static void *
run2(void *arg) {
char *message = arg;
RUNTIME_CHECK(isc_rwlock_lock(&lock, isc_rwlocktype_write) ==
ISC_R_SUCCESS);
printf("%s got WRITE lock\n", message);
sleep(1);
printf("%s giving up WRITE lock\n", message);
RUNTIME_CHECK(isc_rwlock_unlock(&lock, isc_rwlocktype_write) ==
ISC_R_SUCCESS);
RUNTIME_CHECK(isc_rwlock_lock(&lock, isc_rwlocktype_write) ==
ISC_R_SUCCESS);
printf("%s got WRITE lock\n", message);
sleep(1);
printf("%s giving up WRITE lock\n", message);
RUNTIME_CHECK(isc_rwlock_unlock(&lock, isc_rwlocktype_write) ==
ISC_R_SUCCESS);
RUNTIME_CHECK(isc_rwlock_lock(&lock, isc_rwlocktype_read) ==
ISC_R_SUCCESS);
printf("%s got READ lock\n", message);
sleep(1);
printf("%s giving up READ lock\n", message);
RUNTIME_CHECK(isc_rwlock_unlock(&lock, isc_rwlocktype_read) ==
ISC_R_SUCCESS);
return (NULL);
}
static isc_threadresult_t
#ifdef WIN32
WINAPI
#endif
run2(void *arg) {
char *message = arg;
RUNTIME_CHECK(isc_rwlock_lock(&lock, isc_rwlocktype_write) ==
ISC_R_SUCCESS);
printf("%s got WRITE lock\n", message);
sleep(1);
printf("%s giving up WRITE lock\n", message);
RUNTIME_CHECK(isc_rwlock_unlock(&lock, isc_rwlocktype_write) ==
ISC_R_SUCCESS);
RUNTIME_CHECK(isc_rwlock_lock(&lock, isc_rwlocktype_write) ==
ISC_R_SUCCESS);
printf("%s got WRITE lock\n", message);
sleep(1);
printf("%s giving up WRITE lock\n", message);
RUNTIME_CHECK(isc_rwlock_unlock(&lock, isc_rwlocktype_write) ==
ISC_R_SUCCESS);
RUNTIME_CHECK(isc_rwlock_lock(&lock, isc_rwlocktype_read) ==
ISC_R_SUCCESS);
printf("%s got READ lock\n", message);
sleep(1);
printf("%s giving up READ lock\n", message);
RUNTIME_CHECK(isc_rwlock_unlock(&lock, isc_rwlocktype_read) ==
ISC_R_SUCCESS);
return ((isc_threadresult_t)0);
}
static void
copy_counters(isc_stats_t *stats) {
int i;
#ifdef ISC_RWLOCK_USEATOMIC
/*
* We use a "write" lock before "reading" the statistics counters as
* an exclusive lock.
*/
isc_rwlock_lock(&stats->counterlock, isc_rwlocktype_write);
#endif
#if ISC_STATS_USEMULTIFIELDS
for (i = 0; i < stats->ncounters; i++) {
stats->copiedcounters[i] =
(isc_uint64_t)(stats->counters[i].hi) << 32 |
stats->counters[i].lo;
}
#else
UNUSED(i);
memcpy(stats->copiedcounters, stats->counters,
stats->ncounters * sizeof(isc_stat_t));
#endif
#ifdef ISC_RWLOCK_USEATOMIC
isc_rwlock_unlock(&stats->counterlock, isc_rwlocktype_write);
#endif
}
static inline void
decrementcounter(isc_stats_t *stats, int counter) {
isc_int32_t prev;
#ifdef ISC_RWLOCK_USEATOMIC
isc_rwlock_lock(&stats->counterlock, isc_rwlocktype_read);
#endif
#if ISC_STATS_USEMULTIFIELDS
prev = isc_atomic_xadd((isc_int32_t *)&stats->counters[counter].lo, -1);
if (prev == 0)
isc_atomic_xadd((isc_int32_t *)&stats->counters[counter].hi,
-1);
#elif defined(ISC_PLATFORM_HAVEXADDQ)
UNUSED(prev);
isc_atomic_xaddq((isc_int64_t *)&stats->counters[counter], -1);
#else
UNUSED(prev);
stats->counters[counter]--;
#endif
#ifdef ISC_RWLOCK_USEATOMIC
isc_rwlock_unlock(&stats->counterlock, isc_rwlocktype_read);
#endif
}
void
isc_stats_set(isc_stats_t *stats, isc_uint64_t val,
isc_statscounter_t counter)
{
REQUIRE(ISC_STATS_VALID(stats));
REQUIRE(counter < stats->ncounters);
#ifdef ISC_RWLOCK_USEATOMIC
/*
* We use a "write" lock before "reading" the statistics counters as
* an exclusive lock.
*/
isc_rwlock_lock(&stats->counterlock, isc_rwlocktype_write);
#endif
#if ISC_STATS_USEMULTIFIELDS
stats->counters[counter].hi = (isc_uint32_t)((val >> 32) & 0xffffffff);
stats->counters[counter].lo = (isc_uint32_t)(val & 0xffffffff);
#else
stats->counters[counter] = val;
#endif
#ifdef ISC_RWLOCK_USEATOMIC
isc_rwlock_unlock(&stats->counterlock, isc_rwlocktype_write);
#endif
}
static inline void
incrementcounter(isc_stats_t *stats, int counter) {
isc_int32_t prev;
#ifdef ISC_RWLOCK_USEATOMIC
/*
* We use a "read" lock to prevent other threads from reading the
* counter while we "writing" a counter field. The write access itself
* is protected by the atomic operation.
*/
isc_rwlock_lock(&stats->counterlock, isc_rwlocktype_read);
#endif
#if ISC_STATS_USEMULTIFIELDS
prev = isc_atomic_xadd((isc_int32_t *)&stats->counters[counter].lo, 1);
/*
* If the lower 32-bit field overflows, increment the higher field.
* Note that it's *theoretically* possible that the lower field
* overlaps again before the higher field is incremented. It doesn't
* matter, however, because we don't read the value until
* isc_stats_copy() is called where the whole process is protected
* by the write (exclusive) lock.
*/
if (prev == (isc_int32_t)0xffffffff)
isc_atomic_xadd((isc_int32_t *)&stats->counters[counter].hi, 1);
#elif defined(ISC_PLATFORM_HAVEXADDQ)
UNUSED(prev);
isc_atomic_xaddq((isc_int64_t *)&stats->counters[counter], 1);
#else
UNUSED(prev);
stats->counters[counter]++;
#endif
#ifdef ISC_RWLOCK_USEATOMIC
isc_rwlock_unlock(&stats->counterlock, isc_rwlocktype_read);
#endif
}