CS 3340 Windows Programming Prog4 Test2 1

2 Program5 Due Friday, March 27

ADT: Database Total ReaderCount WriterCount DataObj (for Monitor) 3 TotalValue (Get & Set) IncreaseReaderCount DecreaseReaderCount IncreaseWriterCount DecreaseWriterCount TheDatabaseStatus (ReadOnly) LockDataObj ReleaseDataObj The properties/methods don’t enforce mutual exclusion.

ADT: Database Does not guarantee any specific rules to access the database. It provides all necessary methods so the clients can enforce different rules to access the database. 4

ADT: ReaderWriter Will enforce the following rules to access the database: Readers can share the database. Writers require exclusive access to the database. First In First Out (FIFO) rule. 5

ADT: ReaderWriter FIFOQueue _database endProgram _thread _passMag _mainForm _ReaderWriterEvent _rondomGenerator 6 TheDatabase (WriteOnly) WakeupNextWhenExiting FinishReadWrite DisplayMsg (WriteOnly) MainForm (WriteOnly) ID (ReadOnly) Type (ReadOnly) Spinup Wakeup Run (MustOverride)

ADT: Reader Sub-class of ReaderWriter Overriding the following: Type ID Run 7

ADT: Writer Sub-class of ReaderWriter Overriding the following: Type ID Run 8

Invoking Delegate ‘ Cannot do it this way! _passMag.Invoke(ID, state, _database.TotalValue) ‘ Must ask the main form to invoke the delegate! _mainForm.Invoke(_passMsg, ID, state, _database.TotalValue) 9

ADT: ReaderWriterForm txtTotal lstWaiting lstWorking txtLog btnNewReader btnNewWriter btnExit dummyThread Delegate 10 FormLoad (Sub New) Create a Database object for ReaderWriter Class Delegate Sub New Reader set MainForm & DisplayMsg New Writer set MainForm & DisplayMsg Exit

Final Exam (Test4) Threads! 11

Project VB Grader Threads Assembly Midterm grade B (A-) or above. me by Wednesday. 12