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2013 FRC Java API

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edu.wpi.first.wpilibj.communication
Class Semaphore

java.lang.Object
  extended by edu.wpi.first.wpilibj.communication.Semaphore

public class Semaphore
extends Object

Class exposing VxWorks semaphores.

Author:
dtjones

Nested Class Summary
static class Semaphore.Options
          Options to create a semaphore with.
 
Field Summary
static int WAIT_FOREVER
          Integer ms value indicating wait forever.
 
Constructor Summary
Semaphore(Semaphore.Options options)
          Create a new semaphore.
Semaphore(Semaphore.Options options, boolean initialState)
          Create a semaphore with the given initial state.
Semaphore(Semaphore.Options options, int count)
          Create a counting semaphore with the given value.
 
Method Summary
 void close()
          Close the semaphore.
 void flush()
          Unblock every task that is blocked by the semaphore.
 void free()
          Release all resources associated with the semaphore.
 Pointer getPointer()
          Get the pointer to the native semaphore.
 void give()
          Release the semaphore.
 void takeForever()
          Take the semaphore.
 void takeMillis(int timeout)
          Take the semaphore.
 boolean tryTake()
           
 
Methods inherited from class java.lang.Object
equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

WAIT_FOREVER

public static final int WAIT_FOREVER
Integer ms value indicating wait forever.

See Also:
Constant Field Values
Constructor Detail

Semaphore

public Semaphore(Semaphore.Options options)
Create a new semaphore.

Parameters:
options - The options to create the semaphore with.

Semaphore

public Semaphore(Semaphore.Options options,
                 boolean initialState)
Create a semaphore with the given initial state.

Parameters:
options - The options to create the semaphore with.
initialState - The initial state for the semaphore to have.

Semaphore

public Semaphore(Semaphore.Options options,
                 int count)
Create a counting semaphore with the given value.

Parameters:
options - The options to create the semaphore with.
count - The initial count for the semaphore to hold.
Method Detail

getPointer

public Pointer getPointer()
Get the pointer to the native semaphore.

Returns:
Pointer to the native semaphore.

flush

public void flush()
           throws SemaphoreException
Unblock every task that is blocked by the semaphore.

Throws:
SemaphoreException

give

public void give()
          throws SemaphoreException
Release the semaphore.

Throws:
SemaphoreException

takeMillis

public void takeMillis(int timeout)
                throws SemaphoreException
Take the semaphore. Block for timeout milliseconds.

Parameters:
timeout - The maximum time in milliseconds to block for the semaphore.
Throws:
SemaphoreException - if the lock can't be take in timeout seconds, or some other semaphore error condition occurs.

takeForever

public void takeForever()
                 throws SemaphoreException
Take the semaphore. Block forever until semaphore is available.

Throws:
SemaphoreException - if some semaphore error condition occurs.

tryTake

public boolean tryTake()
                throws SemaphoreException
Throws:
SemaphoreException

close

public void close()
           throws SemaphoreException
Close the semaphore.

Throws:
SemaphoreException

free

public void free()
          throws SemaphoreException
Release all resources associated with the semaphore.

Throws:
SemaphoreException
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2013 FRC Java API

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