<!DOCTYPE html><htmllang="en"><head><metacharset="utf-8"><metaname="viewport"content="width=device-width, initial-scale=1.0"><metaname="generator"content="rustdoc"><metaname="description"content="API documentation for the Rust `ShardedLock` struct in crate `crossbeam_utils`."><metaname="keywords"content="rust, rustlang, rust-lang, ShardedLock"><title>crossbeam_utils::sync::ShardedLock - Rust</title><linkrel="stylesheet"type="text/css"href="../../normalize.css"><linkrel="stylesheet"type="text/css"href="../../rustdoc.css"id="mainThemeStyle"><linkrel="stylesheet"type="text/css"href="../../dark.css"><linkrel="stylesheet"type="text/css"href="../../light.css"id="themeStyle"><scriptsrc="../../storage.js"></script><noscript><linkrel="stylesheet"href="../../noscript.css"></noscript><linkrel="shortcut icon"href="../../favicon.ico"><styletype="text/css">#crate-search{background-image:url("../../down-arrow.svg");}</style></head><bodyclass="rustdoc struct"><!--[if lte IE 8]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><navclass="sidebar"><divclass="sidebar-menu">☰</div><ahref='../../crossbeam_utils/index.html'><divclass='logo-container'><imgsrc='../../rust-logo.png'alt='logo'></div></a><pclass='location'>Struct ShardedLock</p><divclass="sidebar-elems"><divclass="block items"><aclass="sidebar-title"href="#methods">Methods</a><divclass="sidebar-links"><ahref="#method.get_mut">get_mut</a><ahref="#method.into_inner">into_inner</a><ahref="#method.is_poisoned">is_poisoned</a><ahref="#method.new">new</a><ahref="#method.read">read</a><ahref="#method.try_read">try_read</a><ahref="#method.try_write">try_write</a><ahref="#method.write">write</a></div><aclass="sidebar-title"href="#implementations">Trait Implementations</a><divclass="sidebar-links"><ahref="#impl-Debug">Debug</a><ahref="#impl-Default">Default</a><ahref="#impl-From%3CT%3E">From<T></a><ahref="#impl-RefUnwindSafe">RefUnwindSafe</a><ahref="#impl-Send">Send</a><ahref="#impl-Sync">Sync</a><ahref="#impl-UnwindSafe">UnwindSafe</a></div><aclass="sidebar-title"href="#synthetic-implementations">Auto Trait Implementations</a><divclass="sidebar-links"><ahref="#impl-Unpin">Unpin</a></div><aclass="sidebar-title"href="#blanket-implementations">Blanket Implementations</a><divclass="sidebar-links"><ahref="#impl-Any">Any</a><ahref="#impl-Borrow%3CT%3E">Borrow<T></a><ahref="#impl-BorrowMut%3CT%3E">BorrowMut<T></a><ahref="#impl-From%3CT%3E">From<T></a><ahref="#impl-Into%3CU%3E">Into<U></a><ahref="#impl-TryFrom%3CU%3E">TryFrom<U></a><ahref="#impl-TryInto%3CU%3E">TryInto<U></a></div></div><pclass='location'><ahref='../index.html'>crossbeam_utils</a>::<wbr><ahref='index.html'>sync</a></p><script>window.sidebarCurrent={name:'ShardedLock',ty:'struct',relpath:''};</script><scriptdefersrc="sidebar-items.js"></script></div></nav><divclass="theme-picker"><buttonid="theme-picker"aria-label="Pick another theme!"><imgsrc="../../brush.svg"width="18"alt="Pick another theme!"></button><divid="theme-choices"></div></div><scriptsrc="../../theme.js"></script><navclass="sub"><formclass="search-form js-only"><divclass="search-container"><div><selectid="crate-search"><optionvalue="All crates">All crates</option></select><inputclass="search-input"name="search"autocomplete="off"spellcheck="false"placeholder="Click or press ‘S’ to search, ‘?’ for more options…"type="search"></div><aid="settings-menu"href="../../settings.html"><imgsrc="../../wheel.svg"width="18"alt="Change settings"></a></div></form></nav><sectionid="main"class="content"><h1class='fqn'><spanclass='out-of-band'><spanid='render-detail'><aid="toggle-all-docs"href="javascript:void(0)"title="collapse all docs">[<spanclass='inner'>−</span>]</a></span><aclass='srclink'href='../../src/crossbeam_utils/sync/sharded_lock.rs.html#75-81'title='goto source code'>[src]</a></span><spanclass='in-band'>Struct <ahref='../in
<p>This lock is equivalent to <ahref="https://doc.rust-lang.org/std/sync/struct.RwLock.html"><code>RwLock</code></a>, except read operations are faster and write operations
are slower.</p>
<p>A <code>ShardedLock</code> is internally made of a list of <em>shards</em>, each being a <ahref="https://doc.rust-lang.org/std/sync/struct.RwLock.html"><code>RwLock</code></a> occupying a
single cache line. Read operations will pick one of the shards depending on the current thread
and lock it. Write operations need to lock all shards in succession.</p>
<p>By splitting the lock into shards, concurrent read operations will in most cases choose
different shards and thus update different cache lines, which is good for scalability. However,
write operations need to do more work and are therefore slower than usual.</p>
<p>The priority policy of the lock is dependent on the underlying operating system's
implementation, and this type does not guarantee that any particular policy will be used.</p>
<p>A <code>ShardedLock</code>, like <ahref="https://doc.rust-lang.org/std/sync/struct.RwLock.html"><code>RwLock</code></a>, will become poisoned on a panic. Note that it may only be
poisoned if a panic occurs while a write operation is in progress. If a panic occurs in any
read operation, the lock will not be poisoned.</p>
</div><h4id='method.read'class="method"><codeid='read.v'>pub fn <ahref='#method.read'class='fnname'>read</a>(&self) -><aclass="type"href="https://doc.rust-lang.org/nightly/std/sys_common/poison/type.LockResult.html"title="type std::sys_common::poison::LockResult">LockResult</a><<aclass="struct"href="../../crossbeam_utils/sync/struct.ShardedLockReadGuard.html"title="struct crossbeam_utils::sync::ShardedLockReadGuard">ShardedLockReadGuard</a><T>></code><aclass='srclink'href='../../src/crossbeam_utils/sync/sharded_lock.rs.html#267-285'title='goto source code'>[src]</a></h4><divclass='docblock'><p>Locks with shared read access, blocking the current thread until it can be acquired.</p>
<p>The calling thread will be blocked until there are no more writers which hold the lock.
There may be other readers currently inside the lock when this method returns. This method
does not provide any guarantees with respect to the ordering of whether contentious readers
or writers will acquire the lock first.</p>
<p>Returns a guard which will release the shared access when dropped.</p>
</div><h4id='method.write'class="method"><codeid='write.v'>pub fn <ahref='#method.write'class='fnname'>write</a>(&self) -><aclass="type"href="https://doc.rust-lang.org/nightly/std/sys_common/poison/type.LockResult.html"title="type std::sys_common::poison::LockResult">LockResult</a><<aclass="struct"href="../../crossbeam_utils/sync/struct.ShardedLockWriteGuard.html"title="struct crossbeam_utils::sync::ShardedLockWriteGuard">ShardedLockWriteGuard</a><T>></code><aclass='srclink'href='../../src/crossbeam_utils/sync/sharded_lock.rs.html#380-413'title='goto source code'>[src]</a></h4><divclass='docblock'><p>Locks with exclusive write access, blocking the current thread until it can be acquired.</p>
<p>The calling thread will be blocked until there are no more writers which hold the lock.
There may be other readers currently inside the lock when this method returns. This method
does not provide any guarantees with respect to the ordering of whether contentious readers
or writers will acquire the lock first.</p>
<p>Returns a guard which will release the exclusive access when dropped.</p>
</div></div><h3id='impl-Debug'class='impl'><codeclass='in-band'>impl<T: ?<aclass="trait"href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html"title="trait core::marker::Sized">Sized</a> + <aclass="trait"href="https://doc.rust-lang.org/nightly/core/fmt/trait.Debug.html"title="trait core::fmt::Debug">Debug</a>><aclass="trait"href="https://doc.rust-lang.org/nightly/core/fmt/trait.Debug.html"title="trait core::fmt::Debug">Debug</a> for <aclass="struct"href="../../crossbeam_utils/sync/struct.ShardedLock.html"title="struct crossbeam_utils::sync::ShardedLock">ShardedLock</a><T></code><ahref='#impl-Debug'class='anchor'></a><aclass='srclink'href='../../src/crossbeam_utils/sync/sharded_lock.rs.html#416-434'title='goto source code'>[src]</a></h3><divclass='impl-items'><h4id='method.fmt'class="method hidden"><codeid='fmt.v'>fn <ahref='https://doc.rust-lang.org/nightly/core/fmt/trait.Debug.html#tymethod.fmt'class='fnname'>fmt</a>(&self, f: &mut <aclass="struct"href="https://doc.rust-lang.org/nightly/core/fmt/struct.Formatter.html"title="struct core::fmt::Formatter">Formatter</a>) -><aclass="type"href="https://doc.rust-lang.org/nightly/core/fmt/type.Result.html"title="type core::fmt::Result">Result</a></code><aclass='srclink'href='../../src/crossbeam_utils/sync/sharded_lock.rs.html#417-433'title='goto source code'>[src]</a></h4><divclass='docblock hidden'><p>Formats the value using the given formatter. <ahref="https://doc.rust-lang.org/nightly/core/fmt/trait.Debug.html#tymethod.fmt">Read more</a></p>
</div></div><h3id='impl-From%3CT%3E-1'class='impl'><codeclass='in-band'>impl<T><aclass="trait"href="https://doc.rust-lang.org/nightly/core/convert/trait.From.html"title="trait core::convert::From">From</a><T> for T</code><ahref='#impl-From%3CT%3E-1'class='anchor'></a><aclass='srclink'href='https://doc.rust-lang.org/nightly/src/core/convert.rs.html#552-554'title='goto source code'>[src]</a></h3><divclass='impl-items'><h4id='method.from-1'class="method hidden"><codeid='from.v-1'>fn <ahref='https://doc.rust-lang.org/nightly/core/convert/trait.From.html#tymethod.from'class='fnname'>from</a>(t: T) -> T</code><aclass='srclink'href='https://doc.rust-lang.org/nightly/src/core/convert.rs.html#553'title='goto source code'>[src]</a></h4><divclass='docblock hidden'><p>Performs the conversion.</p>
</div></div><h3id='impl-TryFrom%3CU%3E'class='impl'><codeclass='in-band'>impl<T, U><aclass="trait"href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html"title="trait core::convert::TryFrom">TryFrom</a><U> for T <spanclass="where fmt-newline">where<br> U: <aclass="trait"href="https://doc.rust-lang.org/nightly/core/convert/trait.Into.html"title="trait core::convert::Into">Into</a><T>, </span></code><ahref='#impl-TryFrom%3CU%3E'class='anchor'></a><aclass='srclink'href='https://doc.rust-lang.org/nightly/src/core/convert.rs.html#571-577'title='goto source code'>[src]</a></h3><divclass='impl-items'><h4id='associatedtype.Error'class="type"><codeid='Error.t'>type <ahref='https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html#associatedtype.Error'class="type">Error</a> = <aclass="enum"href="https://doc.rust-lang.org/nightly/core/convert/enum.Infallible.html"title="enum core::convert::Infallible">Infallible</a></code></h4><divclass='docblock'><p>The type returned in the event of a conversion error.</p>
</div><h4id='method.try_from'class="method hidden"><codeid='try_from.v'>fn <ahref='https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html#tymethod.try_from'class='fnname'>try_from</a>(value: U) -><aclass="enum"href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html"title="enum core::result::Result">Result</a><T, <T as <aclass="trait"href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html"title="trait core::convert::TryFrom">TryFrom</a><U>>::<aclass="type"href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html#associatedtype.Error"title="type core::convert::TryFrom::Error">Error</a>></code><aclass='srclink'href='https://doc.rust-lang.org/nightly/src/core/convert.rs.html#574-576'title='goto source code'>[src]</a></h4><divclass='docblock hidden'><p>Performs the conversion.</p>
</div></div><h3id='impl-TryInto%3CU%3E'class='impl'><codeclass='in-band'>impl<T, U><aclass="trait"href="https://doc.rust-lang.org/nightly/core/convert/trait.TryInto.html"title="trait core::convert::TryInto">TryInto</a><U> for T <spanclass="where fmt-newline">where<br> U: <aclass="trait"href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html"title="trait core::convert::TryFrom">TryFrom</a><T>, </span></code><ahref='#impl-TryInto%3CU%3E'class='anchor'></a><aclass='srclink'href='https://doc.rust-lang.org/nightly/src/core/convert.rs.html#559-566'title='goto source code'>[src]</a></h3><divclass='impl-items'><h4id='associatedtype.Error-1'class="type"><codeid='Error.t-1'>type <ahref='https://doc.rust-lang.org/nightly/core/convert/trait.TryInto.html#associatedtype.Error'class="type">Error</a> = <U as <aclass="trait"href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html"title="trait core::convert::TryFrom">TryFrom</a><T>>::<aclass="type"href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html#associatedtype.Error"title="type core::convert::TryFrom::Error">Error</a></code></h4><divclass='docblock'><p>The type returned in the event of a conversion error.</p>
</div><h4id='method.try_into'class="method hidden"><codeid='try_into.v'>fn <ahref='https://doc.rust-lang.org/nightly/core/convert/trait.TryInto.html#tymethod.try_into'class='fnname'>try_into</a>(self) -><aclass="enum"href="https://doc.rust-lang.org/nightly/core/result/enum.Result.html"title="enum core::result::Result">Result</a><U, <U as <aclass="trait"href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html"title="trait core::convert::TryFrom">TryFrom</a><T>>::<aclass="type"href="https://doc.rust-lang.org/nightly/core/convert/trait.TryFrom.html#associatedtype.Error"title="type core::convert::TryFrom::Error">Error</a>></code><aclass='srclink'href='https://doc.rust-lang.org/nightly/src/core/convert.rs.html#563-565'title='goto source code'>[src]</a></h4><divclass='docblock hidden'><p>Performs the conversion.</p>
</div></div><h3id='impl-BorrowMut%3CT%3E'class='impl'><codeclass='in-band'>impl<T><aclass="trait"href="https://doc.rust-lang.org/nightly/core/borrow/trait.BorrowMut.html"title="trait core::borrow::BorrowMut">BorrowMut</a><T> for T <spanclass="where fmt-newline">where<br> T: ?<aclass="trait"href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html"title="trait core::marker::Sized">Sized</a>, </span></code><ahref='#impl-BorrowMut%3CT%3E'class='anchor'></a><aclass='srclink'href='https://doc.rust-lang.org/nightly/src/core/borrow.rs.html#218-220'title='goto source code'>[src]</a></h3><divclass='impl-items'><h4id='method.borrow_mut'class="method hidden"><codeid='borrow_mut.v'>fn <ahref='https://doc.rust-lang.org/nightly/core/borrow/trait.BorrowMut.html#tymethod.borrow_mut'class='fnname'>borrow_mut</a>(&mut self) -><aclass="primitive"href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&mut </a>T</code><aclass='srclink'href='https://doc.rust-lang.org/nightly/src/core/borrow.rs.html#219'title='goto source code'>[src]</a></h4><divclass='docblock hidden'><p>Mutably borrows from an owned value. <ahref="https://doc.rust-lang.org/nightly/core/borrow/trait.BorrowMut.html#tymethod.borrow_mut">Read more</a></p>
</div></div><h3id='impl-Borrow%3CT%3E'class='impl'><codeclass='in-band'>impl<T><aclass="trait"href="https://doc.rust-lang.org/nightly/core/borrow/trait.Borrow.html"title="trait core::borrow::Borrow">Borrow</a><T> for T <spanclass="where fmt-newline">where<br> T: ?<aclass="trait"href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html"title="trait core::marker::Sized">Sized</a>, </span></code><ahref='#impl-Borrow%3CT%3E'class='anchor'></a><aclass='srclink'href='https://doc.rust-lang.org/nightly/src/core/borrow.rs.html#213-215'title='goto source code'>[src]</a></h3><divclass='impl-items'><h4id='method.borrow'class="method hidden"><codeid='borrow.v'>fn <ahref='https://doc.rust-lang.org/nightly/core/borrow/trait.Borrow.html#tymethod.borrow'class='fnname'>borrow</a>(&self) -><aclass="primitive"href="https://doc.rust-lang.org/nightly/std/primitive.reference.html">&</a>T</code><aclass='srclink'href='https://doc.rust-lang.org/nightly/src/core/borrow.rs.html#214'title='goto source code'>[src]</a></h4><divclass='docblock hidden'><p>Immutably borrows from an owned value. <ahref="https://doc.rust-lang.org/nightly/core/borrow/trait.Borrow.html#tymethod.borrow">Read more</a></p>
</div></div><h3id='impl-Any'class='impl'><codeclass='in-band'>impl<T><aclass="trait"href="https://doc.rust-lang.org/nightly/core/any/trait.Any.html"title="trait core::any::Any">Any</a> for T <spanclass="where fmt-newline">where<br> T: 'static + ?<aclass="trait"href="https://doc.rust-lang.org/nightly/core/marker/trait.Sized.html"title="trait core::marker::Sized">Sized</a>, </span></code><ahref='#impl-Any'class='anchor'></a><aclass='srclink'href='https://doc.rust-lang.org/nightly/src/core/any.rs.html#100-102'title='goto source code'>[src]</a></h3><divclass='impl-items'><h4id='method.type_id'class="method hidden"><codeid='type_id.v'>fn <ahref='https://doc.rust-lang.org/nightly/core/any/trait.Any.html#tymethod.type_id'class='fnname'>type_id</a>(&self) -><aclass="struct"href="https://doc.rust-lang.org/nightly/core/any/struct.TypeId.html"title="struct core::any::TypeId">TypeId</a></code><aclass='srclink'href='https://doc.rust-lang.org/nightly/src/core/any.rs.html#101'title='goto source code'>[src]</a></h4><divclass='docblock hidden'><p>Gets the <code>TypeId</code> of <code>self</code>. <ahref="https://doc.rust-lang.org/nightly/core/any/trait.Any.html#tymethod.type_id">Read more</a></p>
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