This class implements a thread‐enabled multipriority queue whose priorities are restricted to a (small) set of contiguous N integer values, [ 0 .. N ‐ 1 ], with 0 being the most urgent.

Synopsis

Declared in <bdlcc_multipriorityqueue.h>

template<class TYPE>
class MultipriorityQueue;

Description

This class does have a notion of value, namely the sequence of priority/element pairs, constrained to be in decreasing order of urgency (i.e., monotonically increasing priority values). However, no value‐semantic operations are implemented. Note that elements having the same priority are maintained in First‐In‐First‐Out (FIFO) order. Note that the current implementation supports up to a maximum of sizeof(int) * CHAR_BIT priorities.

This class is implemented as a set of linked lists, one for each priority. Two vectors are used to maintain head and tail pointers for the lists.

Member Functions

Name

Description

MultipriorityQueue [constructor]

Constructors

~MultipriorityQueue [destructor]

Destroy this container. The behavior is undefined unless all access or modification of the container has completed prior to this call.

disable

Disable pushes to this multipriority queue. This method has no effect unless the queue was enabled.

enable

Enable pushes to this multipriority queue. This method has no effect unless the queue was disabled.

isEmpty

Return true if there are no items in this multi‐priority queue, and false otherwise.

isEnabled

Return true if this multipriority queue is enable and false otherwise.

length

Return the total number of items in this multi‐priority queue.

numPriorities

Return the number of distinct priorities (indicated at construction) that are supported by this multi‐priority queue.

popFront

Remove the least‐recently added item having the most urgent priority (lowest value) from this multi‐priority queue and load its value into the specified item. If this queue is empty, this method blocks the calling thread until an item becomes available. If the optionally specified itemPriority is non‐null, load the priority of the popped item into itemPriority. The behavior is undefined unless item is non‐null. Note this is unaffected by the enabled / disabled state of the queue.

pushBack

pushBack overloads

pushBackMultipleRaw

Insert the value of the specified item with the specified itemPriority onto the back of this multipriority queue before any queued items having a less urgent priority (higher value) than itemPriority, and after any items having the same or more urgent priority (lower value) than itemPriority. All of the specified numItems items are pushed as a single atomic action, unless the copy constructor for one of them throws an exception, in which case a possibly empty subset of the pushes will have completed and no memory will be leaked. Raw means that the push will succeed even if the multipriority queue is disabled. Note that this method is targeted for specific use by the class bdlmt::MultipriorityThreadPool. The behavior is undefined unless 0 <= itemPriority < numPriorities().

pushFrontMultipleRaw

Insert the value of the specified item with the specified itemPriority into the front of this multipriority queue the specified numItems times, before any queued items having the same or less urgent priority (higher value) than itemPriority, and after any items having more urgent priority (lower value) than itemPriority. All numItems items are pushed as a single atomic action, unless the copy constructor throws while creating one of them, in which case a possibly empty subset of the pushes will have completed and no memory will be leaked. Raw means that the push will succeed even if the multipriority queue is disabled. The behavior is undefined unless 0 <= itemPriority < numPriorities(). Note that this method is targeted at specific uses by the class bdlmt::MultipriorityThreadPool.

removeAll

Remove and destroy all items from this multi‐priority queue.

tryPopFront

Attempt to remove (immediately) the least‐recently added item having the most urgent priority (lowest value) from this multi‐priority queue. On success, load the value of the popped item into the specified item; if the optionally specified itemPriority is non‐null, load the priority of the popped item into itemPriority; and return 0. Otherwise, leave item and itemPriority unmodified, and return a non‐zero value indicating that this queue was empty. The behavior is undefined unless item is non‐null. Note this is unaffected by the enabled / disabled state of the queue.

operator BloombergLP::bslmf::NestedTraitDeclaration<MultipriorityQueue, UsesBslmaAllocator>

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