Class MpscLinkedQueue<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.BaseLinkedQueuePad0<E>
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- org.jctools.queues.BaseLinkedQueueProducerNodeRef<E>
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- org.jctools.queues.BaseLinkedQueuePad1<E>
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- org.jctools.queues.BaseLinkedQueueConsumerNodeRef<E>
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- org.jctools.queues.BaseLinkedQueuePad2<E>
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- org.jctools.queues.BaseLinkedQueue<E>
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- org.jctools.queues.MpscLinkedQueue<E>
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- All Implemented Interfaces:
java.lang.Iterable<E>
,java.util.Collection<E>
,java.util.Queue<E>
,MessagePassingQueue<E>
public class MpscLinkedQueue<E> extends BaseLinkedQueue<E>
This is a Java port of the MPSC algorithm as presented on 1024 Cores by D. Vyukov. The original has been adapted to Java and it's quirks with regards to memory model and layout:- Use inheritance to ensure no false sharing occurs between producer/consumer node reference fields.
- Use XCHG functionality to the best of the JDK ability (see differences in JDK7/8 impls).
- Conform to
Queue
contract on poll. The original semantics are available via relaxedPoll.
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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.BaseLinkedQueuePad2
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
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Fields inherited from class org.jctools.queues.BaseLinkedQueueProducerNodeRef
P_NODE_OFFSET
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Fields inherited from interface org.jctools.queues.MessagePassingQueue
UNBOUNDED_CAPACITY
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Constructor Summary
Constructors Constructor Description MpscLinkedQueue()
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description 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 wait, MessagePassingQueue.ExitCondition exit)
Stuff the queue with elements from the supplier forever.private LinkedQueueNode<E>
getNextConsumerNode(LinkedQueueNode<E> currConsumerNode)
boolean
offer(E e)
Called from a producer thread subject to the restrictions appropriate to the implementation and according to theQueue.offer(Object)
interface.boolean
remove(java.lang.Object o)
private LinkedQueueNode<E>
xchgProducerNode(LinkedQueueNode<E> newVal)
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Methods inherited from class org.jctools.queues.BaseLinkedQueue
capacity, drain, drain, drain, getSingleConsumerNodeValue, isEmpty, iterator, newNode, newNode, peek, poll, relaxedOffer, relaxedPeek, relaxedPoll, size, spinWaitForNextNode, toString
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Methods inherited from class org.jctools.queues.BaseLinkedQueueConsumerNodeRef
lpConsumerNode, lvConsumerNode, spConsumerNode
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Methods inherited from class org.jctools.queues.BaseLinkedQueueProducerNodeRef
casProducerNode, lpProducerNode, lvProducerNode, soProducerNode, spProducerNode
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Methods inherited from class java.util.AbstractCollection
contains, containsAll, 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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Methods inherited from interface java.util.Collection
contains, containsAll, equals, hashCode, parallelStream, removeAll, removeIf, retainAll, spliterator, stream, toArray, toArray, toArray
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Methods inherited from interface org.jctools.queues.MessagePassingQueue
clear
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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.
IMPLEMENTATION NOTES:
Offer is allowed from multiple threads.
Offer allocates a new node and:- Swaps it atomically with current producer node (only one producer 'wins')
- Sets the new node as the node following from the swapped producer node
- Parameters:
e
- notnull
, will throw NPE if it is- Returns:
- true if element was inserted into the queue, false iff full
- See Also:
MessagePassingQueue.offer(Object)
,Queue.offer(java.lang.Object)
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remove
public boolean remove(java.lang.Object o)
This method is only safe to call from the (single) consumer thread, and is subject to best effort when racing with producers. This method is potentially blocking when "bubble"s in the queue are visible.
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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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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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fill
public void fill(MessagePassingQueue.Supplier<E> s, MessagePassingQueue.WaitStrategy wait, MessagePassingQueue.ExitCondition exit)
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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xchgProducerNode
private LinkedQueueNode<E> xchgProducerNode(LinkedQueueNode<E> newVal)
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getNextConsumerNode
private LinkedQueueNode<E> getNextConsumerNode(LinkedQueueNode<E> currConsumerNode)
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