Package org.jctools.queues
Class ConcurrentCircularArrayQueue<E>
java.lang.Object
java.util.AbstractCollection<E>
java.util.AbstractQueue<E>
org.jctools.queues.ConcurrentCircularArrayQueueL0Pad<E>
org.jctools.queues.ConcurrentCircularArrayQueue<E>
- All Implemented Interfaces:
Iterable<E>
,Collection<E>
,Queue<E>
,IndexedQueueSizeUtil.IndexedQueue
,MessagePassingQueue<E>
,QueueProgressIndicators
,SupportsIterator
- Direct Known Subclasses:
ConcurrentSequencedCircularArrayQueue
,FFBufferL1Pad
,MpscArrayQueueL1Pad
,SpmcArrayQueueL1Pad
,SpscArrayQueueColdField
abstract class ConcurrentCircularArrayQueue<E>
extends ConcurrentCircularArrayQueueL0Pad<E>
implements MessagePassingQueue<E>, IndexedQueueSizeUtil.IndexedQueue, QueueProgressIndicators, SupportsIterator
Common functionality for array backed queues. The class is pre-padded and the array is padded on either side to help
with False Sharing prevention. It is expected that subclasses handle post padding.
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Nested Class Summary
Nested ClassesModifier and TypeClassDescriptionprivate static class
Nested classes/interfaces inherited from interface org.jctools.queues.MessagePassingQueue
MessagePassingQueue.Consumer<T>, MessagePassingQueue.ExitCondition, MessagePassingQueue.Supplier<T>, MessagePassingQueue.WaitStrategy
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Field Summary
FieldsFields inherited from class org.jctools.queues.ConcurrentCircularArrayQueueL0Pad
b000, b001, b002, b003, b004, b005, b006, b007, b010, b011, b012, b013, b014, b015, b016, b017, b020, b021, b022, b023, b024, b025, b026, b027, b030, b031, b032, b033, b034, b035, b036, b037, b040, b041, b042, b043, b044, b045, b046, b047, b050, b051, b052, b053, b054, b055, b056, b057, b060, b061, b062, b063, b064, b065, b066, b067, b070, b071, b072, b073, b074, b075, b076, b077, b100, b101, b102, b103, b104, b105, b106, b107, b110, b111, b112, b113, b114, b115, b116, b117, b120, b121, b122, b123, b124, b125, b126, b127, b130, b131, b132, b133, b134, b135, b136, b137, b140, b141, b142, b143, b144, b145, b146, b147, b150, b151, b152, b153, b154, b155, b156, b157, b160, b161, b162, b163, b164, b165, b166, b167, b170, b171, b172, b173, b174, b175, b176, b177
Fields inherited from interface org.jctools.queues.MessagePassingQueue
UNBOUNDED_CAPACITY
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Constructor Summary
Constructors -
Method Summary
Modifier and TypeMethodDescriptionint
capacity()
void
clear()
Removes all items from the queue.long
This method has no concurrent visibility semantics.long
This method has no concurrent visibility semantics.boolean
isEmpty()
This method's accuracy is subject to concurrent modifications happening as the observation is carried out.iterator()
Get an iterator for this queue.int
size()
This method's accuracy is subject to concurrent modifications happening as the size is estimated and as such is a best effort rather than absolute value.toString()
Methods inherited from class java.util.AbstractQueue
add, addAll, element, remove
Methods inherited from class java.util.AbstractCollection
contains, containsAll, remove, removeAll, retainAll, toArray, toArray
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
Methods inherited from interface java.util.Collection
contains, containsAll, equals, hashCode, parallelStream, remove, removeAll, removeIf, retainAll, spliterator, stream, toArray, toArray, toArray
Methods inherited from interface org.jctools.queues.IndexedQueueSizeUtil.IndexedQueue
lvConsumerIndex, lvProducerIndex
Methods inherited from interface org.jctools.queues.MessagePassingQueue
drain, drain, drain, fill, fill, fill, offer, peek, poll, relaxedOffer, relaxedPeek, relaxedPoll
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Field Details
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mask
protected final long mask -
buffer
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Constructor Details
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ConcurrentCircularArrayQueue
ConcurrentCircularArrayQueue(int capacity)
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Method Details
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size
public int size()Description copied from interface:MessagePassingQueue
This method's accuracy is subject to concurrent modifications happening as the size is estimated and as such is a best effort rather than absolute value. For some implementations this method may be O(n) rather than O(1).- Specified by:
size
in interfaceCollection<E>
- Specified by:
size
in interfaceMessagePassingQueue<E>
- Specified by:
size
in classAbstractCollection<E>
- Returns:
- number of messages in the queue, between 0 and
Integer.MAX_VALUE
but less or equals to capacity (if bounded).
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isEmpty
public boolean isEmpty()Description copied from interface:MessagePassingQueue
This method's accuracy is subject to concurrent modifications happening as the observation is carried out.- Specified by:
isEmpty
in interfaceCollection<E>
- Specified by:
isEmpty
in interfaceMessagePassingQueue<E>
- Overrides:
isEmpty
in classAbstractCollection<E>
- Returns:
- true if empty, false otherwise
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toString
- Overrides:
toString
in classAbstractCollection<E>
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clear
public void clear()Description copied from interface:MessagePassingQueue
Removes all items from the queue. Called from the consumer thread subject to the restrictions appropriate to the implementation and according to theCollection.clear()
interface.- Specified by:
clear
in interfaceCollection<E>
- Specified by:
clear
in interfaceMessagePassingQueue<E>
- Overrides:
clear
in classAbstractQueue<E>
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capacity
public int capacity()- Specified by:
capacity
in interfaceIndexedQueueSizeUtil.IndexedQueue
- Specified by:
capacity
in interfaceMessagePassingQueue<E>
- Returns:
- the capacity of this queue or
MessagePassingQueue.UNBOUNDED_CAPACITY
if not bounded
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currentProducerIndex
public long currentProducerIndex()Description copied from interface:QueueProgressIndicators
This method has no concurrent visibility semantics. The value returned may be negative. Under normal circumstances 2 consecutive calls to this method can offer an idea of progress made by producer threads by subtracting the 2 results though in extreme cases (if producers have progressed by more than 2^64) this may also fail.
This value will normally indicate number of elements passed into the queue, but may under some circumstances be a derivative of that figure. This method should not be used to derive size or emptiness.- Specified by:
currentProducerIndex
in interfaceQueueProgressIndicators
- Returns:
- the current value of the producer progress index
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currentConsumerIndex
public long currentConsumerIndex()Description copied from interface:QueueProgressIndicators
This method has no concurrent visibility semantics. The value returned may be negative. Under normal circumstances 2 consecutive calls to this method can offer an idea of progress made by consumer threads by subtracting the 2 results though in extreme cases (if consumers have progressed by more than 2^64) this may also fail.
This value will normally indicate number of elements taken out of the queue, but may under some circumstances be a derivative of that figure. This method should not be used to derive size or emptiness.- Specified by:
currentConsumerIndex
in interfaceQueueProgressIndicators
- Returns:
- the current value of the consumer progress index
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iterator
Get an iterator for this queue. This method is thread safe.The iterator provides a best-effort snapshot of the elements in the queue. The returned iterator is not guaranteed to return elements in queue order, and races with the consumer thread may cause gaps in the sequence of returned elements. Like {link #relaxedPoll}, the iterator may not immediately return newly inserted elements.
- Specified by:
iterator
in interfaceCollection<E>
- Specified by:
iterator
in interfaceIterable<E>
- Specified by:
iterator
in classAbstractCollection<E>
- Returns:
- The iterator.
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