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/*
* rwlock7.c
*
* Hammer on a bunch of rwlocks to test robustness and fairness.
* Printed stats should be roughly even for each thread.
*/
#include "test.h"
#include <sys/timeb.h>
#ifdef __GNUC__
#include <stdlib.h>
#endif
#define THREADS 5
#define DATASIZE 15
#define ITERATIONS 1000000
/*
* Keep statistics for each thread.
*/
typedef struct thread_tag {
int thread_num;
pthread_t thread_id;
int updates;
int reads;
int interval;
} thread_t;
/*
* Read-write lock and shared data
*/
typedef struct data_tag {
pthread_rwlock_t lock;
int data;
int updates;
} data_t;
static thread_t threads[THREADS];
static data_t data[DATASIZE];
/*
* Thread start routine that uses read-write locks
*/
void *thread_routine (void *arg)
{
thread_t *self = (thread_t*)arg;
int repeats = 0;
int iteration;
int element = 0;
for (iteration = 0; iteration < ITERATIONS; iteration++)
{
if (iteration % (ITERATIONS / 10) == 0)
{
putchar('.');
fflush(stdout);
}
/*
* Each "self->interval" iterations, perform an
* update operation (write lock instead of read
* lock).
*/
if ((iteration % self->interval) == 0)
{
assert(pthread_rwlock_wrlock (&data[element].lock) == 0);
data[element].data = self->thread_num;
data[element].updates++;
self->updates++;
assert(pthread_rwlock_unlock (&data[element].lock) == 0);
} else {
/*
* Look at the current data element to see whether
* the current thread last updated it. Count the
* times, to report later.
*/
assert(pthread_rwlock_rdlock (&data[element].lock) == 0);
self->reads++;
if (data[element].data == self->thread_num)
{
repeats++;
}
assert(pthread_rwlock_unlock (&data[element].lock) == 0);
}
element++;
if (element >= DATASIZE)
{
element = 0;
}
}
if (repeats > 0)
{
printf ("\nThread %d found unchanged elements %d times",
self->thread_num, repeats);
fflush(stdout);
}
return NULL;
}
int
main (int argc, char *argv[])
{
int count;
int data_count;
int thread_updates = 0;
int data_updates = 0;
int seed = 1;
struct _timeb currSysTime1;
struct _timeb currSysTime2;
/*
* Initialize the shared data.
*/
for (data_count = 0; data_count < DATASIZE; data_count++)
{
data[data_count].data = 0;
data[data_count].updates = 0;
assert(pthread_rwlock_init (&data[data_count].lock, NULL) == 0);
}
_ftime(&currSysTime1);
/*
* Create THREADS threads to access shared data.
*/
for (count = 0; count < THREADS; count++)
{
threads[count].thread_num = count;
threads[count].updates = 0;
threads[count].reads = 0;
threads[count].interval = rand_r (&seed) % 71;
assert(pthread_create (&threads[count].thread_id,
NULL, thread_routine, (void*)&threads[count]) == 0);
}
/*
* Wait for all threads to complete, and collect
* statistics.
*/
for (count = 0; count < THREADS; count++)
{
assert(pthread_join (threads[count].thread_id, NULL) == 0);
thread_updates += threads[count].updates;
printf ("%02d: interval %d, updates %d, reads %d\n",
count, threads[count].interval,
threads[count].updates, threads[count].reads);
}
putchar('\n');
fflush(stdout);
/*
* Collect statistics for the data.
*/
for (data_count = 0; data_count < DATASIZE; data_count++)
{
data_updates += data[data_count].updates;
printf ("data %02d: value %d, %d updates\n",
data_count, data[data_count].data, data[data_count].updates);
assert(pthread_rwlock_destroy (&data[data_count].lock) == 0);
}
printf ("%d thread updates, %d data updates\n",
thread_updates, data_updates);
_ftime(&currSysTime2);
printf( "\nstart: %ld/%d, stop: %ld/%d, duration:%ld\n",
currSysTime1.time,currSysTime1.millitm,
currSysTime2.time,currSysTime2.millitm,
(currSysTime2.time*1000+currSysTime2.millitm) -
(currSysTime1.time*1000+currSysTime1.millitm));
return 0;
}
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