[#BloombergLP-bslmt-Once-OnceLock]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bslmt.adoc[bslmt]::xref:BloombergLP/bslmt/Once.adoc[Once]::OnceLock
:relfileprefix: ../../../
:mrdocs:

Special token created by a single thread to pass to the `enter`, `leave`, and `cancel` methods.

== Synopsis

Declared in `<bslmt_once.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
typedef xref:BloombergLP/bslmt/QLockGuard.adoc[QLockGuard] OnceLock;
----


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