CS 3340
Windows Programming
Test 3: Threading
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Barbershop
Similar to Prog5 (Reader & Writer)
Tuesday, April 4
Lab 206
80 minutes
Initial solution
2
Barber Shop
Customer Queue
Barber
One Barber with one Customer Queue
3
Before Opening
Barber
The queue could be empty
4
Barber Shop Opens
Barber
Barber goes to sleep if the Barber shop
opens with an empty queue
5
Before Opening
C1
C2
C3
Barber
There may be customers waiting in the queue
6
Barber Shop Opens
C1
C2
C2
C3
C3
Barber removes customer
from the queue
Barber
C1
Barber wakes up customer
after the hair cut
7
Barber Shop is Open
C2
C3
C3
Barber
C2
C1
8
Barber Shop is Open
C3
Barber
C3
C2
9
Barber Shop is Open
Barber
Barber goes to sleep when the queue is empty
10
New Customer Comes when
the Barber is Sleeping
C4
Customer enters queue,
wakes up barber,
Then goes to sleep.
Barber
11
New Customer Comes when
the Barber is Sleeping
C4
Barber will remove customer
from the queue.
Barber
C4
12
New Customer Comes
C5
C6
Barber
C4
13
Barber Shop Closing
C5
C6
Barber should finish all
waiting customers
Barber
C4
14
Barber Shop Closing
C7
C5
C6
New customers don’t wait
when shop is closing
Barber
C4
15
Barber Shop Closing
C8
C6
New customers don’t wait
when shop is closing
Barber
C5
16
Barber Shop Closing
C9
New customers don’t wait
when shop is closing
Barber
C6
17
Barber Shop Closed
Barber shop can open again
Barber
18
Barber Shop Closed
C10 C11
New customers wait when
shop is closed
Barber
19
Barber Shop Opens
C11 C11
C10
Barber removes customer
from the queue
Barber
C10
Barber wakes up customer
after the hair cut
20
Closing Before Exiting
C11
Barber
C11
21
Closing Before Exiting
Asking user Yes/No
Barber
22
User No
C1
C2
C3
Customers come and wait
Barber
23
Exiting Before Opening
C1
C2
C3
Clear customer queue
Barber
24
Barber Thread
• Creating a new thread when the Barber shop opens
• The thread will be terminated when the Shop closed
• When the Shop opens again, a new thread is created
• The run sub of the Barber class is for one iteration of
Open-Close to make code simpler
25
Prog5
‘ Waits for all readers and writers to finish the work in order to
‘ terminate the program.
‘ Mutual exclusion on the DataObj and the queue must be enforced.
Public Shared Sub FinishReadWrite()
_database.LockDataObj()
Monitor.Enter(FIFOQueue)
If FIFOQueue.Count > 0 or _database.TheDatabaseStatus <>
DataBaseClass.DatabaseStatus.Empty
endProgram.Reset()
Else
endProgram.Set()
End If
Then
Monitor.Exit(FIFOQueue)
_database.ReleaseDataObj()
endProgram.WaitOne()
End Sub
‘do not know which thread will wake it up
26
JOIN Method
Public Sub CloseBarberShop()
Monitor.Enter(BarberShopClass.TheBarberStateObj)
BarberShopClass.theBarberState =
BarberShopClass.BarberState.Closing
Monitor.Exit(BarberShopClass.TheBarberStateObj)
barberEvent.Set()
‘ Wait until _barberThread is terminated
_barberThread.Join()
End Sub
27