edu.wpi.first.wpilibj.communication
Class Semaphore

java.lang.Object
  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