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PSyncPoint Class Reference

This class defines a thread synchronisation object. More...

#include <syncpoint.h>

Inheritance diagram for PSyncPoint:
PSemaphore PSync PObject PSyncPointAck

Public Member Functions

 PSyncPoint ()
 Create a new sync point.
 PSyncPoint (const PSyncPoint &)
- Public Member Functions inherited from PSemaphore
unsigned GetInitial () const
unsigned GetMaxCount () const
 PSemaphore (unsigned initial, unsigned maximum)
 Create a new semaphore with maximum count and initial value specified.
 PSemaphore (const PSemaphore &)
 Create a new semaphore with the same initial and maximum values as the original.
 ~PSemaphore ()
 Destroy the semaphore.
virtual void Wait ()
 If the semaphore count is > 0, decrement the semaphore and return.
virtual PBoolean Wait (const PTimeInterval &timeout)
 If the semaphore count is > 0, decrement the semaphore and return.
virtual void Signal ()
 If there are waiting (blocked) threads then unblock the first one that was blocked.
virtual PBoolean WillBlock () const
 Determine if the semaphore would block if the Wait() function were called.
Operations
- Public Member Functions inherited from PObject
virtual ~PObject ()
virtual PObjectClone () const
 Create a copy of the class on the heap.
virtual PINDEX HashFunction () const
 This function yields a hash value required by the PDictionary class.
virtual const char * GetClass (unsigned ancestor=0) const
 Get the current dynamic type of the object instance.
PBoolean IsClass (const char *cls) const
virtual PBoolean InternalIsDescendant (const char *clsName) const
 Determine if the dynamic type of the current instance is a descendent of the specified class.
virtual Comparison Compare (const PObject &obj) const
 Compare the two objects and return their relative rank.
virtual Comparison CompareObjectMemoryDirect (const PObject &obj) const
 Determine the byte wise comparison of two objects.
bool operator== (const PObject &obj) const
 Compare the two objects.
bool operator!= (const PObject &obj) const
 Compare the two objects.
bool operator< (const PObject &obj) const
 Compare the two objects.
bool operator> (const PObject &obj) const
 Compare the two objects.
bool operator<= (const PObject &obj) const
 Compare the two objects.
bool operator>= (const PObject &obj) const
 Compare the two objects.
virtual void PrintOn (ostream &strm) const
 Output the contents of the object to the stream.
virtual void ReadFrom (istream &strm)
 Input the contents of the object from the stream.

Additional Inherited Members

- Public Types inherited from PObject
enum  Comparison { LessThan = -1, EqualTo = 0, GreaterThan = 1 }
 Result of the comparison operation performed by the Compare() function. More...
- Static Public Member Functions inherited from PObject
static const char * Class ()
 Get the name of the class as a C string.
static Comparison InternalCompareObjectMemoryDirect (const PObject *obj1, const PObject *obj2, PINDEX size)
 Internal function caled from CompareObjectMemoryDirect()
- Protected Member Functions inherited from PSemaphore
 PQUEUE (ThreadQueue, PThread)
- Protected Attributes inherited from PSemaphore
unsigned initialVar
unsigned maxCountVar
ThreadQueue waitQueue
- Friends inherited from PObject

Detailed Description

This class defines a thread synchronisation object.

This form of semaphore is used to indicate an event has occurred. A thread may block on the sync point and wait until another thread signals that it may continue. eg:


    ... thread one
    while (condition) {
      sync.Wait();
      do_something();
    }
    ... thread 2
    do_something_else();
    sync.Signal();    // At this point thread 1 wake up and does something.
    do_yet_more();

Note that events are boolean in nature. If "thread one" is not waiting on the event, multiple calls to Signal() are ignored, thread one will only exit the Wait() call a single time once it gets there. Similarly, if multiple threads are waiting on the event, only one thread will be released. As you cannot know which thread will be released this mode of use is not recommended.

Constructor & Destructor Documentation

PSyncPoint::PSyncPoint ( )

Create a new sync point.

PSyncPoint::PSyncPoint ( const PSyncPoint )

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