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

This class provides the means to acquire and release the lock on a `QLock` object. Typically, the lock is acquired at construction and released automatically on destruction. This class also provides explicit `lock`, `tryLock`, and `unlock` primitives.

== Synopsis

Declared in `<bslmt_qlock.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
class QLockGuard;
----

== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslmt/QLockGuard/2constructor-09.adoc[`QLockGuard`]         [.small]#[constructor]#
| Constructors
| xref:BloombergLP/bslmt/QLockGuard/2destructor.adoc[`~QLockGuard`] [.small]#[destructor]#
| Destroy this object. If this object holds a lock, automatically free it.
| xref:BloombergLP/bslmt/QLockGuard/lock-0f.adoc[`lock`] 
| `lock` overloads
| xref:BloombergLP/bslmt/QLockGuard/setQLock.adoc[`setQLock`] 
| Associate this guard with the specified `qlock`. The behavior is undefined if this object is already in a locked state.
| xref:BloombergLP/bslmt/QLockGuard/tryLock.adoc[`tryLock`] 
| Attempt to acquire a lock on the associated `QLock` object. Return 0 on success, a positive value of the associated QLock object is already locked, or a negative value if an error occurs.
| xref:BloombergLP/bslmt/QLockGuard/unlock.adoc[`unlock`] 
| Release the lock on the associated `QLock`. The behavior is undefined unless this guard previously acquired the lock and has not already released it.
|===



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