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On Wednesday, 26 February 2025 at 16:21:20 UTC, Michael Lee wrote:
>On Monday, 24 February 2025 at 10:51:09 UTC, Lewis wrote:
>I don't strictly use betterC, but I do avoid GC usage in all frame-to-frame gameplay code. I allow myself GC usage for debug code, editor tools, and major state changes where a hitch is okay (eg. startup, loading a save game).
The bulk of my frame-to-frame allocations are handled by an object pooling system that reuses elements and grows if needed. I also have a per-thread linear allocator that resets after each frame, useful for scratch allocations that don't need to outlive a frame. I made some minor changes to druntime so that in any given scope I can switch into "scrapheap mode" as I call it, at which point all GC allocations get redirected to my linear allocator until the scope exits. This lets me use phobos, druntime, and other libraries even if they would allocate to the GC in a problematic way. As long as the allocation doesn't need to outlive the frame, I can use the library unmodified by just switching into scrapheap mode.
This sounds ideal to me. How much of phobos did you mod? What kind of lift was it? Does it take much maintenance? Does using phobos feel seamless or is there some reluctance/superstition about using it in complex scenarios e.g. threads.
I'm an indie game dev, and am moving to D from C++. Congrats on the release! The game looks fantastic. A crowning achievement for a solo dev.
I didn't make all that many changes, and I don't think any of them were strictly mandatory to ship a game. They broadly fall into a few catagories:
- Support for "scrapheap mode" (temporarily rerouting GC allocations to a linear frame allocator)
- Support for DLL-based hotswapping. This required piping a few calls in the DLL's druntime/phobos over to the EXE's druntime (eg. using a GC proxy, thread management). Also, a couple small changes to stuff like the GC initialization in the DLL so the proxy gets set up correctly. This was completely worth it, DLL hotswapping is a gamechanger, just a massive improvement to iteration time. My changes are a tad hacky, but the release build of the game skips the DLL and links everything statically, so any bugs from this hackiness are debug-only.
- Reducing build times. I use string formatting absolutely everywhere, so in debug I use the old C-style string formatting implementation, since it's non-templated and compiles very slightly faster (which for 10 calls is pointless, but 1000 calls it adds up).
- Added a couple minor features to the phobos thread pool implementation
- Added some missing bits of the windows API
- Modified std.experimental.logger to better suit my exact needs (and use no templates, again I log everywhere and want to keep build times fast)
I use phobos all over the place without any issues.
