/* This Source Code Form is subject to the terms of the Mozilla Public

 * License, v. 2.0. If a copy of the MPL was not distributed with this

 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/*

 * pkix_pl_rwlock.c

 *

 * Read/Write Lock Functions

 *

 */

#include "pkix_pl_rwlock.h"

/* --Private-Functions-------------------------------------------- */

static PKIX_Error *

pkix_pl_RWLock_Destroy(

        PKIX_PL_Object *object,

        void *plContext)

{

        PKIX_PL_RWLock* rwlock = NULL;

        PKIX_ENTER(RWLOCK, "pkix_pl_RWLock_Destroy");

        PKIX_NULLCHECK_ONE(object);

        PKIX_CHECK(pkix_CheckType(object, PKIX_RWLOCK_TYPE, plContext),

                    PKIX_OBJECTNOTRWLOCK);

        rwlock = (PKIX_PL_RWLock*) object;

        PKIX_RWLOCK_DEBUG("Calling PR_DestroyRWLock)\n");

        PR_DestroyRWLock(rwlock->lock);

        rwlock->lock = NULL;

cleanup:

        PKIX_RETURN(RWLOCK);

}

/*

 * FUNCTION: pkix_pl_RWLock_RegisterSelf

 * DESCRIPTION:

 *  Registers PKIX_RWLOCK_TYPE and its related functions with systemClasses[]

 * THREAD SAFETY:

 *  Not Thread Safe - for performance and complexity reasons

 *

 *  Since this function is only called by PKIX_PL_Initialize, which should

 *  only be called once, it is acceptable that this function is not

 *  thread-safe.

 */

PKIX_Error *

pkix_pl_RWLock_RegisterSelf(

        void *plContext)

{

        extern pkix_ClassTable_Entry systemClasses[PKIX_NUMTYPES];

        pkix_ClassTable_Entry entry;

        PKIX_ENTER(RWLOCK, "pkix_pl_RWLock_RegisterSelf");

        entry.description = "RWLock";

        entry.objCounter = 0;

        entry.typeObjectSize = sizeof(PKIX_PL_RWLock);

        entry.destructor = pkix_pl_RWLock_Destroy;

        entry.equalsFunction = NULL;

        entry.hashcodeFunction = NULL;

        entry.toStringFunction = NULL;

        entry.comparator = NULL;

        entry.duplicateFunction = NULL;

        systemClasses[PKIX_RWLOCK_TYPE] = entry;

        PKIX_RETURN(RWLOCK);

}

/* --Public-Functions--------------------------------------------- */

PKIX_Error *

PKIX_PL_RWLock_Create(

        PKIX_PL_RWLock **pNewLock,

        void *plContext)

{

        PKIX_PL_RWLock *rwLock = NULL;

        PKIX_ENTER(RWLOCK, "PKIX_PL_RWLock_Create");

        PKIX_NULLCHECK_ONE(pNewLock);

        PKIX_CHECK(PKIX_PL_Object_Alloc

                    (PKIX_RWLOCK_TYPE,

                    sizeof (PKIX_PL_RWLock),

                    (PKIX_PL_Object **)&rwLock,

                    plContext),

                    PKIX_ERRORALLOCATINGRWLOCK);

        PKIX_RWLOCK_DEBUG("\tCalling PR_NewRWLock)\n");

        rwLock->lock = PR_NewRWLock(PR_RWLOCK_RANK_NONE, "PKIX RWLock");

        if (rwLock->lock == NULL) {

                PKIX_DECREF(rwLock);

                PKIX_ERROR(PKIX_OUTOFMEMORY);

        }

        rwLock->readCount = 0;

        rwLock->writeLocked = PKIX_FALSE;

        *pNewLock = rwLock;

cleanup:

        PKIX_RETURN(RWLOCK);

}

PKIX_Error *

PKIX_PL_AcquireReaderLock(

        PKIX_PL_RWLock *lock,

        void *plContext)

{

        PKIX_ENTER(RWLOCK, "PKIX_PL_AcquireReaderLock");

        PKIX_NULLCHECK_ONE(lock);

        PKIX_RWLOCK_DEBUG("\tCalling PR_RWLock_Rlock)\n");

        (void) PR_RWLock_Rlock(lock->lock);

        lock->readCount++;

        PKIX_RETURN(RWLOCK);

}

PKIX_Error *

PKIX_PL_ReleaseReaderLock(

        PKIX_PL_RWLock *lock,

        void *plContext)

{

        PKIX_ENTER(RWLOCK, "PKIX_PL_ReleaseReaderLock");

        PKIX_NULLCHECK_ONE(lock);

        PKIX_RWLOCK_DEBUG("\tCalling PR_RWLock_Unlock)\n");

        (void) PR_RWLock_Unlock(lock->lock);

        lock->readCount--;

        PKIX_RETURN(RWLOCK);

}

PKIX_Error *

PKIX_PL_IsReaderLockHeld(

        PKIX_PL_RWLock *lock,

        PKIX_Boolean *pIsHeld,

        void *plContext)

{

        PKIX_ENTER(RWLOCK, "PKIX_PL_IsReaderLockHeld");

        PKIX_NULLCHECK_TWO(lock, pIsHeld);

        *pIsHeld = (lock->readCount > 0)?PKIX_TRUE:PKIX_FALSE;

        PKIX_RETURN(RWLOCK);

}

PKIX_Error *

PKIX_PL_AcquireWriterLock(

        PKIX_PL_RWLock *lock,

        void *plContext)

{

        PKIX_ENTER(RWLOCK, "PKIX_PL_AcquireWriterLock");

        PKIX_NULLCHECK_ONE(lock);

        PKIX_RWLOCK_DEBUG("\tCalling PR_RWLock_Wlock\n");

        (void) PR_RWLock_Wlock(lock->lock);

        if (lock->readCount > 0) {

                PKIX_ERROR(PKIX_LOCKHASNONZEROREADCOUNT);

        }

        /* We should never acquire a write lock if the lock is held */

        lock->writeLocked = PKIX_TRUE;

cleanup:

        PKIX_RETURN(RWLOCK);

}

PKIX_Error *

PKIX_PL_ReleaseWriterLock(

        PKIX_PL_RWLock *lock,

        void *plContext)

{

        PKIX_ENTER(RWLOCK, "PKIX_PL_ReleaseWriterLock");

        PKIX_NULLCHECK_ONE(lock);

        if (lock->readCount > 0) {

                PKIX_ERROR(PKIX_LOCKHASNONZEROREADCOUNT);

        }

        PKIX_RWLOCK_DEBUG("\tCalling PR_RWLock_Unlock)\n");

        (void) PR_RWLock_Unlock(lock->lock);

        /* XXX Need to think about thread safety here */

        /* There should be a single lock holder  */

        lock->writeLocked = PKIX_FALSE;

cleanup:

        PKIX_RETURN(RWLOCK);

}

PKIX_Error *

PKIX_PL_IsWriterLockHeld(

        PKIX_PL_RWLock *lock,

        PKIX_Boolean *pIsHeld,

        void *plContext)

{

        PKIX_ENTER(RWLOCK, "PKIX_PL_IsWriterLockHeld");

        PKIX_NULLCHECK_TWO(lock, pIsHeld);

        *pIsHeld = lock->writeLocked;

        PKIX_RETURN(RWLOCK);

}