Priority Queue
Priority queue is a regular blocking queue which orders items using a comparator. Items in this queue do not necessarily follow the FIFO or LIFO order; you assign a comparator which defines the order in which items will be stored in the queue. Items with higher priority get polled first, regardless of when they have been added.
Its configuration is same as the regular queue as explained in [configuring-queue] except the additional comparator configuration element. A declarative example is shown below:
<queue name="default">
<max-size>10</max-size>
<backup-count>1</backup-count>
<item-listeners>
<item-listener include-value="true">com.hazelcast.examples.ItemListener</item-listener>
</item-listeners>
<queue-store>
<class-name>com.hazelcast.QueueStoreImpl</class-name>
<properties>
<property name="binary">false</property>
<property name="memory-limit">10000</property>
<property name="bulk-load">500</property>
</properties>
</queue-store>
<priority-comparator-class-name>com.hazelcast.collection.impl.queue.model.PriorityElementComparator</priority-comparator-class-name>
</queue>queue:
default:
statistics-enabled: true
max-size: 10
backup-count: 1
item-listeners:
- include-value: true
class-name: com.hazelcast.examples.ItemListener
queue-store:
class-name: com.hazelcast.QueueStoreImpl
properties:
binary: false
memory-limit: 1000
bulk-load: 500
priority-comparator-class-name: com.hazelcast.collection.impl.queue.model.PriorityElementComparatorThe priority-comparator-class-name element is the
fully-qualified comparator’s class name to be used for the priority queue.
If you do not provide a value, then the queue behaves as a regular FIFO queue.
When you provide a comparator, Hazelcast ignores the queue store
memory-limit configuration value.
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