Package com.google.common.collect
Class EvictingQueue<E>
- java.lang.Object
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- com.google.common.collect.ForwardingObject
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- com.google.common.collect.ForwardingCollection<E>
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- com.google.common.collect.ForwardingQueue<E>
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- com.google.common.collect.EvictingQueue<E>
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- All Implemented Interfaces:
java.io.Serializable
,java.lang.Iterable<E>
,java.util.Collection<E>
,java.util.Queue<E>
@GwtCompatible public final class EvictingQueue<E> extends ForwardingQueue<E> implements java.io.Serializable
A non-blocking queue which automatically evicts elements from the head of the queue when attempting to add new elements onto the queue and it is full. This queue orders elements FIFO (first-in-first-out). This data structure is logically equivalent to a circular buffer (i.e., cyclic buffer or ring buffer).An evicting queue must be configured with a maximum size. Each time an element is added to a full queue, the queue automatically removes its head element. This is different from conventional bounded queues, which either block or reject new elements when full.
This class is not thread-safe, and does not accept null elements.
- Since:
- 15.0
- Author:
- Kurt Alfred Kluever
- See Also:
- Serialized Form
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Method Summary
All Methods Static Methods Instance Methods Concrete Methods Modifier and Type Method Description boolean
add(E e)
Adds the given element to this queue.boolean
addAll(java.util.Collection<? extends E> collection)
static <E> EvictingQueue<E>
create(int maxSize)
Creates and returns a new evicting queue that will hold up tomaxSize
elements.protected java.util.Queue<E>
delegate()
Returns the backing delegate instance that methods are forwarded to.boolean
offer(E e)
Adds the given element to this queue.int
remainingCapacity()
Returns the number of additional elements that this queue can accept without evicting; zero if the queue is currently full.java.lang.Object[]
toArray()
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Methods inherited from class com.google.common.collect.ForwardingQueue
element, peek, poll, remove, standardOffer, standardPeek, standardPoll
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Methods inherited from class com.google.common.collect.ForwardingCollection
clear, contains, containsAll, isEmpty, iterator, remove, removeAll, retainAll, size, standardAddAll, standardClear, standardContains, standardContainsAll, standardIsEmpty, standardRemove, standardRemoveAll, standardRetainAll, standardToArray, standardToArray, standardToString, toArray
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Methods inherited from class com.google.common.collect.ForwardingObject
toString
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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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create
public static <E> EvictingQueue<E> create(int maxSize)
Creates and returns a new evicting queue that will hold up tomaxSize
elements.When
maxSize
is zero, elements will be evicted immediately after being added to the queue.
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remainingCapacity
public int remainingCapacity()
Returns the number of additional elements that this queue can accept without evicting; zero if the queue is currently full.- Since:
- 16.0
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delegate
protected java.util.Queue<E> delegate()
Description copied from class:ForwardingObject
Returns the backing delegate instance that methods are forwarded to. Abstract subclasses generally override this method with an abstract method that has a more specific return type, such asForwardingSet.delegate()
. Concrete subclasses override this method to supply the instance being decorated.- Specified by:
delegate
in classForwardingQueue<E>
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offer
@CanIgnoreReturnValue public boolean offer(E e)
Adds the given element to this queue. If the queue is currently full, the element at the head of the queue is evicted to make room.- Specified by:
offer
in interfacejava.util.Queue<E>
- Overrides:
offer
in classForwardingQueue<E>
- Returns:
true
always
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add
@CanIgnoreReturnValue public boolean add(E e)
Adds the given element to this queue. If the queue is currently full, the element at the head of the queue is evicted to make room.- Specified by:
add
in interfacejava.util.Collection<E>
- Specified by:
add
in interfacejava.util.Queue<E>
- Overrides:
add
in classForwardingCollection<E>
- Returns:
true
always
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addAll
@CanIgnoreReturnValue public boolean addAll(java.util.Collection<? extends E> collection)
- Specified by:
addAll
in interfacejava.util.Collection<E>
- Overrides:
addAll
in classForwardingCollection<E>
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toArray
public java.lang.Object[] toArray()
- Specified by:
toArray
in interfacejava.util.Collection<E>
- Overrides:
toArray
in classForwardingCollection<E>
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