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The projectm_eval_memory_host_lock/unlock_mutex() callbacks were no-ops, providing no protection when multiple preset expressions access shared memory blocks from different threads. Add a real std::mutex so the eval library's built-in synchronization actually works. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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There's no synchronization needed as no code calls the expressions from separate threads, ever. All calls are serialized, plus each preset has its own megabufs/gmegabuf, so they're not even interfering with each other (I contrast to Milkdrop where all presets share the same megabufs). Adding a mutex will only reduce performance due to locking overhead when accessing megabufs, but with no real issue fixed. |
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Summary
The
projectm_eval_memory_host_lock/unlock_mutex()callbacks inEvalLibMutex.cppwere empty stubs ({}), providing no synchronization when multiple preset expressions access shared memory blocks (megabuf/gmegabuf) concurrently — e.g., during a soft-cut transition where both the active and transitioning presets evaluate simultaneously.The projectm-eval library already calls these callbacks around shared memory access in
MemoryBuffer.cand documents them as host-provided. This commit implements them with astd::mutex.Changes
src/libprojectM/MilkdropPreset/EvalLibMutex.cpp(+13, -2)Test plan