OFMutex Class Reference

provides an operating system independent abstraction for mutexes (mutual exclusion locks). More...

Public Member Functions
	OFMutex ()
	default constructor
	~OFMutex ()
	destructor
OFBool	initialized () const
	checks whether creation of the object was successful. More...
int	lock ()
	locks the mutex object. More...
int	trylock ()
	tries to lock the mutex object. More...
int	unlock ()
	releases the lock on the mutex object. More...

Static Public Member Functions
static void	errorstr (OFString &description, int code)
	converts any of the error codes returned by the methods of this class into a textual description, which is written into the string object. More...

Static Public Attributes
static const int	busy
	this constant is returned by the trylock() method if the mutex is already locked. More...

Private Member Functions
	OFMutex (const OFMutex &arg)
	unimplemented private copy constructor
OFMutex &	operator= (const OFMutex &arg)
	unimplemented private assignment operator

Private Attributes
void *	theMutex
	mutex resource

Detailed Description

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().

Member Function Documentation

errorstr()

static void OFMutex::errorstr ( OFString &  description, int  code  )

static

converts any of the error codes returned by the methods of this class into a textual description, which is written into the string object.

Parameters

description	string object into which the error description is written.
code	error code

initialized()

OFBool OFMutex::initialized

(

)

const

checks whether creation of the object was successful.

Returns

OFTrue if the object was successfully created, OFFalse otherwise.

lock()

int OFMutex::lock

(

)

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.

Returns

0 upon success, an error code otherwise.

Referenced by OFshared_ptr< T >::Data::decrement_count(), OFGlobal< T >::get(), OFshared_ptr< T >::Data::increment_count(), OFGlobal< T >::set(), and OFGlobal< T >::xget().

trylock()

int OFMutex::trylock

(

)

tries to lock the mutex object.

If the mutex is already locked, returns OFMutex::busy.

Returns

0 upon success, OFMutex::busy if the mutex is already locked, an error code otherwise.

unlock()

int OFMutex::unlock

(

)

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.

Returns

0 upon success, an error code otherwise.

Referenced by OFshared_ptr< T >::Data::decrement_count(), OFGlobal< T >::get(), OFshared_ptr< T >::Data::increment_count(), OFGlobal< T >::set(), and OFGlobal< T >::xget().

Member Data Documentation

busy

const int OFMutex::busy

static

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.

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The documentation for this class was generated from the following file:

• ofstd/include/dcmtk/ofstd/ofthread.h