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

This class provides a thread‐safe bounded queue of values that supports a single producer and a single consumer.

== Synopsis

Declared in `<bdlcc_singleproducersingleconsumerboundedqueue.h>`

[source,cpp,subs="verbatim,replacements,macros,-callouts"]
----
template<class TYPE>
class SingleProducerSingleConsumerBoundedQueue;
----

== Type Aliases

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bdlcc/SingleProducerSingleConsumerBoundedQueue/value_type.adoc[`value_type`] 
| The type for elements stored in this queue.
|===


== Enums

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bdlcc/SingleProducerSingleConsumerBoundedQueue/_04enum.adoc[`Unnamed enum`] 
| Status codes returned by queue operations.
|===


== Member Functions

[cols="1,4"]
|===
| Name| Description
| xref:BloombergLP/bdlcc/SingleProducerSingleConsumerBoundedQueue/2constructor.adoc[`SingleProducerSingleConsumerBoundedQueue`]         [.small]#[constructor]#
| Create a thread‐aware queue with at least the specified `capacity`. Optionally specify a `basicAllocator` used to supply memory. If `basicAllocator` is 0, the currently installed default allocator is used.
| xref:BloombergLP/bdlcc/SingleProducerSingleConsumerBoundedQueue/2destructor.adoc[`~SingleProducerSingleConsumerBoundedQueue`] [.small]#[destructor]#
| Destroy this object.
| xref:BloombergLP/bdlcc/SingleProducerSingleConsumerBoundedQueue/allocator.adoc[`allocator`] 
| Return the allocator used by this object to supply memory.
| xref:BloombergLP/bdlcc/SingleProducerSingleConsumerBoundedQueue/capacity.adoc[`capacity`] 
| Return the maximum number of elements that may be stored in this queue. Note that the value returned may be greater than that supplied at construction.
| xref:BloombergLP/bdlcc/SingleProducerSingleConsumerBoundedQueue/disablePopFront.adoc[`disablePopFront`] 
| Disable dequeueing from this queue. All subsequent invocations of `popFront` or `tryPopFront` will fail immediately. If the single consumer is blocked in `popFront`, the invocation of `popFront` will fail immediately. Any blocked invocations of `waitUntilEmpty` will fail immediately. If the queue is already dequeue disabled, this method has no effect.
| xref:BloombergLP/bdlcc/SingleProducerSingleConsumerBoundedQueue/disablePushBack.adoc[`disablePushBack`] 
| Disable enqueueing into this queue. All subsequent invocations of `pushBack` or `tryPushBack` will fail immediately. If the single producer is blocked in `pushBack`, the invocation of `pushBack` will fail immediately. If the queue is already enqueue disabled, this method has no effect.
| xref:BloombergLP/bdlcc/SingleProducerSingleConsumerBoundedQueue/enablePopFront.adoc[`enablePopFront`] 
| Enable dequeueing. If the queue is not dequeue disabled, this call has no effect.
| xref:BloombergLP/bdlcc/SingleProducerSingleConsumerBoundedQueue/enablePushBack.adoc[`enablePushBack`] 
| Enable queuing. If the queue is not enqueue disabled, this call has no effect.
| xref:BloombergLP/bdlcc/SingleProducerSingleConsumerBoundedQueue/isEmpty.adoc[`isEmpty`] 
| Return `true` if this queue is empty (has no elements), or `false` otherwise.
| xref:BloombergLP/bdlcc/SingleProducerSingleConsumerBoundedQueue/isFull.adoc[`isFull`] 
| Return `true` if this queue is full (has no available capacity), or `false` otherwise.
| xref:BloombergLP/bdlcc/SingleProducerSingleConsumerBoundedQueue/isPopFrontDisabled.adoc[`isPopFrontDisabled`] 
| Return `true` if this queue is dequeue disabled, and `false` otherwise. Note that the queue is created in the "dequeue enabled" state.
| xref:BloombergLP/bdlcc/SingleProducerSingleConsumerBoundedQueue/isPushBackDisabled.adoc[`isPushBackDisabled`] 
| Return `true` if this queue is enqueue disabled, and `false` otherwise. Note that the queue is created in the "enqueue enabled" state.
| xref:BloombergLP/bdlcc/SingleProducerSingleConsumerBoundedQueue/numElements.adoc[`numElements`] 
| Returns the number of elements currently in this queue.
| xref:BloombergLP/bdlcc/SingleProducerSingleConsumerBoundedQueue/popFront.adoc[`popFront`] 
| Remove the element from the front of this queue and load that element into the specified `value`. If the queue is empty, block until it is not empty. Return 0 on success, and a non‐zero value otherwise. Specifically, return `e_SUCCESS` on success, `e_DISABLED` if `isPopFrontDisabled()` and `e_FAILED` if an underlying mechanism returns an error. On failure, `value` is not changed. Threads blocked due to the queue being empty will return `e_DISABLED` if `disablePopFront` is invoked. The behavior is undefined unless the invoker of this method is the single consumer.
| xref:BloombergLP/bdlcc/SingleProducerSingleConsumerBoundedQueue/pushBack-0a.adoc[`pushBack`] 
| `pushBack` overloads
| xref:BloombergLP/bdlcc/SingleProducerSingleConsumerBoundedQueue/removeAll.adoc[`removeAll`] 
| Remove all items currently in this queue. Note that this operation is not atomic; if other threads are concurrently pushing items into the queue the result of `numElements()` after this function returns is not guaranteed to be 0. The behavior is undefined unless the invoker of this method is the single consumer.
| xref:BloombergLP/bdlcc/SingleProducerSingleConsumerBoundedQueue/tryPopFront.adoc[`tryPopFront`] 
| Attempt to remove the element from the front of this queue without blocking, and, if successful, load the specified `value` with the removed element. Return 0 on success, and a non‐zero value otherwise. Specifically, return `e_SUCCESS` on success, `e_DISABLED` if `isPopFrontDisabled()`, and `e_EMPTY` if `!isPopFrontDisabled()` and the queue was empty. On failure, `value` is not changed. The behavior is undefined unless the invoker of this method is the single consumer.
| xref:BloombergLP/bdlcc/SingleProducerSingleConsumerBoundedQueue/tryPushBack-0d5.adoc[`tryPushBack`] 
| `tryPushBack` overloads
| xref:BloombergLP/bdlcc/SingleProducerSingleConsumerBoundedQueue/waitUntilEmpty.adoc[`waitUntilEmpty`] 
| Block until all the elements in this queue are removed. Return 0 on success, and a non‐zero value otherwise. Specifically, return `e_SUCCESS` on success, `e_DISABLED` if `isPopFrontDisabled()` and `e_FAILED` if an underlying mechanism returns an error. A blocked thread waiting for the queue to empty will return a non‐zero value if `disablePopFront` is invoked.
| xref:BloombergLP/bdlcc/SingleProducerSingleConsumerBoundedQueue/2conversion.adoc[`operator BloombergLP::bslmf::NestedTraitDeclaration<SingleProducerSingleConsumerBoundedQueue, UsesBslmaAllocator>`] 
| Declare that this type uses a `bslma` allocator.
|===


== Friends

[cols="1,4"]
|===
| Name| Description
| `xref:BloombergLP/bdlcc/SingleProducerSingleConsumerBoundedQueue_PopCompleteGuard.adoc[BloombergLP::bdlcc::SingleProducerSingleConsumerBoundedQueue_PopCompleteGuard]`
| This class implements a guard that invokes `TYPE::popComplete` on a `NODE` upon destruction.
|===


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