com.screenscraper.concurrent

Class ThreadGate

java.lang.Object

com.screenscraper.concurrent.ThreadGate

public class ThreadGate
extends java.lang.Object

Class Description

Version:

1.0

Constructor Summary

Constructors

Constructor and Description
ThreadGate(boolean open) Creates a new gate in the state specified
ThreadGate(boolean open, boolean fair) Creates a new gate in the state specified.

Method Summary

Modifier and Type	Method and Description
void	closeGate() Closes the gate so no more threads can get through the gate
boolean	isOpen() Returns whether or not the gate is currently open
boolean	isStateLocked() Returns whether or not the state is currently locked
void	lockGateClosed() Locks the gate in the closed position.
void	lockGateOpen() Locks the gate in the open position.
void	lockGateState() Locks the current state of this gate.
void	openGate() Opens the gate to allow all threads through.
void	passGate() Blocks until the gate is open, the thread is interrupted, or returns immediately if the gate is open
void	passGate(long waitDurationMilliseconds) Blocks until the gate is open, the thread is interrupted, or returns immediately if the gate is open
boolean	tryPassGate() Attempts to pass through the gate.
void	unlockGateState() Unlocks the current state of this gate.

Methods inherited from class java.lang.Object

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

Constructor Detail

ThreadGate

public ThreadGate(boolean open)

Creates a new gate in the state specified

Parameters:

open - The state of the gate.

ThreadGate

public ThreadGate(boolean open,
                  boolean fair)

Creates a new gate in the state specified. This also allows setting whether or not the gate is 'fair'. A fair gate means that when it is opened it guarantees that when it is opened all threads that were already waiting on it will get through, even if it is closed immediately thereafter

Parameters:

open - The state of the gate.

fair - True if all threads waiting at the gate should be allowed through when it is opened, even if it is closed again before they all get started again. False to enforce a strict policy that threads only proceed when the gate is open, regardless of when they got there.

Method Detail

passGate

public void passGate()
              throws java.lang.InterruptedException

Blocks until the gate is open, the thread is interrupted, or returns immediately if the gate is open

Throws:

java.lang.InterruptedException - If the thread was interrupted.

passGate

public void passGate(long waitDurationMilliseconds)
              throws java.util.concurrent.TimeoutException,
                     java.lang.InterruptedException

Blocks until the gate is open, the thread is interrupted, or returns immediately if the gate is open

Parameters:

waitDurationMilliseconds - The maximum amount of time to wait before timing out, a negative or zero value indicates to wait indefinitely

Throws:

java.lang.InterruptedException - If the thread was interrupted.

java.util.concurrent.TimeoutException - If the gate was not open during the given duration (or was opened but closed again before this thread was awakened and run, and the gate is operating in an unfair mode)

tryPassGate

public boolean tryPassGate()

Attempts to pass through the gate. If the gate is closed, this method will return false rather than blocking

Returns:

True if the gate was successfully passed through, or false if the gate was closed

openGate

public void openGate()

Opens the gate to allow all threads through. This will also release any threads waiting on the gate

closeGate

public void closeGate()

Closes the gate so no more threads can get through the gate

lockGateState

public void lockGateState()

Locks the current state of this gate. No future calls to open or close will have any affect. Use with care since the state may have changed since you last checked it before this call was issued

unlockGateState

public void unlockGateState()

Unlocks the current state of this gate. If the gate state is not currently locked this will have no effect

lockGateOpen

public void lockGateOpen()

Locks the gate in the open position. This will work even if the gate is currently locked

lockGateClosed

public void lockGateClosed()

Locks the gate in the closed position. This will work even if the gate is currently locked

isOpen

public boolean isOpen()

Returns whether or not the gate is currently open

Returns:

True if the gate is open, false otherwise

isStateLocked

public boolean isStateLocked()

Returns whether or not the state is currently locked

Returns:

True if the state of the gate is currently locked, false otherwise