Sleeping thread and thread initialization inside constructor - c++

Question

Im trying to make a thread run out of a ctor , the thread should sleep , wake up and then perform a buffer dump and then sleep again and so on this is the code for the ctor:
Logger::Logger()
{
BufferInUse = &CyclicBuffer1; //buffer 1 will be used at beggining
MaxBufferSize = 5; //initial state
NumOfCycles = 0;
CurrentMaxStringLength = 0;
position = BufferInUse->end();
OutPutMethod = odBuffer; //by default
Thresh = 1; //by default
hTimer = CreateWaitableTimer(NULL, TRUE, NULL);
EventTime.QuadPart = -20000000; //1 second by default
Mutex = CreateMutex(NULL,FALSE,NULL);
if (Mutex == NULL)
{
OutputDebugStringA("CreateMutex error! the Logger will close \n");
return ;
}
_beginthread( Logger::WorkerThread , 0,(void*)this ); //run the thread
}
when I debug it , it takes lots of time for the thread to even be created and finish the ctor function but in that time my object member functions get called lots of times (i see it when debugging).
1.I want the thread to be created before my member functions get called, what is the best way to achieve that?
now my thread implementation is:
void Logger::WorkerThread ( void *lpParam )
{
Logger *log = static_cast <Logger*> (lpParam);
if (NULL == log->hTimer)
{
log->LogStringToOutput("CreateWaitableTimer() failed , Logger will close \n");
return;
}
for(;;)
{
//set timer for time specified by the EventTime variable inside the Logger
if (!SetWaitableTimer(log->hTimer, & (log->EventTime), 0, NULL, NULL, 0))
{
log->LogStringToOutput("SetWaitableTimer() failed , Logger will close\n" );
_endthread();
}
//wait for timer
if (WaitForSingleObject(log->hTimer, INFINITE) != WAIT_OBJECT_0)
{
log->LogStringToOutput("WaitForSingleObject() failed! Logger will close\n");
_endthread();
return;
}
if(log->getOutputMethod() == odBuffer && log->BufferInUse->size() >= log->Thresh && !log->BufferInUse->empty())
{
TTFW_LogRet ret;
ret = log->FullBufferDump();
if (ret != SUCCESS)
{
log->LogStringToOutput("Error occured in dumping cyclic buffer , the buffer will be cleared\n");
}
}
}
}
is there more elegant implementation of this thread functionality?

Answer 1

you need some mechanism to synchronous WorkerThread starting and member function access.
for example, use a condition variable (documents in msdn):
add 3 member to Logger:
class Logger{
...
private:
CRITICAL_SECTION CritSection;
CONDITION_VARIABLE ConditionVar;
bool WorkerThreadStarted;
...
};
and
Logger::Logger():WorkerThreadStarted(false)
{
EnterCriticalSection(&CritSection); //added
BufferInUse = &CyclicBuffer1; //buffer 1 will be used at beggining
...
}
void Logger::WorkerThread ( void *lpParam )
{
WorkerThreadStarted=true; //added
LeaveCriticalSection(&CritSection);
Logger *log = static_cast <Logger*> (lpParam);
if (NULL == log->hTimer)
{
log->LogStringToOutput("CreateWaitableTimer() failed , Logger will close \n");
return;
}
...
}
add such a function:
void Logger::EnsureInitiallized(){
EnterCriticalSection(&CritSection);
// Wait until the predicate is TRUE
while( !WorkerThreadStarted )
{
SleepConditionVariableCS(&ConditionVar, &CritSection, INFINITE);
}
LeaveCriticalSection(&CritSection);
}
and at every member function's entry, call EnsureInitiallized();
void Logger::yourFunction(){
EnsureInitiallized();
...
}
that is a example , you can also use a read_write lock , a atomic integer etc