, <span class="string">"send failed because receiver is gone"</span>)
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span>: <span class="ident">Any</span><span class="op">></span> <span class="ident">Error</span> <span class="kw">for</span> <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="kw">fn</span> <span class="ident">description</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-></span> <span class="kw-2">&</span><span class="ident">str</span> {
<span class="string">"send failed because receiver is gone"</span>
}
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> <span class="ident">SendError</span><span class="op"><</span><span class="ident">T</span><span class="op">></span> {
<span class="doccomment">/// Returns the message that was attempted to be sent but failed.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">into_inner</span>(<span class="self">self</span>) <span class="op">-></span> <span class="ident">T</span> {
<span class="self">self</span>.<span class="number">0</span>
}
}
</pre>
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