// Copyright (c) 1998-2009 Nokia Corporation and/or its subsidiary(-ies).

// All rights reserved.

// This component and the accompanying materials are made available

// under the terms of "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 "UT_STD.H"

// Class RDbTransaction::CNotifier

NONSHARABLE_CLASS(RDbTransaction::CNotifier) : public CDbNotifier

	{

public:

	inline CNotifier( RDbTransaction& aTransaction );

	~CNotifier();

//

	void Event( RDbNotifier::TEvent aEvent );

private:

	void Complete( TInt aStatus );

// from CDbNotifier

	void Notify( TType aEvent, TRequestStatus& aStatus );

	void Cancel();

private:

	RDbTransaction* iTransaction;

	TRequestStatus* iStatus;

	TInt iPending;

	};

inline RDbTransaction::CNotifier::CNotifier( RDbTransaction& aTransaction )

 :	iTransaction( &aTransaction )

	{}

RDbTransaction::CNotifier::~CNotifier()

//

// Cancel any outstanding request and extract from the transaction

//

	{

	Cancel();

	if ( iTransaction )

		{

		__ASSERT( iTransaction->iNotifier == this );

		iTransaction->iNotifier = 0;

		}

	}

void RDbTransaction::CNotifier::Complete( TInt aStatus )

	{

	if ( iStatus )

		{

		iPending = 0;

		User::RequestComplete( iStatus, aStatus );

		}

	}

void RDbTransaction::CNotifier::Notify( CDbNotifier::TType aType, TRequestStatus& aStatus )

//

// Request for future notification. If the database is closed complete immediately

//

	{

	__ASSERT( !iStatus );

	__ASSERT( iPending >= 0 );

	iStatus = &aStatus;

	if ( iPending > RDbNotifier::EUnlock )

		Complete( iPending );

	else if ( !iTransaction )

		Complete( RDbNotifier::EClose );

	else

		{

		iPending = aType;

		aStatus = KRequestPending;

		}

	}

void RDbTransaction::CNotifier::Cancel()

	{

	Complete( KErrCancel );

	}

void RDbTransaction::CNotifier::Event( RDbNotifier::TEvent aEvent )

	{

	if ( aEvent == RDbNotifier::EClose )

		iTransaction = 0;

	if ( iStatus )

		{

		__ASSERT( iPending < 0 );

		if (aEvent == RDbNotifier::EUnlock && iPending == CDbNotifier::EChange )

			;	// not interested in unlock events

		else

			Complete( aEvent );

		}

	else

		{

		__ASSERT( iPending >= 0 );

		if ( aEvent > iPending )

			iPending = aEvent;		// save the event

		}

	}

// Class RDbTransaction

#ifdef _ASSERTIONS

void RDbTransaction::_Invariant() const

//

// Invariance test

//

	{

	if ( iLockCount == 0 )

		{	// nothing must be happening in this state

		__ASSERT( iLockState == EDbReadLock );

		__ASSERT( iAction == EDbReadLock );

		__ASSERT( iUpdaters == 0 );

		return;

		}

	switch ( iLockState & EState )

		{

	default:

		__ASSERT( 0 );

	case EDbReadLock:

		{

		__ASSERT( iAction == EDbReadLock );

		__ASSERT( iLockCount > 0 );		// someone must have a lock

		__ASSERT( iLockCount <= iMaxLock );

		__ASSERT( iUpdaters == 0 );

		__ASSERT( iPrimary.iState != 0 );

		for (TInt ii = iLockCount - 1; --ii >= 0; )

			__ASSERT( iSharers[ii].iState != 0 );

		}

		break;

	case EDbCompactLock:		// not allowed in user-transactions

	case EDbRecoveryLock:

		__ASSERT( iAction == iLockState );

		__ASSERT( iLockCount == 1 );	// exactly one lock allowed

		__ASSERT( iUpdaters == 0 );

		__ASSERT( iPrimary.iState == 0 );

		break;

	case EDbXReadLock:	// intention to write. No updates but exclusive

		__ASSERT( iLockCount == 1 );	// exactly one lock allowed

		switch ( iAction )

			{

		default:

			__ASSERT( 0 );

		case EDbReadLock:	// must be in a transaction: cannot commit a write/schema mod when releasing a read lock

			__ASSERT( iUpdaters == 0 );

			__ASSERT( iPrimary.iState & static_cast<TUint>( ETransactionLock ) );

			break;

		case EDbWriteLock:

			__ASSERT( iUpdaters > 0 );

			break;

			}

		break;

	case EDbWriteLock:

	case EDbSchemaLock:

		__ASSERT( iLockCount == 1 );	// exactly one lock allowed

		switch ( iAction )

			{

		default:

			__ASSERT( 0 );

		case EDbReadLock:	// must be in a transaction: cannot commit a write/schema mod when releasing a read lock

			__ASSERT( iUpdaters == 0 );

			__ASSERT( iPrimary.iState & static_cast<TUint>( ETransactionLock ) );

			break;

		case EDbWriteLock:

			__ASSERT( iUpdaters > 0 );

			__ASSERT( ( iLockState & EState ) == EDbWriteLock || ( iPrimary.iState & static_cast<TUint>( ETransactionLock ) ) );

			break;

		case EDbSchemaLock:

			__ASSERT( ( iLockState & EState ) == EDbSchemaLock );

			__ASSERT( iUpdaters == 0 );

			break;

			}

		break;

		}

	}

template <class T> struct _InvariantFunc

	{

	static void Invariant( TAny* aPtr ) { ( (const T*)aPtr )->_Invariant(); }

	};

template <class T> inline TCleanupOperation _InvariantFunction( T* )

	{ return _InvariantFunc<T>::Invariant; }

struct _Invariant

	{

	inline _Invariant( TCleanupOperation aOp, TAny* aPtr )

	 :	iOp( aOp ), iPtr( aPtr )

		{ aOp( aPtr ); }

	inline ~_Invariant()

		{ iOp( iPtr ); }

private:

	TCleanupOperation iOp;

	TAny* iPtr;

	};

#ifndef __LEAVE_EQUALS_THROW

struct _InvariantL

	{

	inline _InvariantL( TCleanupOperation aOp, TAny* aPtr )

		{ aOp( aPtr ); CleanupStack::PushL( TCleanupItem( aOp, aPtr ) ); }

	inline ~_InvariantL()

        { CleanupStack::PopAndDestroy(); }

	};

#endif //__LEAVE_EQUALS_THROW__

#define __INVARIANT   struct _Invariant _invariant( _InvariantFunction( this ), this );

#ifdef __LEAVE_EQUALS_THROW__

	#define __INVARIANT_L __INVARIANT

#else

	#define __INVARIANT_L struct _InvariantL _invariant( _InvariantFunction( this ), this );

#endif //__LEAVE_EQUALS_THROW__

#else // _ASSERTIONS

#define __INVARIANT   ( (void)0 )

#define __INVARIANT_L ( (void)0 )

#endif // _ASSERTIONS

inline TDbLockType RDbTransaction::LockState() const

	{ return TDbLockType( iLockState & EState ); }

void RDbTransaction::Close()

	{

	__ASSERT( !IsLocked() );

	User::Free( iSharers );

	Event( RDbNotifier::EClose );

	}

void RDbTransaction::DoCommitL()

//

// Commit any changes

//

	{

	__ASSERT_ALWAYS( ( iPrimary.iState & ~ETransactionLock ) == 0, Panic( EDbStreamsPendingOnCommit ) );

	iLockState |= EFailed;

	Database().FlushL( LockState() );

	Database().SynchL( LockState() );

	Unlock( RDbNotifier::ECommit );

	}

void RDbTransaction::DoRollback()

//

// Rollback any changes

//

	{

	__ASSERT_ALWAYS( ( iPrimary.iState & ~ETransactionLock ) == 0, Panic( EDbStreamsPendingOnRollback ) );

	Database().Revert( LockState() );

	Database().Abandon( LockState() );

	if ( LockState() >= EDbWriteLock )

		++iRollback;

	Unlock( RDbNotifier::ERollback );

	}

// explicit transactions

void RDbTransaction::BeginL( const CDbObject& aObject )

//

// begin a user transaction. This first gains a shared read-lock

//

	{

	__INVARIANT_L;

	__ASSERT_ALWAYS( GetLock( aObject ) == 0, Panic( EDbBeginNestedTransaction ) );

	ReadyL();

	PrepareSLockL( aObject, TUint( ETransactionLock ) );

	__ASSERT( iAction == EDbReadLock );

	__ASSERT( iLockState == EDbReadLock );

	++iLockCount;

	}

void RDbTransaction::CommitL( const CDbObject& aObject )

//

// Commit a user transaction and release the lock

// All updates must be complete for a write-lock

//

	{

	__INVARIANT_L;

	__ASSERT_ALWAYS( InTransaction( aObject ), Panic( EDbNoCurrentTransaction ) );

	ReadyL();

	if ( iLockCount > 1 )

		{

		TLock* lock = GetLock( aObject );

		__ASSERT( lock );

		__ASSERT_ALWAYS( lock->iState == static_cast<TUint>( ETransactionLock ), Panic( EDbStreamsPendingOnCommit ) );

		Unlock( *lock );

		}

	else

		{

		__ASSERT_ALWAYS( iAction == EDbReadLock, Panic( EDbUpdatesPendingOnCommit ) );

		DoCommitL();

		}

	}

void RDbTransaction::Rollback( const CDbObject& aObject )

//

// Rollback a user transaction and release the lock

// All updates must be complete/aborted for a write-lock

//

	{

	__INVARIANT;

	__ASSERT_ALWAYS( InTransaction( aObject ), Panic( EDbNoCurrentTransaction ) );

	if ( iLockCount > 1 )

		{

		TLock* lock = GetLock( aObject );

		__ASSERT( lock );

		__ASSERT_ALWAYS( lock->iState == static_cast<TUint>( ETransactionLock ), Panic( EDbStreamsPendingOnRollback ) );

		Unlock( *lock );

		}

	else

		{

		__ASSERT_ALWAYS( iAction == EDbReadLock, Panic( EDbUpdatesPendingOnRollback ) );

		DoRollback();

		}

	}

void RDbTransaction::PrepareSLockL( const CDbObject& aObject, TUint aInitState )

//

// prepare to acquire a shared read lock

// if any holder has an exclusive lock this fails

//

	{

	__ASSERT( GetLock( aObject ) == 0 );	// cannot get a 2nd shared lock

//

	THolder h = aObject.Context();

	if ( iLockCount == 0 )

		{

		iPrimary.iHolder = h;				// first lock, no other checks required

		iPrimary.iState = aInitState;

		}

	else if ( iLockState != EDbReadLock )

		__LEAVE( KErrLocked );

	else

		{						// allocate a Sharers-slot

		TLock* share = iSharers;

		if ( iLockCount == iMaxLock )

			{

			TInt newsize = iMaxLock + ELockListGranularity;

			if ( newsize > EMaxLock )

				{

				__LEAVE( KErrLocked );

				return;

				}

			iSharers = share = ( TLock* )User::ReAllocL( share, ( newsize - 1 ) * sizeof( TLock ) );

			iMaxLock = TUint8( newsize );

			}

		share += iLockCount - 1;

		share->iHolder = h;

		share->iState = aInitState;

		}

	}

void RDbTransaction::PrepareXLockL( const CDbObject& aObject )

//

// prepare to acquire an exclusive lock

// if any other holder has a lock this fails

//

	{

	THolder h = aObject.Context();

	switch ( iLockCount )

		{

	case 0:					// no other holders, acquire the lock

		iPrimary.iHolder = h;

		iPrimary.iState = 0;		// this is not a transaction lock

		break;

	case 1:					// check we are the single Lock holder

		if (iPrimary.iHolder != h)

			__LEAVE( KErrLocked );

		break;

	default:				// cannot get XLock

		__LEAVE( KErrLocked );

		break;

		}

	}

void RDbTransaction::Unlock( RDbNotifier::TEvent aEvent )

//

// Remove the last lock and signal an event to the Notifier

//

	{

	__ASSERT( iLockCount == 1 );

	__ASSERT( ( iPrimary.iState & ~ETransactionLock ) == 0 );

	TDbLockType ls = LockState();

	Event( ls == EDbReadLock || ls == EDbXReadLock ? RDbNotifier::EUnlock : aEvent );

	iLockCount = 0;

	iAction = iLockState = EDbReadLock;

	iUpdaters = 0;

	Database().CheckIdle();

	}

void RDbTransaction::Unlock( RDbTransaction::TLock& aLock )

//

// Remove a shared lock holder from the list

//

	{

	__ASSERT( iLockCount > 1 );

	__ASSERT( LockState() == EDbReadLock );

	__ASSERT( ( aLock.iState & ~ETransactionLock ) == 0 );

	aLock = iSharers[--iLockCount - 1];

	}

RDbTransaction::TLock* RDbTransaction::GetLock( const CDbObject& aObject )

//

// Test if aObject holds any lock, and return it

//

	{

	const THolder h = aObject.Context();

	TInt lc = iLockCount;

	if ( --lc >= 0 )

		{

		if ( iPrimary.iHolder == h )

			return &iPrimary;

		if ( lc > 0 )

			{

			TLock* const base = iSharers;

			TLock* l = base + lc;

			do	{

				if ( ( --l )->iHolder == h )

					return l;

				} while ( l > base );

			}

		}

	return 0;

	}

TBool RDbTransaction::InTransaction( const CDbObject& aObject )

//

// Test if aObject holds a non-auto transaction

//

	{

	__INVARIANT;

	TLock* lock = GetLock( aObject );

	return lock ? lock->iState & static_cast<TUint>( ETransactionLock ) : 0;

	}

void RDbTransaction::ReadPrepareL( const CDbObject& aObject )

//

// Check that aObject can gain a shared read lock and allocate required resources

//

	{

	__INVARIANT_L;

	if ( GetLock( aObject ) == 0 )

		PrepareSLockL( aObject, 0 );		// prepare a S-Lock for the read

	else if ( iAction == EDbCompactLock )	// Cannot already hold a compaction lock

		__LEAVE( KErrAccessDenied );

	}

void RDbTransaction::ReadBegin( const CDbObject& aObject )

//

// Take a read-lock: ReadPrepareL(aObject) _must_ already have been called

//

	{

	__INVARIANT;

	TLock* lock = GetLock( aObject );

	if ( !lock )

		{

		++iLockCount;

		lock = GetLock( aObject );

		__ASSERT( lock );

		}

	++lock->iState;

	}

void RDbTransaction::ReadRelease( const CDbObject& aObject )

	{

	__INVARIANT;

	TLock* lock = GetLock( aObject );

	__ASSERT( lock );

	__ASSERT( ( lock->iState & ~ETransactionLock ) > 0 );

	if ( --lock->iState == 0 )

		{	// not transaction-lock

		if ( iLockCount > 1 )

			Unlock( *lock );

		else if ( iAction == EDbReadLock )	// no other locks to this client

			Unlock( RDbNotifier::EUnlock );

		}

	}

void RDbTransaction::DMLCheckL()

//

// Check that we can open a new rowset

//

	{

	__INVARIANT_L;

	ReadyL();

	if ( iAction > EDbCompactLock )	

		__LEAVE( KErrAccessDenied );

	}

void RDbTransaction::DMLPrepareL( const CDbObject& aObject )

//

// Check that we can do DML, this should be called immediately prior to DMLBegin

//

	{

	__INVARIANT_L;

	PrepareXLockL( aObject );

	if ( iAction>EDbWriteLock )

		__LEAVE( KErrAccessDenied );

	}

void RDbTransaction::DMLBegin()

//

// A Rowset begins an update

//

	{

	__INVARIANT;

	__ASSERT( iAction == EDbReadLock || iAction == EDbWriteLock );

	__ASSERT( ( iLockState & EFailed ) == 0 );

	__ASSERT( iLockCount <= 1 );

	if ( iAction == EDbReadLock )

		iAction = EDbWriteLock;

	if (iLockState == EDbReadLock )

		iLockState = EDbXReadLock;		// escalate lock to exclusive as we are now writing

	++iUpdaters;

	iLockCount = 1;

	}

void RDbTransaction::DMLTouch()