Class MpscChunkedArrayQueue<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.MpscChunkedArrayQueue<E>
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- All Implemented Interfaces:
Iterable<E>
,Collection<E>
,Queue<E>
,IndexedQueueSizeUtil.IndexedQueue
,MessagePassingQueue<E>
,QueueProgressIndicators
- Direct Known Subclasses:
MpscGrowableArrayQueue
public class MpscChunkedArrayQueue<E> extends AbstractQueue<E>
An MPSC array queue which starts at initialCapacity and grows to maxCapacity in linked chunks of the initial size. The queue grows only when the current chunk is full and elements are not copied on resize, instead a link to the new chunk is stored in the old chunk for the consumer to follow.
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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
Fields Modifier and Type Field Description protected E[]
consumerBuffer
protected long
consumerMask
protected long
maxQueueCapacity
protected E[]
producerBuffer
protected long
producerMask
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Fields inherited from interface org.jctools.queues.MessagePassingQueue
UNBOUNDED_CAPACITY
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Constructor Summary
Constructors Constructor Description MpscChunkedArrayQueue(int maxCapacity)
MpscChunkedArrayQueue(int initialCapacity, int maxCapacity)
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description protected long
availableInQueue(long pIndex, long cIndex)
int
capacity()
long
currentConsumerIndex()
This method has no concurrent visibility semantics.long
currentProducerIndex()
This method has no concurrent visibility semantics.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 wait, 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 wait, MessagePassingQueue.ExitCondition exit)
Stuff the queue with elements from the supplier forever.protected long
getCurrentBufferCapacity(long mask)
protected int
getNextBufferSize(E[] buffer)
boolean
isEmpty()
This method's accuracy is subject to concurrent modifications happening as the observation is carried out.Iterator<E>
iterator()
Get an iterator for this queue.long
lvConsumerIndex()
long
lvProducerIndex()
boolean
offer(E e)
Called from a producer thread subject to the restrictions appropriate to the implementation and according to theQueue.offer(Object)
interface.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 e)
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.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.String
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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Methods inherited from interface java.util.Collection
contains, containsAll, equals, hashCode, parallelStream, remove, 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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Constructor Detail
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MpscChunkedArrayQueue
public MpscChunkedArrayQueue(int maxCapacity)
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MpscChunkedArrayQueue
public MpscChunkedArrayQueue(int initialCapacity, int maxCapacity)
- Parameters:
initialCapacity
- the queue initial capacity. If chunk size is fixed this will be the chunk size. Must be 2 or more.maxCapacity
- the maximum capacity will be rounded up to the closest power of 2 and will be the upper limit of number of elements in this queue. Must be 4 or more and round up to a larger power of 2 than initialCapacity.
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Method Detail
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availableInQueue
protected long availableInQueue(long pIndex, long cIndex)
- Returns:
- available elements in queue * 2
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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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getNextBufferSize
protected int getNextBufferSize(E[] buffer)
- Returns:
- next buffer size(inclusive of next array pointer)
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getCurrentBufferCapacity
protected long getCurrentBufferCapacity(long mask)
- Returns:
- current buffer capacity for elements (excluding next pointer and jump entry) * 2
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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
public String toString()
- Overrides:
toString
in classAbstractCollection<E>
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offer
public boolean offer(E e)
Description copied from interface:MessagePassingQueue
Called from a producer thread subject to the restrictions appropriate to the implementation and according to theQueue.offer(Object)
interface.- Specified by:
offer
in interfaceMessagePassingQueue<E>
- Specified by:
offer
in interfaceQueue<E>
- 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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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.
- Specified by:
poll
in interfaceMessagePassingQueue<E>
- Specified by:
poll
in interfaceQueue<E>
- 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.
- Specified by:
peek
in interfaceMessagePassingQueue<E>
- Specified by:
peek
in interfaceQueue<E>
- Returns:
- a message from the queue if one is available,
null
iff empty
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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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relaxedOffer
public boolean relaxedOffer(E e)
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.- Specified by:
relaxedOffer
in interfaceMessagePassingQueue<E>
- Parameters:
e
- 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.- Specified by:
relaxedPoll
in interfaceMessagePassingQueue<E>
- 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.- Specified by:
relaxedPeek
in interfaceMessagePassingQueue<E>
- Returns:
- a message from the queue if one is available,
null
if unable to peek
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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.- Specified by:
fill
in interfaceMessagePassingQueue<E>
- 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.- Specified by:
fill
in interfaceMessagePassingQueue<E>
- 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.- Specified by:
fill
in interfaceMessagePassingQueue<E>
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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.- Specified by:
drain
in interfaceMessagePassingQueue<E>
- Returns:
- the number of polled 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.- Specified by:
drain
in interfaceMessagePassingQueue<E>
- Returns:
- the number of polled elements
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drain
public void drain(MessagePassingQueue.Consumer<E> c, MessagePassingQueue.WaitStrategy wait, 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.- Specified by:
drain
in interfaceMessagePassingQueue<E>
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iterator
public Iterator<E> 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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lvConsumerIndex
public final long lvConsumerIndex()
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lvProducerIndex
public final long lvProducerIndex()
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