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Commit cac09ba7 authored by Xavier Thompson's avatar Xavier Thompson
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Reimplement cypclass lock using nonrecursive pthread_rwlock_t

parent 5403c6dd
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Showing with 11 additions and 247 deletions
Cython/Utility/CyObjects.cpp
View file @ cac09ba7
......@@ -16,13 +16,6 @@
#include <atomic>
using namespace std;
#define CyObject_ATOMIC_REFCOUNT_TYPE atomic_int
#define CyObject_NO_OWNER -1
#define CyObject_MANY_OWNERS -2
#define CyObject_CONTENDING_WRITER_FLAG (1 << 0)
#define CyObject_CONTENDING_READER_FLAG (1 << 1)
#define CyObject_RAISE_ON_CONTENTION 0
#include <pthread.h>
......@@ -40,28 +33,14 @@
class CyLock {
static pthread_mutex_t log_guard;
protected:
pthread_mutex_t guard;
pthread_cond_t readers_have_left;
pthread_cond_t writer_has_left;
atomic<pid_t> owner_id;
atomic_int readers_nb;
uint32_t write_count;
const char *owner_context;
pthread_rwlock_t rwlock;
public:
CyLock() {
pthread_mutex_init(&this->guard, NULL);
pthread_cond_init(&this->readers_have_left, NULL);
pthread_cond_init(&this->writer_has_left, NULL);
this->owner_id = CyObject_NO_OWNER;
this->readers_nb = 0;
this->write_count = 0;
pthread_rwlock_init(&this->rwlock, NULL);
}
~CyLock() {
pthread_mutex_destroy(&this->guard);
pthread_cond_destroy(&this->readers_have_left);
pthread_cond_destroy(&this->writer_has_left);
pthread_rwlock_destroy(&this->rwlock);
}
void wlock(const char * context);
void rlock(const char * context);
......@@ -70,9 +49,6 @@
int tryrlock();
int trywlock();
};
#if CyObject_RAISE_ON_CONTENTION == 0
pthread_mutex_t CyLock::log_guard = PTHREAD_MUTEX_INITIALIZER;
#endif
struct CyPyObject {
PyObject_HEAD
......@@ -541,240 +517,28 @@
#endif /* __cplusplus */
void CyLock::rlock(const char *context) {
pid_t caller_id = syscall(SYS_gettid);
if (this->owner_id == caller_id) {
++this->readers_nb;
return;
}
pthread_mutex_lock(&this->guard);
if (this->write_count > 0) {
#if CyObject_RAISE_ON_CONTENTION
pid_t owner_id = this->owner_id;
std::ostringstream msg;
msg << "Data Race between [this] reader #" << caller_id
<< " and [other] writer #" << owner_id
<< " on lock " << this;
if (context != NULL) {
msg << std::endl << "In [this] context: " << context;
}
if (this->owner_context != NULL) {
msg << std::endl << "In [other] context: " << this->owner_context;
}
throw std::runtime_error(msg.str());
#else
pid_t owner_id = this->owner_id;
pthread_mutex_lock(&(CyLock::log_guard));
std::cerr
<< "Data Race between [this] reader #" << caller_id
<< " and [other] writer #" << owner_id
<< " on lock " << this << std::endl;
if (context != NULL) {
std::cerr << "In [this] context: " << context << std::endl;
}
if (this->owner_context != NULL) {
std::cerr << "In [other] context: " << this->owner_context << std::endl;
}
pthread_mutex_unlock(&(CyLock::log_guard));
#endif
}
while (this->write_count > 0) {
pthread_cond_wait(&this->writer_has_left, &this->guard);
}
this->owner_id = this->readers_nb++ ? CyObject_MANY_OWNERS : caller_id;
this->owner_context = context;
pthread_mutex_unlock(&this->guard);
void CyLock::rlock(CYTHON_UNUSED const char *context) {
pthread_rwlock_rdlock(&this->rwlock);
}
int CyLock::tryrlock() {
pid_t caller_id = syscall(SYS_gettid);
if (this->owner_id == caller_id) {
++this->readers_nb;
return 0;
}
// we must lock here, because a trylock could fail also when another thread is currently read-locking or read-unlocking
// but this means we might miss a writer arriving and leaving
pthread_mutex_lock(&this->guard);
if (this->write_count > 0) {
pthread_mutex_unlock(&this->guard);
return CyObject_CONTENDING_WRITER_FLAG;
}
this->owner_id = this->readers_nb++ ? CyObject_MANY_OWNERS : caller_id;
pthread_mutex_unlock(&this->guard);
return 0;
return pthread_rwlock_tryrdlock(&this->rwlock);
}
void CyLock::unrlock() {
pthread_mutex_lock(&this->guard);
if (--this->readers_nb == 0) {
if (this->write_count == 0) {
this->owner_id = CyObject_NO_OWNER;
}
// broadcast to wake up all the waiting writers
pthread_cond_broadcast(&this->readers_have_left);
}
pthread_mutex_unlock(&this->guard);
pthread_rwlock_unlock(&this->rwlock);
}
void CyLock::wlock(const char *context) {
pid_t caller_id = syscall(SYS_gettid);
if (this->owner_id == caller_id) {
if (this->write_count) {
++this->write_count;
return;
}
}
pthread_mutex_lock(&this->guard);
pid_t owner_id = this->owner_id;
if (owner_id != caller_id) {
// Since we use a reader-preferring approach, we wait first for all readers to leave, and then all writers.
// The other way around could result in several writers acquiring the lock.
if (this->readers_nb > 0) {
#if CyObject_RAISE_ON_CONTENTION
pid_t owner_id = this->owner_id;
std::ostringstream msg;
msg << "Data Race between [this] writer #" << caller_id
<< " and [other] reader #" << owner_id
<< " on lock " << this;
if (context != NULL) {
msg << std::endl << "In [this] context: " << context;
}
if (this->owner_context != NULL) {
msg << std::endl << "In [other] context: " << this->owner_context;
}
throw std::runtime_error(msg.str());
#else
pthread_mutex_lock(&(CyLock::log_guard));
std::cerr
<< "Data Race between [this] writer #" << caller_id
<< " and [other] reader #" << owner_id
<< " on lock " << this << std::endl;
if (context != NULL) {
std::cerr << "In [this] context: " << context << std::endl;
}
if (this->owner_context != NULL) {
std::cerr << "In [other] context: " << this->owner_context << std::endl;
}
pthread_mutex_unlock(&(CyLock::log_guard));
#endif
}
while (this->readers_nb > 0) {
pthread_cond_wait(&this->readers_have_left, &this->guard);
}
if (this->write_count > 0) {
#if CyObject_RAISE_ON_CONTENTION
pid_t owner_id = this->owner_id;
std::ostringstream msg;
msg << "Data Race between [this] writer #" << caller_id
<< " and [other] writer #" << owner_id
<< " on lock " << this;
if (context != NULL) {
msg << std::endl << "In [this] context: " << context;
}
if (this->owner_context != NULL) {
msg << std::endl << "In [other] context: " << this->owner_context;
}
throw std::runtime_error(msg.str());
#else
pthread_mutex_lock(&(CyLock::log_guard));
std::cerr
<< "Data Race between [this] writer #" << caller_id
<< " and [other] writer #" << owner_id
<< " on lock " << this << std::endl;
if (context != NULL) {
std::cerr << "In [this] context: " << context << std::endl;
}
if (this->owner_context != NULL) {
std::cerr << "In [other] context: " << this->owner_context << std::endl;
}
pthread_mutex_unlock(&(CyLock::log_guard));
#endif
}
while (this->write_count > 0) {
pthread_cond_wait(&this->writer_has_left, &this->guard);
}
this->owner_id = caller_id;
}
this->write_count = 1;
this->owner_context = context;
pthread_mutex_unlock(&this->guard);
void CyLock::wlock(CYTHON_UNUSED const char *context) {
pthread_rwlock_wrlock(&this->rwlock);
}
int CyLock::trywlock() {
pid_t caller_id = syscall(SYS_gettid);
if (this->owner_id == caller_id) {
if (this->write_count) {
++this->write_count;
return 0;
}
}
pthread_mutex_lock(&this->guard);
if (this->owner_id != caller_id) {
if (this->readers_nb > 0) {
pthread_mutex_unlock(&this->guard);
return CyObject_CONTENDING_READER_FLAG;
}
if (this->write_count > 0) {
pthread_mutex_unlock(&this->guard);
return CyObject_CONTENDING_WRITER_FLAG;
}
this->owner_id = caller_id;
}
this->write_count = 1;
pthread_mutex_unlock(&this->guard);
return 0;
return pthread_rwlock_trywrlock(&this->rwlock);
}
void CyLock::unwlock() {
pthread_mutex_lock(&this->guard);
if (--this->write_count == 0) {
if (this->readers_nb == 0) {
this->owner_id = CyObject_NO_OWNER;
}
// broadcast to wake up all the waiting readers, + maybe one waiting writer
// more efficient to count r waiting readers and w waiting writers and signal n + (w > 0) times
pthread_cond_broadcast(&this->writer_has_left);
}
pthread_mutex_unlock(&this->guard);
pthread_rwlock_unlock(&this->rwlock);
}
......
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