[#BloombergLP-bslmt-QLock-d_guardQueueTail]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bslmt.adoc[bslmt]::xref:BloombergLP/bslmt/QLock.adoc[QLock]::d&lowbar;guardQueueTail
:relfileprefix: ../../../
:mrdocs:

Pointer to the last guard in the queue of guards waiting for this lock, or 0 if the lock is unlocked&period;

== Synopsis

Declared in `&lt;bslmt&lowbar;qlock&period;h&gt;`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
xref:BloombergLP/bsls/Atomic_TypeTraits-0b/Pointer.adoc[bsls::AtomicOperations::AtomicTypes::Pointer] d&lowbar;guardQueueTail;
----

== Description

Note that the first guard in the queue owns the lock so that `d&lowbar;guardQueueTail` points to the owner of the lock when the lock is locked and there are no additional guards waiting&period;

It would have been preferable for this member to be private, but then this class would not be statically initializable&period; Also, it would have been preferable to make this member an instance of `bsls&colon;&colon;AtomicPointer&lt;&gt;`, but again, we would lose the ability to initialize statically&period;


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