ACE/examples/Threads/wfmo.cpp

   1 // This test program illustrates that the Win32
   2 // <WaitForMultipleObjects> function can be called in multiple
   3 // threads, all of which wait on the same set of HANDLEs.  Note that
   4 // the dispatching of the threads should be relatively "fair" (i.e.,
   5 // everyone gets a chance to process the various HANDLEs as they
   6 // become active).  Thanks to Ari Erev <Ari_Erev@comverse.com> for
   7 // suggesting this and providing the initial code.
   8
   9 #include "ace/Task.h"
  10 #include "ace/OS_NS_unistd.h"
  11 #include "ace/OS_main.h"
  12
  13
  14 #if defined (ACE_WIN32)
  15
  16 // Number of threads.
  17 static const int THREAD_COUNT = 5;
  18
  19 // Number of iterations.
  20 static const int MAX_ITERATIONS = 100;
  21
  22 class WFMO_Test : public ACE_Task <ACE_NULL_SYNCH>
  23 {
  24 public:
  25   //FUZZ: disable check_for_lack_ACE_OS
  26   virtual int open (void *);
  27   //FUZZ: enable check_for_lack_ACE_OS
  28
  29   virtual int svc ();
  30
  31   // Use two handles here..
  32   ACE_sema_t sema_handles_[2];
  33   int semaphore_count_;
  34 };
  35
  36 static WFMO_Test wfmo_test;
  37
  38 int
  39 WFMO_Test::open (void *arg)
  40 {
  41   int thread_count = int (arg);
  42   int result = this->activate (0, thread_count);
  43
  44   ACE_ASSERT (result != -1);
  45   return 0;
  46 }
  47
  48 int
  49 WFMO_Test::svc ()
  50 {
  51   while(1)
  52     {
  53       int result = ::WaitForMultipleObjects (2, this->sema_handles_,
  54                                              FALSE, INFINITE);
  55       if (result == WAIT_OBJECT_0)
  56         {
  57           // Signal the other semaphore just to see if we can get
  58           // another thread to wakeup.
  59           result = ACE_OS::sema_post (&sema_handles_[1]);
  60           ACE_ASSERT (result != -1);
  61         }
  62       else if (result == WAIT_OBJECT_0 + 1)
  63         ;
  64       else
  65         {
  66           ACE_ERROR ((LM_ERROR, "Error in WaitForMultipleObejcts\n"));
  67           ACE_OS::exit (0);
  68         }
  69
  70       // semaphore_count_ will be displayed by the "main" thread.
  71       // It's value must be 2.  Note that although this is a shared
  72       // resource it's not protected via a mutex because the ++
  73       // operation on Intel is atomic.
  74
  75       semaphore_count_++;
  76       ACE_DEBUG ((LM_DEBUG,
  77                   "(%t) thread has been signaled.\n"));
  78
  79       // Yield this thread so that the other one(s) have a chance to
  80       // run.
  81       ACE_OS::thr_yield ();
  82     }
  83
  84   return 0;
  85 }
  86
  87 int
  88 ACE_TMAIN (int argc, ACE_TCHAR *argv[])
  89 {
  90   int thread_count = THREAD_COUNT;
  91
  92   if (argc > 1)
  93     thread_count = ACE_OS::atoi (argv[1]);
  94
  95   wfmo_test.open ((void *) thread_count);
  96
  97   // Initialize the semaphores.
  98   int result = ACE_OS::sema_init (&wfmo_test.sema_handles_[0], thread_count + 5);
  99   ACE_ASSERT (result != -1);
 100
 101   result = ACE_OS::sema_init (&wfmo_test.sema_handles_[1], thread_count + 5);
 102   ACE_ASSERT (result != -1);
 103
 104   for (int i = 0; i < MAX_ITERATIONS; i++)
 105     {
 106       wfmo_test.semaphore_count_ = 0;
 107
 108       result = ACE_OS::sema_post (&wfmo_test.sema_handles_[0]);
 109       ACE_ASSERT (result != -1);
 110
 111       // No real synchronization here. Just sleep enough so that at
 112       // least one (or two threads) run as a result of the semaphore.
 113       ACE_OS::sleep (1);
 114
 115       // Add one for the other thread that was signaled.
 116       ACE_DEBUG ((LM_DEBUG,
 117                   "semaphore_count_ = %d  (should have been %d).\n",
 118                   wfmo_test.semaphore_count_,
 119                   2)); // Two semaphores should have been released.
 120     }
 121
 122   ACE_OS::exit (0);
 123
 124   return 0;
 125 }
 126 #else
 127 int
 128 ACE_TMAIN (int, ACE_TCHAR *[])
 129 {
 130   ACE_DEBUG ((LM_DEBUG, "this test only runs on Win32\n"));
 131 }
 132 #endif /* ACE_WIN32 */