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package org.glassfish.hk2.internal;
import java.util.Collections;
import java.util.HashSet;
import java.util.List;
import java.util.concurrent.Executor;
import java.util.concurrent.SynchronousQueue;
import java.util.concurrent.ThreadFactory;
import java.util.concurrent.ThreadPoolExecutor;
import java.util.concurrent.TimeUnit;
import javax.inject.Inject;
import javax.inject.Singleton;
import org.glassfish.hk2.api.ActiveDescriptor;
import org.glassfish.hk2.api.DescriptorVisibility;
import org.glassfish.hk2.api.DynamicConfigurationListener;
import org.glassfish.hk2.api.ErrorInformation;
import org.glassfish.hk2.api.ErrorService;
import org.glassfish.hk2.api.ErrorType;
import org.glassfish.hk2.api.Filter;
import org.glassfish.hk2.api.ImmediateController;
import org.glassfish.hk2.api.MultiException;
import org.glassfish.hk2.api.Operation;
import org.glassfish.hk2.api.ServiceLocator;
import org.glassfish.hk2.api.ValidationInformation;
import org.glassfish.hk2.api.ValidationService;
import org.glassfish.hk2.api.Validator;
import org.glassfish.hk2.api.Visibility;
import org.glassfish.hk2.utilities.ImmediateContext;
/**
* The implementation of the immediate context. This should NOT be added
* automatically, and hence is not annotated with {@link org.jvnet.hk2.annotations.Service}
*
* This implementation uses a lot of facilities of hk2, so lets explain each one.
*
* The thing that makes Immediate services immediate is that they are started as soon as
* they are noticed. This is done by implementing the DynamicConfigurationListener, as it
* will get notified when a configuration has changed. However, since the creation of user
* services can take an arbitrarily long time it is better to do that work on a separate
* thread, which is why we implement Runnable. The run method is the method that will pull
* from the queue of work and instantiate (and destroy) the immediate services.
*
* However, there is also a desire to be highly efficient. This means we should not be
* creating this thread if there is no work for the thread to do. For this to work
* we need to know which configuration changes have added or removed an Immediate service.
* To know this we have implemented the Validation service and Validator. The validation
* service records the thread id of a configuration operation that is adding or removing
* services. This thread id goes into a map. But we have to be sure that the map does not
* grow without bound. To do this we clear the map both when the configuration service has
* succeeded (in the DynamicConfigurationListener) and when the configuration service has failed
* (in the ErrorService). This is why we have implemented the ErrorService.
*
* @author jwells
*/
@Singleton @Visibility(DescriptorVisibility.LOCAL)
public class ImmediateHelper implements DynamicConfigurationListener, Runnable,
ValidationService, ErrorService, Validator, ImmediateController {
private static final ThreadFactory THREAD_FACTORY = new ImmediateThreadFactory();
private static final Executor DEFAULT_EXECUTOR = new ThreadPoolExecutor(0, Integer.MAX_VALUE,
60L, TimeUnit.SECONDS,
new SynchronousQueue(true),
THREAD_FACTORY);
private final ServiceLocator locator;
private final ImmediateContext immediateContext;
private final HashSet tidsWithWork = new HashSet();
private final Object queueLock = new Object();
private boolean threadAvailable;
private boolean outstandingJob;
private boolean waitingForWork;
private boolean firstTime = true;
private ImmediateServiceState currentState = ImmediateServiceState.SUSPENDED;
private Executor currentExecutor = DEFAULT_EXECUTOR;
private long decayTime = 20 * 1000;
@Inject
private ImmediateHelper(ServiceLocator serviceLocator, ImmediateContext immediateContext) {
this.locator = serviceLocator;
this.immediateContext = immediateContext;
}
/**
* Must have queueLock held
* @return true if there is work to be done
*/
private boolean hasWork() {
long tid = Thread.currentThread().getId();
boolean wasFirst = firstTime;
firstTime = false;
boolean retVal = tidsWithWork.contains(tid);
tidsWithWork.remove(tid);
if (retVal || !wasFirst) return retVal;
// OK, we added no Immediate services BUT this is the
// first DynamicConfigurationService callback, which means
// that there may already be immediate services in the
// service locator
List> immediates = getImmediateServices();
return !immediates.isEmpty();
}
/**
* Must have queueLock held
*/
private void doWorkIfWeHaveSome() {
if (!hasWork()) {
return;
}
outstandingJob = true;
if (!threadAvailable) {
threadAvailable = true;
currentExecutor.execute(this);
}
else if (waitingForWork) {
queueLock.notify();
}
}
@Override
public void configurationChanged() {
synchronized (queueLock) {
if (currentState.equals(ImmediateServiceState.SUSPENDED)) return;
doWorkIfWeHaveSome();
}
}
@Override
public Filter getLookupFilter() {
return immediateContext.getValidationFilter();
}
@Override
public Validator getValidator() {
return this;
}
@Override
public void onFailure(ErrorInformation errorInformation)
throws MultiException {
if (!(ErrorType.DYNAMIC_CONFIGURATION_FAILURE.equals(errorInformation.getErrorType()))) {
// Only interested in dynamic configuration failures
long tid = Thread.currentThread().getId();
synchronized (queueLock) {
tidsWithWork.remove(tid);
}
return;
}
}
@Override
public boolean validate(ValidationInformation info) {
if (info.getOperation().equals(Operation.BIND) ||
info.getOperation().equals(Operation.UNBIND)) {
long tid = Thread.currentThread().getId();
synchronized (queueLock) {
tidsWithWork.add(tid);
}
}
return true;
}
/**
* This thread will wait twenty seconds for new work to come in, and then
* kill itself
*/
@Override
public void run() {
for(;;) {
synchronized (queueLock) {
long decayTime = this.decayTime;
while (currentState.equals(ImmediateServiceState.RUNNING) &&
!outstandingJob &&
(decayTime > 0L)) {
waitingForWork = true;
long currentTime = System.currentTimeMillis();
try {
queueLock.wait(decayTime);
}
catch (InterruptedException ie) {
threadAvailable = false;
waitingForWork = false;
return;
}
long elapsedTime = System.currentTimeMillis() - currentTime;
decayTime -= elapsedTime;
}
waitingForWork = false;
if (!outstandingJob || currentState.equals(ImmediateServiceState.SUSPENDED)) {
threadAvailable = false;
return;
}
outstandingJob = false;
}
immediateContext.doWork();
}
}
/* (non-Javadoc)
* @see org.glassfish.hk2.api.ImmediateController#getExecutor()
*/
@Override
public Executor getExecutor() {
synchronized (queueLock) {
return currentExecutor;
}
}
/* (non-Javadoc)
* @see org.glassfish.hk2.api.ImmediateController#setExecutor(java.util.concurrent.Executor)
*/
@Override
public void setExecutor(Executor executor) throws IllegalStateException {
synchronized (queueLock) {
if (currentState.equals(ImmediateServiceState.RUNNING)) {
throw new IllegalStateException("ImmediateSerivce attempt made to change executor while in RUNNING state");
}
currentExecutor = (executor == null) ? DEFAULT_EXECUTOR : executor ;
}
}
/* (non-Javadoc)
* @see org.glassfish.hk2.api.ImmediateController#getThreadInactivityTimeout()
*/
@Override
public long getThreadInactivityTimeout() {
synchronized (queueLock) {
return decayTime;
}
}
/* (non-Javadoc)
* @see org.glassfish.hk2.api.ImmediateController#setThreadInactivityTimeout(long)
*/
@Override
public void setThreadInactivityTimeout(long timeInMillis)
throws IllegalStateException {
synchronized (queueLock) {
if (timeInMillis < 0) {
throw new IllegalArgumentException();
}
decayTime = timeInMillis;
}
}
/* (non-Javadoc)
* @see org.glassfish.hk2.api.ImmediateController#getImmediateState()
*/
@Override
public ImmediateServiceState getImmediateState() {
synchronized (queueLock) {
return currentState;
}
}
/* (non-Javadoc)
* @see org.glassfish.hk2.api.ImmediateController#setImmediateState(org.glassfish.hk2.api.ImmediateController.ImmediateServiceState)
*/
@Override
public void setImmediateState(ImmediateServiceState state) {
synchronized (queueLock) {
if (state == null) throw new IllegalArgumentException();
if (state == currentState) return;
currentState = state;
if (currentState.equals(ImmediateServiceState.RUNNING)) {
doWorkIfWeHaveSome();
}
}
}
private List> getImmediateServices() {
List> inScopeAndInThisLocator;
try {
inScopeAndInThisLocator = locator.getDescriptors(immediateContext.getValidationFilter());
}
catch (IllegalStateException ise) {
// locator has been shutdown
inScopeAndInThisLocator = Collections.emptyList();
}
return inScopeAndInThisLocator;
}
private static class ImmediateThread extends Thread {
private ImmediateThread(Runnable r) {
super(r);
setDaemon(true);
setName(getClass().getSimpleName() + "-"
+ System.currentTimeMillis());
}
}
private static class ImmediateThreadFactory implements ThreadFactory {
@Override
public Thread newThread(Runnable runnable) {
Thread activeThread = new ImmediateThread(runnable);
return activeThread;
}
}
}