ComputerSurge/bind9
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add write quota

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This commit is contained in:
Bob Halley
1998-11-12 22:27:30 +00:00
parent c8e7460242
commit 994ba9c913
3 changed files with 27 additions and 8 deletions
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4
bin/tests/rwlock_test.c
View File

@@ -79,14 +79,14 @@ main(int argc, char *argv[]) {
nworkers = 24;
printf("%d workers\n", nworkers);
INSIST(isc_rwlock_init(&lock) == ISC_R_SUCCESS);
INSIST(isc_rwlock_init(&lock, 5, 10) == ISC_R_SUCCESS);
for (i = 0; i < nworkers; i++) {
sprintf(name, "%02u", i);
dupname = strdup(name);
INSIST(dupname != NULL);
if (i != 0 && i % 3 == 0)
INSIST(isc_thread_create(run2, dupname, &workers[i]) ==
INSIST(isc_thread_create(run1, dupname, &workers[i]) ==
ISC_R_SUCCESS);
else
INSIST(isc_thread_create(run1, dupname, &workers[i]) ==

4
lib/isc/include/isc/rwlock.h
View File

@@ -21,10 +21,12 @@ typedef struct isc_rwlock {
unsigned int readers_waiting;
unsigned int writers_waiting;
unsigned int read_quota;
unsigned int write_quota;
} isc_rwlock_t;
isc_result_t
isc_rwlock_init(isc_rwlock_t *rwl);
isc_rwlock_init(isc_rwlock_t *rwl, unsigned int read_quota,
unsigned int write_quota);
isc_result_t
isc_rwlock_lock(isc_rwlock_t *rwl, isc_rwlocktype_t type);

27
lib/isc/rwlock.c
View File

@@ -32,7 +32,10 @@ print_lock(char *operation, isc_rwlock_t *rwl, isc_rwlocktype_t type) {
}
isc_result_t
isc_rwlock_init(isc_rwlock_t *rwl) {
isc_rwlock_init(isc_rwlock_t *rwl,
unsigned int read_quota,
unsigned int write_quota)
{
isc_result_t result;
REQUIRE(rwl != NULL);
@@ -42,7 +45,12 @@ isc_rwlock_init(isc_rwlock_t *rwl) {
rwl->granted = 0;
rwl->readers_waiting = 0;
rwl->writers_waiting = 0;
rwl->read_quota = 5; /* XXX */
if (read_quota == 0)
read_quota = 4;
rwl->read_quota = read_quota;
if (write_quota == 0)
write_quota = 4;
rwl->write_quota = write_quota;
result = isc_mutex_init(&rwl->lock);
if (result != ISC_R_SUCCESS) {
UNEXPECTED_ERROR(__FILE__, __LINE__,
@@ -105,6 +113,7 @@ isc_rwlock_lock(isc_rwlock_t *rwl, isc_rwlocktype_t type) {
if (!skip && rwl->active == 0) {
rwl->type = isc_rwlocktype_write;
rwl->active = 1;
rwl->granted++;
done = ISC_TRUE;
} else {
skip = ISC_FALSE;
@@ -135,19 +144,27 @@ isc_rwlock_unlock(isc_rwlock_t *rwl, isc_rwlocktype_t type) {
rwl->active--;
if (rwl->active == 0) {
rwl->granted = 0;
if (rwl->type == isc_rwlocktype_read) {
rwl->granted = 0;
if (rwl->writers_waiting > 0) {
rwl->type = isc_rwlocktype_write;
SIGNAL(&rwl->writeable);
} else if (rwl->readers_waiting > 0) {
/* Does this case ever happen? */
BROADCAST(&rwl->readable);
}
} else {
if (rwl->readers_waiting > 0) {
rwl->type = isc_rwlocktype_read;
BROADCAST(&rwl->readable);
if (rwl->writers_waiting > 0 &&
rwl->granted < rwl->write_quota) {
SIGNAL(&rwl->writeable);
} else {
rwl->granted = 0;
rwl->type = isc_rwlocktype_read;
BROADCAST(&rwl->readable);
}
} else if (rwl->writers_waiting > 0) {
rwl->granted = 0;
SIGNAL(&rwl->writeable);
}
}