[#BloombergLP-bslmt-TimedSemaphoreImpl-041]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bslmt.adoc[bslmt]::xref:BloombergLP/bslmt/TimedSemaphoreImpl-09.adoc[TimedSemaphoreImpl]<xref:BloombergLP/bslmt/Platform/PosixAdvTimedSemaphore.adoc[Platform::PosixAdvTimedSemaphore]>
:relfileprefix: ../../
:mrdocs:

This class implements a timed semaphore in terms of POSIX operations. Note that only certain platforms provide `sem_timedwait`; on those that do not, `TimedSemaphoreImpl<PthreadTimedSemaphore>` is used.

== Synopsis

Declared in `<bslmt_timedsemaphoreimpl_posixadv.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<>
class xref:BloombergLP/bslmt/TimedSemaphoreImpl-09.adoc[TimedSemaphoreImpl]<xref:BloombergLP/bslmt/Platform/PosixAdvTimedSemaphore.adoc[Platform::PosixAdvTimedSemaphore]>;
----

== Enums

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslmt/TimedSemaphoreImpl-041/_04enum.adoc[`Unnamed enum`] 
| The value `timedWait` returns when a timeout occurs.
|===


== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bslmt/TimedSemaphoreImpl-041/2constructor-06.adoc[`TimedSemaphoreImpl`]         [.small]#[constructor]#
| Constructors
| xref:BloombergLP/bslmt/TimedSemaphoreImpl-041/2destructor.adoc[`~TimedSemaphoreImpl`] [.small]#[destructor]#
| Destroy this semaphore object.
| xref:BloombergLP/bslmt/TimedSemaphoreImpl-041/clockType.adoc[`clockType`] 
| Return the clock type used for timeouts.
| xref:BloombergLP/bslmt/TimedSemaphoreImpl-041/post-0d.adoc[`post`] 
| `post` overloads
| xref:BloombergLP/bslmt/TimedSemaphoreImpl-041/timedWait.adoc[`timedWait`] 
| Block until the count of this semaphore is a positive value, or until the specified `absTime` timeout expires. `absTime` is an _absolute_ time represented as an interval from some epoch, which is determined by the clock indicated at construction (see {Supported Clock‐Types} in the component documentation). If the `absTime` timeout did not expire before the count attained a positive value, atomically decrement the count and return 0; otherwise, return a non‐zero value with no effect on the count.
| xref:BloombergLP/bslmt/TimedSemaphoreImpl-041/tryWait.adoc[`tryWait`] 
| Decrement the count of this semaphore if it is positive and return 0. Return a non‐zero value otherwise.
| xref:BloombergLP/bslmt/TimedSemaphoreImpl-041/wait.adoc[`wait`] 
| Block until the count is a positive value and atomically decrement it.
|===



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