On Mon, 2 Jun 2025 20:22:28 GMT, Laurent Bourgès <lbour...@openjdk.org> wrote:
>> PR to replace the use of sun.misc.Unsafe memory access methods in the Marlin >> rasterizer with FFM. >> >> I broke this up into the following commits. The bulk of the work is in the >> first two: >> >> 1. Encapsulate all off-heap access in OffHeapArray -- All of the memory >> allocation and management was already done in the OffHeapArray class, but >> the users of OffHeapArray, primarily Renderer and RendererNoAA, called >> Unsafe methods directly. I encapsulated all of the calls to Unsafe in >> OffHeapArray. The main impact on calling code is that the base address is no >> longer accessible or needed. Instead, the `(put|get)(Byte|Int)` methods take >> only an offset. This commit was straight refactoring with no behavioral >> changes. >> 2. Initial FFM implementation -- I changed the memory management and access >> methods to use FFM. Each OffHeap array uses a shared Arena to manage the >> single memory segment allocated at construction time. The resize method >> creates a new Arena and memory segment, copying the data from the old and >> then closing it >> 3. Set `used` to 0 in `dispose()` -- While testing and instrumenting the >> code, I discovered that the Renderer dispose methods resize the edges array >> back to the default size without clearing the "used" field. The used field >> will be cleared before the next time it is accessed, but clearing it in >> dispose allows optimizing resize to not copy any data. >> 4. Remove '--sun-misc-unsafe-memory-access=allow' from test and app >> execution, since it is no longer needed. This also enables `-Werror` for the >> `javafx.graphics` module. >> 5. ~~Temporary debug prints that will be removed before making this "rfr"~~ >> >> Additional commits address review comments. > > Few mlnor comments. It looks good to me ! If it helps at this point, we did an initial prototype in the sandbox: https://github.com/openjdk/jfx-sandbox/tree/Marlin_FFM with several commits and reverts, so might need to go through them. What @bourgesl and I weren't sure about was which `Arena` to use. I thought `Confined` was more suitable than `Shared` because there's no multithreaded access. ------------- PR Comment: https://git.openjdk.org/jfx/pull/1814#issuecomment-2937611540
