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Commit d4a204b6 authored by Xavier Thompson's avatar Xavier Thompson
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Clean up cypclass object lock implementation

parent b8672147
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Showing with 68 additions and 136 deletions
Cython/Utility/CyObjects.cpp
View file @ d4a204b6
......@@ -34,19 +34,20 @@
#include <type_traits>
class RecursiveUpgradeableRWLock {
class CyLock {
static pthread_mutex_t log_guard;
protected:
pthread_mutex_t guard;
pthread_cond_t wait_readers_depart;
pthread_cond_t wait_writer_depart;
pthread_cond_t readers_have_left;
pthread_cond_t writer_has_left;
atomic<pid_t> owner_id;
atomic_int32_t readers_nb;
uint32_t write_count;
public:
RecursiveUpgradeableRWLock() {
CyLock() {
pthread_mutex_init(&this->guard, NULL);
pthread_cond_init(&this->wait_readers_depart, NULL);
pthread_cond_init(&this->wait_writer_depart, 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;
......@@ -58,14 +59,7 @@
int tryrlock();
int trywlock();
};
class LogLock : public RecursiveUpgradeableRWLock {
static pthread_mutex_t log_guard;
public:
void wlock();
void rlock();
};
pthread_mutex_t LogLock::log_guard = PTHREAD_MUTEX_INITIALIZER;
pthread_mutex_t CyLock::log_guard = PTHREAD_MUTEX_INITIALIZER;
struct CyPyObject {
PyObject_HEAD
......@@ -74,7 +68,7 @@
class CyObject : public CyPyObject {
private:
CyObject_ATOMIC_REFCOUNT_TYPE nogil_ob_refcnt;
LogLock ob_lock;
CyLock ob_lock;
public:
CyObject(): nogil_ob_refcnt(1) {}
virtual ~CyObject() {}
......@@ -315,7 +309,7 @@
#endif /* __cplusplus */
void RecursiveUpgradeableRWLock::rlock() {
void CyLock::rlock() {
pid_t caller_id = syscall(SYS_gettid);
if (this->owner_id == caller_id) {
......@@ -325,8 +319,20 @@ void RecursiveUpgradeableRWLock::rlock() {
pthread_mutex_lock(&this->guard);
if (this->write_count > 0) {
pid_t owner_id = this->owner_id;
pthread_mutex_lock(&(CyLock::log_guard));
printf(
"Contention with a writer detected while rlocking lock [%p] in thread #%d:\n"
" - lock was already wlocked by thread %d\n"
"\n"
,this, caller_id, owner_id
);
pthread_mutex_unlock(&(CyLock::log_guard));
}
while (this->write_count > 0) {
pthread_cond_wait(&this->wait_writer_depart, &this->guard);
pthread_cond_wait(&this->writer_has_left, &this->guard);
}
this->owner_id = this->readers_nb++ ? CyObject_MANY_OWNERS : caller_id;
......@@ -334,7 +340,7 @@ void RecursiveUpgradeableRWLock::rlock() {
pthread_mutex_unlock(&this->guard);
}
int RecursiveUpgradeableRWLock::tryrlock() {
int CyLock::tryrlock() {
pid_t caller_id = syscall(SYS_gettid);
if (this->owner_id == caller_id) {
......@@ -358,8 +364,7 @@ int RecursiveUpgradeableRWLock::tryrlock() {
return 0;
}
void RecursiveUpgradeableRWLock::unrlock() {
void CyLock::unrlock() {
pthread_mutex_lock(&this->guard);
if (--this->readers_nb == 0) {
......@@ -368,13 +373,13 @@ void RecursiveUpgradeableRWLock::unrlock() {
}
// broadcast to wake up all the waiting writers
pthread_cond_broadcast(&this->wait_readers_depart);
pthread_cond_broadcast(&this->readers_have_left);
}
pthread_mutex_unlock(&this->guard);
}
void RecursiveUpgradeableRWLock::wlock() {
void CyLock::wlock() {
pid_t caller_id = syscall(SYS_gettid);
if (this->owner_id == caller_id) {
......@@ -386,26 +391,52 @@ void RecursiveUpgradeableRWLock::wlock() {
pthread_mutex_lock(&this->guard);
if (this->owner_id != caller_id) {
// we wait for readers first and bottleneck the writers after
// this works for a readers preferring approach
pid_t owner_id = this->owner_id;
// because the other way around would require setting write_count to 1 before waiting on the readers
// in order to ensure only one writer at a times goes beyound waiting for the other writers to leave
if (owner_id != caller_id) {
// this would be more in line with a writers preferring approach, but that can deadlock when a thread recurses on a readlock
// this also means that we must broadcast when the readers leave in order to give all the waiting writers a chance to wake up
// 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.
// new readers might still pass before some of the waiting writers, but then they'll just wait some more
// OTOH, if the new readers come, not broadcasting would let some writers wait forever
if (this->readers_nb > 0) {
if (owner_id == CyObject_MANY_OWNERS) {
pthread_mutex_lock(&(CyLock::log_guard));
printf(
"Contention with several other reader threads detected while wlocking lock [%p] in thread #%d:\n"
"\n"
,this, caller_id
);
pthread_mutex_unlock(&(CyLock::log_guard));
}
else {
pthread_mutex_lock(&(CyLock::log_guard));
printf(
"Contention with a reader thread detected while wlocking lock [%p] in thread #%d:\n"
" - reader thread is %d\n"
"\n"
,this, caller_id, owner_id
);
pthread_mutex_unlock(&(CyLock::log_guard));
}
}
while (this->readers_nb > 0) {
pthread_cond_wait(&this->wait_readers_depart, &this->guard);
pthread_cond_wait(&this->readers_have_left, &this->guard);
}
if (this->write_count > 0) {
pthread_mutex_lock(&(CyLock::log_guard));
printf(
"Contention with another writer detected while wlocking lock [%p] in thread #%d:\n"
" - lock was already wlocked by thread %d\n"
"\n"
,this, caller_id, owner_id
);
pthread_mutex_unlock(&(CyLock::log_guard));
}
while (this->write_count > 0) {
pthread_cond_wait(&this->wait_writer_depart, &this->guard);
pthread_cond_wait(&this->writer_has_left, &this->guard);
}
this->owner_id = caller_id;
......@@ -416,7 +447,7 @@ void RecursiveUpgradeableRWLock::wlock() {
pthread_mutex_unlock(&this->guard);
}
int RecursiveUpgradeableRWLock::trywlock() {
int CyLock::trywlock() {
pid_t caller_id = syscall(SYS_gettid);
if (this->owner_id == caller_id) {
......@@ -450,8 +481,7 @@ int RecursiveUpgradeableRWLock::trywlock() {
return 0;
}
void RecursiveUpgradeableRWLock::unwlock() {
void CyLock::unwlock() {
pthread_mutex_lock(&this->guard);
if (--this->write_count == 0) {
if (this->readers_nb == 0) {
......@@ -460,109 +490,11 @@ void RecursiveUpgradeableRWLock::unwlock() {
// 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->wait_writer_depart);
}
pthread_mutex_unlock(&this->guard);
}
void LogLock::rlock() {
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) {
pid_t owner_id = this->owner_id;
pthread_mutex_lock(&(LogLock::log_guard));
printf(
"Contention with a writer detected while rlocking lock [%p] in thread #%d:\n"
" - lock was already wlocked by thread %d\n"
"\n"
,this, caller_id, owner_id
);
pthread_mutex_unlock(&(LogLock::log_guard));
pthread_cond_broadcast(&this->writer_has_left);
}
while (this->write_count > 0) {
pthread_cond_wait(&this->wait_writer_depart, &this->guard);
}
this->owner_id = this->readers_nb++ ? CyObject_MANY_OWNERS : caller_id;
pthread_mutex_unlock(&this->guard);
}
void LogLock::wlock() {
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) {
if (this->readers_nb > 0) {
if (owner_id == CyObject_MANY_OWNERS) {
pthread_mutex_lock(&(LogLock::log_guard));
printf(
"Contention with several other reader threads detected while wlocking lock [%p] in thread #%d:\n"
"\n"
,this, caller_id
);
pthread_mutex_unlock(&(LogLock::log_guard));
}
else {
pthread_mutex_lock(&(LogLock::log_guard));
printf(
"Contention with a reader thread detected while wlocking lock [%p] in thread #%d:\n"
" - reader thread is %d\n"
"\n"
,this, caller_id, owner_id
);
pthread_mutex_unlock(&(LogLock::log_guard));
}
}
while (this->readers_nb > 0) {
pthread_cond_wait(&this->wait_readers_depart, &this->guard);
}
if (this->write_count > 0) {
pthread_mutex_lock(&(LogLock::log_guard));
printf(
"Contention with another writer detected while wlocking lock [%p] in thread #%d:\n"
" - lock was already wlocked by thread %d\n"
"\n"
,this, caller_id, owner_id
);
pthread_mutex_unlock(&(LogLock::log_guard));
}
while (this->write_count > 0) {
pthread_cond_wait(&this->wait_writer_depart, &this->guard);
}
this->owner_id = caller_id;
}
this->write_count = 1;
pthread_mutex_unlock(&this->guard);
}
/*
* Atomic counter increment and decrement implementation based on
......
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