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// $Id$
// ============================================================================
//
// = LIBRARY
// tests
//
// = FILENAME
// Reader_Writer_Test.cpp
//
// = DESCRIPTION
// This test program verifies the functionality of the ACE_OS
// implementation of readers/writer locks on Win32 and Posix
// pthreads.
//
// = AUTHOR
// Prashant Jain and Doug C. Schmidt
//
// ============================================================================
#include "ace/Synch.h"
#include "ace/Thread.h"
#include "ace/Service_Config.h"
#include "ace/Get_Opt.h"
#include "test_config.h"
#if defined (ACE_HAS_THREADS)
// Default number of iterations.
static size_t n_iterations = 1000;
// Default number of loops.
static size_t n_loops = 100;
// Default number of readers.
static size_t n_readers = 6;
// Default number of writers.
static size_t n_writers = 4;
// Thread id of last writer.
static volatile int shared_data;
// Lock for shared_data.
static ACE_RW_Mutex rw_mutex;
// Count of the number of readers and writers.
static ACE_Atomic_Op<ACE_Thread_Mutex, int> current_readers, current_writers;
// 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);
}
// Iterate <n_iterations> each time checking that nobody modifies the data
// while we have a read lock.
static void *
reader (void *)
{
ACE_Thread_Control tc (ACE_Service_Config::thr_mgr ());
ACE_NEW_THREAD;
ACE_DEBUG ((LM_DEBUG, "(%t) reader starting\n"));
for (size_t iterations = 1; iterations <= n_iterations; iterations++)
{
ACE_Read_Guard<ACE_RW_Mutex> g(rw_mutex);
int n = ++current_readers;
//ACE_DEBUG ((LM_DEBUG, "(%t) I'm reader number %d\n", n));
if (current_writers > 0)
ACE_DEBUG ((LM_DEBUG, "(%t) writers found!!!\n"));
int data = shared_data;
for (size_t loop = 1; loop <= n_loops; loop++)
{
ACE_Thread::yield();
if (shared_data != data)
ACE_DEBUG ((LM_DEBUG,
"(%t) somebody changed %d to %d\n",
data, shared_data));
}
--current_readers;
//ACE_DEBUG ((LM_DEBUG, "(%t) done with reading guarded data\n"));
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_Thread_Control tc (ACE_Service_Config::thr_mgr ());
ACE_NEW_THREAD;
ACE_DEBUG ((LM_DEBUG, "(%t) writer starting\n"));
for (size_t iterations = 1; iterations <= n_iterations; iterations++)
{
ACE_Write_Guard<ACE_RW_Mutex> g(rw_mutex);
++current_writers;
//ACE_DEBUG ((LM_DEBUG, "(%t) writing to guarded data\n"));
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"));
int self = (int) ACE_Thread::self ();
shared_data = self;
for (size_t loop = 1; loop <= n_loops; loop++)
{
ACE_Thread::yield();
if (shared_data != self)
ACE_DEBUG ((LM_DEBUG, "(%t) somebody wrote on my data %d\n", shared_data));
}
--current_writers;
//ACE_DEBUG ((LM_DEBUG, "(%t) done with guarded data\n"));
ACE_Thread::yield ();
}
return 0;
}
#if defined (ACE_TEMPLATES_REQUIRE_SPECIALIZATION)
template class ACE_Atomic_Op<ACE_Thread_Mutex, int>;
#endif /* ACE_TEMPLATES_REQUIRE_SPECIALIZATION */
#endif /* ACE_HAS_THREADS */
// Spawn off threads.
int main (int, char *[])
{
ACE_START_TEST ("Reader_Writer_Test");
#if defined (ACE_HAS_THREADS)
current_readers = 0; // Possibly already done
current_writers = 0; // Possibly already done
ACE_DEBUG ((LM_DEBUG, "(%t) main thread starting\n"));
if (ACE_Service_Config::thr_mgr ()->spawn_n (n_readers,
ACE_THR_FUNC (reader),
0,
THR_NEW_LWP) == -1)
ACE_ERROR_RETURN ((LM_ERROR, "%p\n", "spawn_n"), 1);
else if (ACE_Service_Config::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);
ACE_Service_Config::thr_mgr ()->wait ();
ACE_DEBUG ((LM_DEBUG, "(%t) exiting main thread\n"));
#else
ACE_ERROR ((LM_ERROR, "threads not supported on this platform\n"));
#endif /* ACE_HAS_THREADS */
ACE_END_TEST;
return 0;
}
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