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package iaik.pkcs.pkcs11;

import iaik.pkcs.pkcs11.wrapper.PKCS11Exception;

/**
 * Objects that implement this interface can be used in the InitializeArgs to
 * handle mutex functionality.
 *
 * @author <a href="mailto:Karl.Scheibelhofer@iaik.at"> Karl Scheibelhofer </a>
 * @version 1.0
 * @invariants
 */
public interface MutexHandler {

	/**
	 * Create a new mutex object.
	 *
	 * @return The new mutex object.
	 * @exception PKCS11Exception If the wrapper should return a differnet value
	 *                            than CKR_OK to the library. It gets the
	 *                            error-code and returns it as CK_RV.
	 * @preconditions
	 * @postconditions (result <> null)
	 */
	public Object createMutex()
	    throws PKCS11Exception;

	/**
	 * Destroy a mutex object.
	 *
	 * @param mutex The mutex object to destroy.
	 * @exception PKCS11Exception If the wrapper should return a differnet value
	 *                            than CKR_OK to the library. It gets the
	 *                            error-code and returns it as CK_RV.
	 * @preconditions (mutex <> null)
	 * @postconditions
	 */
	public void destroyMutex(Object mutex)
	    throws PKCS11Exception;

	/**
	 * If this method is called on with a mutex object which is not locked, the
	 * calling thread obtains a lock on that mutex object and returns.
	 * If this method is called with a mutex object which is locked by some
	 * thread other than the calling thread, the calling thread blocks and waits
	 * for that mutex to be unlocked.
	 * If this method is called with a a mutex object which is locked by the calling
	 + thread, the behavior of this method call is undefined.
	 *
	 * @param mutex The mutex object to lock.
	 * @exception PKCS11Exception If the wrapper should return a differnet value
	 *                            than CKR_OK to the library. It gets the
	 *                            error-code and returns it as CK_RV.
	 * @preconditions (mutex <> null)
	 * @postconditions
	 */
	public void lockMutex(Object mutex)
	    throws PKCS11Exception;

	/**
	 * If this method is called with a mutex object which is locked by the
	 * calling thread, that mutex object is unlocked and the function call
	 * returns. Furthermore: If exactly one thread was blocking on that
	 * particular mutex object, then that thread stops blocking, obtains a lock
	 * on that mutex object, and its lockMutex(Object) call returns.
	 * If more than one thread was blocking on that particular mutex objet, then
	 * exactly one of the blocking threads is selected somehow. That lucky thread
	 * stops blocking, obtains a lock on the mutex object, and its
	 * lockMutex(Object) call returns. All other threads blocking on that
	 * particular mutex object continue to block.
	 * If this method is called with a mutex object which is not locked, then
	 * the method call throws an exception with the error code
	 * PKCS11Constants.CKR_MUTEX_NOT_LOCKED.
	 * If this method is called with a mutex object which is locked by some
	 * thread other than the calling thread, the behavior of this method call is
	 * undefined.
	 *
	 * @param mutex The mutex object to unlock.
	 * @exception PKCS11Exception If the wrapper should return a differnet value
	 *                            than CKR_OK to the library. It gets the
	 *                            error-code and returns it as CK_RV.
	 * @preconditions (mutex <> null)
	 * @postconditions
	 */
	public void unlockMutex(Object mutex)
	    throws PKCS11Exception;

}