Public Member Functions | |
| OFSemaphore (unsigned int numResources) | |
| constructor. | |
| ~OFSemaphore () | |
| destructor | |
| OFBool | initialized () const |
| checks whether creation of the object was successful. | |
| int | wait () |
| blocks the calling thread until the semaphore counter is greater than zero and then atomically decreases the counter. | |
| int | trywait () |
| atomically decreases the counter if it is larger than zero, otherwise returns OFSemaphore::busy. | |
| int | post () |
| atomically increases the counter. | |
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. | |
Static Public Attributes | |
| static const int | busy |
| this constant is returned by the trywait() method if the semaphore is already locked. | |
Private Member Functions | |
| OFSemaphore (const OFSemaphore &arg) | |
| unimplemented private copy constructor | |
| OFSemaphore & | operator= (const OFSemaphore &arg) |
| unimplemented private assignment operator | |
Private Attributes | |
| void * | theSemaphore |
| semaphore resource | |
A semaphore is a non-negative integer counter that is used to coordinate access to resources. The initial and maximum value of the counter is defined by the constructor. Each call to wait() decreases the counter by one and each call to post() increases the count by one. If a thread calls wait() while the counter is zero, the thread is blocked until another thread has increased the counter using post().
Definition at line 277 of file ofthread.h.
| OFSemaphore::OFSemaphore | ( | unsigned int | numResources | ) |
constructor.
| numResources | is the initial and maximum value for the semaphore. |
| OFBool OFSemaphore::initialized | ( | ) | const |
checks whether creation of the object was successful.
| int OFSemaphore::wait | ( | ) |
blocks the calling thread until the semaphore counter is greater than zero and then atomically decreases the counter.
| int OFSemaphore::trywait | ( | ) |
atomically decreases the counter if it is larger than zero, otherwise returns OFSemaphore::busy.
| int OFSemaphore::post | ( | ) |
atomically increases the counter.
If threads are blocked on the semaphore, at least one of them is unblocked.
| static void OFSemaphore::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.
| description | string object into which the error description is written. | |
| code | error code |
const int OFSemaphore::busy [static] |
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.
Definition at line 325 of file ofthread.h.