ca.uhn.hl7v2.concurrent

Class Service

java.lang.Object

ca.uhn.hl7v2.concurrent.Service

All Implemented Interfaces:

Runnable

Direct Known Subclasses:

HL7Service, Receiver

public abstract class Service
extends Object
implements Runnable

Base class for a unified management of threads with a defined lifecycle. It uses a keepRunning flag to regularly terminate a thread. Classes implementing this class must implement handle() to do the main processing. afterStartup() and afterTermination() can be overridden to acquire and release resources required for processing.

Constructor Summary

Constructors

Constructor and Description
Service(String name, ExecutorService executorService)

Method Summary

Modifier and Type	Method and Description
protected void	afterStartup() Prepare any resources before entering the main thread.
protected void	afterTermination() Clean up any resources initialized in afterStartup().
ExecutorService	getExecutorService()
Throwable	getServiceExitedWithException() If this service exited with an exception, ths method returns that exception.
protected abstract void	handle() The main task of the thread, called in a loop as long as isRunning() returns true.
boolean	isRunning()
protected void	prepareTermination() Prepare thread to leave its main loop.
void	run() Runs the thread.
protected void	setServiceExitedWithException(Throwable theThreadExitedWithException) Provide the exception which caused this service to fail
void	setShutdownTimeout(long shutdownTimeout) Sets the time in milliseconds how long stopAndWait() should wait for the thread to terminate.
void	start() Starts the server listening for connections in a new thread.
void	startAndWait() Starts the server listening for connections in a new thread.
void	stop() Advises the thread to leave its main loop.
void	stopAndWait() Stops the thread by leaving its main loop.
void	waitForTermination()

Methods inherited from class java.lang.Object

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

Constructor Detail

Service

public Service(String name,
               ExecutorService executorService)

Method Detail

isRunning

public boolean isRunning()

Returns:

Returns true if the server has been started, and has not yet been stopped.

getExecutorService

public ExecutorService getExecutorService()

setShutdownTimeout

public void setShutdownTimeout(long shutdownTimeout)

Sets the time in milliseconds how long stopAndWait() should wait for the thread to terminate. Defaults to 3000ms.

Parameters:

shutdownTimeout - timout in milliseconds

start

public void start()

Starts the server listening for connections in a new thread. This continues until stop() is called.

Throws:

IllegalStateException - If the service is already running (i.e. start() has already been called.

startAndWait

public void startAndWait()
                  throws InterruptedException

Starts the server listening for connections in a new thread. This continues until stop() is called.

Unlike start(), this method will not return until the processing loop has completed at least once. This does not imply any kind of successful processing, but should at least provide a guarantee that the service has finished initializing itself.

Throws:

InterruptedException

afterStartup

protected void afterStartup()

Prepare any resources before entering the main thread.

Throws:

RuntimeException - if resources could not acquired. In this case, the thread will shutdown. Note that afterTermination() is called before.

handle

protected abstract void handle()

The main task of the thread, called in a loop as long as isRunning() returns true. Overridden methods are responsible for yielding or pausing the thread when it's idle. The method must also not block indefinitely so that a call to stop() is able to gracefully terminate the thread.

stop

public void stop()

Advises the thread to leave its main loop. prepareTermination() is called before this method returns. afterTermination() is called after the thread has left its main loop.

waitForTermination

public void waitForTermination()

stopAndWait

public final void stopAndWait()

Stops the thread by leaving its main loop. afterTermination() is called before the thread is terminated. The method waits until the thread has stopped.

afterTermination

protected void afterTermination()

Clean up any resources initialized in afterStartup().

prepareTermination

protected void prepareTermination()

Prepare thread to leave its main loop. By default sets keepRunning to false, but some implementations may need to do additional stuff.

run

public final void run()

Runs the thread.

Specified by:

run in interface Runnable

See Also:

Runnable.run()

setServiceExitedWithException

protected void setServiceExitedWithException(Throwable theThreadExitedWithException)

Provide the exception which caused this service to fail

getServiceExitedWithException

public Throwable getServiceExitedWithException()

If this service exited with an exception, ths method returns that exception. This is useful for detecting if the service failed unexpectedly