czekanie na otwarcie procesu potomnego

[banita]

mam taki schemat do wykonania:

moj program:

// instrukcje 1
// odpalenie procesu potomnego
// instrukcje 2
// zamkniecie programu


chodzi o to ze instrukcje 2 nie moga sie wykonac dopuki proces potomny nie bedzie otwarty. czasem (wystarczy ze komp przytnie) wykonuja sie instrukcje 2 a proces dopiero sie "laduje".
wiem jak poczekac na wykonanie procesu ale to mnie nie ratuje poniewaz instrukcje 2 musza sie wykonac przed zakonczeniem procesu. zatem jak uruchamiajac proces potomny moge sprawdzic czy zostal on juz otwarty?

[Cyfrowy Baron]

Odpwiedź w serwisie Cyfrowy Baron dział: porady API: Uruchomienie aplikacji i oczekiwanie na jej zamknięcie.

[banita]

wiem jak poczekac na wykonanie procesu ale to mnie nie ratuje poniewaz instrukcje 2 musza sie wykonac przed zakonczeniem procesu.

chodzi o to ze wiem jak zawiesic swoj program do czasu az uruchomy proces bedzie zamkniety. ja potrzebuje zidentyfikowac ze proces zostal w pelni otwarty, wykonac instrukcje 2 i zamknac swoj program, a ten otwarty proces dziala dalej.

chodzi o to ze wywolanie otwarcia procesu nie powoduje jego natychmiastowego fizycznego zaladowania. czasem "zamulenie" komputera spowoduje ze wywolywany proces otworzy sie z sekundowym opuznieniem a w tym czasie wykonaja sie instrukcje 2 co jest wlasnie moim problemem.

[Cyfrowy Baron]

Znalazłem coś w pliku pomocy pod hasłami:

► Waiting for a Thread to Finish Executing 

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To wait for another thread to finish executing, use the WaitFor method of that other thread. WaitFor doesn't return until the other thread terminates, either by finishing its own Execute method or by terminating due to an exception. For example, the following code waits until another thread fills a thread list object before accessing the objects in the list: if ListFillingThread.WaitFor then begin with ThreadList1.LockList do begin for I := 0 to Count - 1 do ProcessItem(Items[I]); end; ThreadList1.UnlockList; end; if (pListFillingThread->WaitFor()) { TList *pList = ThreadList1->LockList(); for (int i = 0; i < pList->Count; i++) ProcessItem(pList->Items[i]); ThreadList1->UnlockList(); } In the previous example, the list items were only accessed when the WaitFor method indicated that the list was successfully filled. This return value must be assigned by the Execute method of the thread that was waited for. However, because threads that call WaitFor want to know the result of thread execution, not code that calls Execute, the Execute method does not return any value. Instead, the Execute method sets the ReturnValue property. ReturnValue is then returned by the WaitFor method when it is called by other threads. Return values are integers. Your application determines their meaning.

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► Waiting for a Task to Be Completed 

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Sometimes, you need to wait for a thread to finish some operation rather than waiting for a particular thread to complete execution. To do this, use an event object. Event objects (TEvent) should be created with global scope so that they can act like signals that are visible to all threads. When a thread completes an operation that other threads depend on, it calls TEvent.SetEvent. SetEvent turns on the signal, so any other thread that checks will know that the operation has completed. To turn off the signal, use the ResetEvent method. For example, consider a situation where you must wait for several threads to complete their execution rather than a single thread. Because you don't know which thread will finish last, you can't simply use the WaitFor method of one of the threads. Instead, you can have each thread increment a counter when it is finished, and have the last thread signal that they are all done by setting an event. The following code shows the end of the OnTerminate event handler for all of the threads that must complete. CounterGuard is a global critical section object that prevents multiple threads from using the counter at the same time. Counter is a global variable that counts the number of threads that have completed. procedure TDataModule.TaskThreadTerminate(Sender: TObject); begin ... CounterGuard.Acquire; { obtain a lock on the counter } Dec(Counter); { decrement the global counter variable } if Counter = 0 then Event1.SetEvent; { signal if this is the last thread } CounterGuard.Release; { release the lock on the counter } ... end; void __fastcall TDataModule::TaskThreadTerminate(TObject *Sender) { ... CounterGuard->Acquire(); // lock the counter if (--Counter == 0) // decrement the global counter Event1->SetEvent(); // signal if this is the last thread CounterGuard->Release(); // release the lock on the counter } The main thread initializes the Counter variable, launches the task threads, and waits for the signal that they are all done by calling the WaitFor method. WaitFor waits for a specified time period for the signal to be set, and returns one of the values from the following table: WaitFor return values Value Meaning wrSignaled The signal of the event was set. wrTimeout The specified time elapsed without the signal being set. wrAbandoned The event object was destroyed before the time-out period elapsed. wrError An error occurred while waiting. The following shows how the main thread launches the task threads and then resumes when they have all completed: Event1.ResetEvent; { clear the event before launching the threads } for i := 1 to Counter do TaskThread.Create(False); { create and launch task threads } if Event1.WaitFor(20000) <> wrSignaled then raise Exception; { now continue with the main thread. All task threads have finished } Event1->ResetEvent(); // clear the event before launching the threads for (int i = 0; i < Counter; i++) new TaskThread(false); // create and launch task threads if (Event1->WaitFor(20000) != wrSignaled) throw Exception; // now continue with the main thread, all task threads have finished Note: If you do not want to stop waiting for an event after a specified time period, pass the WaitFor method a parameter value of INFINITE. Be careful when using INFINITE, because your thread will hang if the anticipated signal is never received.

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► Waiting for Threads 

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The following are procedures that can be used to wait for threads. Wait for a thread to finish executing. Wait for a task to complete. Check if another thread is waiting for your thread to terminate. To wait for a thread to finish executing Use the WaitFor method of the other thread. Code your logic. For example, the following code waits for another thread to fill a thread list object before accessing the objects in the list: if ListFillingThread.WaitFor then begin with ThreadList1.LockList do begin for I := 0 to Count - 1 do ProcessItem(Items[I]; end; ThreadList1.UnlockList; end; if( ListFillingThread->WaitFor() ) { TList* list = ThreadList1–>LockList(); for( int i = 0; i < list->Count; i++ ) { DoSomething( list->Items[i] ); } ThreadList1–>UnlockList(); } To wait for a task to complete Create a TEvent object of global scope. When a thread completes an operation other threads are waiting for, have the thread call TEvent.SetEvent. To turn off the signal, call TEvent.ResetEvent. The following example is an OnTerminate event handler that uses a global counter in a critical section to keep track of the number of terminating threads. When Counter reaches 0, the handler calls the SetEvent method to signal that all processes have terminated: procedure TDataModule.TaskTerminateThread(Sender: TObject); begin ... CounterGuard.Acquire; {obtain a lock on the counter} Dec(Counter); {decrement the global counter variable} if Counter = 0 then Event1.SetEvent; {signal if this is the last thread} Counter.Release; {release the lock on the counter} ... end; void __fastcall TDataModule::TaskThreadTerminate( TObject *Sender ) { ... CounterGuard->Acquire(); // lock the counter if( ––Counter == 0 ) // decrement counter Event1–>SetEvent(); // signal if this is the last thread CounterGuard->Release(); // release lock } The main thread initializes Counter, launches the task threads, and waits for the signal that they are all done by calling the TEvent::WaitFor method. WaitFor waits a specified time period for the signal to be set and returns one of the values in the table below. The following code example shows how the main thread launches the task threads and resumes when they have completed. Event1.ResetEvent; {clear the event before launching the threads} for i := 1 to Counter do TaskThread.Create(False); {create and launch the task threads} if Event1.WaitFor(20000) <> wrSignaled then raise Exception; {continue with main thread} Event1–>ResetEvent(); // clear the event before launching threads for( int i = 0; i < Counter; i++ ) { new TaskThread( false ); if( Event1–>WaitFor(20000) != wrSignaled ) throw Exception; // now continue with the main thread Note: If you do not want to stop waiting for an event handler after a specified time period, pass the WaitFor method a parameter value of INFINITE. Be careful when using INFINITE, because your thread will hang if the anticipated signal is never received. To check if another thread is waiting on your thread to terminate In your Execute procedure, implement the Terminate method by checking and responding to the Terminated property. This is one way to code the logic: procedure TMyThread.Execute; begin while not Terminated do PerformSomeTask; end; void __fastcall TMyThread::Execute() { while( !Terminated ) DoSomething(); } WaitFor return values Value Meaning wrSignaled The signal of the event was set. wrTimeout The specified time elapsed without the signal being set. wrAbandoned The event object was destroyed before the timeout period elapsed. wrError An error occurred while waiting.

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[banita]

niestety ale to nie pomoze. w momencie gdy proces sie uruchamia to juz pojawia sie na liscie uruchomionych procesow ale nie znaczy to ze program zostal w pelni zaladowany i jest gotowy do uzycia. przykladowo c++builder, proces bds pojawia sie momentalnie ale zanim srodowisko jest gotowe do uzycia mija kilka sekund.

problem rozwiazalem troceh an okretke ale chwilowo to rozwiazanie mi wystarczy. poprostu daje kilka sekund uspienia dla aplikacji i po tym czasie uznaje ze proces jest juz w pelni odpalony. czas uspienia mozna modyfikowac. cialge bede szukal lepszego rozwiaznia.

problem bylby mniejszy gdyby proces potomny byl moja aplikacja i moglbym za jej pomoca dac sygnal ze nastapilo "pelne" zaladowanie, niestety nie mam takiej mozliwosci.

[Cyfrowy Baron]

Można by też spróbować ze zdarzeniem OnIdle aplikacji. Gdy uruchamiany program angażuje na proces na proces uruchamiania cały czas procesora, to zdarzenie OnIdle nie będzie się wykonywać, gdy program zostanie uruchomiony ruszy również to zdarzenie.

Inna sposób, w chwili uruchamiania program z reguły angażuje więcej czasu procesora niż tuż po uruchomieniu, więc po uruchomieniu procesu możesz sprawdzać procent użycia procesora dla tego programu, gdy spadnie do zera znaczy się, że program został w pełni uruchomiony.

Inny sposób, wykorzystanie funkcji DWORD WINAPI WaitForSingleObject(HANDLE hHandle, DWORD dwMilliseconds); ale zamiast wartości INFINITE, określasz czas oczekiwania, czyli to co sam juz zrobiłeś, tylko nie usypiasz aplikacji za pomocą funkcji Sleep, lecz po uruchomieniu czekasz określony czas:

Kod: Zaznacz cały

if(ShellExecuteEx(&sei))
  try
  {
   WaitForSingleObject(sei.hProcess, 20000);
  }
  __finally
{
  // instrukcje
}