ofthread.h

转化为DIB位图再显示出来的dicom文件C++代码

 */
class OFSemaphore
{
public:

  /** constructor.
   *  @param numResources is the initial and maximum value for the semaphore.
   */
  OFSemaphore(unsigned int numResources);

  /** destructor */
  ~OFSemaphore();

  /** checks whether creation of the object was successful.
   *  @return OFTrue if the object was successfully created, OFFalse otherwise.
   */
  OFBool initialized() const;

  /** blocks the calling thread until the semaphore counter is greater than zero
   *  and then atomically decreases the counter.
   *  @return 0 upon success, an error code otherwise.
   */
  int wait();

  /** atomically decreases the counter if it is larger than zero,
   *  otherwise returns OFSemaphore::busy.
   *  @return 0 upon success, OFSemaphore::busy if the semaphore is already locked,
   *    an error code otherwise.
   */
  int trywait();

  /** atomically increases the counter. If threads are blocked on the semaphore,
   *  at least one of them is unblocked.
   *  @return 0 upon success, an error code otherwise.
   */
  int post();

  /** converts any of the error codes returned by the methods of this class
   *  into a textual description, which is written into the string object.
   *  @param description string object into which the error description is written.
   *  @param code error code
   */
  static void errorstr(OFString& description, int code);

  /** this constant is returned by the trywait() method if the semaphore
   *  is already locked. Since this value is operating system dependent,
   *  comparisons should always compare the return value of trywait()
   *  with this constant.
   */
  static const int busy;

private:
  /** semaphore resource */
#ifdef HAVE_CXX_VOLATILE
  volatile
#endif
  void * theSemaphore;

  /** unimplemented private copy constructor */
  OFSemaphore(const OFSemaphore& arg);

  /** unimplemented private assignment operator */
  OFSemaphore& operator=(const OFSemaphore& arg);
};


/** provides an operating system independent abstraction for mutexes
 *  (mutual exclusion locks).
 *  Mutexes prevent multiple threads from simultaneously executing critical
 *  sections of code which access shared data. A successful call for a
 *  mutex lock by way of lock() will cause another thread that is also
 *  trying to lock the same mutex to block until the owner thread unlocks
 *  it by way of unlock().
 */
class OFMutex
{
public:

  /** default constructor */
  OFMutex();

  /** destructor */
  ~OFMutex();

  /** checks whether creation of the object was successful.
   *  @return OFTrue if the object was successfully created, OFFalse otherwise.
   */
  OFBool initialized() const;

  /** locks the mutex object. If the mutex is already locked, the calling
   *  thread blocks until the mutex is freed; If the current owner of a
   *  mutex tries to relock the mutex, it may or may not result in
   *  deadlock.
   *  @return 0 upon success, an error code otherwise.
   */
  int lock();

  /** tries to lock the mutex object. If the mutex is already locked,
   *  returns OFMutex::busy.
   *  @return 0 upon success, OFMutex::busy if the mutex is already locked,
   *    an error code otherwise.
   */
  int trylock();

  /** releases the lock on the mutex object. The mutex must be locked and
   *  the calling thread must be the owner of the lock, otherwise the
   *  behaviour is undefined. If there are threads blocked on the mutex
   *  when unlock() is called, one of them is unblocked and receives
   *  ownership of the mutex lock.
   *  @return 0 upon success, an error code otherwise.
   */
  int unlock();

  /** converts any of the error codes returned by the methods of this class
   *  into a textual description, which is written into the string object.
   *  @param description string object into which the error description is written.
   *  @param code error code
   */
  static void errorstr(OFString& description, int code);

  /** this constant is returned by the trylock() method if the mutex
   *  is already locked. Since this value is operating system dependent,
   *  comparisons should always compare the return value of trylock()
   *  with this constant.
   */
  static const int busy;

private:
  /** mutex resource */
#ifdef HAVE_CXX_VOLATILE
  volatile
#endif
  void * theMutex;

  /** unimplemented private copy constructor */
  OFMutex(const OFMutex& arg);

  /** unimplemented private assignment operator */
  OFMutex& operator=(const OFMutex& arg);
};


/** provides an operating system independent abstraction for read/write
 *  locks. Many threads can have simultaneous read-only access to data,
 *  while only one thread can have write access at any given time.
 *  Multiple read access with single write access is controlled by
 *  read/write locks, which are generally used to protect data that is
 *  frequently searched.
 */
class OFReadWriteLock
{
public:

  /** default constructor */
  OFReadWriteLock();

  /** destructor */
  ~OFReadWriteLock();

  /** checks whether creation of the object was successful.
   *  @return OFTrue if the object was successfully created, OFFalse otherwise.
   */
  OFBool initialized() const;

  /** gets a read lock. If the read/write lock is currently locked for
   *  writing, the calling thread blocks until the write lock is freed.
   *  Multiple threads may simultaneously hold a read lock on a read/write
   *  lock.
   *  @return 0 upon success, an error code otherwise.
   */
  int rdlock();

  /** gets a write lock. If the read/write lock is currently locked for
   *  reading or writing, the calling thread blocks until all the read and
   *  write locks are freed. At any given time, only one thread may have a
   *  write lock on a read/write lock.
   *  @return 0 upon success, an error code otherwise.
   */
  int wrlock();

  /** trys to get a read lock. If the read/write lock is locked for
   *  writing, returns OFReadWriteLock::busy.
   *  @return 0 upon success, OFReadWriteLock::busy if the read/write lock
   *    is already locked, an error code otherwise.
   */
  int tryrdlock();

  /** trys to get a write lock. If the read/write lock is currently locked
   *  for reading or writing, returns OFReadWriteLock::busy.
   *  @return 0 upon success, OFReadWriteLock::busy if the read/write lock
   *    is already locked, an error code otherwise.
   */
  int trywrlock();

  /** unlocks the read/write lock. The read/write lock must be locked and
   *  the calling thread must be the owner of the lock, otherwise the
   *  behaviour is undefined. One of the other threads that is waiting for
   *  the read/write lock to be freed will be unblocked, provided there are
   *  other waiting threads.
   *  @return 0 upon success, an error code otherwise.
   */
  int unlock();

  /** converts any of the error codes returned by the methods of this class
   *  into a textual description, which is written into the string object.
   *  @param description string object into which the error description is written.
   *  @param code error code
   */
  static void errorstr(OFString& description, int code);

  /** this constant is returned by the tryrdlock() and trywrlock() methods
   *  if the read/write lock is already locked. Since this value is operating
   *  system dependent, comparisons should always compare the return value
   *  of tryrdlock() and trywrlock() with this constant.
   */
  static const int busy;

private:
  /** read/write lock resource */
#ifdef HAVE_CXX_VOLATILE
  volatile
#endif
  void * theLock;

  /** unimplemented private copy constructor */
  OFReadWriteLock(const OFReadWriteLock& arg);

  /** unimplemented private assignment operator */
  OFReadWriteLock& operator=(const OFReadWriteLock& arg);
};

#endif

/*
 *
 * CVS/RCS Log:
 * $Log: ofthread.h,v $
 * Revision 1.9  2005/12/08 16:06:08  meichel
 * Changed include path schema for all DCMTK header files
 *
 * Revision 1.8  2004/08/03 16:44:16  meichel
 * Updated code to correctly handle pthread_t both as an integral integer type
 *   (e.g. Linux, Solaris) and as a pointer type (e.g. BSD, OSF/1).
 *
 * Revision 1.7  2003/12/05 10:37:41  joergr
 * Removed leading underscore characters from preprocessor symbols (reserved
 * symbols). Updated copyright date where appropriate.
 *
 * Revision 1.6  2003/07/04 13:29:51  meichel
 * Replaced forward declarations for OFString with explicit includes,
 *   needed when compiling with HAVE_STD_STRING
 *
 * Revision 1.5  2003/06/06 10:31:04  meichel
 * Added volatile keyword to data pointers in multi-thread wrapper classes
 *
 * Revision 1.4  2002/02/27 14:13:19  meichel
 * Changed initialized() methods to const. Fixed some return values when
 *   compiled without thread support.
 *
 * Revision 1.3  2001/06/01 15:51:36  meichel
 * Updated copyright header
 *
 * Revision 1.2  2000/06/26 09:27:26  joergr
 * Replaced _WIN32 by HAVE_WINDOWS_H to avoid compiler errors using CygWin-32.
 *
 * Revision 1.1  2000/03/29 16:41:23  meichel
 * Added new classes providing an operating system independent abstraction
 *   for threads, thread specific data, semaphores, mutexes and read/write locks.
 *
 *
 */