feat: Access to whiteboard from Python (acts-project#5158)

Author: paulgessinger

Core/include/Acts/Utilities/Any.hpp

@@ -364,12 +364,6 @@ class AnyBase : public AnyBaseAll {
     }
   }
 
-  template <typename T>
-  static std::uint64_t typeHash() {
-    const static std::uint64_t value = detail::fnv1a_64(typeid(T).name());
-    return value;
-  }
-
   struct Handler {
     void (*destroy)(void* ptr) = nullptr;
     void (*moveConstruct)(void* from, void* to) = nullptr;

Core/include/Acts/Utilities/HashedString.hpp

@@ -12,8 +12,7 @@
 #include <cstddef>
 #include <cstdint>
 #include <string_view>
-#include <type_traits>
-#include <utility>
+#include <typeinfo>
 
 namespace Acts {
 /// @brief Type alias for hashed string representation
@@ -76,4 +75,15 @@ constexpr HashedString operator""_hash(char const* s, std::size_t count) {
 }
 
 }  // namespace HashedStringLiteral
+
+/// Hash for a type. Since it's not possible to hash a type at compile-time,
+/// this function returns a runtime hash but caches it in a static variable.
+/// @tparam T Type to hash
+/// @return Hashed string representation
+template <typename T>
+std::uint64_t typeHash() {
+  const static std::uint64_t value = detail::fnv1a_64(typeid(T).name());
+  return value;
+}
+
 }  // namespace Acts

Examples/Framework/include/ActsExamples/Framework/DataHandle.hpp

@@ -8,6 +8,7 @@
 
 #pragma once
 
+#include "Acts/Utilities/HashedString.hpp"
 #include "ActsExamples/Framework/AlgorithmContext.hpp"
 #include "ActsExamples/Framework/SequenceElement.hpp"
 #include "ActsExamples/Framework/WhiteBoard.hpp"
@@ -51,6 +52,7 @@ class DataHandleBase {
   const std::string& key() const { return m_key.value(); }
 
   virtual const std::type_info& typeInfo() const = 0;
+  virtual std::uint64_t typeHash() const = 0;
 
   bool isInitialized() const { return m_key.has_value(); }
 
@@ -88,6 +90,10 @@ class DataHandleBase {
     return wb.pop<T>(m_key.value());
   }
 
+  WhiteBoard::IHolder* getHolder(const WhiteBoard& wb) const {
+    return wb.getHolder(m_key.value());
+  }
+
   SequenceElement* m_parent{nullptr};
   std::string m_name;
   std::optional<std::string> m_key{};
@@ -180,6 +186,7 @@ class WriteDataHandle final : public WriteDataHandleBase {
   }
 
   const std::type_info& typeInfo() const override { return typeid(T); };
+  std::uint64_t typeHash() const override { return Acts::typeHash<T>(); };
 };
 
 /// A read handle for accessing data from the WhiteBoard.
@@ -213,6 +220,7 @@ class ReadDataHandle final : public ReadDataHandleBase {
   }
 
   const std::type_info& typeInfo() const override { return typeid(T); };
+  std::uint64_t typeHash() const override { return Acts::typeHash<T>(); };
 };
 
 /// A consume handle for taking ownership of data from the WhiteBoard.
@@ -247,6 +255,7 @@ class ConsumeDataHandle final : public ConsumeDataHandleBase {
   }
 
   const std::type_info& typeInfo() const override { return typeid(T); };
+  std::uint64_t typeHash() const override { return Acts::typeHash<T>(); };
 };
 
 }  // namespace ActsExamples

Examples/Framework/include/ActsExamples/Framework/WhiteBoard.hpp

@@ -9,6 +9,7 @@
 #pragma once
 
 #include "Acts/Utilities/Concepts.hpp"
+#include "Acts/Utilities/HashedString.hpp"
 #include "Acts/Utilities/Logger.hpp"
 
 #include <algorithm>
@@ -36,13 +37,17 @@ class WhiteBoard {
   struct IHolder {
     virtual ~IHolder() = default;
     virtual const std::type_info& type() const = 0;
+    virtual const void* data() const = 0;
+    virtual std::uint64_t typeHash() const = 0;
   };
   template <Acts::Concepts::nothrow_move_constructible T>
   struct HolderT : public IHolder {
     T value;
 
     explicit HolderT(T&& v) : value(std::move(v)) {}
     const std::type_info& type() const override { return typeid(T); }
+    std::uint64_t typeHash() const override { return Acts::typeHash<T>(); }
+    const void* data() const override { return std::addressof(value); }
   };
 
   struct StringHash {
@@ -116,6 +121,8 @@ class WhiteBoard {
   template <typename T>
   HolderT<T>* getHolder(const std::string& name) const;
 
+  IHolder* getHolder(const std::string& name) const;
+
   template <typename T>
   T pop(const std::string& name);
 

Examples/Framework/src/Framework/DataHandle.cpp

@@ -12,6 +12,8 @@
 #include "ActsExamples/Framework/Sequencer.hpp"
 
 #include <regex>
+#include <typeindex>
+#include <typeinfo>
 
 #include <boost/algorithm/string.hpp>
 #include <boost/core/demangle.hpp>
@@ -73,8 +75,7 @@ void DataHandleBase::maybeInitialize(std::optional<std::string_view> key) {
 }
 
 bool WriteDataHandleBase::isCompatible(const DataHandleBase& other) const {
-  return dynamic_cast<const ReadDataHandleBase*>(&other) != nullptr &&
-         typeInfo() == other.typeInfo();
+  return typeHash() == other.typeHash();
 }
 
 void WriteDataHandleBase::emulate(StateMapType& state,
@@ -114,8 +115,7 @@ void ReadDataHandleBase::initialize(std::string_view key) {
 }
 
 bool ReadDataHandleBase::isCompatible(const DataHandleBase& other) const {
-  return dynamic_cast<const WriteDataHandleBase*>(&other) != nullptr &&
-         typeInfo() == other.typeInfo();
+  return typeHash() == other.typeHash();
 }
 
 void ReadDataHandleBase::emulate(StateMapType& state,

Examples/Framework/src/Framework/WhiteBoard.cpp

@@ -136,4 +136,12 @@ std::vector<std::string> WhiteBoard::getKeys() const {
   return keys;
 }
 
+WhiteBoard::IHolder *WhiteBoard::getHolder(const std::string &name) const {
+  auto it = m_store.find(name);
+  if (it == m_store.end()) {
+    throw std::out_of_range("Object '" + name + "' does not exists");
+  }
+  return it->second.get();
+}
+
 }  // namespace ActsExamples

Examples/Io/Podio/include/ActsExamples/Io/Podio/CollectionBaseWriteHandle.hpp

@@ -75,6 +75,8 @@ class CollectionBaseWriteHandle : public WriteDataHandleBase {
   /// Get the type info for this handle
   /// @return The type info for std::unique_ptr<podio::CollectionBase>
   const std::type_info& typeInfo() const override;
+
+  std::uint64_t typeHash() const override;
 };
 
 }  // namespace ActsExamples

Examples/Io/Podio/src/CollectionBaseWriteHandle.cpp

@@ -36,4 +36,8 @@ const std::type_info& CollectionBaseWriteHandle::typeInfo() const {
   return typeid(std::unique_ptr<podio::CollectionBase>);
 }
 
+std::uint64_t CollectionBaseWriteHandle::typeHash() const {
+  return Acts::typeHash<std::unique_ptr<podio::CollectionBase>>();
+}
+
 }  // namespace ActsExamples

Python/Examples/src/Framework.cpp

@@ -8,6 +8,7 @@
 
 #include "Acts/Utilities/Logger.hpp"
 #include "ActsExamples/Framework/AlgorithmContext.hpp"
+#include "ActsExamples/Framework/DataHandle.hpp"
 #include "ActsExamples/Framework/IAlgorithm.hpp"
 #include "ActsExamples/Framework/IReader.hpp"
 #include "ActsExamples/Framework/IWriter.hpp"
@@ -16,9 +17,12 @@
 #include "ActsExamples/Framework/SequenceElement.hpp"
 #include "ActsExamples/Framework/Sequencer.hpp"
 #include "ActsExamples/Framework/WhiteBoard.hpp"
-#include "ActsPython/Utilities/Helpers.hpp"
 #include "ActsPython/Utilities/Macros.hpp"
+#include "ActsPython/Utilities/WhiteBoardTypeRegistry.hpp"
 
+#include <stdexcept>
+
+#include <boost/core/demangle.hpp>
 #include <pybind11/pybind11.h>
 #include <pybind11/stl.h>
 
@@ -82,11 +86,72 @@ class PyIAlgorithm : public IAlgorithm {
     }
   }
 
+  ProcessCode initialize() override {
+    py::gil_scoped_acquire acquire{};
+    PYBIND11_OVERRIDE(ProcessCode, IAlgorithm, initialize, );
+  }
+
+  ProcessCode finalize() override {
+    py::gil_scoped_acquire acquire{};
+    PYBIND11_OVERRIDE(ProcessCode, IAlgorithm, finalize, );
+  }
+
   std::string_view typeName() const override { return "Algorithm"; }
 
   const Acts::Logger& pyLogger() const { return logger(); }
 };
 
+class PyReadDataHandle : public ReadDataHandleBase {
+ public:
+  PyReadDataHandle(SequenceElement* parent, py::object pytype,
+                   const std::string& name)
+      : ReadDataHandleBase(parent, name) {
+    m_entry = WhiteBoardRegistry::find(pytype);
+    if (m_entry == nullptr) {
+      throw py::type_error("Type '" +
+                           pytype.attr("__qualname__").cast<std::string>() +
+                           "' is not registered for WhiteBoard access");
+    }
+    if (m_entry->typeinfo == nullptr) {
+      throw py::type_error("Type '" +
+                           pytype.attr("__qualname__").cast<std::string>() +
+                           "' is not registered for WhiteBoard access");
+    }
+
+    registerAsReadHandle();
+  }
+
+  const std::type_info& typeInfo() const override { return *m_entry->typeinfo; }
+
+  std::uint64_t typeHash() const override { return m_entry->typeHash; }
+
+  py::object call(const py::object& wbPy) const {
+    if (!isInitialized()) {
+      throw std::runtime_error("ReadDataHandle '" + name() +
+                               "' not initialized");
+    }
+    const auto& wb = wbPy.cast<const ActsExamples::WhiteBoard&>();
+
+    if (!wb.exists(key())) {
+      throw py::key_error("Key '" + key() + "' does not exist");
+    }
+
+    const auto& holder = getHolder(wb);
+
+    if (m_entry->typeHash != holder->typeHash()) {
+      const auto& expected = boost::core::demangle(m_entry->typeinfo->name());
+      const auto& actual = boost::core::demangle(holder->type().name());
+      throw py::type_error("Type mismatch for key '" + key() + "'. Expected " +
+                           expected + " but got " + actual);
+    }
+
+    return m_entry->fn(holder->data(), wbPy);
+  }
+
+ private:
+  const WhiteBoardRegistry::RegistryEntry* m_entry{nullptr};
+};
+
 void trigger_divbyzero() {
   volatile float j = 0.0;
   volatile float r = 123 / j;  // MARK: divbyzero
@@ -132,6 +197,23 @@ void addFramework(py::module& mex) {
       .def("exists", &WhiteBoard::exists)
       .def_property_readonly("keys", &WhiteBoard::getKeys);
 
+  py::class_<PyReadDataHandle>(mex, "ReadDataHandle")
+      .def(py::init([](const py::object& parent_py, py::object pytype,
+                       const std::string& name) {
+             auto* parent = parent_py.cast<SequenceElement*>();
+             return std::make_unique<PyReadDataHandle>(parent,
+                                                       std::move(pytype), name);
+           }),
+           py::arg("parent"), py::arg("type"), py::arg("name"),
+           py::keep_alive<1, 2>())
+      .def(
+          "initialize",
+          [](PyReadDataHandle& self, std::string_view key) {
+            self.initialize(key);
+          },
+          py::arg("key"))
+      .def("__call__", &PyReadDataHandle::call, py::arg("whiteboard"));
+
   py::class_<AlgorithmContext>(mex, "AlgorithmContext")
       .def(py::init<std::size_t, std::size_t, WhiteBoard&, std::size_t>(),
            "alg"_a, "event"_a, "store"_a, "thread"_a)

Python/Examples/src/Generators.cpp

@@ -14,6 +14,7 @@
 #include "ActsExamples/Utilities/ParametricParticleGenerator.hpp"
 #include "ActsExamples/Utilities/VertexGenerators.hpp"
 #include "ActsPython/Utilities/Macros.hpp"
+#include "ActsPython/Utilities/WhiteBoardTypeRegistry.hpp"
 
 #include <cstddef>
 #include <memory>
@@ -136,7 +137,15 @@ void addGenerators(py::module& mex) {
       .def_readwrite("fixed", &FixedPrimaryVertexPositionGenerator::fixed);
 
   py::class_<SimParticle>(mex, "SimParticle");
-  py::class_<SimParticleContainer>(mex, "SimParticleContainer");
+  auto simParticleContainer =
+      py::class_<SimParticleContainer>(mex, "SimParticleContainer")
+          .def("__len__",
+               [](const SimParticleContainer& self) { return self.size(); })
+          .def("__iter__", [](const SimParticleContainer& self) {
+            return py::make_iterator(self.begin(), self.end());
+          });
+
+  WhiteBoardRegistry::registerClass(simParticleContainer);
 
   {
     using Config = ParametricParticleGenerator::Config;