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</pre><div class="example-wrap"><pre class="rust ">
<span class="comment">// Copyright 2020 Shin Yoshida</span>
<span class="comment">//</span>
<span class="comment">// "LGPL-3.0-or-later OR Apache-2.0 OR BSD-2-Clause"</span>
<span class="comment">//</span>
<span class="comment">// This is part of spin-sync</span>
<span class="comment">//</span>
<span class="comment">// spin-sync is free software: you can redistribute it and/or modify</span>
<span class="comment">// it under the terms of the GNU Lesser General Public License as published by</span>
<span class="comment">// the Free Software Foundation, either version 3 of the License, or</span>
<span class="comment">// (at your option) any later version.</span>
<span class="comment">//</span>
<span class="comment">// spin-sync is distributed in the hope that it will be useful,</span>
<span class="comment">// but WITHOUT ANY WARRANTY; without even the implied warranty of</span>
<span class="comment">// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the</span>
<span class="comment">// GNU Lesser General Public License for more details.</span>
<span class="comment">//</span>
<span class="comment">// You should have received a copy of the GNU Lesser General Public License</span>
<span class="comment">// along with spin-sync. If not, see <http://www.gnu.org/licenses/>.</span>
<span class="comment">//</span>
<span class="comment">//</span>
<span class="comment">// Licensed under the Apache License, Version 2.0 (the "License");</span>
<span class="comment">// you may not use this file except in compliance with the License.</span>
<span class="comment">// You may obtain a copy of the License at</span>
<span class="comment">//</span>
<span class="comment">// http://www.apache.org/licenses/LICENSE-2.0</span>
<span class="comment">//</span>
<span class="comment">// Unless required by applicable law or agreed to in writing, software</span>
<span class="comment">// distributed under the License is distributed on an "AS IS" BASIS,</span>
<span class="comment">// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.</span>
<span class="comment">// See the License for the specific language governing permissions and</span>
<span class="comment">// limitations under the License.</span>
<span class="comment">//</span>
<span class="comment">//</span>
<span class="comment">// Redistribution and use in source and binary forms, with or without modification, are permitted</span>
<span class="comment">// provided that the following conditions are met:</span>
<span class="comment">//</span>
<span class="comment">// 1. Redistributions of source code must retain the above copyright notice, this list of</span>
<span class="comment">// conditions and the following disclaimer.</span>
<span class="comment">// 2. Redistributions in binary form must reproduce the above copyright notice, this</span>
<span class="comment">// list of conditions and the following disclaimer in the documentation and/or other</span>
<span class="comment">// materials provided with the distribution.</span>
<span class="comment">//</span>
<span class="comment">// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND</span>
<span class="comment">// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED</span>
<span class="comment">// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.</span>
<span class="comment">// IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,</span>
<span class="comment">// INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT</span>
<span class="comment">// NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR</span>
<span class="comment">// PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,</span>
<span class="comment">// WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)</span>
<span class="comment">// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE</span>
<span class="comment">// POSSIBILITY OF SUCH DAMAGE.</span>
<span class="kw">use</span> <span class="kw">crate</span>::<span class="ident">misc</span>::<span class="ident">PhantomMutexGuard</span>;
<span class="kw">use</span> <span class="kw">crate</span>::<span class="ident">result</span>::{<span class="ident">TryLockError</span>, <span class="ident">TryLockResult</span>};
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">fmt</span>::{<span class="self">self</span>, <span class="ident">Debug</span>, <span class="ident">Display</span>};
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">sync</span>::<span class="ident">atomic</span>::{<span class="ident">AtomicU8</span>, <span class="ident">Ordering</span>};
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">thread</span>;
<span class="doccomment">/// `Mutex8` is a set of mutexes. Each instance includes 8 mutexes.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The differences between `Mutex8` and [`Mutex`] are as follows.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// - `Mutex8` is not template structure. User must make sure to acquire lock before accessing to</span>
<span class="doccomment">/// the protected object. (Compiler cannot check it.)</span>
<span class="doccomment">/// - `Mutex8` gives up poisoning strategy. (This feature makes the performance better. It is a</span>
<span class="doccomment">/// good idea to use `Mutex8` instead of [`Mutex`] for the performance.)</span>
<span class="doccomment">/// - User can acquire 2 or more than 2 locks of one `Mutex8` instance at once.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`Mutex`]: struct.Mutex.html</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Mutex8</span>(<span class="ident">AtomicU8</span>);
<span class="kw">impl</span> <span class="ident">Mutex8</span> {
<span class="doccomment">/// The number of mutexes that one `Mutex8` has.</span>
<span class="kw">pub</span> <span class="kw">const</span> <span class="ident">LEN</span>: <span class="ident">usize</span> <span class="op">=</span> <span class="number">8</span>;
<span class="doccomment">/// Creates a new instance in an unlocked state ready for use.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Unlike to `std::sync::Mutex` , this is a const function.</span>
<span class="doccomment">/// It can be use to initialize static variable.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Declaring a static variable.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use spin_sync::Mutex8;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// static mutex8: Mutex8 = Mutex8::new();</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Declaring a local variable.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use spin_sync::Mutex8;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let mutex8 = Mutex8::new();</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">pub</span> <span class="kw">const</span> <span class="kw">fn</span> <span class="ident">new</span>() <span class="op">-</span><span class="op">></span> <span class="self">Self</span> {
<span class="self">Self</span>(<span class="ident">AtomicU8</span>::<span class="ident">new</span>(<span class="number">0</span>))
}
}
<span class="kw">impl</span> <span class="ident">Display</span> <span class="kw">for</span> <span class="ident">Mutex8</span> {
<span class="attribute">#[<span class="ident">inline</span>]</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="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">f</span>, <span class="string">"Mutex8"</span>)
}
}
<span class="kw">impl</span> <span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">Mutex8</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="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">"Mutex8"</span>)
.<span class="ident">field</span>(<span class="string">"locked_bits"</span>, <span class="kw-2">&</span><span class="self">self</span>.<span class="ident">locked_bits</span>())
.<span class="ident">finish</span>()
}
}
<span class="kw">impl</span> <span class="ident">Mutex8</span> {
<span class="doccomment">/// Blocks the current thread until acquiring the lock(s) indicated by `lock_bits` and returns</span>
<span class="doccomment">/// an RAII guard object.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Each bit of `lock_bits` indicates the lock of `Mutex8` . For example, '0x01' corresponds</span>
<span class="doccomment">/// to the first lock and '0x02' does to the second lock. If 2 or more than 2 bits are set, the</span>
<span class="doccomment">/// `lock_bits` means all of them. In case of '0x03', for example, it means both the first and</span>
<span class="doccomment">/// the second locks.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use spin_sync::Mutex8;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let mutex8 = Mutex8::new();</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // Acquire '0x01' and '0x02' in order.</span>
<span class="doccomment">/// {</span>
<span class="doccomment">/// let guard1 = mutex8.lock(0x01);</span>
<span class="doccomment">/// let guard2 = mutex8.lock(0x02);</span>
<span class="doccomment">/// }</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // Acquire '0x01' and '0x02' at the same time.</span>
<span class="doccomment">/// {</span>
<span class="doccomment">/// let guard3 = mutex8.lock(0x03);</span>
<span class="doccomment">/// }</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">lock</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">lock_bits</span>: <span class="ident">u8</span>) <span class="op">-</span><span class="op">></span> <span class="ident">Mutex8Guard</span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">expected</span> <span class="op">=</span> <span class="number">0</span>;
<span class="kw">while</span> {
<span class="macro">debug_assert_eq</span><span class="macro">!</span>(<span class="number">0</span>, <span class="ident">expected</span> <span class="op">&</span> <span class="ident">lock_bits</span>);
<span class="kw">let</span> <span class="ident">locked</span> <span class="op">=</span> <span class="ident">expected</span> <span class="op">+</span> <span class="ident">lock_bits</span>;
<span class="kw">let</span> <span class="ident">current</span> <span class="op">=</span> <span class="self">self</span>.<span class="number">0</span>.<span class="ident">compare_and_swap</span>(<span class="ident">expected</span>, <span class="ident">locked</span>, <span class="ident">Ordering</span>::<span class="ident">Acquire</span>);
<span class="kw">if</span> <span class="ident">expected</span> <span class="op">=</span><span class="op">=</span> <span class="ident">current</span> {
<span class="comment">// Succeeded to acquire</span>
<span class="bool-val">false</span>
} <span class="kw">else</span> <span class="kw">if</span> <span class="ident">current</span> <span class="op">&</span> <span class="ident">lock_bits</span> <span class="op">=</span><span class="op">=</span> <span class="number">0</span> {
<span class="comment">// The first assumuption was wrong.</span>
<span class="comment">// Try again soon.</span>
<span class="ident">expected</span> <span class="op">=</span> <span class="ident">current</span>;
<span class="bool-val">true</span>
} <span class="kw">else</span> {
<span class="comment">// Lock competition.</span>
<span class="ident">thread</span>::<span class="ident">yield_now</span>();
<span class="bool-val">true</span>
}
} {}
<span class="ident">Mutex8Guard</span> {
<span class="ident">bits</span>: <span class="ident">lock_bits</span>,
<span class="ident">mutex8</span>: <span class="kw-2">&</span><span class="self">self</span>,
<span class="ident">_phantom</span>: <span class="ident">Default</span>::<span class="ident">default</span>(),
}
}
<span class="doccomment">/// Attempts to acquire lock(s) indicated by `lock_bits` and returns an RAII guard object if</span>
<span class="doccomment">/// succeeded.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Each bit of `lock_bits` indicates the lock of `Mutex8` . For example, '0x01' corresponds</span>
<span class="doccomment">/// to the first lock and '0x02' does to the second lock. If 2 or more than 2 bits are set, the</span>
<span class="doccomment">/// `lock_bits` means all of them. In case of '0x03', for example, it means both the first and</span>
<span class="doccomment">/// the second locks.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Behaves like [`lock`] except for this method returns an error immediately if another user</span>
<span class="doccomment">/// is holding the lock.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This method does not block.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Errors</span>
<span class="doccomment">///</span>
<span class="doccomment">/// If another user is holding this mutex, [`TryLockError::WouldBlock`] is returned.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`lock`]: #method.lock</span>
<span class="doccomment">/// [`TryLockError::WouldBlock`]: type.TryLockError.html</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use spin_sync::Mutex8;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let mutex8 = Mutex8::new();</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // Try to acquire 0x01 twice. The second try will be fail.</span>
<span class="doccomment">/// {</span>
<span class="doccomment">/// let result1 = mutex8.try_lock(0x01);</span>
<span class="doccomment">/// assert_eq!(true, result1.is_ok());</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let result2 = mutex8.try_lock(0x01);</span>
<span class="doccomment">/// assert_eq!(true, result2.is_err());</span>
<span class="doccomment">/// }</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // Try to acquire 0x01 and 0x02 at the same time.</span>
<span class="doccomment">/// // After that, neither 0x01 nor 0x02 can be locked.</span>
<span class="doccomment">/// {</span>
<span class="doccomment">/// // Acquire locks 0x01 and 0x02 at once.</span>
<span class="doccomment">/// let result1 = mutex8.try_lock(0x03);</span>
<span class="doccomment">/// assert_eq!(true, result1.is_ok());</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let result2 = mutex8.try_lock(0x01);</span>
<span class="doccomment">/// assert_eq!(true, result2.is_err());</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let result3 = mutex8.try_lock(0x02);</span>
<span class="doccomment">/// assert_eq!(true, result3.is_err());</span>
<span class="doccomment">/// }</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">try_lock</span>(<span class="kw-2">&</span><span class="self">self</span>, <span class="ident">lock_bits</span>: <span class="ident">u8</span>) <span class="op">-</span><span class="op">></span> <span class="ident">TryLockResult</span><span class="op"><</span><span class="ident">Mutex8Guard</span><span class="op">></span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">expected</span> <span class="op">=</span> <span class="number">0</span>;
<span class="kw">while</span> {
<span class="macro">debug_assert_eq</span><span class="macro">!</span>(<span class="number">0</span>, <span class="ident">expected</span> <span class="op">&</span> <span class="ident">lock_bits</span>);
<span class="kw">let</span> <span class="ident">locked</span> <span class="op">=</span> <span class="ident">expected</span> <span class="op">+</span> <span class="ident">lock_bits</span>;
<span class="kw">let</span> <span class="ident">current</span> <span class="op">=</span> <span class="self">self</span>.<span class="number">0</span>.<span class="ident">compare_and_swap</span>(<span class="ident">expected</span>, <span class="ident">locked</span>, <span class="ident">Ordering</span>::<span class="ident">Acquire</span>);
<span class="kw">if</span> <span class="ident">expected</span> <span class="op">=</span><span class="op">=</span> <span class="ident">current</span> {
<span class="comment">// Succeeded to acquire</span>
<span class="bool-val">false</span>
} <span class="kw">else</span> <span class="kw">if</span> <span class="ident">current</span> <span class="op">&</span> <span class="ident">lock_bits</span> <span class="op">=</span><span class="op">=</span> <span class="number">0</span> {
<span class="comment">// The first assumuption was wrong.</span>
<span class="comment">// Try again soon.</span>
<span class="ident">expected</span> <span class="op">=</span> <span class="ident">current</span>;
<span class="bool-val">true</span>
} <span class="kw">else</span> {
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">TryLockError</span>::<span class="ident">WouldBlock</span>);
}
} {}
<span class="prelude-val">Ok</span>(<span class="ident">Mutex8Guard</span> {
<span class="ident">bits</span>: <span class="ident">lock_bits</span>,
<span class="ident">mutex8</span>: <span class="kw-2">&</span><span class="self">self</span>,
<span class="ident">_phantom</span>: <span class="ident">Default</span>::<span class="ident">default</span>(),
})
}
<span class="doccomment">/// Returns the bits that some [`Mutex8Guard`] instance(s) is holding.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Example</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use spin_sync::Mutex8;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let mutex8 = Mutex8::new();</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // Acquire 0x01.</span>
<span class="doccomment">/// let guard1 = mutex8.lock(0x01);</span>
<span class="doccomment">/// assert_eq!(0x01, mutex8.locked_bits());</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // Acquire 0x02.</span>
<span class="doccomment">/// let guard2 = mutex8.lock(0x02);</span>
<span class="doccomment">/// assert_eq!(0x03, mutex8.locked_bits());</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // Acquire 0x04 and 0x08 at the same time.</span>
<span class="doccomment">/// let mut guard3 = mutex8.lock(0x0c);</span>
<span class="doccomment">/// assert_eq!(0x0f, mutex8.locked_bits());</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // Release 0x08.</span>
<span class="doccomment">/// guard3.release(0x08);</span>
<span class="doccomment">/// assert_eq!(0x07, mutex8.locked_bits());</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">locked_bits</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">u8</span> {
<span class="self">self</span>.<span class="number">0</span>.<span class="ident">load</span>(<span class="ident">Ordering</span>::<span class="ident">Relaxed</span>)
}
<span class="doccomment">/// The number of mutexes that one `Mutex8` has.</span>
<span class="kw">pub</span> <span class="kw">const</span> <span class="kw">fn</span> <span class="ident">len</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">usize</span> {
<span class="self">Self</span>::<span class="ident">LEN</span>
}
}
<span class="doccomment">/// An RAII implementation of a "scoped lock(s)" of a [`Mutex8`] .</span>
<span class="doccomment">///</span>
<span class="doccomment">/// When this structure is dropped, all the lock(s) will be released at once.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`Mutex8`]: struct.Mutex8.html</span>
<span class="attribute">#[<span class="ident">must_use</span> <span class="op">=</span> <span class="string">"if unused the Mutex8 will immediately unlock"</span>]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Mutex8Guard</span><span class="op"><</span><span class="lifetime">'a</span><span class="op">></span> {
<span class="ident">bits</span>: <span class="ident">u8</span>,
<span class="ident">mutex8</span>: <span class="kw-2">&</span><span class="lifetime">'a</span> <span class="ident">Mutex8</span>,
<span class="ident">_phantom</span>: <span class="ident">PhantomMutexGuard</span><span class="op"><</span><span class="lifetime">'a</span>, <span class="ident">u8</span><span class="op">></span>, <span class="comment">// To implement !Send</span>
}
<span class="kw">impl</span> <span class="ident">Drop</span> <span class="kw">for</span> <span class="ident">Mutex8Guard</span><span class="op"><</span><span class="lifetime">'_</span><span class="op">></span> {
<span class="attribute">#[<span class="ident">inline</span>]</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">if</span> <span class="self">self</span>.<span class="ident">bits</span> <span class="op">!</span><span class="op">=</span> <span class="number">0</span> {
<span class="self">self</span>.<span class="ident">release</span>(<span class="self">self</span>.<span class="ident">bits</span>);
}
}
}
<span class="kw">impl</span> <span class="ident">Display</span> <span class="kw">for</span> <span class="ident">Mutex8Guard</span><span class="op"><</span><span class="lifetime">'_</span><span class="op">></span> {
<span class="attribute">#[<span class="ident">inline</span>]</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="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">f</span>, <span class="string">"Mutex8Guard"</span>)
}
}
<span class="kw">impl</span> <span class="ident">Debug</span> <span class="kw">for</span> <span class="ident">Mutex8Guard</span><span class="op"><</span><span class="lifetime">'_</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="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">"Mutex8Guard"</span>)
.<span class="ident">field</span>(<span class="string">"lock_bits"</span>, <span class="kw-2">&</span><span class="self">self</span>.<span class="ident">lock_bits</span>())
.<span class="ident">finish</span>()
}
}
<span class="kw">impl</span> <span class="ident">Mutex8Guard</span><span class="op"><</span><span class="lifetime">'_</span><span class="op">></span> {
<span class="doccomment">/// Releases the lock(s) partially indicated by `lock_bits` .</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Each bit of `lock_bits` indicates the lock of [`Mutex8`] . For example, '0x01' corresponds</span>
<span class="doccomment">/// to the first lock and '0x02' does to the second lock. If 2 or more than 2 bits are set, the</span>
<span class="doccomment">/// `lock_bits` means all of them. In case of '0x03', for example, it means both the first and</span>
<span class="doccomment">/// the second locks.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// If `lock_bits` is same to that is being holded, `self` releases all the locks; otherwise,</span>
<span class="doccomment">/// the others will still be being holded after the method returns.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// `lock_bits` must not include a bit that `self` is not holding.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Panics</span>
<span class="doccomment">///</span>
<span class="doccomment">/// Panics if `lock_bits` includes a bit that `self` is not holding.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// [`Mutex8`]: struct.Mutex8.html</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Examples</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use spin_sync::Mutex8;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let mutex8 = Mutex8::new();</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // Acquire 0x01 and 0x02 at the same time.</span>
<span class="doccomment">/// let mut guard = mutex8.lock(0x03);</span>
<span class="doccomment">///</span>
<span class="doccomment">/// {</span>
<span class="doccomment">/// // Fail to acquire 0x01 again.</span>
<span class="doccomment">/// let e = mutex8.try_lock(0x01);</span>
<span class="doccomment">/// assert!(e.is_err());</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // Fail to acquire 0x02 again.</span>
<span class="doccomment">/// let e = mutex8.try_lock(0x02);</span>
<span class="doccomment">/// assert!(e.is_err());</span>
<span class="doccomment">/// }</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // Release only 0x01. (0x02 is left.)</span>
<span class="doccomment">/// guard.release(0x01);</span>
<span class="doccomment">///</span>
<span class="doccomment">/// {</span>
<span class="doccomment">/// // Success to acquire 0x01 now.</span>
<span class="doccomment">/// let o = mutex8.try_lock(0x01);</span>
<span class="doccomment">/// assert!(o.is_ok());</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // Still fail to acquire 0x02.</span>
<span class="doccomment">/// let e = mutex8.try_lock(0x02);</span>
<span class="doccomment">/// assert!(e.is_err());</span>
<span class="doccomment">/// }</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">release</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">lock_bits</span>: <span class="ident">u8</span>) {
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">lock_bits</span>, <span class="self">self</span>.<span class="ident">bits</span> <span class="op">&</span> <span class="ident">lock_bits</span>);
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">expected</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">bits</span>;
<span class="kw">while</span> {
<span class="macro">debug_assert_eq</span><span class="macro">!</span>(<span class="self">self</span>.<span class="ident">bits</span>, <span class="ident">expected</span> <span class="op">&</span> <span class="self">self</span>.<span class="ident">bits</span>);
<span class="kw">let</span> <span class="ident">unlocked</span> <span class="op">=</span> <span class="ident">expected</span> <span class="op">-</span> <span class="ident">lock_bits</span>;
<span class="kw">let</span> <span class="ident">current</span> <span class="op">=</span> <span class="self">self</span>
.<span class="ident">mutex8</span>
.<span class="number">0</span>
.<span class="ident">compare_and_swap</span>(<span class="ident">expected</span>, <span class="ident">unlocked</span>, <span class="ident">Ordering</span>::<span class="ident">Release</span>);
<span class="kw">if</span> <span class="ident">current</span> <span class="op">=</span><span class="op">=</span> <span class="ident">expected</span> {
<span class="comment">// Succeeded to release.</span>
<span class="self">self</span>.<span class="ident">bits</span> <span class="op">-</span><span class="op">=</span> <span class="ident">lock_bits</span>;
<span class="bool-val">false</span>
} <span class="kw">else</span> {
<span class="comment">// First assumption was wrong.</span>
<span class="comment">// Try again.</span>
<span class="ident">expected</span> <span class="op">=</span> <span class="ident">current</span>;
<span class="bool-val">true</span>
}
} {}
}
<span class="doccomment">/// Returns the bits that `self` is holding.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// # Example</span>
<span class="doccomment">///</span>
<span class="doccomment">/// ```</span>
<span class="doccomment">/// use spin_sync::Mutex8;</span>
<span class="doccomment">///</span>
<span class="doccomment">/// let mutex8 = Mutex8::new();</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // Acquire 0x01 and 0x02 at the same time.</span>
<span class="doccomment">/// let mut guard = mutex8.lock(0x03);</span>
<span class="doccomment">/// assert_eq!(0x03, guard.lock_bits());</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // Release only 0x02. (0x01 is left.)</span>
<span class="doccomment">/// guard.release(0x02);</span>
<span class="doccomment">/// assert_eq!(0x01, guard.lock_bits());</span>
<span class="doccomment">///</span>
<span class="doccomment">/// // Release 0x01. (No lock is left.)</span>
<span class="doccomment">/// guard.release(0x01);</span>
<span class="doccomment">/// assert_eq!(0x00, guard.lock_bits());</span>
<span class="doccomment">/// ```</span>
<span class="attribute">#[<span class="ident">inline</span>]</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">lock_bits</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">u8</span> {
<span class="self">self</span>.<span class="ident">bits</span>
}
}
</pre></div>
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