// Copyright (c) 2007-2009 Nokia Corporation and/or its subsidiary(-ies).

// All rights reserved.

// This component and the accompanying materials are made available

// under the terms of the License "Eclipse Public License v1.0"

// which accompanies this distribution, and is available

// at the URL "http://www.eclipse.org/legal/epl-v10.html".

//

// Initial Contributors:

// Nokia Corporation - initial contribution.

//

// Contributors:

//

// Description:

//

#include <kernel.h>

#include "mpagecleaner.h"

#include "mm.h"

#include "mmu.h"

#include "mpager.h"

#ifdef __PAGING_PRE_CLEAN_DIRTY_PAGES

inline void IgnorePrintf(...) { }

#define PAGE_CLEANER_TRACE IgnorePrintf

//#define PAGE_CLEANER_TRACE Kern::Printf

_LIT(KThreadName, "PageCleaner");

const TInt KThreadPriority = 25;

/// The length of time the paging device is idle before we decide to use it for cleaning dirty

/// pages, in milliseconds.

const TInt KIdleDelayInMillis = 2;

class DPageCleaner

	{

public:

	DPageCleaner();

	void Start();

	void NotifyPagingDeviceIdle();

	void NotifyPagingDeviceBusy();

	void NotifyPagesToClean();

private:

	inline TBool IsRunning();

	void UpdateBusyCount(TInt aChange);

	void IdleTimerExpired(TUint aInitialNotificationCount);

	void TryToClean();

private:

	static void TimerDfcFn(TAny*);

	static void CleanerDfcFn(TAny*);

private:

	TInt iIdleDelayInTicks;

	NTimer iDelayTimer;

	TDfcQue iDfcQue;

	TDfc iTimerDfc;

	TDfc iCleanerDfc;

	TBool iRunning;

	// All state below is accessed with the MmuLock held.

	/// Whether the paging device is currently idle.

	TBool iPagingDeviceIdle;

	/// Whether the paging device has been idle for longer than the wait period.

	TBool iIdleForAWhile;

	/// Whether the page cleaner is currently running.

	TBool iCleaningInProgress;	

	};

DPageCleaner ThePageCleaner;

DPageCleaner::DPageCleaner() :

	iTimerDfc(TimerDfcFn, NULL, 1),

	iCleanerDfc(CleanerDfcFn, NULL, 1),

	iRunning(EFalse),

	iPagingDeviceIdle(ETrue),

	iIdleForAWhile(ETrue),

	iCleaningInProgress(EFalse)

	{

	}

void DPageCleaner::Start()

	{

	TBool alreadyRunning = __e32_atomic_swp_ord32(&iRunning, ETrue);

	if (alreadyRunning)

		return;

	iIdleDelayInTicks = NKern::TimerTicks(KIdleDelayInMillis);

	TInt r = Kern::DfcQInit(&iDfcQue, KThreadPriority, &KThreadName);

	__NK_ASSERT_ALWAYS(r == KErrNone);

	iTimerDfc.SetDfcQ(&iDfcQue);

	iCleanerDfc.SetDfcQ(&iDfcQue);

	PAGE_CLEANER_TRACE("PageCleaner started");

	}

FORCE_INLINE TBool DPageCleaner::IsRunning()

	{

	return __e32_atomic_load_acq32(&iRunning);

	}

void DPageCleaner::NotifyPagingDeviceIdle()

	{

	__NK_ASSERT_DEBUG(MmuLock::IsHeld());

	if (IsRunning())

		{

		iPagingDeviceIdle = ETrue;

		if (!iDelayTimer.IsPending())

			iDelayTimer.OneShot(iIdleDelayInTicks, iTimerDfc);

		}

	}

void DPageCleaner::NotifyPagingDeviceBusy()

	{

	__NK_ASSERT_DEBUG(MmuLock::IsHeld());

	if (IsRunning())

		{

		iDelayTimer.Cancel();

		iPagingDeviceIdle = EFalse;

		iIdleForAWhile = EFalse;

		}		

	}

void DPageCleaner::NotifyPagesToClean()

	{

	__NK_ASSERT_DEBUG(MmuLock::IsHeld());

	if (IsRunning())

		{

		if (!iCleaningInProgress && iIdleForAWhile)

			iCleanerDfc.Enque();

		}

	}

void DPageCleaner::TimerDfcFn(TAny* aPtr)

	{

	ThePageCleaner.IdleTimerExpired((TUint)aPtr);	

	}

void DPageCleaner::IdleTimerExpired(TUint aInitialNotificationCount)

	{

	MmuLock::Lock();	

	if (iPagingDeviceIdle)

		{

		iIdleForAWhile = ETrue;

		if (!iCleaningInProgress && ThePager.HasPagesToClean())

			iCleanerDfc.Enque();

		}

	MmuLock::Unlock();

	}

void DPageCleaner::CleanerDfcFn(TAny*)

	{

	ThePageCleaner.TryToClean();

	}

void DPageCleaner::TryToClean()

	{

	MmuLock::Lock();

	TBool workToDo = iIdleForAWhile && ThePager.HasPagesToClean();

	iCleaningInProgress = workToDo;

	MmuLock::Unlock();

	if (!workToDo)

		{

		PAGE_CLEANER_TRACE("PageCleaner - started but no work to do");

		return;

		}

	for (;;)

		{

		PageCleaningLock::Lock();

		MmuLock::Lock();

		if (!iIdleForAWhile)

			break;

		TInt attempted = ThePager.CleanSomePages(ETrue);

		if (attempted == 0)

			break;

		PAGE_CLEANER_TRACE("PageCleaner - attempted to clean %d pages", attempted);

		MmuLock::Unlock();

		PageCleaningLock::Unlock();

		}

	if (iIdleForAWhile)

		PAGE_CLEANER_TRACE("PageCleaner - no more pages to clean");

	else

		PAGE_CLEANER_TRACE("PageCleaner - device now busy");

	iCleaningInProgress = EFalse;

	MmuLock::Unlock();

	PageCleaningLock::Unlock();

	}

void PageCleaner::Start()

	{

	ThePageCleaner.Start();

	}

void PageCleaner::NotifyPagesToClean()

	{

	ThePageCleaner.NotifyPagesToClean();

	}

EXPORT_C void DPagingDevice::NotifyIdle()

	{

	ThePageCleaner.NotifyPagingDeviceIdle();

	}

EXPORT_C void DPagingDevice::NotifyBusy()

	{

	ThePageCleaner.NotifyPagingDeviceBusy();

	}

#else  // __PAGING_PRE_CLEAN_DIRTY_PAGES not defined

void PageCleaner::Start()

	{

	}

void PageCleaner::NotifyPagesToClean()

	{

	}

EXPORT_C void DPagingDevice::NotifyIdle()

	{

	}

EXPORT_C void DPagingDevice::NotifyBusy()

	{

	}

#endif

EXPORT_C NFastMutex* DPagingDevice::NotificationLock()

	{

	// use the MmuLock

	return &MmuLock::iLock;

	}