Algorithm Harmonization #6 KF, main branch (2026.06.22.)

.vscode/settings.json

@@ -2,7 +2,8 @@
    "files.associations": {
       "*.hip": "cpp",
       "*.sycl": "cpp",
-      "*.ipp": "cpp"
+      "*.ipp": "cpp",
+      "*.cu.in": "cpp"
    },
    "sonarlint.connectedMode.project": {
       "connectionId": "acts-project",

core/include/traccc/edm/track_container.hpp

@@ -74,6 +74,8 @@ struct track_container {
     };
 
     struct view {
+        /// Default constructor
+        view() = default;
         /// Constructor from a buffer
         TRACCC_HOST_DEVICE
         view(const buffer& b)
@@ -95,6 +97,8 @@ struct track_container {
     };
 
     struct const_view {
+        /// Default constructor
+        const_view() = default;
         /// Constructor from a buffer
         TRACCC_HOST_DEVICE
         const_view(const buffer& b)

core/include/traccc/geometry/move_only_any.hpp

@@ -1,6 +1,6 @@
 /** TRACCC library, part of the ACTS project (R&D line)
  *
- * (c) 2024 CERN for the benefit of the ACTS project
+ * (c) 2024-2026 CERN for the benefit of the ACTS project
  *
  * Mozilla Public License Version 2.0
  */
@@ -113,6 +113,9 @@ class move_only_any {
                 "Value for `traccc::move_only_any` requested, but no value "
                 "exists.");
         }
+        if (!is<obj_t>()) {
+            throw std::bad_any_cast();
+        }
 
         return *static_cast<obj_t *>(m_obj);
     }

device/alpaka/CMakeLists.txt

@@ -60,7 +60,6 @@ traccc_add_alpaka_library( traccc_alpaka alpaka TYPE SHARED
   # Track fitting algorithm(s).
   "include/traccc/alpaka/fitting/kalman_fitting_algorithm.hpp"
   "src/fitting/kalman_fitting_algorithm.cpp"
-  "src/fitting/kalman_fitting.hpp"
 )
 
 # Set up Thrust specifically for the traccc::alpaka library.

device/alpaka/include/traccc/alpaka/fitting/kalman_fitting_algorithm.hpp

@@ -1,44 +1,26 @@
 /** TRACCC library, part of the ACTS project (R&D line)
  *
- * (c) 2025 CERN for the benefit of the ACTS project
+ * (c) 2025-2026 CERN for the benefit of the ACTS project
  *
  * Mozilla Public License Version 2.0
  */
 
 #pragma once
 
 // Library include(s).
+#include "traccc/alpaka/utils/algorithm_base.hpp"
 #include "traccc/alpaka/utils/queue.hpp"
 
 // Project include(s).
-#include "traccc/bfield/magnetic_field.hpp"
-#include "traccc/edm/track_container.hpp"
-#include "traccc/fitting/fitting_config.hpp"
-#include "traccc/geometry/detector.hpp"
-#include "traccc/geometry/detector_buffer.hpp"
-#include "traccc/utils/algorithm.hpp"
-#include "traccc/utils/memory_resource.hpp"
-#include "traccc/utils/messaging.hpp"
-
-// VecMem include(s).
-#include <vecmem/utils/copy.hpp>
-
-// System include(s).
-#include <functional>
+#include "traccc/fitting/device/kalman_fitting_algorithm.hpp"
 
 namespace traccc::alpaka {
 
-/// Kalman filter based track fitting algorithm
-class kalman_fitting_algorithm
-    : public algorithm<edm::track_container<default_algebra>::buffer(
-          const detector_buffer&, const magnetic_field&,
-          const edm::track_container<default_algebra>::const_view&)>,
-      public messaging {
+/// Kalman filter based track fitting algorithm using Alpaka
+class kalman_fitting_algorithm : public device::kalman_fitting_algorithm,
+                                 public alpaka::algorithm_base {
 
     public:
-    /// Configuration type
-    using config_type = fitting_config;
-
     /// Constructor with the algorithm's configuration
     ///
     /// @param config The configuration object
@@ -49,31 +31,63 @@ class kalman_fitting_algorithm
     ///
     kalman_fitting_algorithm(
         const config_type& config, const traccc::memory_resource& mr,
-        const vecmem::copy& copy, queue& q,
+        const vecmem::copy& copy, alpaka::queue& q,
         std::unique_ptr<const Logger> logger = getDummyLogger().clone());
 
-    /// Execute the algorithm
+    private:
+    /// @name Function(s) implemented from @c device::kalman_fitting_algorithm
+    /// @{
+
+    /// Prepare a buffer with the index order with which to fit the tracks
     ///
-    /// @param det             The detector object
-    /// @param bfield          The magnetic field object
-    /// @param track_candidates All track candidates to fit
+    /// @param[in] tracks The tracks to be fitted
+    /// @param[out] track_sort_keys Buffer storing temporary sorting keys
+    /// @param[out] track_indices The buffer to write the fitting order into
     ///
-    /// @return A container of the fitted track states
+    void prepare_track_fit_order(
+        const edm::track_collection<default_algebra>::const_view& tracks,
+        vecmem::data::vector_view<device::sort_key>& track_sort_keys,
+        vecmem::data::vector_view<unsigned int>& track_indices) const override;
+
+    /// Kernel to prepare the fitting payloads
+    ///
+    /// @param payload The payload for the kernel(s)
     ///
-    output_type operator()(
-        const detector_buffer& det, const magnetic_field& bfield,
-        const edm::track_container<default_algebra>::const_view&
-            track_candidates) const override;
+    void fit_prelude_kernel(
+        const device::fit_prelude_payload& payload) const override;
 
-    private:
-    /// Algorithm configuration
-    config_type m_config;
-    /// Memory resource used by the algorithm
-    traccc::memory_resource m_mr;
-    /// Copy object used by the algorithm
-    std::reference_wrapper<const vecmem::copy> m_copy;
-    /// Queue wrapper
-    std::reference_wrapper<queue> m_queue;
+    /// Function preparing the fitting payload
+    ///
+    /// @param det             The detector buffer to prepare the payload for
+    /// @param field           The magnetic field to prepare the payload for
+    /// @param n_surfaces      The number of surfaces for each track to be
+    ///                        fitted
+    /// @param payload         The (non-templated) payload for the kernel(s)
+    ///
+    /// @return The prepared payload for the fitting kernel(s)
+    ///
+    fit_payload prepare_fit_payload(
+        const detector_buffer& det, const magnetic_field& field,
+        const std::vector<unsigned int>& n_surfaces,
+        const device::fit_payload& payload) const override;
+
+    /// Function launching the "forward fitting" kernel(s)
+    ///
+    /// @param config The fitting configuration
+    /// @param payload The payload for the fitting kernel(s)
+    ///
+    void fit_forward_kernel(const fitting_config& config,
+                            const fit_payload& payload) const override;
+
+    /// Function launching the "backward fitting" kernel(s)
+    ///
+    /// @param config The fitting configuration
+    /// @param payload The payload for the fitting kernel(s)
+    ///
+    void fit_backward_kernel(const fitting_config& config,
+                             const fit_payload& payload) const override;
+
+    /// @}
 
 };  // class kalman_fitting_algorithm