org.rhq.enterprise.agent

Class AgentShutdownHook

java.lang.Object

java.lang.Thread

org.rhq.enterprise.agent.AgentShutdownHook

All Implemented Interfaces:

Runnable

public class AgentShutdownHook
extends Thread

Provides a way to gracefully shutdown the agent. This can be used as a shutdown hook, and it can also be used to perform some shutdown functions, like attempting to interrupt hanging threads.

Author:

John Mazzitelli

Nested Class Summary

Nested classes/interfaces inherited from class java.lang.Thread

Thread.State, Thread.UncaughtExceptionHandler

Field Summary

Fields inherited from class java.lang.Thread

MAX_PRIORITY, MIN_PRIORITY, NORM_PRIORITY

Constructor Summary

Constructors

Constructor and Description
AgentShutdownHook(AgentMain agent) Constructor for AgentShutdownHook that retains the reference to the agent that will be shutdown when the shutdown hook is triggered.

Method Summary

Methods

Modifier and Type	Method and Description
List<Thread>	interruptAllThreads() We need to make sure our VM can die quickly, so this method will send interrupts to most of the threads running in the VM to try to get them to hurry up and die.
void	run() This is executed when the VM is shutting down.
void	spawnKillThread(long doomsday) If something goes wrong and the VM does not die on its own when we think it should, the thread created by this method will explicitly kill the VM.
int	waitForNonDaemonThreads() If you want the current agent to be dead this method will attept to wait for all other non-daemon threads to die before returning.

Methods inherited from class java.lang.Thread

activeCount, checkAccess, clone, countStackFrames, currentThread, destroy, dumpStack, enumerate, getAllStackTraces, getContextClassLoader, getDefaultUncaughtExceptionHandler, getId, getName, getPriority, getStackTrace, getState, getThreadGroup, getUncaughtExceptionHandler, holdsLock, interrupt, interrupted, isAlive, isDaemon, isInterrupted, join, join, join, resume, setContextClassLoader, setDaemon, setDefaultUncaughtExceptionHandler, setName, setPriority, setUncaughtExceptionHandler, sleep, sleep, start, stop, stop, suspend, toString, yield

Methods inherited from class java.lang.Object

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

Constructor Detail

AgentShutdownHook

public AgentShutdownHook(AgentMain agent)

Constructor for AgentShutdownHook that retains the reference to the agent that will be shutdown when the shutdown hook is triggered.

Parameters:

agent - the agent to be shutdown when shutdown hook is triggered.

Method Detail

run

public void run()

This is executed when the VM is shutting down.

Specified by:

run in interface Runnable

Overrides:

run in class Thread

waitForNonDaemonThreads

public int waitForNonDaemonThreads()

If you want the current agent to be dead this method will attept to wait for all other non-daemon threads to die before returning. We log messages if we can't wait for them all for whatever reason. Note that obviously this method will not wait for the calling thread that is currently running this method.

Returns:

the number of still active non-daemon threads that haven't died even after waiting

interruptAllThreads

public List<Thread> interruptAllThreads()

We need to make sure our VM can die quickly, so this method will send interrupts to most of the threads running in the VM to try to get them to hurry up and die.

Returns:

the non-daemon threads that were interrupted

spawnKillThread

public void spawnKillThread(long doomsday)

If something goes wrong and the VM does not die on its own when we think it should, the thread created by this method will explicitly kill the VM. Calling this method sets a timebomb that will kill the VM after a timer runs out. There is no way to stop this timebomb short of performing 007-type heroics.

Parameters:

doomsday - the number of milliseconds that the VM has left to live; once this time expires, a kill thread will execute System.exit(0).