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DeclareModule ConcurrentQueue
	Interface type
		destroy.i()
		CountElements.i()
		isEmpty.i()
		push.i(element.s)
		pop.s()
	EndInterface	
	Declare.i new()
EndDeclareModule	
Module ConcurrentQueue
	
	Structure Type_s
		*vTable
		semaphore.i
		lock.i
		List elements.s()
	EndStructure	
	Procedure new ()
		Protected *this.Type_s=AllocateMemory(SizeOf(Type_s))
		If (Not *this)
			ProcedureReturn #False
		EndIf 
		
		InitializeStructure(*this, Type_s)
		With *this
			\vTable			=?vTable
			\semaphore 	=CreateSemaphore(0)
			\lock				=CreateMutex()
		EndWith	
		ProcedureReturn *this
	EndProcedure	
	
	Procedure destroy(*this.Type_s)
		With *this
			FreeMutex(\lock)
			FreeSemaphore(\semaphore)
			ClearStructure(*this, Type_s)
			FreeMemory(*this)
		EndWith	
	EndProcedure	
	
	Procedure.i countElements(*this.Type_S)
		Protected Size.i
		With	*this
			LockMutex(\lock) 
			size= ListSize(\elements())
			UnlockMutex(\lock)
		EndWith	
		ProcedureReturn size
	EndProcedure	
	
	Procedure.i isEmpty(*this.type)
		ProcedureReturn Bool(*this\CountElements() = 0)
	EndProcedure	
	
	Procedure push(*this.Type_s, element.s)
		Protected result.i = #False
		With *this
			LockMutex(\lock)
			LastElement(\elements())
			If AddElement(\elements())
				\elements()=element
				SignalSemaphore(\semaphore)
				result=#True
			EndIf 
			UnlockMutex(\lock)
		EndWith	
		;ProcedureReturn result
	EndProcedure 	
	
	Procedure.s pop(*this.type_s)
		Protected element.s
		With *this
			LockMutex(\lock)
			If Not TrySemaphore(\semaphore)
				UnlockMutex(\lock)
				WaitSemaphore(\semaphore)
				LockMutex(\lock)
			EndIf 	
			FirstElement(\elements())
			element = \elements()
			DeleteElement(\elements())
			UnlockMutex(\lock)
		EndWith	
		ProcedureReturn element
	EndProcedure	
	DataSection
		vTable:
		Data.i @destroy(), @countElements(), @isEmpty(), @push(), @pop()
	EndDataSection	
EndModule	

Define q.ConcurrentQueue::type =ConcurrentQueue::new()
q\push("1")
q\push("2")
Debug q\CountElements()
Debug q\pop()
Debug q\pop()