<main><divclass="width-limiter"><navclass="sub"><formclass="search-form"><span></span><divid="sidebar-button"tabindex="-1"><ahref="../../tracing/all.html"title="show sidebar"></a></div><inputclass="search-input"name="search"aria-label="Run search in the documentation"autocomplete="off"spellcheck="false"placeholder="Click or press ‘S’ to search, ‘?’ for more options…"type="search"><divid="help-button"tabindex="-1"><ahref="../../help.html"title="help">?</a></div><divid="settings-menu"tabindex="-1"><ahref="../../settings.html"title="settings"><imgwidth="22"height="22"alt="Change settings"src="../../static.files/wheel-7b819b6101059cd0.svg"></a></div></form></nav><sectionid="main-content"class="content"><divclass="main-heading"><h1>Struct <ahref="../index.html">tracing</a>::<wbr><ahref="index.html">dispatcher</a>::<wbr><aclass="struct"href="#">WeakDispatch</a><buttonid="copy-path"title="Copy item path to clipboard"><imgsrc="../../static.files/clipboard-7571035ce49a181d.svg"width="19"height="18"alt="Copy item path"></button></h1><spanclass="out-of-band"><aclass="src"href="../../src/tracing_core/dispatcher.rs.html#178">source</a> · <buttonid="toggle-all-docs"title="collapse all docs">[<span>−</span>]</button></span></div><preclass="rust item-decl"><code>pub struct WeakDispatch { <spanclass="comment">/* private fields */</span> }</code></pre><detailsclass="toggle top-doc"open><summaryclass="hideme"><span>Expand description</span></summary><divclass="docblock"><p><code>WeakDispatch</code> is a version of <ahref="../struct.Dispatch.html"title="struct tracing::Dispatch"><code>Dispatch</code></a> that holds a non-owning reference
to a <ahref="../trait.Subscriber.html"title="trait tracing::Subscriber"><code>Subscriber</code></a>.</p>
<p>The Subscriber<code> may be accessed by calling [</code>WeakDispatch::upgrade<code>], which returns an </code>Option<Dispatch><code>. If all [</code>Dispatch<code>] clones that point at the </code>Subscriber<code> have been dropped, [</code>WeakDispatch::upgrade<code>] will return </code>None<code>. Otherwise, it will return </code>Some(Dispatch)`.</p>
<p>A <code>WeakDispatch</code> may be created from a <ahref="../struct.Dispatch.html"title="struct tracing::Dispatch"><code>Dispatch</code></a> by calling the
<ahref="../struct.Dispatch.html#method.downgrade"title="method tracing::Dispatch::downgrade"><code>Dispatch::downgrade</code></a> method. The primary use for creating a
<ahref="struct.WeakDispatch.html"title="struct tracing::dispatcher::WeakDispatch"><code>WeakDispatch</code></a> is to allow a Subscriber` to hold a cyclical reference to
itself without creating a memory leak. See <ahref="../trait.Subscriber.html#avoiding-memory-leaks"title="trait tracing::Subscriber">here</a> for details.</p>
<p>This type is analogous to the <ahref="https://doc.rust-lang.org/1.78.0/alloc/sync/struct.Weak.html"title="struct alloc::sync::Weak"><code>std::sync::Weak</code></a> type, but for a
<ahref="../struct.Dispatch.html"title="struct tracing::Dispatch"><code>Dispatch</code></a> rather than an <ahref="https://doc.rust-lang.org/1.78.0/alloc/sync/struct.Arc.html"title="struct alloc::sync::Arc"><code>Arc</code></a>.</p>
</div></details><h2id="implementations"class="section-header">Implementations<ahref="#implementations"class="anchor">§</a></h2><divid="implementations-list"><detailsclass="toggle implementors-toggle"open><summary><sectionid="impl-WeakDispatch"class="impl"><aclass="src rightside"href="../../src/tracing_core/dispatcher.rs.html#768">source</a><ahref="#impl-WeakDispatch"class="anchor">§</a><h3class="code-header">impl <aclass="struct"href="struct.WeakDispatch.html"title="struct tracing::dispatcher::WeakDispatch">WeakDispatch</a></h3></section></summary><divclass="impl-items"><detailsclass="toggle method-toggle"open><summary><sectionid="method.upgrade"class="method"><aclass="src rightside"href="../../src/tracing_core/dispatcher.rs.html#787">source</a><h4class="code-header">pub fn <ahref="#method.upgrade"class="fn">upgrade</a>(&self) -><aclass="enum"href="https://doc.rust-lang.org/1.78.0/core/option/enum.Option.html"title="enum core::option::Option">Option</a><<aclass="struct"href="../struct.Dispatch.html"title="struct tracing::Dispatch">Dispatch</a>></h4></section></summary><divclass="docblock"><p>Attempts to upgrade this <code>WeakDispatch</code> to a <ahref="../struct.Dispatch.html"title="struct tracing::Dispatch"><code>Dispatch</code></a>.</p>
</div></details></div></details><detailsclass="toggle implementors-toggle"><summary><sectionid="impl-Instrument-for-T"class="impl"><aclass="src rightside"href="../../src/tracing/instrument.rs.html#325">source</a><ahref="#impl-Instrument-for-T"class="anchor">§</a><h3class="code-header">impl<T><aclass="trait"href="../trait.Instrument.html"title="trait tracing::Instrument">Instrument</a> for T</h3></section></summary><divclass="impl-items"><detailsclass="toggle method-toggle"open><summary><sectionid="method.instrument"class="method trait-impl"><aclass="src rightside"href="../../src/tracing/instrument.rs.html#86-91">source</a><ahref="#method.instrument"class="anchor">§</a><h4class="code-header">fn <ahref="../trait.Instrument.html#method.instrument"class="fn">instrument</a>(self, span: <aclass="struct"href="../struct.Span.html"title="struct tracing::Span">Span</a>) -><aclass="struct"href="../instrument/struct.Instrumented.html"title="struct tracing::instrument::Instrumented">Instrumented</a><Self><ahref="#"class="tooltip"data-notable-ty="Instrumented<Self>">ⓘ</a></h4></section></summary><divclass='docblock'>Instruments this type with the provided <ahref="../struct.Span.html"title="struct tracing::Span"><code>Span</code></a>, returning an
<code>Instrumented</code> wrapper. <ahref="../trait.Instrument.html#method.instrument">Read more</a></div></details><detailsclass="toggle method-toggle"open><summary><sectionid="method.in_current_span"class="method trait-impl"><aclass="src rightside"href="../../src/tracing/instrument.rs.html#128-130">source</a><ahref="#method.in_current_span"class="anchor">§</a><h4class="code-header">fn <ahref="../trait.Instrument.html#method.in_current_span"class="fn">in_current_span</a>(self) -><aclass="struct"href="../instrument/struct.Instrumented.html"title="struct tracing::instrument::Instrumented">Instrumented</a><Self><ahref="#"class="tooltip"data-notable-ty="Instrumented<Self>">ⓘ</a></h4></section></summary><divclass='docblock'>Instruments this type with the <ahref="../struct.Span.html#method.current"title="associated function tracing::Span::current">current</a><ahref="../struct.Span.html"title="struct tracing::Span"><code>Span</code></a>, returning an
<code><ahref="https://doc.rust-lang.org/1.78.0/core/convert/trait.From.html"title="trait core::convert::From">From</a><T> for U</code> chooses to do.</p>
</div></details></div></details><detailsclass="toggle implementors-toggle"><summary><sectionid="impl-ToOwned-for-T"class="impl"><aclass="src rightside"href="https://doc.rust-lang.org/1.78.0/src/alloc/borrow.rs.html#83-85">source</a><ahref="#impl-ToOwned-for-T"class="anchor">§</a><h3class="code-header">impl<T><aclass="trait"href="https://doc.rust-lang.org/1.78.0/alloc/borrow/trait.ToOwned.html"title="trait alloc::borrow::ToOwned">ToOwned</a> for T<divclass="where">where
T: <aclass="trait"href="https://doc.rust-lang.org/1.78.0/core/clone/trait.Clone.html"title="trait core::clone::Clone">Clone</a>,</div></h3></section></summary><divclass="impl-items"><detailsclass="toggle"open><summary><sectionid="associatedtype.Owned"class="associatedtype trait-impl"><ahref="#associatedtype.Owned"class="anchor">§</a><h4class="code-header">type <ahref="https://doc.rust-lang.org/1.78.0/alloc/borrow/trait.ToOwned.html#associatedtype.Owned"class="associatedtype">Owned</a> = T</h4></section></summary><divclass='docblock'>The resulting type after obtaining ownership.</div></details><detailsclass="toggle method-toggle"open><summary><sectionid="method.to_owned"class="method trait-impl"><aclass="src rightside"href="https://doc.rust-lang.org/1.78.0/src/alloc/borrow.rs.html#88">source</a><ahref="#method.to_owned"class="anchor">§</a><h4class="code-header">fn <ahref="https://doc.rust-lang.org/1.78.0/alloc/borrow/trait.ToOwned.html#tymethod.to_owned"class="fn">to_owned</a>(&self) -> T</h4></section></summary><divclass='docblock'>Creates owned data from borrowed data, usually by cloning. <ahref="https://doc.rust-lang.org/1.78.0/alloc/borrow/trait.ToOwned.html#tymethod.to_owned">Read more</a></div></details><detailsclass="toggle method-toggle"open><summary><sectionid="method.clone_into"class="method trait-impl"><aclass="src rightside"href="https://doc.rust-lang.org/1.78.0/src/alloc/borrow.rs.html#92">source</a><ahref="#method.clone_into"class="anchor">§</a><h4class="code-header">fn <ahref="https://doc.rust-lang.org/1.78.0/alloc/borrow/trait.ToOwned.html#method.clone_into"class="fn">clone_into</a>(&self, target: <aclass="primitive"href="https://doc.rust-lang.org/1.78.0/std/primitive.reference.html">&mut T</a>)</h4></section></summary><divclass='docblock'>Uses borrowed data to replace owned data, usually by cloning. <ahref="https://doc.rust-lang.org/1.78.0/alloc/borrow/trait.ToOwned.html#method.clone_into">Read more</a></div></details></div></details><detailsclass="toggle implementors-toggle"><summary><sectionid="impl-TryFrom%3CU%3E-for-T"class="impl"><aclass="src rightside"href="https://doc.rust-lang.org/1.78.0/src/core/convert/mod.rs.html#805-807">source</a><ahref="#impl-TryFrom%3CU%3E-for-T"class="anchor">§</a><h3class="code-header">impl<T, U><aclass="trait"href="https://doc.rust-lang.org/1.78.0/core/convert/trait.TryFrom.html"title="trait core::convert::TryFrom">TryFrom</a><U> for T<divclass="where">where
U: <aclass="trait"href="https://doc.rust-lang.org/1.78.0/core/convert/trait.Into.html"title="trait core::convert::Into">Into</a><T>,</div></h3></section></summary><divclass="impl-items"><detailsclass="toggle"open><summary><sectionid="associatedtype.Error-1"class="associatedtype trait-impl"><ahref="#associatedtype.Error-1"class="anchor">§</a><h4class="code-header">type <ahref="https://doc.rust-lang.org/1.78.0/core/convert/trait.TryFrom.html#associatedtype.Error"class="associatedtype">Error</a> = <aclass="enum"href="https://doc.rust-lang.org/1.78.0/core/convert/enum.Infallible.html"title="enum core::convert::Infallible">Infallible</a></h4></section></summary><divclass='docblock'>The type returned in the event of a conversion error.</div></details><detailsclass="toggle method-toggle"open><summary><sectionid="method.try_from"class="method trait-impl"><aclass="src rightside"href="https://doc.rust-lang.org/1.78.0/src/core/convert/mod.rs.html#812">source</a><ahref="#method.try_from"class="anchor">§</a><h4class="code-header">fn <ahref="https://doc.rust-lang.org/1.78.0/core/convert/trait.TryFrom.html#tymethod.try_from"class="fn">try_from</a>(value: U) -><aclass="enum"href="https://doc.rust-lang.org/1.78.0/core/result/enum.Result.html"title="enum core::result::Result">Result</a><T, <T as <aclass="trait"href="https://doc.rust-lang.org/1.78.0/core/convert/trait.TryFrom.html"title="trait core::convert::TryFrom">TryFrom</a><U>>::<aclass="associatedtype"href="https://doc.rust-lang.org/1.78.0/core/convert/trait.TryFrom.html#associatedtype.Error"title="type core::convert::TryFrom::Error">Error</a>></h4></section></summary><divclass='docblock'>Performs the conversion.</div></details></div></details><detailsclass="toggle implementors-toggle"><summary><sectionid="impl-TryInto%3CU%3E-for-T"class="impl"><aclass="src rightside"href="https://doc.rust-lang.org/1.78.0/src/core/convert/mod.rs.html#790-792">source</a><ahref="#impl-TryInto%3CU%3E-for-T"class="anchor">§</a><h3class="code-header">impl<T, U><aclass="trait"href="https://doc.rust-lang.org/1.78.0/core/convert/trait.TryInto.html"title="trait core::convert::TryInto">TryInto</a><U> for T<divclass="where">where
U: <aclass="trait"href="https://doc.rust-lang.org/1.78.0/core/convert/trait.TryFrom.html"title="trait core::convert::TryFrom">TryFrom</a><T>,</div></h3></section></summary><divclass="impl-items"><detailsclass="toggle"open><summary><sectionid="associatedtype.Error"class="associatedtype trait-impl"><ahref="#associatedtype.Error"class="anchor">§</a><h4class="code-header">type <ahref="https://doc.rust-lang.org/1.78.0/core/convert/trait.TryInto.html#associatedtype.Error"class="associatedtype">Error</a> = <U as <aclass="trait"href="https://doc.rust-lang.org/1.78.0/core/convert/trait.TryFrom.html"title="trait core::convert::TryFrom">TryFrom</a><T>>::<aclass="associatedtype"href="https://doc.rust-lang.org/1.78.0/core/convert/trait.TryFrom.html#associatedtype.Error"title="type core::convert::TryFrom::Error">Error</a></h4></section></summary><divclass='docblock'>The type returned in the event of a conversion error.</div></details><detailsclass="toggle method-toggle"open><summary><sectionid="method.try_into"class="method trait-impl"><aclass="src rightside"href="https://doc.rust-lang.org/1.78.0/src/core/convert/mod.rs.html#797">source</a><ahref="#method.try_into"class="anchor">§</a><h4class="code-header">fn <ahref="https://doc.rust-lang.org/1.78.0/core/convert/trait.TryInto.html#tymethod.try_into"class="fn">try_into</a>(self) -><aclass="enum"href="https://doc.rust-lang.org/1.78.0/core/result/enum.Result.html"title="enum core::result::Result">Result</a><U, <U as <aclass="trait"href="https://doc.rust-lang.org/1.78.0/core/convert/trait.TryFrom.html"title="trait core::convert::TryFrom">TryFrom</a><T>>::<aclass="associatedtype"href="https://doc.rust-lang.org/1.78.0/core/convert/trait.TryFrom.html#associatedtype.Error"title="type core::convert::TryFrom::Error">Error</a>></h4></section></summary><divclass='docblock'>Performs the conversion.</div></details></div></details><detailsclass="toggle implementors-toggle"><summary><sectionid="impl-WithSubscriber-for-T"class="impl"><aclass="src rightside"href="../../src/tracing/instrument.rs.html#393">source</a><ahref="#impl-WithSubscriber-for-T"class="anchor">§</a><h3class="code-header">impl<T><aclass="trait"href="../instrument/trait.WithSubscriber.html"title="trait tracing::instrument::WithSubscriber">WithSubscriber</a> for T</h3></section></summary><divclass="impl-items"><detailsclass="toggle method-toggle"open><summary><sectionid="method.with_subscriber"class="method trait-impl"><aclass="src rightside"href="../../src/tracing/instrument.rs.html#176-184">source</a><ahref="#method.with_subscriber"class="anchor">§</a><h4class="code-header">fn <ahref="../instrument/trait.WithSubscriber.html#method.with_subscriber"class="fn">with_subscriber</a><S>(self, subscriber: S) -><aclass="struct"href="../instrument/struct.WithDispatch.html"title="struct tracing::instrument::WithDispatch">WithDispatch</a><Self><ahref="#"class="tooltip"data-notable-ty="WithDispatch<Self>">ⓘ</a><divclass="where">where
S: <aclass="trait"href="https://doc.rust-lang.org/1.78.0/core/convert/trait.Into.html"title="trait core::convert::Into">Into</a><<aclass="struct"href="../struct.Dispatch.html"title="struct tracing::Dispatch">Dispatch</a>>,</div></h4></section></summary><divclass='docblock'>Attaches the provided <ahref="../trait.Subscriber.html"title="trait tracing::Subscriber"><code>Subscriber</code></a> to this type, returning a
<ahref="../instrument/struct.WithDispatch.html"title="struct tracing::instrument::WithDispatch"><code>WithDispatch</code></a> wrapper. <ahref="../instrument/trait.WithSubscriber.html#method.with_subscriber">Read more</a></div></details><detailsclass="toggle method-toggle"open><summary><sectionid="method.with_current_subscriber"class="method trait-impl"><aclass="src rightside"href="../../src/tracing/instrument.rs.html#228-233">source</a><ahref="#method.with_current_subscriber"class="anchor">§</a><h4class="code-header">fn <ahref="../instrument/trait.WithSubscriber.html#method.with_current_subscriber"class="fn">with_current_subscriber</a>(self) -><aclass="struct"href="../instrument/struct.WithDispatch.html"title="struct tracing::instrument::WithDispatch">WithDispatch</a><Self><ahref="#"class="tooltip"data-notable-ty="WithDispatch<Self>">ⓘ</a></h4></section></summary><divclass='docblock'>Attaches the current <ahref="index.html#setting-the-default-subscriber"title="mod tracing::dispatcher">default</a><ahref="../trait.Subscriber.html"title="trait tracing::Subscriber"><code>Subscriber</code></a> to this type, returning a
