This reimplements the spinlock on top of std::atomic_flag, which is guaranteed to be lockless. It also inserts the PAUSE (REP NOP) instruction which is strongly recommended to be placed in busy-wait loops by Intel.
This also includes a recursive spinlock implementation.
The spinlock implementation is disabled by default, but can be enabled by adding the --override MUTEX_SPINLOCK=1 flag to makepanda.
This is done using a Python extension function, which also happens to make the call more efficient as this avoids an extra copy. The C++ version still returns std::string as there is still a lot of C++ code that relies on that.
Fixes#297
This might have only been an issue in some drivers (not sure, spec is a bit vague here).
Apparently we need to call glMaterial *after* the color material setting has been disabled for it to stick.
Fixes#369
This setting causes asserts when modifying certain material flags after they are assigned to a node, in case a shader has been generated that uses the materials, which cannot efficiently detect whether the material has changed. However, we already sort of have a (inefficient, but effective) solution for this in TextureStage (see #178) that we could just apply here as well: changing the material attributes after such a shader has been generated could call GraphicsStateGuardianBase::mark_rehash_generated_shaders().
In the future, we should replace the material model with one that does not require shader regeneration for such seemingly trivial property changes.
Fixes#370
Currently, the WeakPointerTo comparison operators compare the raw pointers, but this is not useful as it may cause a false equality if one weak pointer in the comparison is expired and points to memory that has since been reused.
Instead, we can define a comparison based on the control block pointer, which exists since the new weak pointer implementation in 0bb81a43c9. This is implemented in the owner_before method, matching C++11 std::weak_ptr semantics.
I would now recommend deprecating most comparison operators of WeakPointerTo or redefining them to make more sense, ie. comparing equal if they (once) referred to the same object and not if they simply point to the same memory address. This has not yet been done, though code that uses the comparison operators has been fixed in this commit.
Overloads of std::owner_less have been provided for creating a map or set with Weak(Const)PointerTo keys.
rdb
Sam Edwards
Mitchell Stokes
deflected