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#include "shared_mutex_debug.h"
#include <system_error>
#include "acconfig.h"
#include "common/valgrind.h"
namespace ceph {
shared_mutex_debug::shared_mutex_debug(const std::string& n,
bool track_lock,
bool enable_lock_dep,
bool prioritize_write)
: mutex_debugging_base{n, false /* backtrace */},
track(track_lock),
lockdep(enable_lock_dep)
{
#ifdef HAVE_PTHREAD_RWLOCKATTR_SETKIND_NP
if (prioritize_write) {
pthread_rwlockattr_t attr;
pthread_rwlockattr_init(&attr);
// PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP
// Setting the lock kind to this avoids writer starvation as long as
// long as any read locking is not done in a recursive fashion.
pthread_rwlockattr_setkind_np(&attr,
PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP);
pthread_rwlock_init(&rwlock, &attr);
pthread_rwlockattr_destroy(&attr);
} else
#endif
// Next block is in {} to possibly connect to the above if when code is used.
{
pthread_rwlock_init(&rwlock, NULL);
}
ANNOTATE_BENIGN_RACE_SIZED(&id, sizeof(id), "shared_mutex_debug lockdep id");
ANNOTATE_BENIGN_RACE_SIZED(&nlock, sizeof(nlock), "shared_mutex_debug nwlock");
ANNOTATE_BENIGN_RACE_SIZED(&nrlock, sizeof(nrlock), "shared_mutex_debug nrlock");
}
// exclusive
void shared_mutex_debug::lock()
{
if (g_lockdep && lockdep) {
_will_lock();
}
if (int r = pthread_rwlock_wrlock(&rwlock); r != 0) {
throw std::system_error(r, std::generic_category());
}
if (lockdep && g_lockdep) {
_locked();
}
_post_lock();
}
bool shared_mutex_debug::try_lock()
{
int r = pthread_rwlock_trywrlock(&rwlock);
switch (r) {
case 0:
if (lockdep && g_lockdep) {
_locked();
}
_post_lock();
return true;
case EBUSY:
return false;
default:
throw std::system_error(r, std::generic_category());
}
}
void shared_mutex_debug::unlock()
{
_pre_unlock();
if (lockdep && g_lockdep) {
_will_unlock();
}
if (int r = pthread_rwlock_unlock(&rwlock); r != 0) {
throw std::system_error(r, std::generic_category());
}
}
// shared locking
void shared_mutex_debug::lock_shared()
{
if (lockdep && g_lockdep) {
_will_lock();
}
if (int r = pthread_rwlock_rdlock(&rwlock); r != 0) {
throw std::system_error(r, std::generic_category());
}
if (lockdep && g_lockdep) {
_locked();
}
_post_lock_shared();
}
bool shared_mutex_debug::try_lock_shared()
{
if (lockdep && g_lockdep) {
_will_unlock();
}
switch (int r = pthread_rwlock_rdlock(&rwlock); r) {
case 0:
if (lockdep && g_lockdep) {
_locked();
}
_post_lock_shared();
return true;
case EBUSY:
return false;
default:
throw std::system_error(r, std::generic_category());
}
}
void shared_mutex_debug::unlock_shared()
{
_pre_unlock_shared();
if (lockdep && g_lockdep) {
_will_unlock();
}
if (int r = pthread_rwlock_unlock(&rwlock); r != 0) {
throw std::system_error(r, std::generic_category());
}
}
// exclusive locking
void shared_mutex_debug::_pre_unlock()
{
if (track) {
ceph_assert(nlock > 0);
--nlock;
ceph_assert(locked_by == std::this_thread::get_id());
ceph_assert(nlock == 0);
locked_by = std::thread::id();
}
}
void shared_mutex_debug::_post_lock()
{
if (track) {
ceph_assert(nlock == 0);
locked_by = std::this_thread::get_id();
++nlock;
}
}
// shared locking
void shared_mutex_debug::_pre_unlock_shared()
{
if (track) {
ceph_assert(nrlock > 0);
nrlock--;
}
}
void shared_mutex_debug::_post_lock_shared()
{
if (track) {
++nrlock;
}
}
} // namespace ceph
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