Package EDU.oswego.cs.dl.util.concurrent
Class BoundedBuffer
- java.lang.Object
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- EDU.oswego.cs.dl.util.concurrent.BoundedBuffer
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- All Implemented Interfaces:
BoundedChannel
,Channel
,Puttable
,Takable
public class BoundedBuffer extends java.lang.Object implements BoundedChannel
Efficient array-based bounded buffer class. Adapted from CPJ, chapter 8, which describes design.
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Field Summary
Fields Modifier and Type Field Description protected java.lang.Object[]
array_
protected int
emptySlots_
protected java.lang.Object
putMonitor_
Helper monitor to handle puts.protected int
putPtr_
protected int
takePtr_
protected int
usedSlots_
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Constructor Summary
Constructors Constructor Description BoundedBuffer()
Create a buffer with the current default capacityBoundedBuffer(int capacity)
Create a BoundedBuffer with the given capacity.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description int
capacity()
Return the maximum number of elements that can be held.protected java.lang.Object
extract()
protected void
incEmptySlots()
protected void
incUsedSlots()
protected void
insert(java.lang.Object x)
boolean
offer(java.lang.Object x, long msecs)
Place item in channel only if it can be accepted within msecs milliseconds.java.lang.Object
peek()
Return, but do not remove object at head of Channel, or null if it is empty.java.lang.Object
poll(long msecs)
Return and remove an item from channel only if one is available within msecs milliseconds.void
put(java.lang.Object x)
Place item in the channel, possibly waiting indefinitely until it can be accepted.int
size()
Return the number of elements in the buffer.java.lang.Object
take()
Return and remove an item from channel, possibly waiting indefinitely until such an item exists.
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Constructor Detail
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BoundedBuffer
public BoundedBuffer(int capacity) throws java.lang.IllegalArgumentException
Create a BoundedBuffer with the given capacity.- Throws:
java.lang.IllegalArgumentException
- if capacity less or equal to zero
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BoundedBuffer
public BoundedBuffer()
Create a buffer with the current default capacity
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Method Detail
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size
public int size()
Return the number of elements in the buffer. This is only a snapshot value, that may change immediately after returning.
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capacity
public int capacity()
Description copied from interface:BoundedChannel
Return the maximum number of elements that can be held.- Specified by:
capacity
in interfaceBoundedChannel
- Returns:
- the capacity of this channel.
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incEmptySlots
protected void incEmptySlots()
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incUsedSlots
protected void incUsedSlots()
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insert
protected final void insert(java.lang.Object x)
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extract
protected final java.lang.Object extract()
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peek
public java.lang.Object peek()
Description copied from interface:Channel
Return, but do not remove object at head of Channel, or null if it is empty.
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put
public void put(java.lang.Object x) throws java.lang.InterruptedException
Description copied from interface:Channel
Place item in the channel, possibly waiting indefinitely until it can be accepted. Channels implementing the BoundedChannel subinterface are generally guaranteed to block on puts upon reaching capacity, but other implementations may or may not block.- Specified by:
put
in interfaceChannel
- Specified by:
put
in interfacePuttable
- Parameters:
x
- the element to be inserted. Should be non-null.- Throws:
java.lang.InterruptedException
- if the current thread has been interrupted at a point at which interruption is detected, in which case the element is guaranteed not to be inserted. Otherwise, on normal return, the element is guaranteed to have been inserted.
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offer
public boolean offer(java.lang.Object x, long msecs) throws java.lang.InterruptedException
Description copied from interface:Channel
Place item in channel only if it can be accepted within msecs milliseconds. The time bound is interpreted in a coarse-grained, best-effort fashion.- Specified by:
offer
in interfaceChannel
- Specified by:
offer
in interfacePuttable
- Parameters:
x
- the element to be inserted. Should be non-null.msecs
- the number of milliseconds to wait. If less than or equal to zero, the method does not perform any timed waits, but might still require access to a synchronization lock, which can impose unbounded delay if there is a lot of contention for the channel.- Returns:
- true if accepted, else false
- Throws:
java.lang.InterruptedException
- if the current thread has been interrupted at a point at which interruption is detected, in which case the element is guaranteed not to be inserted (i.e., is equivalent to a false return).
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take
public java.lang.Object take() throws java.lang.InterruptedException
Description copied from interface:Channel
Return and remove an item from channel, possibly waiting indefinitely until such an item exists.- Specified by:
take
in interfaceChannel
- Specified by:
take
in interfaceTakable
- Returns:
- some item from the channel. Different implementations may guarantee various properties (such as FIFO) about that item
- Throws:
java.lang.InterruptedException
- if the current thread has been interrupted at a point at which interruption is detected, in which case state of the channel is unchanged.
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poll
public java.lang.Object poll(long msecs) throws java.lang.InterruptedException
Description copied from interface:Channel
Return and remove an item from channel only if one is available within msecs milliseconds. The time bound is interpreted in a coarse grained, best-effort fashion.- Specified by:
poll
in interfaceChannel
- Specified by:
poll
in interfaceTakable
- Parameters:
msecs
- the number of milliseconds to wait. If less than or equal to zero, the operation does not perform any timed waits, but might still require access to a synchronization lock, which can impose unbounded delay if there is a lot of contention for the channel.- Returns:
- some item, or null if the channel is empty.
- Throws:
java.lang.InterruptedException
- if the current thread has been interrupted at a point at which interruption is detected, in which case state of the channel is unchanged (i.e., equivalent to a null return).
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