perf(allocations): reduced overall allocations by 95%, increaseed jacobian applicatin by 2x

This commit uses global pre allocated work space to dramatically reduce memory usage and allocation time
2026-09-10 06:50:56 -04:00
parent b3c04d507a
commit 75cc638739
66 changed files with 207183 additions and 99552 deletions
--- a/libmeanfield/interface/fem/reference_tables.cppm
+++ b/libmeanfield/interface/fem/reference_tables.cppm
@@ -0,0 +1,78 @@
+module;
+
+#include <memory>
+#include <vector>
+
+#include <mfem.hpp>
+
+export module mean_field:fem.reference_tables;
+
+export namespace mean_field::fem {
+    // These tables contain only reference-element data: no mesh coordinates,
+    // orientation, element DOF transforms, or state-dependent mapping factors.
+    class ScalarReferenceTable {
+    public:
+        [[nodiscard]] const mfem::DenseMatrix &GetValues() const;
+        // Available for GRAD elements; otherwise throws std::out_of_range.
+        [[nodiscard]] const mfem::DenseMatrix &GetGradients(int point) const;
+        [[nodiscard]] int GetPointCount() const;
+        [[nodiscard]] int GetDofCount() const;
+        [[nodiscard]] int GetDimension() const;
+
+    private:
+        friend class ReferenceTableCache;
+        ScalarReferenceTable(
+            const mfem::FiniteElement &element,
+            const mfem::IntegrationRule &rule
+        );
+
+        mfem::DenseMatrix m_values;
+        std::vector<mfem::DenseMatrix> m_gradients;
+        int m_dimension;
+    };
+
+    class VectorReferenceTable {
+    public:
+        [[nodiscard]] const mfem::DenseMatrix &GetValues(int point) const;
+        [[nodiscard]] int GetPointCount() const;
+        [[nodiscard]] int GetDofCount() const;
+        [[nodiscard]] int GetDimension() const;
+
+    private:
+        friend class ReferenceTableCache;
+        VectorReferenceTable(
+            const mfem::FiniteElement &element,
+            const mfem::IntegrationRule &rule
+        );
+
+        std::vector<mfem::DenseMatrix> m_values;
+        int m_dof_count;
+        int m_dimension;
+    };
+
+    // Owned by one discretization, never process-global. Finite elements must
+    // remain alive and immutable while this cache is used; rebuild the cache if
+    // their collections are replaced. Rules are keyed by their actual points
+    // and weights, so temporary, copied, or modified rules are safe to use.
+    // Returned immutable handles also keep tables alive after cache destruction.
+    class ReferenceTableCache {
+    public:
+        ReferenceTableCache();
+        ~ReferenceTableCache();
+        ReferenceTableCache(const ReferenceTableCache &)            = delete;
+        ReferenceTableCache &operator=(const ReferenceTableCache &) = delete;
+
+        [[nodiscard]] std::shared_ptr<const ScalarReferenceTable> GetScalarTable(
+            const mfem::FiniteElement &element,
+            const mfem::IntegrationRule &rule
+        ) const;
+        [[nodiscard]] std::shared_ptr<const VectorReferenceTable> GetVectorTable(
+            const mfem::FiniteElement &element,
+            const mfem::IntegrationRule &rule
+        ) const;
+
+    private:
+        struct Storage;
+        std::unique_ptr<Storage> m_storage;
+    };
+} // namespace mean_field::fem