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

Decrement the event count by `numEvents` and release waiters if 0.

== Synopsis

Declared in `<bslmt_latch.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
void
countDown(int numEvents);
----

== Description

Decrement the number of events that this latch is waiting for by the specified `numEvents`, and if the resulting number of events is 0 release any waiting threads. The behavior is undefined unless `numEvents > 0` and the sum of all events that have arrived at this latch does not exceed the count with which it was initialized. Note that the initial count of events is supplied at construction.

== Parameters

[cols="1,4"]
|===
| Name| Description
| *numEvents*
| number of events by which to decrement the count
|===


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