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package flex.messaging.util.concurrent;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import com.ibm.websphere.asynchbeans.Work;
import com.ibm.websphere.asynchbeans.WorkEvent;
import com.ibm.websphere.asynchbeans.WorkException;
import com.ibm.websphere.asynchbeans.WorkListener;
import com.ibm.websphere.asynchbeans.WorkManager;
import flex.messaging.config.ConfigurationException;
import flex.messaging.log.Log;
import flex.messaging.log.LogCategories;
/**
* Implements {@link Executor} by delegating command execution to a WAS asynchbeans <code>WorkManager</code>.
* For more information on the asynchbeans API, refer to the WAS Javadoc for
* <a href="http://publib.boulder.ibm.com/infocenter/wasinfo/v5r0/index.jsp?topic=/com.ibm.wasee.doc/info/ee/javadoc/ee/com/ibm/websphere/asynchbeans/WorkManager.html">WorkManager</a>.
*
* @exclude
*/
public class AsynchBeansWorkManagerExecutor implements Executor
{
//--------------------------------------------------------------------------
//
// Constructor
//
//--------------------------------------------------------------------------
/**
* Constructs an <code>AsynchBeansWorkManagerExecutor</code> that will delegate command execution
* to the specified <code>WorkManager</code> instance that is registered in JNDI.
*
* @param workManagerJNDIName The JNDI resource ref name for the <code>WorkManager</code>.
* @see com.ibm.websphere.asynchbeans.WorkManager
*/
public AsynchBeansWorkManagerExecutor(String workManagerJNDIName)
{
try
{
InitialContext ic = new InitialContext();
workManager = (WorkManager)ic.lookup(workManagerJNDIName);
}
catch(NamingException ne)
{
ConfigurationException ce = new ConfigurationException();
ce.setMessage(13600, new Object[] {workManagerJNDIName});
ce.setRootCause(ne);
throw ce;
}
workListener = new WorkListener() {
public void workAccepted(WorkEvent event)
{
/* No-op */
}
public void workCompleted(WorkEvent event)
{
// This only needs to be handled if execution of the Runnable failed.
WorkException e = event.getException();
if (e != null)
{
if (Log.isDebug())
Log.getLogger(LogCategories.EXECUTOR).error("AsynchBeansWorkManager's WorkListener.workCompleted() callback invoked for failed execution.", e);
handleFailedExecution(((WorkCommandWrapper)event.getWork()).command, e);
}
}
public void workRejected(WorkEvent event)
{
WorkException e = event.getException();
if (Log.isDebug())
Log.getLogger(LogCategories.EXECUTOR).error("AsynchBeansWorkManager's WorkListener.workRejected() callback invoked. WorkException? " + e);
handleFailedExecution(((WorkCommandWrapper)event.getWork()).command, e);
}
public void workStarted(WorkEvent event)
{
/* No-op */
}
};
}
//--------------------------------------------------------------------------
//
// Variables
//
//--------------------------------------------------------------------------
/**
* Instance level lock for thread-safe state changes.
*/
private final Object lock = new Object();
/**
* Reference to the WorkManager instance configured in WAS that this executor instance delegates to.
*/
private final WorkManager workManager;
/**
* Listener that monitors scheduled work for errors and notifies the FailedExecutionHandler if one has been set.
*/
private final WorkListener workListener;
//--------------------------------------------------------------------------
//
// Properties
//
//--------------------------------------------------------------------------
//----------------------------------
// failedExecutionHandler
//----------------------------------
private FailedExecutionHandler failedExecutionHandler;
/** {@inheritDoc} */
public FailedExecutionHandler getFailedExecutionHandler()
{
synchronized (lock)
{
return failedExecutionHandler;
}
}
/** {@inheritDoc} */
public void setFailedExecutionHandler(FailedExecutionHandler value)
{
synchronized (lock)
{
failedExecutionHandler = value;
}
}
//--------------------------------------------------------------------------
//
// Public Methods
//
//--------------------------------------------------------------------------
/** {@inheritDoc} */
public void execute(Runnable command)
{
try
{
// Register our listener to monitor each scheduled work, and set the start timeout for the work to indefinite (no queue timeout).
workManager.startWork(new WorkCommandWrapper(command), WorkManager.INDEFINITE, workListener);
}
catch (WorkException e)
{
handleFailedExecution(command, e);
}
}
//--------------------------------------------------------------------------
//
// Private Methods
//
//--------------------------------------------------------------------------
/**
* Handles command execution problems by notifying the FailedExecutionHandler if one has been set
* and otherwise logging the failure.
*
* @param command The command that failed to execute successfully.
* @param e The exception generated by the failed command.
*/
private void handleFailedExecution(Runnable command, Exception e)
{
FailedExecutionHandler handler = getFailedExecutionHandler();
if (handler != null)
{
handler.failedExecution(command, this, e);
}
else if (Log.isError())
{
Log.getLogger(LogCategories.EXECUTOR).error("AsynchBeansWorkManager hit an Exception but no FailedExecutionHandler is registered to handle the error.", e);
}
}
//--------------------------------------------------------------------------
//
// Inner Classes
//
//--------------------------------------------------------------------------
/**
* Helper class that wraps Runnable commands in the WAS Work interface.
*/
class WorkCommandWrapper implements Work
{
public WorkCommandWrapper(Runnable command)
{
this.command = command;
}
private final Runnable command;
public void run()
{
command.run();
}
/**
* This is invoked by WAS when the server is shutting down to signal long-running daemon threads spawned by the WorkManager
* to exit from their run() method. Our works are all short lived so this is a no-op; in this case WAS will force any
* works that are executing at server shutdown to terminate.
*/
public void release()
{
// No-op.
}
}
}