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</pre><pre class='rust '>
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<span class='doccomment'>//! Epoch-based memory management</span>
|
||
<span class='doccomment'>//!</span>
|
||
<span class='doccomment'>//! This module provides fast, easy to use memory management for lock free data</span>
|
||
<span class='doccomment'>//! structures. It's inspired by [Keir Fraser's *epoch-based</span>
|
||
<span class='doccomment'>//! reclamation*](https://www.cl.cam.ac.uk/techreports/UCAM-CL-TR-579.pdf).</span>
|
||
<span class='doccomment'>//!</span>
|
||
<span class='doccomment'>//! The basic problem this is solving is the fact that when one thread has</span>
|
||
<span class='doccomment'>//! removed a node from a data structure, other threads may still have pointers</span>
|
||
<span class='doccomment'>//! to that node (in the form of snapshots that will be validated through things</span>
|
||
<span class='doccomment'>//! like compare-and-swap), so the memory cannot be immediately freed. Put differently:</span>
|
||
<span class='doccomment'>//!</span>
|
||
<span class='doccomment'>//! 1. There are two sources of reachability at play -- the data structure, and</span>
|
||
<span class='doccomment'>//! the snapshots in threads accessing it. Before we delete a node, we need to know</span>
|
||
<span class='doccomment'>//! that it cannot be reached in either of these ways.</span>
|
||
<span class='doccomment'>//!</span>
|
||
<span class='doccomment'>//! 2. Once a node has been unliked from the data structure, no *new* snapshots</span>
|
||
<span class='doccomment'>//! reaching it will be created.</span>
|
||
<span class='doccomment'>//!</span>
|
||
<span class='doccomment'>//! Using the epoch scheme is fairly straightforward, and does not require</span>
|
||
<span class='doccomment'>//! understanding any of the implementation details:</span>
|
||
<span class='doccomment'>//!</span>
|
||
<span class='doccomment'>//! - When operating on a shared data structure, a thread must "pin the current</span>
|
||
<span class='doccomment'>//! epoch", which is done by calling `pin()`. This function returns a `Guard`</span>
|
||
<span class='doccomment'>//! which unpins the epoch when destroyed.</span>
|
||
<span class='doccomment'>//!</span>
|
||
<span class='doccomment'>//! - When the thread subsequently reads from a lock-free data structure, the</span>
|
||
<span class='doccomment'>//! pointers it extracts act like references with lifetime tied to the</span>
|
||
<span class='doccomment'>//! `Guard`. This allows threads to safely read from snapshotted data, being</span>
|
||
<span class='doccomment'>//! guaranteed that the data will remain allocated until they exit the epoch.</span>
|
||
<span class='doccomment'>//!</span>
|
||
<span class='doccomment'>//! To put the `Guard` to use, Crossbeam provides a set of three pointer types meant to work together:</span>
|
||
<span class='doccomment'>//!</span>
|
||
<span class='doccomment'>//! - `Owned<T>`, akin to `Box<T>`, which points to uniquely-owned data that has</span>
|
||
<span class='doccomment'>//! not yet been published in a concurrent data structure.</span>
|
||
<span class='doccomment'>//!</span>
|
||
<span class='doccomment'>//! - `Shared<'a, T>`, akin to `&'a T`, which points to shared data that may or may</span>
|
||
<span class='doccomment'>//! not be reachable from a data structure, but it guaranteed not to be freed</span>
|
||
<span class='doccomment'>//! during lifetime `'a`.</span>
|
||
<span class='doccomment'>//!</span>
|
||
<span class='doccomment'>//! - `Atomic<T>`, akin to `std::sync::atomic::AtomicPtr`, which provides atomic</span>
|
||
<span class='doccomment'>//! updates to a pointer using the `Owned` and `Shared` types, and connects them</span>
|
||
<span class='doccomment'>//! to a `Guard`.</span>
|
||
<span class='doccomment'>//!</span>
|
||
<span class='doccomment'>//! Each of these types provides further documentation on usage.</span>
|
||
<span class='doccomment'>//!</span>
|
||
<span class='doccomment'>//! # Example</span>
|
||
<span class='doccomment'>//!</span>
|
||
<span class='doccomment'>//! ```</span>
|
||
<span class='doccomment'>//! use std::sync::atomic::Ordering::{Acquire, Release, Relaxed};</span>
|
||
<span class='doccomment'>//! use std::ptr;</span>
|
||
<span class='doccomment'>//!</span>
|
||
<span class='doccomment'>//! use crossbeam::mem::epoch::{self, Atomic, Owned};</span>
|
||
<span class='doccomment'>//!</span>
|
||
<span class='doccomment'>//! struct TreiberStack<T> {</span>
|
||
<span class='doccomment'>//! head: Atomic<Node<T>>,</span>
|
||
<span class='doccomment'>//! }</span>
|
||
<span class='doccomment'>//!</span>
|
||
<span class='doccomment'>//! struct Node<T> {</span>
|
||
<span class='doccomment'>//! data: T,</span>
|
||
<span class='doccomment'>//! next: Atomic<Node<T>>,</span>
|
||
<span class='doccomment'>//! }</span>
|
||
<span class='doccomment'>//!</span>
|
||
<span class='doccomment'>//! impl<T> TreiberStack<T> {</span>
|
||
<span class='doccomment'>//! fn new() -> TreiberStack<T> {</span>
|
||
<span class='doccomment'>//! TreiberStack {</span>
|
||
<span class='doccomment'>//! head: Atomic::null()</span>
|
||
<span class='doccomment'>//! }</span>
|
||
<span class='doccomment'>//! }</span>
|
||
<span class='doccomment'>//!</span>
|
||
<span class='doccomment'>//! fn push(&self, t: T) {</span>
|
||
<span class='doccomment'>//! // allocate the node via Owned</span>
|
||
<span class='doccomment'>//! let mut n = Owned::new(Node {</span>
|
||
<span class='doccomment'>//! data: t,</span>
|
||
<span class='doccomment'>//! next: Atomic::null(),</span>
|
||
<span class='doccomment'>//! });</span>
|
||
<span class='doccomment'>//!</span>
|
||
<span class='doccomment'>//! // become active</span>
|
||
<span class='doccomment'>//! let guard = epoch::pin();</span>
|
||
<span class='doccomment'>//!</span>
|
||
<span class='doccomment'>//! loop {</span>
|
||
<span class='doccomment'>//! // snapshot current head</span>
|
||
<span class='doccomment'>//! let head = self.head.load(Relaxed, &guard);</span>
|
||
<span class='doccomment'>//!</span>
|
||
<span class='doccomment'>//! // update `next` pointer with snapshot</span>
|
||
<span class='doccomment'>//! n.next.store_shared(head, Relaxed);</span>
|
||
<span class='doccomment'>//!</span>
|
||
<span class='doccomment'>//! // if snapshot is still good, link in the new node</span>
|
||
<span class='doccomment'>//! match self.head.cas_and_ref(head, n, Release, &guard) {</span>
|
||
<span class='doccomment'>//! Ok(_) => return,</span>
|
||
<span class='doccomment'>//! Err(owned) => n = owned,</span>
|
||
<span class='doccomment'>//! }</span>
|
||
<span class='doccomment'>//! }</span>
|
||
<span class='doccomment'>//! }</span>
|
||
<span class='doccomment'>//!</span>
|
||
<span class='doccomment'>//! fn pop(&self) -> Option<T> {</span>
|
||
<span class='doccomment'>//! // become active</span>
|
||
<span class='doccomment'>//! let guard = epoch::pin();</span>
|
||
<span class='doccomment'>//!</span>
|
||
<span class='doccomment'>//! loop {</span>
|
||
<span class='doccomment'>//! // take a snapshot</span>
|
||
<span class='doccomment'>//! match self.head.load(Acquire, &guard) {</span>
|
||
<span class='doccomment'>//! // the stack is non-empty</span>
|
||
<span class='doccomment'>//! Some(head) => {</span>
|
||
<span class='doccomment'>//! // read through the snapshot, *safely*!</span>
|
||
<span class='doccomment'>//! let next = head.next.load(Relaxed, &guard);</span>
|
||
<span class='doccomment'>//!</span>
|
||
<span class='doccomment'>//! // if snapshot is still good, update from `head` to `next`</span>
|
||
<span class='doccomment'>//! if self.head.cas_shared(Some(head), next, Release) {</span>
|
||
<span class='doccomment'>//! unsafe {</span>
|
||
<span class='doccomment'>//! // mark the node as unlinked</span>
|
||
<span class='doccomment'>//! guard.unlinked(head);</span>
|
||
<span class='doccomment'>//!</span>
|
||
<span class='doccomment'>//! // extract out the data from the now-unlinked node</span>
|
||
<span class='doccomment'>//! return Some(ptr::read(&(*head).data))</span>
|
||
<span class='doccomment'>//! }</span>
|
||
<span class='doccomment'>//! }</span>
|
||
<span class='doccomment'>//! }</span>
|
||
<span class='doccomment'>//!</span>
|
||
<span class='doccomment'>//! // we observed the stack empty</span>
|
||
<span class='doccomment'>//! None => return None</span>
|
||
<span class='doccomment'>//! }</span>
|
||
<span class='doccomment'>//! }</span>
|
||
<span class='doccomment'>//! }</span>
|
||
<span class='doccomment'>//! }</span>
|
||
<span class='doccomment'>//! ```</span>
|
||
|
||
<span class='comment'>// FIXME: document implementation details</span>
|
||
|
||
<span class='kw'>mod</span> <span class='ident'>atomic</span>;
|
||
<span class='kw'>mod</span> <span class='ident'>garbage</span>;
|
||
<span class='kw'>mod</span> <span class='ident'>global</span>;
|
||
<span class='kw'>mod</span> <span class='ident'>guard</span>;
|
||
<span class='kw'>mod</span> <span class='ident'>local</span>;
|
||
<span class='kw'>mod</span> <span class='ident'>participant</span>;
|
||
<span class='kw'>mod</span> <span class='ident'>participants</span>;
|
||
|
||
<span class='kw'>pub</span> <span class='kw'>use</span> <span class='self'>self</span>::<span class='ident'>atomic</span>::<span class='ident'>Atomic</span>;
|
||
<span class='kw'>pub</span> <span class='kw'>use</span> <span class='self'>self</span>::<span class='ident'>guard</span>::{<span class='ident'>pin</span>, <span class='ident'>Guard</span>};
|
||
|
||
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>ops</span>::{<span class='ident'>Deref</span>, <span class='ident'>DerefMut</span>};
|
||
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>ptr</span>;
|
||
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>mem</span>;
|
||
|
||
<span class='doccomment'>/// Like `Box<T>`: an owned, heap-allocated data value of type `T`.</span>
|
||
<span class='kw'>pub</span> <span class='kw'>struct</span> <span class='ident'>Owned</span><span class='op'><</span><span class='ident'>T</span><span class='op'>></span> {
|
||
<span class='ident'>data</span>: <span class='ident'>Box</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'>Owned</span><span class='op'><</span><span class='ident'>T</span><span class='op'>></span> {
|
||
<span class='doccomment'>/// Move `t` to a new heap allocation.</span>
|
||
<span class='kw'>pub</span> <span class='kw'>fn</span> <span class='ident'>new</span>(<span class='ident'>t</span>: <span class='ident'>T</span>) <span class='op'>-></span> <span class='ident'>Owned</span><span class='op'><</span><span class='ident'>T</span><span class='op'>></span> {
|
||
<span class='ident'>Owned</span> { <span class='ident'>data</span>: <span class='ident'>Box</span>::<span class='ident'>new</span>(<span class='ident'>t</span>) }
|
||
}
|
||
|
||
<span class='kw'>fn</span> <span class='ident'>as_raw</span>(<span class='kw-2'>&</span><span class='self'>self</span>) <span class='op'>-></span> <span class='op'>*</span><span class='kw-2'>mut</span> <span class='ident'>T</span> {
|
||
<span class='self'>self</span>.<span class='ident'>deref</span>() <span class='kw'>as</span> <span class='op'>*</span><span class='kw'>const</span> _ <span class='kw'>as</span> <span class='op'>*</span><span class='kw-2'>mut</span> _
|
||
}
|
||
|
||
<span class='doccomment'>/// Move data out of the owned box, deallocating the box.</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='op'>*</span><span class='self'>self</span>.<span class='ident'>data</span>
|
||
}
|
||
}
|
||
|
||
<span class='kw'>impl</span><span class='op'><</span><span class='ident'>T</span><span class='op'>></span> <span class='ident'>Deref</span> <span class='kw'>for</span> <span class='ident'>Owned</span><span class='op'><</span><span class='ident'>T</span><span class='op'>></span> {
|
||
<span class='kw'>type</span> <span class='ident'>Target</span> <span class='op'>=</span> <span class='ident'>T</span>;
|
||
<span class='kw'>fn</span> <span class='ident'>deref</span>(<span class='kw-2'>&</span><span class='self'>self</span>) <span class='op'>-></span> <span class='kw-2'>&</span><span class='ident'>T</span> {
|
||
<span class='kw-2'>&</span><span class='self'>self</span>.<span class='ident'>data</span>
|
||
}
|
||
}
|
||
|
||
<span class='kw'>impl</span><span class='op'><</span><span class='ident'>T</span><span class='op'>></span> <span class='ident'>DerefMut</span> <span class='kw'>for</span> <span class='ident'>Owned</span><span class='op'><</span><span class='ident'>T</span><span class='op'>></span> {
|
||
<span class='kw'>fn</span> <span class='ident'>deref_mut</span>(<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>) <span class='op'>-></span> <span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='ident'>T</span> {
|
||
<span class='kw-2'>&</span><span class='kw-2'>mut</span> <span class='self'>self</span>.<span class='ident'>data</span>
|
||
}
|
||
}
|
||
|
||
<span class='attribute'>#[<span class='ident'>derive</span>(<span class='ident'>PartialEq</span>, <span class='ident'>Eq</span>)]</span>
|
||
<span class='doccomment'>/// Like `&'a T`: a shared reference valid for lifetime `'a`.</span>
|
||
<span class='kw'>pub</span> <span class='kw'>struct</span> <span class='ident'>Shared</span><span class='op'><</span><span class='lifetime'>'a</span>, <span class='ident'>T</span>: <span class='lifetime'>'a</span><span class='op'>></span> {
|
||
<span class='ident'>data</span>: <span class='kw-2'>&</span><span class='lifetime'>'a</span> <span class='ident'>T</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'>Copy</span> <span class='kw'>for</span> <span class='ident'>Shared</span><span class='op'><</span><span class='lifetime'>'a</span>, <span class='ident'>T</span><span class='op'>></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'>Clone</span> <span class='kw'>for</span> <span class='ident'>Shared</span><span class='op'><</span><span class='lifetime'>'a</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='ident'>Shared</span><span class='op'><</span><span class='lifetime'>'a</span>, <span class='ident'>T</span><span class='op'>></span> {
|
||
<span class='ident'>Shared</span> { <span class='ident'>data</span>: <span class='self'>self</span>.<span class='ident'>data</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'>Deref</span> <span class='kw'>for</span> <span class='ident'>Shared</span><span class='op'><</span><span class='lifetime'>'a</span>, <span class='ident'>T</span><span class='op'>></span> {
|
||
<span class='kw'>type</span> <span class='ident'>Target</span> <span class='op'>=</span> <span class='kw-2'>&</span><span class='lifetime'>'a</span> <span class='ident'>T</span>;
|
||
<span class='kw'>fn</span> <span class='ident'>deref</span>(<span class='kw-2'>&</span><span class='self'>self</span>) <span class='op'>-></span> <span class='op'>&&</span><span class='lifetime'>'a</span> <span class='ident'>T</span> {
|
||
<span class='kw-2'>&</span><span class='self'>self</span>.<span class='ident'>data</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'>Shared</span><span class='op'><</span><span class='lifetime'>'a</span>, <span class='ident'>T</span><span class='op'>></span> {
|
||
<span class='kw'>unsafe</span> <span class='kw'>fn</span> <span class='ident'>from_raw</span>(<span class='ident'>raw</span>: <span class='op'>*</span><span class='kw-2'>mut</span> <span class='ident'>T</span>) <span class='op'>-></span> <span class='prelude-ty'>Option</span><span class='op'><</span><span class='ident'>Shared</span><span class='op'><</span><span class='lifetime'>'a</span>, <span class='ident'>T</span><span class='op'>>></span> {
|
||
<span class='kw'>if</span> <span class='ident'>raw</span> <span class='op'>==</span> <span class='ident'>ptr</span>::<span class='ident'>null_mut</span>() { <span class='prelude-val'>None</span> }
|
||
<span class='kw'>else</span> {
|
||
<span class='prelude-val'>Some</span>(<span class='ident'>Shared</span> {
|
||
<span class='ident'>data</span>: <span class='ident'>mem</span>::<span class='ident'>transmute</span>::<span class='op'><</span><span class='op'>*</span><span class='kw-2'>mut</span> <span class='ident'>T</span>, <span class='kw-2'>&</span><span class='ident'>T</span><span class='op'>></span>(<span class='ident'>raw</span>)
|
||
})
|
||
}
|
||
}
|
||
|
||
<span class='kw'>unsafe</span> <span class='kw'>fn</span> <span class='ident'>from_ref</span>(<span class='ident'>r</span>: <span class='kw-2'>&</span><span class='ident'>T</span>) <span class='op'>-></span> <span class='ident'>Shared</span><span class='op'><</span><span class='lifetime'>'a</span>, <span class='ident'>T</span><span class='op'>></span> {
|
||
<span class='ident'>Shared</span> { <span class='ident'>data</span>: <span class='ident'>mem</span>::<span class='ident'>transmute</span>(<span class='ident'>r</span>) }
|
||
}
|
||
|
||
<span class='kw'>unsafe</span> <span class='kw'>fn</span> <span class='ident'>from_owned</span>(<span class='ident'>owned</span>: <span class='ident'>Owned</span><span class='op'><</span><span class='ident'>T</span><span class='op'>></span>) <span class='op'>-></span> <span class='ident'>Shared</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'>ret</span> <span class='op'>=</span> <span class='ident'>Shared</span>::<span class='ident'>from_ref</span>(<span class='ident'>owned</span>.<span class='ident'>deref</span>());
|
||
<span class='ident'>mem</span>::<span class='ident'>forget</span>(<span class='ident'>owned</span>);
|
||
<span class='ident'>ret</span>
|
||
}
|
||
|
||
<span class='kw'>pub</span> <span class='kw'>fn</span> <span class='ident'>as_raw</span>(<span class='kw-2'>&</span><span class='self'>self</span>) <span class='op'>-></span> <span class='op'>*</span><span class='kw-2'>mut</span> <span class='ident'>T</span> {
|
||
<span class='self'>self</span>.<span class='ident'>data</span> <span class='kw'>as</span> <span class='op'>*</span><span class='kw'>const</span> _ <span class='kw'>as</span> <span class='op'>*</span><span class='kw-2'>mut</span> _
|
||
}
|
||
}
|
||
|
||
|
||
<span class='attribute'>#[<span class='ident'>cfg</span>(<span class='ident'>test</span>)]</span>
|
||
<span class='kw'>mod</span> <span class='ident'>test</span> {
|
||
<span class='kw'>use</span> <span class='ident'>std</span>::<span class='ident'>sync</span>::<span class='ident'>atomic</span>::<span class='ident'>Ordering</span>;
|
||
<span class='kw'>use</span> <span class='kw'>super</span>::<span class='op'>*</span>;
|
||
<span class='kw'>use</span> <span class='ident'>mem</span>::<span class='ident'>epoch</span>;
|
||
|
||
<span class='attribute'>#[<span class='ident'>test</span>]</span>
|
||
<span class='kw'>fn</span> <span class='ident'>test_no_drop</span>() {
|
||
<span class='kw'>static</span> <span class='kw-2'>mut</span> <span class='ident'>DROPS</span>: <span class='ident'>i32</span> <span class='op'>=</span> <span class='number'>0</span>;
|
||
<span class='kw'>struct</span> <span class='ident'>Test</span>;
|
||
<span class='kw'>impl</span> <span class='ident'>Drop</span> <span class='kw'>for</span> <span class='ident'>Test</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='ident'>DROPS</span> <span class='op'>+=</span> <span class='number'>1</span>;
|
||
}
|
||
}
|
||
}
|
||
<span class='kw'>let</span> <span class='ident'>g</span> <span class='op'>=</span> <span class='ident'>pin</span>();
|
||
|
||
<span class='kw'>let</span> <span class='ident'>x</span> <span class='op'>=</span> <span class='ident'>Atomic</span>::<span class='ident'>null</span>();
|
||
<span class='ident'>x</span>.<span class='ident'>store</span>(<span class='prelude-val'>Some</span>(<span class='ident'>Owned</span>::<span class='ident'>new</span>(<span class='ident'>Test</span>)), <span class='ident'>Ordering</span>::<span class='ident'>Relaxed</span>);
|
||
<span class='ident'>x</span>.<span class='ident'>store_and_ref</span>(<span class='ident'>Owned</span>::<span class='ident'>new</span>(<span class='ident'>Test</span>), <span class='ident'>Ordering</span>::<span class='ident'>Relaxed</span>, <span class='kw-2'>&</span><span class='ident'>g</span>);
|
||
<span class='kw'>let</span> <span class='ident'>y</span> <span class='op'>=</span> <span class='ident'>x</span>.<span class='ident'>load</span>(<span class='ident'>Ordering</span>::<span class='ident'>Relaxed</span>, <span class='kw-2'>&</span><span class='ident'>g</span>);
|
||
<span class='kw'>let</span> <span class='ident'>z</span> <span class='op'>=</span> <span class='ident'>x</span>.<span class='ident'>cas_and_ref</span>(<span class='ident'>y</span>, <span class='ident'>Owned</span>::<span class='ident'>new</span>(<span class='ident'>Test</span>), <span class='ident'>Ordering</span>::<span class='ident'>Relaxed</span>, <span class='kw-2'>&</span><span class='ident'>g</span>).<span class='ident'>ok</span>();
|
||
<span class='kw'>let</span> _ <span class='op'>=</span> <span class='ident'>x</span>.<span class='ident'>cas</span>(<span class='ident'>z</span>, <span class='prelude-val'>Some</span>(<span class='ident'>Owned</span>::<span class='ident'>new</span>(<span class='ident'>Test</span>)), <span class='ident'>Ordering</span>::<span class='ident'>Relaxed</span>);
|
||
<span class='ident'>x</span>.<span class='ident'>swap</span>(<span class='prelude-val'>Some</span>(<span class='ident'>Owned</span>::<span class='ident'>new</span>(<span class='ident'>Test</span>)), <span class='ident'>Ordering</span>::<span class='ident'>Relaxed</span>, <span class='kw-2'>&</span><span class='ident'>g</span>);
|
||
|
||
<span class='kw'>unsafe</span> {
|
||
<span class='macro'>assert_eq</span><span class='macro'>!</span>(<span class='ident'>DROPS</span>, <span class='number'>0</span>);
|
||
}
|
||
}
|
||
|
||
<span class='attribute'>#[<span class='ident'>test</span>]</span>
|
||
<span class='kw'>fn</span> <span class='ident'>test_new</span>() {
|
||
<span class='kw'>let</span> <span class='ident'>guard</span> <span class='op'>=</span> <span class='ident'>epoch</span>::<span class='ident'>pin</span>();
|
||
<span class='kw'>let</span> <span class='ident'>my_atomic</span> <span class='op'>=</span> <span class='ident'>Atomic</span>::<span class='ident'>new</span>(<span class='number'>42</span>);
|
||
|
||
<span class='macro'>assert_eq</span><span class='macro'>!</span>(<span class='op'>*</span><span class='op'>*</span><span class='ident'>my_atomic</span>.<span class='ident'>load</span>(<span class='ident'>Ordering</span>::<span class='ident'>Relaxed</span>, <span class='kw-2'>&</span><span class='ident'>guard</span>).<span class='ident'>unwrap</span>(), <span class='number'>42</span>);
|
||
}
|
||
}
|
||
</pre>
|
||
</section>
|
||
<section id='search' class="content hidden"></section>
|
||
|
||
<section class="footer"></section>
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||
|
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<aside id="help" class="hidden">
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<div>
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<h1 class="hidden">Help</h1>
|
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|
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<div class="shortcuts">
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<h2>Keyboard Shortcuts</h2>
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||
|
||
<dl>
|
||
<dt>?</dt>
|
||
<dd>Show this help dialog</dd>
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<dt>S</dt>
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||
<dd>Focus the search field</dd>
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<dt>⇤</dt>
|
||
<dd>Move up in search results</dd>
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<dt>⇥</dt>
|
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<dd>Move down in search results</dd>
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<dt>⏎</dt>
|
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<dd>Go to active search result</dd>
|
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</dl>
|
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</div>
|
||
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<div class="infos">
|
||
<h2>Search Tricks</h2>
|
||
|
||
<p>
|
||
Prefix searches with a type followed by a colon (e.g.
|
||
<code>fn:</code>) to restrict the search to a given type.
|
||
</p>
|
||
|
||
<p>
|
||
Accepted types are: <code>fn</code>, <code>mod</code>,
|
||
<code>struct</code>, <code>enum</code>,
|
||
<code>trait</code>, <code>type</code>, <code>macro</code>,
|
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and <code>const</code>.
|
||
</p>
|
||
|
||
<p>
|
||
Search functions by type signature (e.g.
|
||
<code>vec -> usize</code> or <code>* -> vec</code>)
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</aside>
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<script>
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