Use simple pthread_rwlock in place of our custom adaptive rwlock

lib/isc/include/isc/rwlock.h

@@ -14,6 +14,7 @@
 #define ISC_RWLOCK_H 1
 
 #include <inttypes.h>
+#include <pthread.h>
 
 /*! \file isc/rwlock.h */
 
@@ -31,6 +32,14 @@ typedef enum {
 	isc_rwlocktype_write
 } isc_rwlocktype_t;
 
+#if HAVE_PTHREAD_RWLOCK_RDLOCK
+
+struct isc_rwlock {
+	pthread_rwlock_t	rwlock;
+};
+
+#else /* HAVE_PTHREAD_RWLOCK_RDLOCK */
+
 struct isc_rwlock {
 	/* Unlocked. */
 	unsigned int		magic;
@@ -68,6 +77,8 @@ struct isc_rwlock {
 
 };
 
+#endif /* HAVE_PTHREAD_RWLOCK_RDLOCK */
+
 isc_result_t
 isc_rwlock_init(isc_rwlock_t *rwl, unsigned int read_quota,
 		unsigned int write_quota);

lib/isc/rwlock.c

@@ -27,6 +27,78 @@
 #include <isc/rwlock.h>
 #include <isc/util.h>
 
+#if HAVE_PTHREAD_RWLOCK_RDLOCK
+
+#include <errno.h>
+#include <pthread.h>
+
+isc_result_t
+isc_rwlock_init(isc_rwlock_t *rwl, unsigned int read_quota,
+		unsigned int write_quota)
+{
+	UNUSED(read_quota);
+	UNUSED(write_quota);
+	REQUIRE(pthread_rwlock_init(&rwl->rwlock, NULL) == 0);
+	return (ISC_R_SUCCESS);
+}
+
+isc_result_t
+isc_rwlock_lock(isc_rwlock_t *rwl, isc_rwlocktype_t type) {
+	switch (type) {
+	case isc_rwlocktype_read: REQUIRE(pthread_rwlock_rdlock(&rwl->rwlock) == 0); break;
+	case isc_rwlocktype_write: REQUIRE(pthread_rwlock_wrlock(&rwl->rwlock) == 0); break;
+	default: INSIST(0);
+	}
+	return (ISC_R_SUCCESS);
+}
+
+isc_result_t
+isc_rwlock_trylock(isc_rwlock_t *rwl, isc_rwlocktype_t type) {
+	int ret = 0;
+	switch (type) {
+	case isc_rwlocktype_read:
+		ret = pthread_rwlock_tryrdlock(&rwl->rwlock);
+		break;
+	case isc_rwlocktype_write:
+		ret = pthread_rwlock_trywrlock(&rwl->rwlock);
+		break;
+	default: INSIST(0);
+	}
+
+	switch (ret) {
+	case 0: return (ISC_R_SUCCESS);
+	case EBUSY: return (ISC_R_LOCKBUSY);
+	case EAGAIN: return (ISC_R_LOCKBUSY);
+	default: INSIST(0); ISC_UNREACHABLE();
+	}
+}
+
+
+isc_result_t
+isc_rwlock_unlock(isc_rwlock_t *rwl, isc_rwlocktype_t type) {
+	UNUSED(type);
+	REQUIRE(pthread_rwlock_unlock(&rwl->rwlock) == 0);
+	return (ISC_R_SUCCESS);
+}
+
+isc_result_t
+isc_rwlock_tryupgrade(isc_rwlock_t *rwl) {
+	return (ISC_R_LOCKBUSY);
+}
+
+void
+isc_rwlock_downgrade(isc_rwlock_t *rwl) {
+	isc_rwlock_unlock(rwl, isc_rwlocktype_write);
+	isc_rwlock_lock(rwl, isc_rwlocktype_read);
+}
+
+void
+isc_rwlock_destroy(isc_rwlock_t *rwl) {
+	pthread_rwlock_destroy(&rwl->rwlock);
+}
+
+#else
+
 #define RWLOCK_MAGIC		ISC_MAGIC('R', 'W', 'L', 'k')
 #define VALID_RWLOCK(rwl)	ISC_MAGIC_VALID(rwl, RWLOCK_MAGIC)
 
@@ -549,3 +621,5 @@ isc_rwlock_unlock(isc_rwlock_t *rwl, isc_rwlocktype_t type) {
 
 	return (ISC_R_SUCCESS);
 }
+
+#endif /* HAVE_PTHREAD_RWLOCK_RDLOCK */