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// $Id: reader_writer.cpp 91671 2010-09-08 18:39:23Z johnnyw $
// This test program verifies the functionality of the ACE_OS
// implementation of readers/writer locks on Win32 and Posix pthreads.
#include "ace/OS_main.h"
#include "ace/Thread.h"
#include "ace/Thread_Manager.h"
#include "ace/Get_Opt.h"
#include "ace/Atomic_Op.h"
#if defined (ACE_HAS_THREADS)
#include "ace/Guard_T.h"
#include "ace/RW_Mutex.h"
// Default number of iterations.
static int n_iterations = 1000;
// Default number of loops.
static int n_loops = 100;
// Default number of readers.
static int n_readers = 6;
// Default number of writers.
static int n_writers = 2;
// Thread id of last writer.
static ACE_thread_t shared_thr_id;
// Lock for shared_thr_id.
static ACE_RW_Mutex rw_mutex;
// Count of the number of readers and writers.
ACE_Atomic_Op<ACE_Thread_Mutex, int> current_readers, current_writers;
// Thread manager
static ACE_Thread_Manager thr_mgr;
// Explain usage and exit.
static void
print_usage_and_die (void)
{
ACE_DEBUG ((LM_DEBUG,
"usage: %n [-r n_readers] [-w n_writers] [-n iteration_count]\n"));
ACE_OS::exit (1);
}
// Parse the command-line arguments and set options.
static void
parse_args (int argc, ACE_TCHAR *argv[])
{
ACE_Get_Opt get_opt (argc, argv, ACE_TEXT("r:w:n:l:"));
int c;
while ((c = get_opt ()) != -1)
switch (c)
{
case 'r':
n_readers = ACE_OS::atoi (get_opt.opt_arg ());
break;
case 'w':
n_writers = ACE_OS::atoi (get_opt.opt_arg ());
break;
case 'n':
n_iterations = ACE_OS::atoi (get_opt.opt_arg ());
break;
case 'l':
n_loops = ACE_OS::atoi (get_opt.opt_arg ());
break;
default:
print_usage_and_die ();
break;
}
}
// Iterate <n_iterations> each time checking that nobody modifies the
// data while we have a read lock.
static void *
reader (void *)
{
ACE_DEBUG ((LM_DEBUG, "(%t) reader starting\n"));
for (int iterations = 1;
iterations <= n_iterations; iterations++)
{
ACE_READ_GUARD_RETURN (ACE_RW_Mutex, g, rw_mutex, 0);
++current_readers;
if (current_writers > 0)
ACE_DEBUG ((LM_DEBUG, "(%t) writers found!!!\n"));
ACE_thread_t thr_id = shared_thr_id;
for (int loop = 1; loop <= n_loops; loop++)
{
ACE_Thread::yield();
if (ACE_OS::thr_equal (shared_thr_id, thr_id) == 0)
ACE_DEBUG ((LM_DEBUG,
"(%t) somebody changed %d to %d\n",
thr_id, shared_thr_id));
}
--current_readers;
ACE_Thread::yield ();
}
return 0;
}
// Iterate <n_iterations> each time modifying the global data
// and checking that nobody steps on it while we can write it.
static void *
writer (void *)
{
ACE_DEBUG ((LM_DEBUG, "(%t) writer starting\n"));
for (int iterations = 1;
iterations <= n_iterations;
iterations++)
{
ACE_WRITE_GUARD_RETURN (ACE_RW_Mutex, g, rw_mutex, 0);
++current_writers;
if (current_writers > 1)
ACE_DEBUG ((LM_DEBUG, "(%t) other writers found!!!\n"));
if (current_readers > 0)
ACE_DEBUG ((LM_DEBUG, "(%t) readers found!!!\n"));
ACE_thread_t self = ACE_Thread::self ();
shared_thr_id = self;
for (int loop = 1; loop <= n_loops; loop++)
{
ACE_Thread::yield();
if (ACE_OS::thr_equal (shared_thr_id, self) == 0)
ACE_DEBUG ((LM_DEBUG, "(%t) somebody wrote on my data %d\n",
shared_thr_id));
}
--current_writers;
ACE_Thread::yield ();
}
return 0;
}
// Spawn off threads.
int ACE_TMAIN (int argc, ACE_TCHAR *argv[])
{
ACE_LOG_MSG->open (argv[0]);
parse_args (argc, argv);
current_readers = 0; // Possibly already done
current_writers = 0; // Possibly already done
ACE_DEBUG ((LM_DEBUG, "(%t) main thread starting\n"));
if (thr_mgr.spawn_n (n_readers, (ACE_THR_FUNC) reader, 0, THR_NEW_LWP) == -1 ||
thr_mgr.spawn_n (n_writers, (ACE_THR_FUNC) writer, 0, THR_NEW_LWP) == -1)
ACE_ERROR_RETURN ((LM_ERROR, "%p\n", "spawn_n"), 1);
thr_mgr.wait ();
ACE_DEBUG ((LM_DEBUG, "(%t) exiting main thread\n"));
return 0;
}
#else
int
ACE_TMAIN (int, ACE_TCHAR *[])
{
ACE_ERROR ((LM_ERROR, "threads not supported on this platform\n"));
return 0;
}
#endif /* ACE_HAS_THREADS */
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