Deadlock testing class for B&S 2.2.1

[Kevin Florish]

The following is adapted from Bob Perillo's original class which was used for Urlybird. Anyone utilisng this class will probably have to make some
adjustments, especially in the FindingRecordsThread() method. One area where your code may differ is that I did my unlocking in a finally block
and I also used a cache map to cut down on I/O. The loop can be increased to whatever you like and exceptions will be thrown dependant upon
input. The program should complete fairly quickly and if it sits there hanging this probably indicates deadlock.

Hope others find the class useful.

Cheers Kevin.

 
package suncertify.testing;

import java.io.IOException;
import java.util.logging.*;

import suncertify.model.Contractor;
import suncertify.model.Data;

/*  
 * @(#)DataClassTest.java    1.0 18/01/2009  
 *   
 * Candidate: Kevin Florish
 * Prometric ID: Your candidade ID here
 * Candidate ID: Your Sun ID here  
 *   
 * Sun Certified Developer for Java 2 Platform, Standard Edition Programming  
 * Assignment (CX-310-252A)  
 *   
 * This class is part of the Programming Assignment of the Sun Certified  
 * Developer for Java 2 Platform, Standard Edition certification program, must  
 * not be used out of this context and must be used exclusively by Sun  
 * Microsystems, Inc.  
 */

/**
 * The <code>DataClassTest</code> tests the main functionalities of the
 * {@link Data} class. In order to simulate several clients trying to use it and
 * exercise the locking mechanism, it also has several inner classes that extend
 * the {@link Thread} class, where each class represents one client requesting
 * one operation.
 * 
 * @author Kevin Florish
 * @version 1.0 18/01/2009
 */
public class DataClassTesting {
    /**
     * The Logger instance through which all log messages from this class are
     * routed. Logger namespace is <code>suncertify</code>.
     */
    private transient Logger log = Logger.getLogger("%t/Deadlock%g.log"); 


	private static final Data data = Data.getDataInstance(
			"C:\\Documents and Settings\\Kevin\\workspace\\SCJD\\db-2x1.db");
	
	int offset = 70;
	//int offset = data.getInitialOffset();
	final int random = (int) (Math.random() * 25);
	final int recNo = (random * Contractor.CONTRACTOR_RECORD_LENGTH) + offset;

	public static void main(String[] args) {
		new DataClassTesting().startTests();
	}

	public void startTests() {
        /*
         * Setup a rotating file in default user directory for machine that will 
    	 * handle logs for the whole application
         */
		try {
			FileHandler contractorFileHandler = new FileHandler("%t/suncertify%g.log", 0, 10);
			contractorFileHandler.setFormatter(new SimpleFormatter());
			Logger log = Logger.getLogger("%t/suncertify%g.log");
			log.addHandler(contractorFileHandler);
			log.setLevel(Level.FINE);
		} catch (IOException e) {
            log.log(Level.SEVERE, e.getMessage(), e);
		}
		try {
			/*
			 * Practically, it is not necessary to execute this loop more than 1
			 * time, but if you want, you can increase the controller variable,
			 * so it is executed as many times as you want
			 */
			for (int i = 0; i < 1; i++) {
				Thread updatingRandom = new UpdatingRandomRecordThread();
				updatingRandom.start();
				Thread updatingRecord1 = new UpdatingRecord1Thread();
				updatingRecord1.start();
				Thread creatingRecord = new CreatingRecordThread();
				creatingRecord.start();
				Thread creatingRecord1 = new CreatingRecordThread1();
				creatingRecord1.start();
				Thread deletingRecord = new DeletingRecord1Thread();
				deletingRecord.start();
				Thread findingRecords = new FindingRecordsThread();
				findingRecords.start();
			}
		} catch (Exception e) {
			System.out.println(e.getMessage());
		}

	}

	private class UpdatingRandomRecordThread extends Thread {

		private long cookie;

		public void run() {
			try {
				/*
				 * The generated record number may not exist in the database, so
				 * a RecordNotFoundException may be thrown by the lock method.
				 * 
				 */
				System.out.println(Thread.currentThread().getName()
						+ " trying to lock record #" + recNo
						+ " on UpdatingRandomRecordThread");

				cookie = data.lockRecord(recNo);
				
				System.out.println(Thread.currentThread().getName()
						+ " trying to update record #" + recNo
						+ " on UpdatingRandomRecordThread"
						+ " Cookie# " + cookie);
				data.updateRecord(recNo, new String[] {null, null, 
						"Mining", "12", "$50.00", " "}, cookie);
				
			} catch (Exception e) {
				System.out.println(e);
			} finally {
				System.out.println(Thread.currentThread().getName()
						+ " trying to unlock record #" + recNo
						+ " on UpdatingRandomRecordThread"
				        + " Cookie# " + cookie);
				data.unlock(recNo, cookie);
			}
		}
	}

	private class UpdatingRecord1Thread extends Thread {

		private long cookie;

		public void run() {
			try {
				System.out.println(Thread.currentThread().getName()
						+ " trying to lock record #1 (70)"
						+ "on UpdatingRecord1Thread");
				cookie = data.lockRecord(70);
				
				System.out.println(Thread.currentThread().getName()
						+ " trying to update record #1 (70)"
						+ " on UpdatingRecord1Thread"
						+ " Cookie# " + cookie);
				data.updateRecord(70, new String[] {null, null, 
						"Mining", "12", "$50.00", " "}, cookie);
				
				/*
				 * In order to see the deadlock, this instruction can be
				 * commented, and the other Threads, waiting to update/delete
				 * record #1 will wait forever and the deadlock will occur
				 */

			} catch (Exception e) {
				System.out.println(e);
			} finally {
				System.out.println(Thread.currentThread().getName()
						+ " trying to unlock record #1 (70)"
						+ "on UpdatingRecord1Thread"
						+ " Cookie# " + cookie);
				data.unlock(70, cookie);
			}
		}
	}

	private class CreatingRecordThread extends Thread {

		public void run() {
			try {
				System.out.println(Thread.currentThread().getName()
						+ " trying to create a record");
				data.createRecord(new String[] {"TestName", "Location", 
						"Mining", "12", "$50.00", " "});
			} catch (Exception e) {
				System.out.println(e);
			}
		}
	}

	private class CreatingRecordThread1 extends Thread {

		public void run() {
			try {
				System.out.println(Thread.currentThread().getName()
						+ " trying to create a record");
				data.createRecord(new String[] {"Buonarotti & Company", "Smallville", 
						"Mining", "12", "$50.00", " "});
			} catch (Exception e) {
				System.out.println(e);
			}
		}
	}

	private class DeletingRecord1Thread extends Thread {

		private long cookie;

		public void run() {
			try {
				System.out.println(Thread.currentThread().getName()
						+ " trying to lock record #" + recNo
						+ " on DeletingRecord1Thread");
				cookie = data.lockRecord(recNo);
				System.out.println(Thread.currentThread().getName()
						+ " trying to delete record #" + recNo
						+ " on DeletingRecord1Thread");
				data.deleteRecord(recNo, cookie);
				System.out.println(Thread.currentThread().getName()
						+ " trying to unlock record #" + recNo
						+ " on DeletingRecord1Thread");

			} catch (Exception e) {
				//System.out.println(e);
			} finally {
				data.unlock(recNo, cookie);
			}
		}
	}

	private class FindingRecordsThread extends Thread {

		public void run() {
			try {
				System.out.println(Thread.currentThread().getName()
						+ " trying to find records");
				final String[] criteria = {"Buonar", "", null, null, null, null};
				final long[] results = data.findByCriteria(criteria);

				for (int i = 0; i < results.length; i++) {
	  				long recNo = results[i];
	  				// Exit loop when no more records to process 
	  				if (recNo == 0) {
	  					break;
	  				}
					try {
		  				Contractor contractor = data.getContractor(recNo);
						final String message = Thread.currentThread().getName()
								+ " Printing found record "  
								+ contractor.toString();
						System.out.println(message);
						System.out.println("Has next? "
								+ (i < (results.length - 1)));
					} catch (Exception e) {
						/*
						 * In case a record was found during the execution of
						 * the find method, but deleted before the execution of
						 * the read instruction, a RecordNotFoundException will
						 * occur, which would be normal then
						 */
						System.out.println("Exception in "
								+ "FindingRecordsThread - " + e);
					}
				}
				System.out.println("Exiting for loop");
			} catch (Exception e) {
				System.out.println(e);
			}
		}
	}
}

[Roel De Nijs]

Kevin,

Does your unlock method doesn't throw any Exception, like a RecordNotFoundException for example?

Because this code in my program result in compiler errors. And adding try/catch block in the finally-block seems a little bit crappy

   
            } finally {   
                data.unlock(recNo, cookie);   
            }   
 

It could be of course that our assignments differ at that point

[Kevin Florish]

My unlock() method throws a SecurityException when the passed cookie doesn't match the cookie held in the locking map.

My Sun DBAccess interface for unlock() method is:

public void unlock(long recNo, long cookie) throws SecurityException;

[Roel De Nijs]

And i guess your SecurityException is a checked exception... But how could this code compile in your test-case? Or maybe i'm missing something here but i would expect a try/catch around the call to unlock in the finally block

     
try {   
    // do stuff
} catch (Exception e) {   
} finally {   
    data.unlock(recNo, cookie);   
}   
   

[Kevin Florish]

Sorry Roel not quite sure what you mean here? And my SecurityException class extends RuntimeException.

My lock/process/unlock method calls are delegated to my Data class. so my RemoteServicesImpl class calls the following on the Data singleton
delegated on SERVER mode startup

data.booking(name, location, customerId);
    

I don't call unlock() within say the Update() method. But yes the whole lock/process/unlock is within a try block.

Both these classes throw either a ServicesException/RemoteServicesException so when the Data instance is called this is also
wrapped in a try/catch block.

[Roel De Nijs]

Hi Kevin,

I was just wondering why your deadlock testing class compiles, but if your SecurityException extends RuntimeException (like you said), then that's the reason why. I thought that your SecurityException was a checked exception (like i did myself in my code, but with the RecordNotFoundException), so i was a bit amazed that your code did compile.

So you solved the "mystery"

Kind regards,
Roel

[Lukas Jenny]

Hi,

Thank you very much for your Test Class.

As I'm currently doing the Version 2.3.2 of the B&S assignment I had to adapt it a bit. Now it runs without exception on my code. I hope this still means that my locking is ok.

btw: Do we have to note the first comment in every class? I can't remember having read something like this...

Best regards
Lukas Jenny

package suncertify.test.db;

import java.io.IOException;
import java.util.logging.FileHandler;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.logging.SimpleFormatter;

import suncertify.db.DBMain;
import suncertify.db.Data;
import suncertify.db.RecordNotFoundException;

/*  
 * @(#)DataClassTest.java    1.1 13/03/2009  
 *   
 * Candidate: Kevin Florish
 * Prometric ID: Your candidade ID here
 * Candidate ID: Your Sun ID here  
 *   
 * Sun Certified Developer for Java 2 Platform, Standard Edition Programming  
 * Assignment (CX-310-252A)  
 *   
 * This class is part of the Programming Assignment of the Sun Certified  
 * Developer for Java 2 Platform, Standard Edition certification program, must  
 * not be used out of this context and must be used exclusively by Sun  
 * Microsystems, Inc.  
 */

/**
 * The <code>DataClassTest</code> tests the main functionalities of the
 * {@link Data} class. In order to simulate several clients trying to use it and
 * exercise the locking mechanism, it also has several inner classes that extend
 * the {@link Thread} class, where each class represents one client requesting
 * one operation.
 * 
 * @author Kevin Florish
 * @author Lukas Jenny
 * @version 1.0 18/01/2009
 * @version 1.1 13/03/2009
 */
public class DataClassTesting {
    /**
     * The Logger instance through which all log messages from this class are
     * routed. Logger namespace is <code>suncertify</code>.
     */
    private transient Logger log = Logger.getLogger("%t/Deadlock%g.log"); 


	private static final DBMain data = new Data();
	
	int offset = 00;
	//int offset = data.getInitialOffset();
	final int random = (int) (Math.random() * 25);
	final int recNo = (this.random * 1) + this.offset;

	public static void main(String[] args) {
		new DataClassTesting().startTests();
	}

	public void startTests() {
        /*
         * Setup a rotating file in default user directory for machine that will 
    	 * handle logs for the whole application
         */
		try {
			FileHandler contractorFileHandler = new FileHandler("%t/suncertify%g.log", 0, 10);
			contractorFileHandler.setFormatter(new SimpleFormatter());
			Logger log = Logger.getLogger("%t/suncertify%g.log");
			log.addHandler(contractorFileHandler);
			log.setLevel(Level.FINE);
		} catch (IOException e) {
            this.log.log(Level.SEVERE, e.getMessage(), e);
		}
		try {
			/*
			 * Practically, it is not necessary to execute this loop more than 1
			 * time, but if you want, you can increase the controller variable,
			 * so it is executed as many times as you want
			 */
			for (int i = 0; i < 1; i++) {
				Thread updatingRandom = new UpdatingRandomRecordThread();
				updatingRandom.start();
				Thread updatingRecord1 = new UpdatingRecord1Thread();
				updatingRecord1.start();
				Thread creatingRecord = new CreatingRecordThread();
				creatingRecord.start();
				Thread creatingRecord1 = new CreatingRecordThread1();
				creatingRecord1.start();
				Thread deletingRecord = new DeletingRecord1Thread();
				deletingRecord.start();
				Thread findingRecords = new FindingRecordsThread();
				findingRecords.start();
			}
		} catch (Exception e) {
			System.out.println(e.getMessage());
		}

	}

	private class UpdatingRandomRecordThread extends Thread {

		@Override
		public void run() {
			try {
				/*
				 * The generated record number may not exist in the database, so
				 * a RecordNotFoundException may be thrown by the lock method.
				 * 
				 */
				System.out.println(Thread.currentThread().getName()
						+ " trying to lock record #" + DataClassTesting.this.recNo
						+ " on UpdatingRandomRecordThread");

				data.lock(DataClassTesting.this.recNo);
				
				System.out.println(Thread.currentThread().getName()
						+ " trying to update record #" + DataClassTesting.this.recNo
						+ " on UpdatingRandomRecordThread");
				data.update(DataClassTesting.this.recNo, new String[] {null, null, 
						"Mining", "12", "$50.00", " "});
				
			} catch (Exception e) {
				System.out.println(e);
			} finally {
				System.out.println(Thread.currentThread().getName()
						+ " trying to unlock record #" + DataClassTesting.this.recNo
						+ " on UpdatingRandomRecordThread");
				try {
					data.unlock(DataClassTesting.this.recNo);
				}
				catch (RecordNotFoundException e) {
					e.printStackTrace();
				}
			}
		}
	}

	private class UpdatingRecord1Thread extends Thread {

		@Override
		public void run() {
			try {
				System.out.println(Thread.currentThread().getName()
						+ " trying to lock record #1 (10)"
						+ "on UpdatingRecord1Thread");
				data.lock(10);
				
				System.out.println(Thread.currentThread().getName()
						+ " trying to update record #1 (10)"
						+ " on UpdatingRecord1Thread"
						);
				data.update(10, new String[] {null, null, 
						"Mining", "12", "$50.00", " "});
				
				/*
				 * In order to see the deadlock, this instruction can be
				 * commented, and the other Threads, waiting to update/delete
				 * record #1 will wait forever and the deadlock will occur
				 */

			} catch (Exception e) {
				System.out.println(e);
			} finally {
				System.out.println(Thread.currentThread().getName()
						+ " trying to unlock record #1 (10)"
						+ "on UpdatingRecord1Thread");
				try {
					data.unlock(10);
				}
				catch (RecordNotFoundException e) {
					e.printStackTrace();
				}
			}
		}
	}

	private class CreatingRecordThread extends Thread {

		@Override
		public void run() {
			try {
				System.out.println(Thread.currentThread().getName()
						+ " trying to create a record");
				data.create(new String[] {"TestName", "Location", 
						"Mining", "12", "$50.00", " "});
			} catch (Exception e) {
				System.out.println(e);
			}
		}
	}

	private class CreatingRecordThread1 extends Thread {

		@Override
		public void run() {
			try {
				System.out.println(Thread.currentThread().getName()
						+ " trying to create a record");
				data.create(new String[] {"Buonarotti & Company", "Smallville", 
						"Mining", "12", "$50.00", " "});
			} catch (Exception e) {
				System.out.println(e);
			}
		}
	}

	private class DeletingRecord1Thread extends Thread {

		@Override
		public void run() {
			try {
				System.out.println(Thread.currentThread().getName()
						+ " trying to lock record #" + DataClassTesting.this.recNo
						+ " on DeletingRecord1Thread");
				data.lock(DataClassTesting.this.recNo);
				System.out.println(Thread.currentThread().getName()
						+ " trying to delete record #" + DataClassTesting.this.recNo
						+ " on DeletingRecord1Thread");
				data.delete(DataClassTesting.this.recNo);
				System.out.println(Thread.currentThread().getName()
						+ " trying to unlock record #" + DataClassTesting.this.recNo
						+ " on DeletingRecord1Thread");

			} catch (Exception e) {
				//System.out.println(e);
			} finally {
				try {					
					data.unlock(DataClassTesting.this.recNo);
				}
				catch (RecordNotFoundException e) {
					e.printStackTrace();
				}
			}
		}
	}

	private class FindingRecordsThread extends Thread {

		@Override
		public void run() {
			try {
				System.out.println(Thread.currentThread().getName()
						+ " trying to find records");
				final String[] criteria = {"Dogs", "", null, null, null, null};
				final int[] results = data.find(criteria);

				for (int i = 0; i < results.length; i++) {
	  				int recNo = results[i];
	  				// Exit loop when no more records to process 
	  				if (recNo == 0) {
	  					break;
	  				}
					try {
		  				String[] contractor = data.read(recNo);
						final String message = Thread.currentThread().getName()
								+ " Printing found record "  
								+ contractor.toString();
						System.out.println(message);
						System.out.println("Has next? "
								+ (i < (results.length - 1)));
					} catch (Exception e) {
						/*
						 * In case a record was found during the execution of
						 * the find method, but deleted before the execution of
						 * the read instruction, a RecordNotFoundException will
						 * occur, which would be normal then
						 */
						System.out.println("Exception in "
								+ "FindingRecordsThread - " + e);
					}
				}
				System.out.println("Exiting for loop");
			} catch (Exception e) {
				System.out.println(e);
			}
		}
	}
}

[Kevin Florish]

btw: Do we have to note the first comment in every class? I can't remember having read something like this...

No you don't is the simple answer, it's just there for clarity.

[Lukas Jenny]

Hi Kevin,

Ok, thanks for your answer.

best regards
Lukas Jenny