Data commit

Task/Atomic-updates/PureBasic/atomic-updates.basic

@@ -0,0 +1,84 @@
+#Buckets=9
+#TotalAmount=200
+Global Dim Buckets(#Buckets)
+Global BMutex=CreateMutex()
+Global Quit=#False
+
+Procedure max(x,y)
+  If x>=y:  ProcedureReturn x
+  Else:     ProcedureReturn y
+  EndIf
+EndProcedure
+
+Procedure Move(WantedAmount, From, Dest)
+  Protected RealAmount
+  If from<>Dest
+    LockMutex(BMutex)
+    RealAmount=max(0, Buckets(from)-WantedAmount)
+    Buckets(From)-RealAmount
+    Buckets(Dest)+RealAmount
+    UnlockMutex(BMutex)
+  EndIf
+  ProcedureReturn RealAmount
+EndProcedure
+
+Procedure Level(A,B)
+  Protected i, j, t
+  If A<>B
+    LockMutex(BMutex)
+    t=Buckets(A)+Buckets(B)
+    i=t/2: j=t-i
+    Buckets(A)=i
+    Buckets(B)=j
+    UnlockMutex(BMutex)
+  EndIf
+EndProcedure
+
+Procedure DoInvent(Array A(1))
+  Protected i, sum
+  LockMutex(BMutex)
+  For i=0 To ArraySize(Buckets())
+    A(i)=Buckets(i)
+    sum+A(i)
+  Next i
+  UnlockMutex(BMutex)
+  ProcedureReturn sum
+EndProcedure
+
+Procedure MixingThread(arg)
+  Repeat
+    Move(Random(#TotalAmount),Random(#Buckets),Random(#Buckets))
+  Until Quit
+EndProcedure
+
+Procedure LevelingThread(arg)
+  Repeat
+    Level(Random(#Buckets),Random(#Buckets))
+  Until Quit
+EndProcedure
+
+If OpenWindow(0,0,0,100,150,"Atomic updates",#PB_Window_SystemMenu)
+  Define Thread1=CreateThread(@MixingThread(),0)
+  Define Thread2=CreateThread(@MixingThread(),0)
+  Define i, Event
+  Dim Inventory(#Buckets)
+  ; Set up a small GUI
+  For i=0 To 9
+    TextGadget(i, 0,i*15,50, 15,"Bucket #"+Str(i))
+  Next i
+  TextGadget(10,55,135,40,15,"=")
+  AddWindowTimer(0,0,500)
+  Buckets(0)=#TotalAmount
+  Repeat
+    Event=WaitWindowEvent()
+    If Event=#PB_Event_Timer
+      i=DoInvent(Inventory())
+      SetGadgetText(10,"="+Str(i))
+      For i=0 To #Buckets
+        SetGadgetText(i, Str(Inventory(i)))
+      Next i
+    EndIf
+  Until Event=#PB_Event_CloseWindow
+  Quit=#True  ; Tell threads to shut down
+  WaitThread(Thread1): WaitThread(Thread2)
+EndIf