We can reach the code that removes the item from the hash table
before or after the weak unref has triggered. Just leave the
weakref in place and let it do its thing, if it hasn't gone
off yet. That matches what we do in free.
Fixes: #6377
Count dead pixels in textures (ie the number of pixels in GPU
textures that are no longer backed by an alive GdkTexture object),
and when the there's too many, do a gc before rendering the next
frame.
Count the uses of cached texture - from the device (via the linked
list) and from the texture (via render data / weak ref), and only
free the item once the use count reaches zero.
Instead of forever running a timeout to do gc, ensure the timeout
is scheduled whenever we render a frame (this is done by calling
gsk_gpu_device_maybe_gc () before gsk_gpu_frame_render (), and
gsk_gpu_device_queue_gc () after).
Read the GSK_CACHE_TIMEOUT environment variable to override the
default 15s timeout for cache gc. This is mainly meant for debugging.
Since we don't really need two knobs, reuse the gc timeout value
for the max age of items too.
Count how many dead pixels we have, and free the atlas if more than
half of its pixels are dead.
As part of this, change when glyphs are freed. We now keep them
in the hash table until their atlas is freed and we only do dead
pixel accounting when should_collect is called. This keeps the
glyphs available for use from the cache as long as are in the atlas.
If a stale glyph is sused, we 'revive' it by removing its pixels
from the dead.
This matches more closely what the gl renderer does.
If we gc a cached texture for which the GdkTexture is still alive,
the cached texture object will remain accessible via the render
data, so need to make sure not to leave a dangling pointer behind
here.
This is straightforward. If a texture hasn't been used for 4 seconds,
we consider it stale, and drop it the next time gc comes around.
The choice of 4 seconds is arbitrary.
Fixes: #6346
Previously, we only checked if the cache had exhausted the maximum
number of slices.
But we also need to check that the height of the slices doesn't exceed
the height of the texture.
Instead of using an enum, use a usual custom class struct like we use
for GskGpuOp.
As a side effect of that refactoring, the display gained a hash table
for textures where we can't use the render data because the texture is
used in multiple renderers.
The goal here is that a texture is always cached and we can ensure that
there is a 1:1 relation between textures and their GskGpuImage. This is
important in particular for external textures - like dmabufs - where we
absolutely don't want 2 images with 2 device memories, and where we use
toggle references to keep them alive.
This adds GSK_GPU_IMAGE_CAN_MIPMAP and GSK_GPU_IMAGE_MIPMAP flags and
support to ensure_image() and image creation functions for creating a
mipmapped image.
Mipmaps are created using the new mipmap op that uses
glGenerateMipmap() on GL and equivalent blit ops on Vulkan.
This is then used to ensure the image is mipmapped when rendering it
with a texture-scale node.
For now, it just renders using cairo, uploads the result to the GPU,
blits it onto the framebuffer and then is happy.
But it can do that using Vulkan and using GL (no idea which version).
The most important thing still missing is shaders.
It also has a bunch of copy/paste from the Vulkan renderer that isn't
used yet.
But I didn't want to rip it out and then try to copy it back later
