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Add tracing probes to the custom isc_rwlock implementation

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Add tracing probes to ISC own isc_rwlock implementation to allow
fine-grained tracing.  The pthread rwlock already has probes inside
glibc, and it's difficult to add probes to headers included from the
other libraries.
This commit is contained in:
Ondřej Surý 2023-01-30 15:42:20 +01:00
parent 784d055809
commit dcd60215ac
No known key found for this signature in database
GPG key ID: 2820F37E873DEA41
2 changed files with 38 additions and 0 deletions
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12
lib/isc/probes.d
View file

@ -12,4 +12,16 @@
*/
provider libisc {
probe rwlock_init(void *);
probe rwlock_rdlock_req(void *);
probe rwlock_rdlock_acq(void *);
probe rwlock_wrlock_req(void *);
probe rwlock_wrlock_acq(void *);
probe rwlock_tryrdlock(void *, int);
probe rwlock_trywrlock(void *, int);
probe rwlock_rdunlock(void *);
probe rwlock_wrunlock(void *);
probe rwlock_downgrade(void *);
probe rwlock_tryupgrade(void *, int);
probe rwlock_destroy(void *);
};

26
lib/isc/rwlock.c
View file

@ -62,6 +62,8 @@
#include <isc/tid.h>
#include <isc/util.h>
#include "probes.h"
static atomic_uint_fast16_t isc__crwlock_workers = 128;
#define ISC_RWLOCK_UNLOCKED false
@ -137,6 +139,8 @@ isc_rwlock_rdlock(isc_rwlock_t *rwl) {
uint32_t cnt = 0;
bool barrier_raised = false;
LIBISC_RWLOCK_RDLOCK_REQ(rwl);
while (true) {
read_indicator_arrive(rwl);
if (!writers_lock_islocked(rwl)) {
@ -158,6 +162,8 @@ isc_rwlock_rdlock(isc_rwlock_t *rwl) {
if (barrier_raised) {
writers_barrier_lower(rwl);
}
LIBISC_RWLOCK_RDLOCK_ACQ(rwl);
}
isc_result_t
@ -167,27 +173,32 @@ isc_rwlock_tryrdlock(isc_rwlock_t *rwl) {
/* Writer has acquired the lock, release the read lock */
read_indicator_depart(rwl);
LIBISC_RWLOCK_TRYRDLOCK(rwl, ISC_R_LOCKBUSY);
return (ISC_R_LOCKBUSY);
}
/* Acquired lock in read-only mode */
LIBISC_RWLOCK_TRYRDLOCK(rwl, ISC_R_SUCCESS);
return (ISC_R_SUCCESS);
}
void
isc_rwlock_rdunlock(isc_rwlock_t *rwl) {
read_indicator_depart(rwl);
LIBISC_RWLOCK_RDUNLOCK(rwl);
}
isc_result_t
isc_rwlock_tryupgrade(isc_rwlock_t *rwl) {
/* Write Barriers has been raised */
if (writers_barrier_israised(rwl)) {
LIBISC_RWLOCK_TRYUPGRADE(rwl, ISC_R_LOCKBUSY);
return (ISC_R_LOCKBUSY);
}
/* Try to acquire the write-lock */
if (!writers_lock_acquire(rwl)) {
LIBISC_RWLOCK_TRYUPGRADE(rwl, ISC_R_LOCKBUSY);
return (ISC_R_LOCKBUSY);
}
@ -200,8 +211,10 @@ isc_rwlock_tryupgrade(isc_rwlock_t *rwl) {
/* Unlock the write-lock */
writers_lock_release(rwl);
LIBISC_RWLOCK_TRYUPGRADE(rwl, ISC_R_LOCKBUSY);
return (ISC_R_LOCKBUSY);
}
LIBISC_RWLOCK_TRYUPGRADE(rwl, ISC_R_SUCCESS);
return (ISC_R_SUCCESS);
}
@ -218,6 +231,8 @@ read_indicator_wait_until_empty(isc_rwlock_t *rwl) {
void
isc_rwlock_wrlock(isc_rwlock_t *rwl) {
LIBISC_RWLOCK_WRLOCK_REQ(rwl);
/* Write Barriers has been raised, wait */
while (writers_barrier_israised(rwl)) {
isc_pause();
@ -229,22 +244,27 @@ isc_rwlock_wrlock(isc_rwlock_t *rwl) {
}
read_indicator_wait_until_empty(rwl);
LIBISC_RWLOCK_WRLOCK_ACQ(rwl);
}
void
isc_rwlock_wrunlock(isc_rwlock_t *rwl) {
writers_lock_release(rwl);
LIBISC_RWLOCK_WRUNLOCK(rwl);
}
isc_result_t
isc_rwlock_trywrlock(isc_rwlock_t *rwl) {
/* Write Barriers has been raised */
if (writers_barrier_israised(rwl)) {
LIBISC_RWLOCK_TRYWRLOCK(rwl, ISC_R_LOCKBUSY);
return (ISC_R_LOCKBUSY);
}
/* Try to acquire the write-lock */
if (!writers_lock_acquire(rwl)) {
LIBISC_RWLOCK_TRYWRLOCK(rwl, ISC_R_LOCKBUSY);
return (ISC_R_LOCKBUSY);
}
@ -252,9 +272,11 @@ isc_rwlock_trywrlock(isc_rwlock_t *rwl) {
/* Unlock the write-lock */
writers_lock_release(rwl);
LIBISC_RWLOCK_TRYWRLOCK(rwl, ISC_R_LOCKBUSY);
return (ISC_R_LOCKBUSY);
}
LIBISC_RWLOCK_TRYWRLOCK(rwl, ISC_R_SUCCESS);
return (ISC_R_SUCCESS);
}
@ -263,6 +285,8 @@ isc_rwlock_downgrade(isc_rwlock_t *rwl) {
read_indicator_arrive(rwl);
writers_lock_release(rwl);
LIBISC_RWLOCK_DOWNGRADE(rwl);
}
void
@ -273,10 +297,12 @@ isc_rwlock_init(isc_rwlock_t *rwl) {
atomic_init(&rwl->writers_barrier, 0);
atomic_init(&rwl->readers_ingress, 0);
atomic_init(&rwl->readers_egress, 0);
LIBISC_RWLOCK_INIT(rwl);
}
void
isc_rwlock_destroy(isc_rwlock_t *rwl) {
LIBISC_RWLOCK_DESTROY(rwl);
/* Check whether write lock has been unlocked */
REQUIRE(atomic_load(&rwl->writers_lock) == ISC_RWLOCK_UNLOCKED);
REQUIRE(read_indicator_isempty(rwl));