package wowodc.background.tasks;
import java.text.DecimalFormat;
import java.text.Format;
import java.util.concurrent.Callable;
import org.apache.log4j.Logger;
import wowodc.background.utilities.Utilities;
import wowodc.eof.ResultItem;
import wowodc.eof.TaskInfo;
import com.webobjects.eocontrol.EOEditingContext;
import com.webobjects.eocontrol.EOGlobalID;
import com.webobjects.foundation.NSArray;
import com.webobjects.foundation.NSTimestamp;
import er.extensions.concurrency.ERXTask;
import er.extensions.concurrency.IERXPercentComplete;
import er.extensions.concurrency.IERXStoppable;
import er.extensions.eof.ERXFetchSpecification;
import er.extensions.eof.ERXFetchSpecificationBatchIterator;
import er.extensions.foundation.IERXStatus;
/**
* This task iterates thru a the ResultItems related to a TaskInfo argument.
*
* For large data sets, the use of a {@link ERXFetchSpecificationBatchIterator} and replacing
* the {@link EOEditingContext} for each batch can help
* Factorial and factorial primes.
* http://en.wikipedia.org/wiki/Factorial_prime
*
* @author kieran
*/
public class T06EOFFactorialUpdateTask extends ERXTask<EOGlobalID> implements Callable<EOGlobalID>, IERXStatus , IERXPercentComplete, IERXStoppable {
private static final Logger log = Logger.getLogger(T06EOFFactorialUpdateTask.class);
// Duration of the example task in milliseconds
// Random between 5 and 15 seconds
private final long DURATION = Utilities.sharedRandom().nextInt(10001) + 5000;
// Task elapsed time in milliseconds
private long _elapsedTime = 0l;
// Value between 0.0 and 1.0 indicating the task's percentage complete
private double _percentComplete = 0.0d;
// A message indicating current status
private String _status = "Starting...";
private long _countCompleted = 0;
private long _totalCount = 0;
private volatile boolean _isStopped = false;
public T06EOFFactorialUpdateTask(TaskInfo taskInfo) {
if (taskInfo.isNewObject()) {
throw new IllegalArgumentException("taskInfo must be already saved to the database before this task can be run");
}
// Check if workflow state is appropriate
if (!taskInfo.workflowState().equals(TaskInfo.WORKFLOW_PRIME_CHECKED)) {
throw new IllegalStateException("The taskInfo must be in the " + TaskInfo.WORKFLOW_PRIME_CHECKED + " before it can begin Factorial processing.");
}
// Grab GID reference before the task is started.
_taskInfoGID = taskInfo.editingContext().globalIDForObject(taskInfo);
}
private final EOGlobalID _taskInfoGID;
@Override
public EOGlobalID _call() {
_elapsedTime = 0;
Format wholeNumberFormatter = new DecimalFormat("#,##0");
long startTime = System.currentTimeMillis();
// Note we use the superclass convenience method here.
EOEditingContext ec = newEditingContext();
ec.lock();
try {
// Fetch the TaskInfo
TaskInfo taskInfo = (TaskInfo) ec.faultForGlobalID(_taskInfoGID, ec);
_totalCount = taskInfo.countResultItems().longValue();
// Task start time
// This is a demo, so we are going to replace the prime processing times with the factorial processing times
taskInfo.setStartTime(new NSTimestamp(startTime));
// For demo purposes we will use batches and EC recycling, which would be common for processing huge data sets
ERXFetchSpecification<ResultItem> fs = taskInfo.fetchSpecificationForResultItems();
// Batch iterator
ERXFetchSpecificationBatchIterator fsIterator = new ERXFetchSpecificationBatchIterator(fs, ec);
// Loop for a period of time
while (fsIterator.hasNext() && !_isStopped) {
@SuppressWarnings("unchecked")
NSArray<ResultItem> batch = fsIterator.nextBatch();
for (ResultItem resultItem : batch) {
resultItem.setWorkflowState(ResultItem.WORKFLOW_CHECKING_FACTORIAL);
performFactorialProcessing(resultItem);
resultItem.setWorkflowState(ResultItem.WORKFLOW_PROCESSING_COMPLETE);
ec.saveChanges();
_elapsedTime = System.currentTimeMillis() - startTime;
// Update progress variables
_countCompleted++;
_percentComplete = (double)(_countCompleted) / (double)_totalCount;
_status = wholeNumberFormatter.format(_countCompleted) + " numbers checked for factorial proximity";
if (_isStopped) {
break;
}
}
// Swap in a fresh EC for the next batch to help with memory management
EOEditingContext freshEC = newEditingContext();
ec.unlock();
ec = freshEC;
freshEC.lock();
fsIterator.setEditingContext(ec);
// We need to refault taskInfo into the new EC after swapping
taskInfo = (TaskInfo) ec.faultForGlobalID(_taskInfoGID, ec);
}
// Complete the stats
taskInfo.setEndTime(new NSTimestamp());
taskInfo.setWorkflowState(TaskInfo.WORKFLOW_PROCESSING_COMPLETE);
long duration = taskInfo.endTime().getTime() - taskInfo.startTime().getTime();
taskInfo.setDuration(duration);
ec.saveChanges();
} finally {
ec.unlock();
}
return _taskInfoGID;
}
/**
* Finds the closest factorial number and corresponding factor and updates resultItem.
* If the resultItem was a prime number, we check if it is a Factorial Prime.
* http://en.wikipedia.org/wiki/Factorial_prime
*
* @param resultItem
*/
private void performFactorialProcessing(ResultItem resultItem) {
long numberToCheck = resultItem.numberToCheck().longValue();
long factor = 1;
long factorial = 1;
long distance = Math.abs(numberToCheck - factorial);
long newDistance = 0;
do {
factor++;
factorial = factorial * factor;
newDistance = Math.abs(numberToCheck - factorial);
log.debug("factor: " + factor + "; factorial: " + factorial + "; distance: " + distance + "; new Distance: " + newDistance);
} while (newDistance < distance);
// Upon exiting the loop, we will have gone one factor too far
factorial = factorial / factor;
factor--;
resultItem.setClosestFactorial(factorial);
resultItem.setFactorNumber((int)factor);
// Check if Factorial prime
if (resultItem.isPrime().booleanValue()) {
if (Math.abs(numberToCheck - factorial) == 1) {
// We have a Factorial Prime number
resultItem.setIsFactorialPrime(Boolean.TRUE);
}
}
}
/* (non-Javadoc)
* @see er.extensions.concurrency.IERXPercentComplete#percentComplete()
*/
public Double percentComplete() {
return _percentComplete;
}
/* (non-Javadoc)
* @see er.extensions.foundation.IERXStatus#status()
*/
public String status() {
return _status;
}
/* (non-Javadoc)
* @see er.extensions.concurrency.IERXStoppable#stop()
*/
public void stop() {
log.info("The task was stopped by the user.");
_isStopped = true;
}
}