PTLib  Version 2.10.10
PSyncPointAck Class Reference

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

#include <syncthrd.h>

Inheritance diagram for PSyncPointAck:
PSyncPoint PSemaphore PSync PObject

Public Member Functions

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

Protected Attributes

PSyncPoint ack
 
- Protected Attributes inherited from PSemaphore
unsigned initialVar
 
unsigned maxCountVar
 
ThreadQueue waitQueue
 

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. More...
 
static Comparison InternalCompareObjectMemoryDirect (const PObject *obj1, const PObject *obj2, PINDEX size)
 Internal function caled from CompareObjectMemoryDirect() More...
 
- Protected Member Functions inherited from PSemaphore
 PQUEUE (ThreadQueue, PThread)
 
- Protected Member Functions inherited from PObject
 PObject ()
 Constructor for PObject, made protected so cannot ever create one on its own. More...
 

Detailed Description

This class defines a thread synchronisation object.

This may be used to send signals to a thread and await an acknowldegement that the signal was processed. This can be be used to initiate an action in another thread and wait for the action to be completed.


    ... thread one
    while (condition) {
      sync.Wait();
      do_something();
      sync.Acknowledge();
    }
    ... thread 2
    do_something_else();
    sync.Signal();    // At this point thread 1 wake up and does something.
    do_yet_more();    // However, this does not get done until Acknowledge()
is called in the other thread.

Member Function Documentation

void PSyncPointAck::Acknowledge ( )

This indicates that the thread that was blocked in a Wait() on this synchronisation object has completed the operation the signal was intended to initiate.

This unblocks the thread that had called the Signal() function to initiate the action.

virtual void PSyncPointAck::Signal ( )
virtual

If there are waiting (blocked) threads then unblock the first one that was blocked.

If no waiting threads and the count is less than the maximum then increment the semaphore.

Unlike the PSyncPoint::Signal() this function will block until the target thread that was blocked by the Wait() function has resumed execution and called the Acknowledge() function.

The waitTime parameter is used as a maximum amount of time to wait for the achnowledgement to be returned from the other thread.

Reimplemented from PSemaphore.

void PSyncPointAck::Signal ( const PTimeInterval waitTime)

Member Data Documentation

PSyncPoint PSyncPointAck::ack
protected

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