Class ReorderingBlockingQueue<E>
- java.lang.Object
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- it.unimi.dsi.util.concurrent.ReorderingBlockingQueue<E>
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public class ReorderingBlockingQueue<E> extends java.lang.Object
A blocking queue holding a fixed amount of timestamped items. A typical use case is that of multiple threads analyzing an input divided in record, one record per thread, and generating some output that must be written preserving the input order. The threads enqueue their output to an instance of this class, and a flushing thread dequeues it in input order.The
put(Object, long)
must be called with an object and a timestamp. Timestamps must be a contiguous interval of the natural numbers starting at zero, and objects will be returned in timestamp order. Failure to comply with the contract (i.e., missing timestamps) will cause the queue to block forever.put(Object, long)
might block if there is not enough space to keep track of the object (i.e., if its timestamp is too far in time w.r.t. the timestamp that would be returned next by the queue).take()
might block if the object with the next timestamp has not beenput(Object, long)
yet.The implementation is based on a circular, fixed-size buffer, so all methods of this class complete in constant time.
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Constructor Summary
Constructors Constructor Description ReorderingBlockingQueue(int capacity)
Creates aReorderingBlockingQueue
with the given fixed capacity.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description boolean
isEmpty()
Returns whether this queue is empty.void
put(E e, long timeStamp)
Inserts an element with given timestamp, waiting for space to become available if the timestamp of the element minus the current timestamp of the queue exceeds the queue capacity.int
size()
Returns the number of elements in this queue.E
take()
Returns the element with the next timestamp, waiting until it is available.
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Method Detail
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put
public void put(E e, long timeStamp) throws java.lang.InterruptedException
Inserts an element with given timestamp, waiting for space to become available if the timestamp of the element minus the current timestamp of the queue exceeds the queue capacity.- Parameters:
e
- an element.timeStamp
- the timestamp ofe
.- Throws:
java.lang.NullPointerException
- ife
is null;java.lang.InterruptedException
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take
public E take() throws java.lang.InterruptedException
Returns the element with the next timestamp, waiting until it is available.Note that because of the reordering semantics, an invocation of this method on a nonempty queue might block nonetheless.
- Returns:
- the element with the next timestamp.
- Throws:
java.lang.InterruptedException
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size
public int size()
Returns the number of elements in this queue.- Returns:
- the number of elements in this queue
- See Also:
isEmpty()
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isEmpty
public boolean isEmpty()
Returns whether this queue is empty.- Returns:
- whether this queue is empty.
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