cz.cuni.jagrlib
Class Semaphore

java.lang.Object
  cz.cuni.jagrlib.Semaphore

public class Semaphore
extends java.lang.Object

General semaphore for inter-thread synchronization.

Since:

0.13

See Also:

Semaphore.java

Field Summary

protected int

counter Number of waiting clients (<0) or number of free signals (>0).

Constructor Summary

Semaphore(int limit)
Initializing constructor.

Method Summary

int	getSignalCount() Returns number of signals available.
void	semSignal(int number) Signals the number of times.
void	semSignalAll(int limit) Resume all waiting threads (at most limit ones).
boolean	semWait() Waits for one signal.
boolean	semWait(long millis) Waits for one signal for the restricted amount of time.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

counter

protected int counter

Number of waiting clients (<0) or number of free signals (>0).

Constructor Detail

Semaphore

public Semaphore(int limit)

Initializing constructor.

Parameters:

limit - Initial number of free signals (should be >= 0)

Method Detail

semWait

public boolean semWait()

Waits for one signal. Blocks the current thread for (potentially) infinite time.

Returns:

true if the current thread becomes a signal (false if it is interrupted by another thread).

See Also:

semWait(long)

semWait

public boolean semWait(long millis)

Waits for one signal for the restricted amount of time.

Parameters:

millis - Number of milliseconds to wait (0L => wait forever).

Returns:

true if the current thread becomes a signal or the given time expires (false if it is interrupted by another thread).

See Also:

semWait()

semSignal

public void semSignal(int number)

Signals the number of times. Resumes at most number of waiting threads.

Parameters:

number - Number of signals to be generated.

See Also:

semSignalAll(int)

semSignalAll

public void semSignalAll(int limit)

Resume all waiting threads (at most limit ones).

Parameters:

limit - Maximum number of waiting threads to be resumed (for <= 0 resumes exactly all currently waiting threads).

See Also:

semSignal(int)

getSignalCount

public int getSignalCount()

Returns number of signals available.

Returns:

Number of signals available in current time.