[#BloombergLP-bdlcc-FixedQueueIndexManager]
= xref:BloombergLP.adoc[BloombergLP]::xref:BloombergLP/bdlcc.adoc[bdlcc]::FixedQueueIndexManager
:relfileprefix: ../../
:mrdocs:

Thread‐enabled index manager for a fixed‐size circular buffer.

== Synopsis

Declared in `<bdlcc_fixedqueueindexmanager.h>`

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

== Description

This class implements a circular buffer of atomic state variables. These are intended to synchronize access to another (non‐atomic) indexed data structure so that the other data structure can be used as a thread‐enabled fixed‐size queue.

== Enums

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bdlcc/FixedQueueIndexManager/_04enum.adoc[`Unnamed enum`] 
| Capacity‐related constants for this index manager.
|===


== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bdlcc/FixedQueueIndexManager/2constructor.adoc[`FixedQueueIndexManager`]         [.small]#[constructor]#
| Create an index manager for a circular buffer having the specified maximum `capacity`.
| xref:BloombergLP/bdlcc/FixedQueueIndexManager/2destructor.adoc[`~FixedQueueIndexManager`] [.small]#[destructor]#
| Destroy this object.
| xref:BloombergLP/bdlcc/FixedQueueIndexManager/abortPushIndexReservation.adoc[`abortPushIndexReservation`] 
| Release the specified `index` for use in the next generation.
| xref:BloombergLP/bdlcc/FixedQueueIndexManager/capacity.adoc[`capacity`] 
| Return the maximum number of items that may be stored in the queue.
| xref:BloombergLP/bdlcc/FixedQueueIndexManager/commitPopIndex.adoc[`commitPopIndex`] 
| Mark the specified `index` as available (empty) in the next generation.
| xref:BloombergLP/bdlcc/FixedQueueIndexManager/commitPushIndex.adoc[`commitPushIndex`] 
| Mark the specified `index` as occupied (full) in the specified `generation`.
| xref:BloombergLP/bdlcc/FixedQueueIndexManager/disable.adoc[`disable`] 
| Mark the queue as disabled. Future calls to `reservePushIndex` will fail.
| xref:BloombergLP/bdlcc/FixedQueueIndexManager/enable.adoc[`enable`] 
| Mark the queue as enabled.
| xref:BloombergLP/bdlcc/FixedQueueIndexManager/isEnabled.adoc[`isEnabled`] 
| Return `true` if the queue is enabled, and `false` if it is disabled.
| xref:BloombergLP/bdlcc/FixedQueueIndexManager/length.adoc[`length`] 
| Return a snapshot of the number of items in the queue.
| xref:BloombergLP/bdlcc/FixedQueueIndexManager/print.adoc[`print`] 
| Print a formatted string describing the current state of this object to the specified `stream`.
| xref:BloombergLP/bdlcc/FixedQueueIndexManager/reservePopIndex.adoc[`reservePopIndex`] 
| Reserve the next available index from which to dequeue an element.
| xref:BloombergLP/bdlcc/FixedQueueIndexManager/reservePopIndexForClear.adoc[`reservePopIndexForClear`] 
| Reserve a pop index for clearing cells up to a push reservation.
| xref:BloombergLP/bdlcc/FixedQueueIndexManager/reservePushIndex.adoc[`reservePushIndex`] 
| Reserve the next available index at which to enqueue an element.
| xref:BloombergLP/bdlcc/FixedQueueIndexManager/2conversion.adoc[`operator BloombergLP::bslmf::NestedTraitDeclaration<FixedQueueIndexManager, UsesBslmaAllocator>`] 
| Declare that this type uses a `bslma` allocator.
|===


== Static Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bdlcc/FixedQueueIndexManager/circularDifference.adoc[`circularDifference`] 
| Return the signed circular difference of two values modulo a bound.
| xref:BloombergLP/bdlcc/FixedQueueIndexManager/numRepresentableGenerations.adoc[`numRepresentableGenerations`] 
| Return the number of representable generations for a circular buffer of the specified `capacity`.
|===



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