Class SpscUnpaddedArrayQueue<E>
- java.lang.Object
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- java.util.AbstractCollection<E>
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- java.util.AbstractQueue<E>
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- org.jctools.queues.unpadded.ConcurrentCircularUnpaddedArrayQueueL0Pad<E>
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- org.jctools.queues.unpadded.ConcurrentCircularUnpaddedArrayQueue<E>
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- org.jctools.queues.unpadded.SpscUnpaddedArrayQueueColdField<E>
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- org.jctools.queues.unpadded.SpscUnpaddedArrayQueueL1Pad<E>
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- org.jctools.queues.unpadded.SpscUnpaddedArrayQueueProducerIndexFields<E>
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- org.jctools.queues.unpadded.SpscUnpaddedArrayQueueL2Pad<E>
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- org.jctools.queues.unpadded.SpscUnpaddedArrayQueueConsumerIndexField<E>
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- org.jctools.queues.unpadded.SpscUnpaddedArrayQueueL3Pad<E>
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- org.jctools.queues.unpadded.SpscUnpaddedArrayQueue<E>
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- All Implemented Interfaces:
java.lang.Iterable<E>
,java.util.Collection<E>
,java.util.Queue<E>
,IndexedQueueSizeUtil.IndexedQueue
,MessagePassingQueue<E>
,QueueProgressIndicators
,SupportsIterator
public class SpscUnpaddedArrayQueue<E> extends SpscUnpaddedArrayQueueL3Pad<E>
NOTE: This class was automatically generated by org.jctools.queues.unpadded.JavaParsingUnpaddedQueueGenerator which can found in the jctools-build module. The original source file is SpscArrayQueue.java. A Single-Producer-Single-Consumer queue backed by a pre-allocated buffer.This implementation is a mashup of the Fast Flow algorithm with an optimization of the offer method taken from the BQueue algorithm (a variation on Fast Flow), and adjusted to comply with Queue.offer semantics with regards to capacity.
For convenience the relevant papers are available in the `resources` folder:
2010 - Pisa - SPSC Queues on Shared Cache Multi-Core Systems.pdf
2012 - Junchang- BQueue- Efficient and Practical Queuing.pdf
This implementation is wait free.
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Nested Class Summary
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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
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Fields inherited from class org.jctools.queues.unpadded.SpscUnpaddedArrayQueueProducerIndexFields
producerLimit
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Fields inherited from class org.jctools.queues.unpadded.SpscUnpaddedArrayQueueColdField
lookAheadStep
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Fields inherited from class org.jctools.queues.unpadded.ConcurrentCircularUnpaddedArrayQueue
buffer, mask
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Fields inherited from interface org.jctools.queues.MessagePassingQueue
UNBOUNDED_CAPACITY
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Constructor Summary
Constructors Constructor Description SpscUnpaddedArrayQueue(int capacity)
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description int
drain(MessagePassingQueue.Consumer<E> c)
Remove all available item from the queue and hand to consume.int
drain(MessagePassingQueue.Consumer<E> c, int limit)
Remove up to limit elements from the queue and hand to consume.void
drain(MessagePassingQueue.Consumer<E> c, MessagePassingQueue.WaitStrategy w, MessagePassingQueue.ExitCondition exit)
Remove elements from the queue and hand to consume forever.int
fill(MessagePassingQueue.Supplier<E> s)
Stuff the queue with elements from the supplier.int
fill(MessagePassingQueue.Supplier<E> s, int limit)
Stuff the queue with up to limit elements from the supplier.void
fill(MessagePassingQueue.Supplier<E> s, MessagePassingQueue.WaitStrategy w, MessagePassingQueue.ExitCondition e)
Stuff the queue with elements from the supplier forever.boolean
offer(E e)
Called from a producer thread subject to the restrictions appropriate to the implementation and according to theQueue.offer(Object)
interface.private boolean
offerSlowPath(E[] buffer, long mask, long producerIndex)
E
peek()
Called from the consumer thread subject to the restrictions appropriate to the implementation and according to theQueue.peek()
interface.E
poll()
Called from the consumer thread subject to the restrictions appropriate to the implementation and according to theQueue.poll()
interface.boolean
relaxedOffer(E message)
Called from a producer thread subject to the restrictions appropriate to the implementation.E
relaxedPeek()
Called from the consumer thread subject to the restrictions appropriate to the implementation.E
relaxedPoll()
Called from the consumer thread subject to the restrictions appropriate to the implementation.-
Methods inherited from class org.jctools.queues.unpadded.SpscUnpaddedArrayQueueConsumerIndexField
lpConsumerIndex, lvConsumerIndex, soConsumerIndex
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Methods inherited from class org.jctools.queues.unpadded.SpscUnpaddedArrayQueueProducerIndexFields
lpProducerIndex, lvProducerIndex, soProducerIndex
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Methods inherited from class org.jctools.queues.unpadded.ConcurrentCircularUnpaddedArrayQueue
capacity, clear, currentConsumerIndex, currentProducerIndex, isEmpty, iterator, size, toString
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Methods inherited from class java.util.AbstractCollection
contains, containsAll, remove, removeAll, retainAll, toArray, toArray
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Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait
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Method Detail
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offer
public boolean offer(E e)
Called from a producer thread subject to the restrictions appropriate to the implementation and according to theQueue.offer(Object)
interface.This implementation is correct for single producer thread use only.
- Parameters:
e
- notnull
, will throw NPE if it is- Returns:
- true if element was inserted into the queue, false iff full
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offerSlowPath
private boolean offerSlowPath(E[] buffer, long mask, long producerIndex)
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poll
public E poll()
Called from the consumer thread subject to the restrictions appropriate to the implementation and according to theQueue.poll()
interface.This implementation is correct for single consumer thread use only.
- Returns:
- a message from the queue if one is available,
null
iff empty
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peek
public E peek()
Called from the consumer thread subject to the restrictions appropriate to the implementation and according to theQueue.peek()
interface.This implementation is correct for single consumer thread use only.
- Returns:
- a message from the queue if one is available,
null
iff empty
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relaxedOffer
public boolean relaxedOffer(E message)
Description copied from interface:MessagePassingQueue
Called from a producer thread subject to the restrictions appropriate to the implementation. As opposed toQueue.offer(Object)
this method may return false without the queue being full.- Parameters:
message
- notnull
, will throw NPE if it is- Returns:
- true if element was inserted into the queue, false if unable to offer
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relaxedPoll
public E relaxedPoll()
Description copied from interface:MessagePassingQueue
Called from the consumer thread subject to the restrictions appropriate to the implementation. As opposed toQueue.poll()
this method may returnnull
without the queue being empty.- Returns:
- a message from the queue if one is available,
null
if unable to poll
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relaxedPeek
public E relaxedPeek()
Description copied from interface:MessagePassingQueue
Called from the consumer thread subject to the restrictions appropriate to the implementation. As opposed toQueue.peek()
this method may returnnull
without the queue being empty.- Returns:
- a message from the queue if one is available,
null
if unable to peek
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drain
public int drain(MessagePassingQueue.Consumer<E> c)
Description copied from interface:MessagePassingQueue
Remove all available item from the queue and hand to consume. This should be semantically similar to:M m; while((m = relaxedPoll()) != null){ c.accept(m); }
There's no strong commitment to the queue being empty at the end of a drain. Called from a consumer thread subject to the restrictions appropriate to the implementation.WARNING: Explicit assumptions are made with regards to
MessagePassingQueue.Consumer.accept(T)
make sure you have read and understood these before using this method.- Returns:
- the number of polled elements
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fill
public int fill(MessagePassingQueue.Supplier<E> s)
Description copied from interface:MessagePassingQueue
Stuff the queue with elements from the supplier. Semantically similar to:while(relaxedOffer(s.get());
There's no strong commitment to the queue being full at the end of a fill. Called from a producer thread subject to the restrictions appropriate to the implementation.Unbounded queues will fill up the queue with a fixed amount rather than fill up to oblivion. WARNING: Explicit assumptions are made with regards to
MessagePassingQueue.Supplier.get()
make sure you have read and understood these before using this method.- Returns:
- the number of offered elements
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drain
public int drain(MessagePassingQueue.Consumer<E> c, int limit)
Description copied from interface:MessagePassingQueue
Remove up to limit elements from the queue and hand to consume. This should be semantically similar to:M m; int i = 0; for(;i < limit && (m = relaxedPoll()) != null; i++){ c.accept(m); } return i;
There's no strong commitment to the queue being empty at the end of a drain. Called from a consumer thread subject to the restrictions appropriate to the implementation.
WARNING: Explicit assumptions are made with regards to
MessagePassingQueue.Consumer.accept(T)
make sure you have read and understood these before using this method.- Returns:
- the number of polled elements
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fill
public int fill(MessagePassingQueue.Supplier<E> s, int limit)
Description copied from interface:MessagePassingQueue
Stuff the queue with up to limit elements from the supplier. Semantically similar to:for(int i=0; i < limit && relaxedOffer(s.get()); i++);
There's no strong commitment to the queue being full at the end of a fill. Called from a producer thread subject to the restrictions appropriate to the implementation. WARNING: Explicit assumptions are made with regards to
MessagePassingQueue.Supplier.get()
make sure you have read and understood these before using this method.- Returns:
- the number of offered elements
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drain
public void drain(MessagePassingQueue.Consumer<E> c, MessagePassingQueue.WaitStrategy w, MessagePassingQueue.ExitCondition exit)
Description copied from interface:MessagePassingQueue
Remove elements from the queue and hand to consume forever. Semantically similar to:int idleCounter = 0; while (exit.keepRunning()) { E e = relaxedPoll(); if(e==null){ idleCounter = wait.idle(idleCounter); continue; } idleCounter = 0; c.accept(e); }
Called from a consumer thread subject to the restrictions appropriate to the implementation.
WARNING: Explicit assumptions are made with regards to
MessagePassingQueue.Consumer.accept(T)
make sure you have read and understood these before using this method.
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fill
public void fill(MessagePassingQueue.Supplier<E> s, MessagePassingQueue.WaitStrategy w, MessagePassingQueue.ExitCondition e)
Description copied from interface:MessagePassingQueue
Stuff the queue with elements from the supplier forever. Semantically similar to:int idleCounter = 0; while (exit.keepRunning()) { E e = s.get(); while (!relaxedOffer(e)) { idleCounter = wait.idle(idleCounter); continue; } idleCounter = 0; }
Called from a producer thread subject to the restrictions appropriate to the implementation. The main difference being that implementors MUST assure room in the queue is available BEFORE calling
MessagePassingQueue.Supplier.get()
. WARNING: Explicit assumptions are made with regards toMessagePassingQueue.Supplier.get()
make sure you have read and understood these before using this method.
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