readwrite lock

Question

aoa sir,

Class ReaderWriterLock {

Semaphore mutex = 1; // declaration of a semaphore

OkToRead = 0; // a flag to check it is OK to read the database

OkToWrite = 0; // a flag to check it it is OK to write the database

int ACTIVEREADERS=0;// number of readers holding the read lock and accessing the database

WAITINGREADERS=0; // number of readers waiting to acquire read lock

ACTIVEWRITERS=0; // number of writers that have acquired write lock

// (practically this will always be 1)

WAITINGWRITERS=0; // number of writers that are waiting for write lock

void AcquireReadLock()

{

P(mutex); // remember that P operation on a semaphore means decrementing its value

if ((ACTIVEWRITERS == 0)

{

V(OkToRead); // remember that V operation on a semaphore means incrementing its value ACTIVEREADERS++;

}

else

{

WAITINGREADERS++;

}

V(mutex);

P(OkToRead);

}

void ReleaseReadLock()

{

P(mutex);

ACTIVEREADERS--;

if ((ACTIVEREADERS == 0) && (WAITINGWRITERS > 0))

{

V(OkToWrite);

ACTIVEWRITERS++;

WAITINGWRITERS--;

}

V(mutex);

}

void AcquireWriteLock()

{

P(mutex);

if (ACTIVEWRITERS + ACTIVEREADERS == 0)

{

V(OkToWrite);

ACTIVEWRITERS++;

}

else

{

WAITINGWRITERS++;

}

V(mutex);

P(OkToWrite);

}

void ReleaseWriteLock()

{

P(mutex);

ACTIVEWRITERS--;

if (WAITINGWRITERS > 0)

{

V(OkToWrite);

ACTIVEWRITERS++;

WAITINGWRITERS--;

}

else

{

while (WAITINGREADERS > 0)

{

V(OkToRead);

ACTIVEREADERS++;

WAITINGREADERS--;

}

}

V(mutex);

}

} // end of class

this is s code sir can you tell me it is either writer preference code or reader priority  code. and kindly suggest me starvation free code.