TheCloud/panda3d
1
0
Fork 0
mirror of https://github.com/panda3d/panda3d.git synced 2025-09-29 08:15:18 -04:00
Code Issues Packages Projects Releases Wiki Activity

Acquire mutex in cache_unref() - fixes race cond in async flatten

Browse Source
This commit is contained in:
rdb 2016-09-11 22:14:18 +02:00
parent 3ce808c705
commit 632ad5e3ef
3 changed files with 37 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
panda/src/putil/copyOnWriteObject.I
View File

@ -83,6 +83,17 @@ cache_ref() const {
MutexHolder holder(_lock_mutex);
CachedTypedWritableReferenceCount::cache_ref();
}
////////////////////////////////////////////////////////////////////
// Function: CopyOnWriteObject::cache_unref
// Access: Published
// Description: See CachedTypedWritableReferenceCount::cache_unref().
////////////////////////////////////////////////////////////////////
INLINE bool CopyOnWriteObject::
cache_unref() const {
MutexHolder holder(_lock_mutex);
return CachedTypedWritableReferenceCount::cache_unref();
}
#endif // COW_THREADED
////////////////////////////////////////////////////////////////////

1
panda/src/putil/copyOnWriteObject.h
View File

@ -51,6 +51,7 @@ PUBLISHED:
#ifdef COW_THREADED
virtual bool unref() const;
INLINE void cache_ref() const;
INLINE bool cache_unref() const;
#endif // COW_THREADED
protected:

31
panda/src/putil/copyOnWritePointer.cxx
View File

@ -13,7 +13,6 @@
////////////////////////////////////////////////////////////////////
#include "copyOnWritePointer.h"
#include "mutexHolder.h"
#include "config_util.h"
#include "config_pipeline.h"
@ -78,7 +77,7 @@ get_write_pointer() {
Thread *current_thread = Thread::get_current_thread();
MutexHolder holder(_cow_object->_lock_mutex);
_cow_object->_lock_mutex.acquire();
while (_cow_object->_lock_status == CopyOnWriteObject::LS_locked_write &&
_cow_object->_locking_thread != current_thread) {
if (util_cat.is_debug()) {
@ -98,10 +97,20 @@ get_write_pointer() {
<< "Making copy of " << _cow_object->get_type()
<< " because it is locked in read mode.\n";
}
PT(CopyOnWriteObject) new_object = _cow_object->make_cow_copy();
cache_unref_delete(_cow_object);
// We can't call cache_unref_delete, because we hold the lock.
if (!_cow_object->CachedTypedWritableReferenceCount::cache_unref()) {
_cow_object->_lock_mutex.release();
delete _cow_object;
} else {
_cow_object->_lock_mutex.release();
}
_cow_object = new_object;
_cow_object->cache_ref();
_cow_object->_lock_status = CopyOnWriteObject::LS_locked_write;
_cow_object->_locking_thread = current_thread;
} else if (_cow_object->get_cache_ref_count() > 1) {
// No one else has it specifically read-locked, but there are
@ -115,9 +124,18 @@ get_write_pointer() {
}
PT(CopyOnWriteObject) new_object = _cow_object->make_cow_copy();
cache_unref_delete(_cow_object);
// We can't call cache_unref_delete, because we hold the lock.
if (!_cow_object->CachedTypedWritableReferenceCount::cache_unref()) {
_cow_object->_lock_mutex.release();
delete _cow_object;
} else {
_cow_object->_lock_mutex.release();
}
_cow_object = new_object;
_cow_object->cache_ref();
_cow_object->_lock_status = CopyOnWriteObject::LS_locked_write;
_cow_object->_locking_thread = current_thread;
} else {
// No other thread has the pointer locked, and we're the only
@ -127,9 +145,10 @@ get_write_pointer() {
// We can't assert that there are no outstanding ordinary
// references to it, though, since the creator of the object might
// have saved himself a reference.
_cow_object->_lock_status = CopyOnWriteObject::LS_locked_write;
_cow_object->_locking_thread = current_thread;
_cow_object->_lock_mutex.release();
}
_cow_object->_lock_status = CopyOnWriteObject::LS_locked_write;
_cow_object->_locking_thread = current_thread;
return _cow_object;
}