Package EDU.oswego.cs.dl.util.concurrent
Class SemaphoreControlledChannel
java.lang.Object
EDU.oswego.cs.dl.util.concurrent.SemaphoreControlledChannel
- All Implemented Interfaces:
BoundedChannel
,Channel
,Puttable
,Takable
- Direct Known Subclasses:
BoundedPriorityQueue
,PipedChannel
,Slot
Abstract class for channels that use Semaphores to
control puts and takes.
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Field Summary
Fields -
Constructor Summary
ConstructorsConstructorDescriptionSemaphoreControlledChannel
(int capacity) Create a channel with the given capacity and default semaphore implementationSemaphoreControlledChannel
(int capacity, Class semaphoreClass) Create a channel with the given capacity and semaphore implementations instantiated from the supplied class -
Method Summary
Modifier and TypeMethodDescriptionint
capacity()
Return the maximum number of elements that can be held.protected abstract Object
extract()
Internal mechanics of take.protected abstract void
Internal mechanics of put.boolean
Place item in channel only if it can be accepted within msecs milliseconds.poll
(long msecs) Return and remove an item from channel only if one is available within msecs milliseconds.void
Place item in the channel, possibly waiting indefinitely until it can be accepted.int
size()
Return the number of elements in the buffer.take()
Return and remove an item from channel, possibly waiting indefinitely until such an item exists.
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Field Details
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putGuard_
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takeGuard_
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capacity_
protected int capacity_
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Constructor Details
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SemaphoreControlledChannel
Create a channel with the given capacity and default semaphore implementation- Throws:
IllegalArgumentException
- if capacity less or equal to zero
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SemaphoreControlledChannel
public SemaphoreControlledChannel(int capacity, Class semaphoreClass) throws IllegalArgumentException, NoSuchMethodException, SecurityException, InstantiationException, IllegalAccessException, InvocationTargetException Create a channel with the given capacity and semaphore implementations instantiated from the supplied class- Throws:
IllegalArgumentException
- if capacity less or equal to zero.NoSuchMethodException
- If class does not have constructor that intializes permitsSecurityException
- if constructor information not accessibleInstantiationException
- if semaphore class is abstractIllegalAccessException
- if constructor cannot be calledInvocationTargetException
- if semaphore constructor throws an exception
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Method Details
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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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size
public int size()Return the number of elements in the buffer. This is only a snapshot value, that may change immediately after returning. -
insert
Internal mechanics of put. -
extract
Internal mechanics of take. -
put
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:
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
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:
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
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:
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
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:
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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