[#BloombergLP-bdlmt-ThreadMultiplexor]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bdlmt.adoc[bdlmt]::ThreadMultiplexor
:relfileprefix: ../../
:mrdocs:

This class provides a mechanism for facilitating the use of multiple threads to perform various user‐defined functions ("jobs") when some degree of collaboration between threads is required. The thread multiplexor is configured with a total number of "processors", representing the number of threads that may process jobs at any particular time. Additional threads enqueue jobs to a pending job queue, which is processed by the next available processing thread.

== Synopsis

Declared in `<bdlmt_threadmultiplexor.h>`

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

== Type Aliases

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bdlmt/ThreadMultiplexor/Job.adoc[`Job`] 
| A callback of this type may be passed to the `processJob` method.
|===


== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bdlmt/ThreadMultiplexor/2constructor.adoc[`ThreadMultiplexor`]         [.small]#[constructor]#
| Create a thread multiplexor which uses, at most, the specified `maxProcessors` number of threads to process user‐specified jobs, identified as callbacks of type `Job`. Jobs that cannot be processed immediately are placed on a queue having the specified `maxQueueSize` to be processed by the next free thread. Optionally specify a `basicAllocator` used to supply memory. If `basicAllocator` is 0, the currently installed default allocator is used. The behavior is undefined unless `0 < maxProcessors` and `0 < maxQueueSize`.
| xref:BloombergLP/bdlmt/ThreadMultiplexor/2destructor.adoc[`~ThreadMultiplexor`] [.small]#[destructor]#
| Destroy this thread multiplexor object.
| xref:BloombergLP/bdlmt/ThreadMultiplexor/maxProcessors.adoc[`maxProcessors`] 
| Return the maximum number of active processors.
| xref:BloombergLP/bdlmt/ThreadMultiplexor/numProcessors.adoc[`numProcessors`] 
| Return the current number of active processors.
| xref:BloombergLP/bdlmt/ThreadMultiplexor/processJob.adoc[`processJob`] 
| Process the specified `job` functor in the calling thread if the current number of processors is less than the maximum number of processors. Otherwise, enqueue `job` to the pending job queue. Return 0 on success, and a non‐zero value otherwise. Note that the only requirements on `t_JOBTYPE` are that it defines `operator()`, having a `void` return type, and that it defines a copy constructor.
| xref:BloombergLP/bdlmt/ThreadMultiplexor/2conversion.adoc[`operator BloombergLP::bslmf::NestedTraitDeclaration<ThreadMultiplexor, UsesBslmaAllocator>`] 
| Declare that this type uses a `bslma` allocator.
|===



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